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Article

Intercropping of Soybean and Common Millet—A Rational Way of Forage Biomass Quality Enhancement

by
Milena Šenk
1,†,
Milena Simić
1,
Dušanka M. Milojković-Opsenica
2,
Milan Brankov
1,
Jelena Trifković
2,
Vesna Perić
1 and
Vesna Dragičević
1,*,†
1
Maize Research Institute, Zemun Polje, Slobodana Bajića 1, 11185 Belgrade, Serbia
2
Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade, Serbia
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Agriculture 2025, 15(19), 2029; https://doi.org/10.3390/agriculture15192029
Submission received: 27 August 2025 / Revised: 24 September 2025 / Accepted: 26 September 2025 / Published: 27 September 2025

Abstract

Sustainable agriculture supports environmental protection, climate change mitigation, and forage security to meet the growing demands of livestock production. Given the critical role of macro- and microelements in animal health, diversified and balanced feed production is essential and can be achieved through the sustainable integration of legumes and cereals. This research evaluated the impact of soybean–common millet intercropping and biofertilizer application on the elemental composition and yield performance of forage biomass. Three intercropping patterns were tested: S1M1—alternating rows, S2M2—alternating two-row strips, and S2M4—alternating two-row soybean with four-row millet strips, alongside monoculture controls. The biofertilizer Coveron (BF) was also assessed. The S2M2 combination provided the highest land equivalent ratios for both fresh and dry biomass (1.10 and 1.12, respectively), despite a reduction in millet yield. Considering the elements, the S2M2 combination notably enhanced the accumulation of Ca and B (by 13.2% and 13.0%, respectively, compared to S1) in the soybean vegetative part and Cr and Mn in the reproductive part (by 53.5% and 17.1%, respectively). In contrast, sole soybean showed the highest P levels in both vegetative (3.45 g kg−1) and reproductive parts (4.56 g kg−1). Regarding Al, its accumulation was reduced in intercropped millet. The S1M1 combination increased Mg and S concentrations in both parts of millet biomass (up to 17.3% and 18.4% in the vegetative part, compared to M1). While BF generally had a limited impact on forage biomass yield and elemental accumulation, it increased Mg, P, and S concentrations in soybean pods, as well as concentrations of B, Mn, and Mo in the panicle, simultaneously decreasing P, Cr, and Zn concentrations in the vegetative part of millet. Accordingly, soybean–common millet intercropping in the S2M2 configuration offers a sustainable solution for efficient land utilization and element-enriched forage production.

1. Introduction

Agriculture is the second-largest source of greenhouse gas emissions in the European Union, with soil management, fertilizers, crops, and residues being major contributors. As a result, sustainable agriculture is a goal of European policies aimed at promoting environmental protection and climate change mitigation, taking into account the food system and biodiversity [1]. Therefore, conventional practices that impair the environment and were used intensively in recent decades are increasingly being replaced by sustainable practices that promote food and forage security in response to the growing trend of human and livestock population growth. This shift presents agriculture with the challenge of meeting high ecological demands while avoiding yield losses and malnutrition at the same time [2,3]. Although diversification is claimed to be a fundamental solution for many problems of today’s agricultural systems, sufficient quantitative evidence is still lacking [4]. In light of the need for high productivity to enhance farm output, including saving time and space, sustainable agriculture is promoted [5].
Intercropping, as one of the sustainable practices, involves growing two or more crops simultaneously on the same field during a single growing season. It is widely used to increase crop diversity and enhance the efficient use of agro-ecosystem services, while simultaneously reducing chemical inputs and minimizing the negative environmental footprint of crop production. In addition to yield increase, it can also increase yield stability under various unfavorable conditions [6]. The inclusion of legumes in intercropping is particularly valuable due to their ability to fix atmospheric nitrogen, thereby increasing soil fertility. Their low dry matter yield can be compensated by combining them with cereals, which are high in fiber. Moreover, legumes are protein-rich plants, contributing to improved livestock productivity. Consequently, combining these two crops is desirable in order to create a balance between the quality and quantity of forage, from both nutritional and economic standpoints. Still, complementarity between legumes and cereals must be optimized to achieve positive outcomes [7]. Depending on the purpose, different types of intercropping can be applied, such as row, mixed, strip, or relay intercropping. Additionally, based on row arrangement and crop proportion, intercropping systems can be classified as additive or replacement systems [5].
Successful forage production relies on both high biomass yield and forage quality [2,8]. Forage quality is defined by its chemical composition and its ability to provide the energy, protein, minerals, and vitamins necessary to support animal productivity [9]. Despite an optimal supply of macronutrients, even slight deficiencies in trace minerals, vital for numerous physiological processes, can disrupt animal health and performance [10]. Mineral composition depends on plant genotype, harvest time, environmental conditions, and soil fertility [7]. Notably, legumes and cereals differ in their elemental profiles, providing the opportunity for a more balanced and diverse feed supply when combined [11]. Nevertheless, the effects of crop type and temporal dynamics on nutrient uptake and yield in cereal–legume intercropping systems remain inadequately understood [12]. Since mineral concentrations tend to decline as plants mature, due to the changing proportions in plant parts, the optimal harvest time is essential to aligning forage yield with the nutritional requirements of animals [13].
One of the main advantages of soybean [Glycine max (L.) Merr.] forage is high-protein content, with digestible protein present in both the foliage and pods, which provides flexibility of harvest over a long period [14]. However, the maximum accumulation rate of most elements tends to occur during the R4 (full pod) growth stage (with the exception of K and Fe) [15]. Therefore, to ensure high dry matter yield and forage quality, soybean harvesting should be completed before the R7 (beginning maturity) stage. Soybean can be successfully used for grazing, hay, or silage [14,16]. Common millet [Panicum miliaceum (L.)], also known as broomcorn or proso millet, is one of the oldest cereals with the potential for widespread use due to its strong tolerance to extreme environmental conditions, high water-use efficiency, and a short growing period. Compared to other staple cereals, common millet has high nutritional quality, characterized by high-quality proteins, vitamins, minerals, and micronutrients, including iron, zinc, copper, and manganese [17,18]. As a C4 crop, it is highly tolerant to elevated CO2 levels [19]. The forage of common millet can be used as natural fodder, hay, or silage [20].
Overreliance on chemical fertilizers in recent decades has not only compromised soil health but also reduced mineral availability. In contrast, biofertilizers, natural formulations of beneficial microorganisms, offer a promising alternative. They can improve soil structure and fertility, enhance plant stress tolerance, and support crop productivity. These microorganisms and their metabolites are able to increase the accessibility of minerals in the soil. Biofertilizer inoculants comprise several microbial groups [21], such as plant growth-promoting rhizobacteria (PGPR), which colonize plant roots and facilitate nutrient uptake through various mechanisms [22]; and arbuscular mycorrhizal fungi (AMF), which improve nutrient availability while helping plants to cope with environmental stress [23]. Trichoderma atroviride in biofertilizer formulations can promote plant growth, phosphate solubilization and macro- and micronutrient utilization [24]. However, the efficacy of biofertilizers is more pronounced in arid environments and in soils that are high in phosphorus, low in organic matter, and have a neutral pH [25].
Currently, there is a lack of information on the intercropping of soybean and common millet, particularly when biofertilizers are applied. Therefore, the aim of this research was to examine the influence of soybean–common millet intercropping, implemented in three different patterns (alternating rows and two combinations of alternating strips), combined with biofertilizer application, on the productivity and elemental composition of forage biomass. This study aims to reveal, for the first time, the potential of combining these two crops to optimize forage quality and yield, through the analysis of elemental partitioning between the vegetative and reproductive parts of the biomass.

2. Materials and Methods

2.1. Experimental Design

The research was conducted at the experimental field of the Maize Research Institute “Zemun Polje”, vicinity of Belgrade, Serbia (44°52′ N; 20°20′ E), during 2018 and 2020. The year 2019 was excluded from the study due to obstructed germination under unfavorable meteorological conditions present after sowing.
The soil was slightly calcareous chernozem, Molcal silt loam (coarse-loamy, mixed, superactive, mesic Vitrandic Calcixerolls) [26], with 17% clay, 30% silt, and 53% sand. The properties of the 0–30 cm soil layer, before sowing, were pH 7.3, 4.32% organic matter [27], and 1.38% of total CaCO3 [28]. Each year, prior to sowing, the soil was sampled, and concentrations of available N and P were determined according to the procedures given by Scharpf and Wehrmann [29] and Watanabe and Olsen [30], respectively, while extractable macro- and microelements (K, Ca, Mg, S, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Se) were determined on inductively coupled plasma optical emission spectroscopy (ICP-OES, Thermo Scientific iCAP 6500 Duo, Thermo Fisher Scientific, Waltham, MA, USA) using a Mehlich 3 solution for extraction [31]. The elemental composition for both years is given in Table 1.
Soybean variety Selena, developed at the Maize Research Institute “Zemun Polje”, Serbia, and common millet, variety Biserka, released by the Institute of Field and Vegetable Crops, Novi Sad, Serbia, were used in the experiment. Field trials encompassed intercrop combinations consisting of alternating rows and alternating strips, as well as mono-crops of soybean and millet. In the trial, the effect of biofertilizer (BF) was also examined. Accordingly, 50 g of biofertilizer Coveron (Hello Nature International Srl, Piemonte, Italy), containing Glomus sp., Trichoderma atroviride, and plant growth-promoting rhizobacteria, was dissolved in 800 mL of water and solution was applied per 100 kg of seeds, inoculating seeds prior to sowing. Both crops were sown at 4 cm depth. Detailed information about experimental design is given in Table 2. Experiment was set up as randomized complete block design, with four replications. Elementary plots were set up as 3 × 5 m, in total 15 m2, except S2M4, where the setting was 4 × 5 m, due to the sowing pattern.

2.2. Measurement of Biomass Yield Parameters

The sowing was performed on 3 May 2018, and 22 April 2020. The experiment was conducted in dry-land conditions while weed control was provided by hoeing. There was no fertilization performed, and it was estimated that there was no necessity for pest control measures application. Harvesting of green biomass was performed at the beginning of seed development for soybean (R5) and at the ripening stage for millet, i.e., on 2 August 2018, and on 22 July 2020. The green biomass was manually harvested (half area per replication from each combination). After measuring the fresh (green) biomass yield (FBY, t ha−1), biomass was air-dried and dry biomass yield (DBY, t ha−1) was determined. Simultaneously, fresh and dry biomass of the vegetative part (leaf and stem) and the reproductive part (pod/panicle) were measured from the five plants from each replication. Drying was performed using a ventilation oven at 60 °C (EU Instruments, EUGE425, Novo Mesto, Slovenia, EU).
Land equivalent ratio (LER) was calculated according to the formula [32]
LER = YA/SA + YB/SB
where YA and YB represent individual crop yields in intercropping, while SA and SB indicate sole crop yields.

2.3. Chemical Analysis

For chemical analyses of biomass, four replications of dried samples were mixed to achieve homogeneity and representative samples of vegetative and reproductive parts for every combination. Dried samples were milled in a micro hammer mill (Cullaty) and used for analysis.
Assessment of element concentration was performed after wet digestion on a Behrotest K16 digestion unit (Behr Labor-Tecnik GmbH, Düsseldorf, Germany) by heating for 4 h (starting at 50 °C, and on every 0.5 h the temperature was gradually raised by 50 °C until 250 °C was reached, and digestion was run until samples became clear). Dilution for further analyses was 1:36. Macroelement concentration (Ca, Mg, P, and S) was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), iCAP 6500 Duo, Thermo Fisher Scientific, Waltham, MA, USA, while micro- and trace elements (B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Mo, Cd, and Pb) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), iCap Q, Thermo Scientific, Altrincham, UK. Standard solutions for macroelements were made from two standard stock solutions: Major Elements Stock, EPA Method Standard, VHG Labs, for Ca and Mg; and 6020A ICS Stock, EPA Method Standard, VHG Labs, for P and S, while those for microelements were made from Multi–Element Plasma Standard Solution 4 (Alfa Aesar, Haverhill, MA, USA), Selenium Standard for AAS (Fluka, Buchs, Switzerland), and Molybdenum Plasma Standard Solution (Alfa Aesar). Measurement of element concentration was accomplished in triplicate.

2.4. Statistical Analysis

The experimental data were processed using Multivariate analysis of variance (MANOVA) at the significance level of p < 0.05 (F test); three-way analysis including year, intercropping, and biofertilizer, as well as their interactions. LSD test (values) was used to determine significant differences between means. Results of mutual interaction of sowing pattern and biofertilizer on quantity and quality parameters of crop biomass were presented as a mean ± standard deviation (SD). Concentrations of Se, Cd, and Pb were below the limit of detection and were not used in statistical processing. Principal component analysis (PCA) was used to determine interdependence between applied treatments and quantity and quality parameters of total biomass. PCA was performed using SPSS for Windows, Version 15.0 (SPSS Inc., Chicago, IL, USA).

2.5. Meteorological Conditions

Both experimental seasons were characterized by an optimal precipitation amount during the vegetative period of soybean and millet (Table 3), although an unequal distribution was observed. Considerably lower values of precipitation were present in April and July 2020 (4.7 mm and 34.8 mm, respectively), as well as May 2018 (39.0 mm), when compared to the ten-year average. On the other hand, a greater precipitation amount was present in June in both years (150.1 mm in 2018 and 125.9 mm in 2020). Regarding temperature, April and May 2018 were characterized by higher average values, including the growing period 2018 (22.3 °C), compared with 2020 (20.2 °C) and the ten-year average (20.8 °C). A lower temperature occurred in May 2020 compared to May 2018 and the ten-year average.

3. Results

3.1. Impact of Intercropping, Biofertilizer, and Year on Biomass Quantity and Quality Parameters of Vegetative and Reproductive Parts of Soybean and Common Millet

3.1.1. Yields and LER Values

FBY and DBY of the vegetative and reproductive parts of millet were significantly affected by intercropping, while the sowing pattern did not have a significant impact on soybean yields. BF did not affect quantity parameters of both crops (Table 4). The highest values of millet FBY and DBY were obtained in the sole crop, while the smallest values were obtained in the S1M1 combination. Comparing yields of fresh and dry biomass of millet among intercrop combinations, S2M2 gave the highest values for fresh biomass, while S2M4 gave the highest values for yields of dry biomass. As far as the influence of Y was concerned, in 2018, yields of both vegetative and reproductive parts of soybean were higher, as well as DBY of the reproductive part of millet, while in 2020 FBY of the vegetative part of millet was significantly higher. Interactions, such as SP × Y and SP × BF × Y, were significant for variability in FBY and DBY of both crops; SP × BF was significant for FBY of the reproductive part and DBY of both parts of millet, while BF × Y was significant for biomass yield, with the exclusion of FBY of the reproductive part and DBY of the vegetative part of millet.
Variations in the LER value (Table 4) for fresh and dry biomass were significantly affected only by intercropping. The highest, and the only ones > 1, were obtained in the S2M2 combination, with a value of 1.10 for fresh and 1.12 for dry biomass. Regarding interactions, it was found that SP × BF, SP × Y, and SP × BF × Y have significant influence on variation in both LER values.

3.1.2. Concentrations of Macro- and Microelements in Biomass

Concentration of macroelements, Ca, P, and S was significantly under the control of sowing pattern when vegetative and reproductive parts of soybean biomass were considered (Table 5 and Table 6). The sole crop had the highest concentration of P and S in the vegetative part, as well as Ca and P in the reproductive part. The greatest accumulation of S was noticed in the reproductive part of soybean in the S1M1 combination, as well as Ca accumulation in the vegetative part in the S2M2 combination. Regarding microelements, Cu was the only element with the greatest accumulation in the sole crop in the vegetative part, while intercropping significantly influenced the higher accumulation of other elements. Thus, S1M1 provided the highest Cr value in the vegetative part and Co and Ni in the soybean pods. The highest levels of B in the vegetative part, and Cr and Mn in the reproductive part of soybean were in the S2M2 combination. The highest concentration of Zn was in the vegetative part in the S2M4 combination. BF did not show significant influence on the accumulation of the examined elements when the vegetative part was considered, but in the reproductive part, it influenced the greater accumulation of Mg, P, and S for 0.16, 0.31, and 0.14 g kg−1, respectively. Y had a significant impact on the variation in element concentration in both parts of biomass. Only the Ca, S, Cu, and Zn level in the vegetative part and the P level in the reproductive part were not affected by this source of variation. The SP × BF interaction was statistically significant for Ca, P, S, Cr, Cu, and Zn in the vegetative and for Ca, P, S, Cr, Mn, and Co in the reproductive part, i.e., the soybean pods. SP × Y and SP × BF × Y were also significant for variation in concentration of all examined elements in both parts of soybean biomass, while the BF × Y interaction was insignificant only for Ca, S, and Cu accumulation in the vegetative part.
Differences in concentrations of macro- and microelements in the biomass of common millet were also observable when SP, BF, and Y were considered (Table 7 and Table 8). The S1M1 combination provided the highest values of Ca, Mg, and S in the vegetative part of millet and of Mg, P, and S in the reproductive part, i.e., panicle. Regarding microelements, the highest accumulation of Al was observed in the sole crop (M1) in both parts, as well as the accumulation of B and Zn in the panicle. The greatest accumulation of Fe in the vegetative part was in the S1M1 combination, while in S2M2 the highest values of Cr, Mn, Fe, and Ni were achieved in the reproductive one. In the S2M4 combination, the highest concentration of Mn and Zn in the vegetative part was measured. In the same combination, S2M4, as well as in M1, the greatest concentration of Mo in the panicle was noticed (0.19 mg kg−1 in both sowing patterns). Concerning BF, the only significant increase in B, Mn, and Mo was in the reproductive part (for 1.43, 2.56, and 0.03 mg kg−1, respectively), with simultaneously reduced Al concentration (for 14.02 mg kg−1). On the contrary, significantly lower P, Cr, and Zn accumulation for 0.34 g kg−1, 1.77 mg kg−1,and 4.24 mg kg−1, respectively, in the vegetative part was noticed. Y also significantly affected variations in all examined elements in the vegetative part and most elements in the panicle. The interaction SP × BF influenced significant variations in concentrations of Mg, P, S, Al, Mn, Fe, and Zn in the vegetative part of millet biomass.

3.2. Integrated Influence of Sowing Pattern and Biofertilizer on Quantity and Quality Parameters of Reproductive and Vegetative Parts of Soybean and Common Millet Biomass

Concerning the vegetative (Table 9) and reproductive (Table 10) parts of soybean biomass, insignificantly greater FBY and DBY in S1M1 and S2M2 combinations (with or without BF) were noted, compared to S1 and S2M4. The highest FBY value of the vegetative part was obtained in S2M2 + BFƟ while for DBY it was in S1M1 + BFƟ. Considering the reproductive part, S2M2 + BFƟ was the most effective combination for both FBY and DBY, achieving 8.90 t ha−1 and 2.20 t ha−1, respectively.
The efficacy of element accumulation in the vegetative parts of biomass also depended on planting pattern (Table 9). Regarding macroelements, the S2M2 combination contributed the most to an increase in Ca concentration, with a value of 17.85 g kg−1 in the variant with BF and 17.54 g kg−1 in the variant without it. On the other hand, the concentrations of P and S were the most pronounced in S1 + BFƟ. When microelements were considered, the S2M4 + BF combination caused the greatest accumulation of Zn, while S1M1 + BFƟ was convenient for Cr and Cu, providing the greatest values. Comparing the same sowing patterns in regard to the use of BF, Cr had smaller values in variants with BF.
However, concentrations of macro- and microelements in the reproductive part of soybean showed different trends (Table 10). Ca and P had the highest values in S1 + BF, while S accumulation was mostly raised by the S1M1 + BF combination. Regarding microelements, Co had the highest and same value in S1M1 + BF and S1M1 + BFƟ. S2M2 + BF was shown to be the combination with the greatest Cr concentration, while in S2M2 + BFƟ, the greatest accumulation of Mn occurred.
Regarding yield, the sole crop of common millet was the most efficient in regard to all tested intercrop combinations (Table 11 and Table 12). The highest values of FBY and DBY were achieved in combination with BF. When intercrop combinations are compared, considerably lower values of millet FBY and DBY were obtained in S1M1 combinations for both the vegetative and reproductive parts.
Nevertheless, the concentration of macro- and microelements in the vegetative part of millet (Table 11) was greater in BFƟ variants. Mg and P had the highest value in S2M2 + BFƟ, while S had the same value in S1M1 + BFƟ and S2M2 + BFƟ. Concerning microelements, the integrated influence of sowing pattern and BF affected only Mn accumulation (with a value of 44.46 mg kg−1 in S2M4 + BF). Results also revealed that the greatest accumulation of Al was in the M1 + BFƟ combination, while the greatest accumulation of Fewas in the S1M1 + BFƟ combination. Regarding alternating strips, S2M4 + BFƟ delivered the highest Zn value. However, a different trend was noticed when the accumulation of elements in the reproductive part was considered (Table 12). Analyzing macroelements, the greatest concentrations of P and S were in the S1M1 + BFƟ combination. Regarding microelements, B, Zn, and Mo showed the highest values in the M1 + BF combination, while Mn was the highest in the reproductive part of millet from S2M2 + BF. Other microelements had the highest accumulation in combinations without BF. The highest concentration of Al occurred in M1 + BFƟ, while the greatest Cr, Fe, and Ni concentrations were in S2M2 + BFƟ.

3.3. PCA for Quantity and Quality Parameters of Soybean and Common Millet Total Biomass

In order to estimate the possible relationship between quantity and quality parameters and different sowing patterns, PCA was performed. For soybean, it resulted in the four-component model, which explained 89.25% of overall variability. The PC1 component explained 40.38% of total variability, PC2 24.90%, PC3 14.98%, while PC4 covered 8.99% of total variability (Figure 1). Mg, P, and Ni correlated positively, while significant negative correlation was found for FBY and DBY with PC1. The significant and positive correlation with PC2 had Mn, Cu, and Mo, while Cr, Fe, and Zn correlated negatively. Regarding PC3, Ca and B had a significant positive correlation, while S and Al correlated negatively. Co correlated positively with PC4. The samples were grouped according to the sowing pattern, and to a lesser extent to BF. The formed groups consisted of the variants with and without BF: S1 and S1 + BF; S1M1 and S1M1 + BF; and S2M4 and S2M4 + BF. It is notable that the sole crop (with and without BF), S2M2 + BF, and S2M4 had a high influence on variability in the concentration of B, S, Al, Ni, P, and Mg, while S1M1 (both variants), S2M2 and S2M4 + BF were connected with Zn, Cr, Ca, Cu, Co, and Mo. FBY and DBY are mostly linked with S1M1 and S1M1 + BF. Additionally, the results revealed an association between S2M4 and Fe.
PCA revealed the five-component model for common millet, which explained 94.61% of overall variability. PC1 and PC2 were described by 42.81% and 20.20% of total variability, respectively, whereas PC3, PC4, and PC5 were explained by 14.56%, 9.21%, and 7.83% of the total variability, respectively (Figure 2). Mg, P, S, Cr, and Mn correlated positively with the first axis, whereas FBY, DBY, Al, and Zn correlated negatively. Furthermore, a significant and positive correlation was found between Fe and Ni with the second axis, and in the same manner, B and Co correlated with PC3. Ca and Cu showed positive correlation with PC4, while Mo correlated significantly and positively with PC5. Regarding the grouping of samples, it was influenced by sowing patterns and BF. The combinations without BF were grouped at the positive side of PC2, while combinations with BF were positioned at the negative side. Additionally, M1 and S2M4 (independently of the BF use) were grouped on the negative side of PC1 and highly associated with FBY and DBY, as well as concentration of Al, Zn, and B. However, S1M1 and S2M2 (with and without BF) were positioned on the positive side of PC1 and connected with Co, Fe, P, Cr, Cu, Mn, Mo, S, Mg, and Ca.

4. Discussion

Intercropping presents a traditional farming practice which supports crop diversification and can fulfill the demand for high-quality feed production [5,7], thus reducing the environmental footprint of modern agriculture with respect to high productivity [33]. As deficiencies of mineral elements may compromise forage quality [7], due to their necessity for normal physiological functions in the animal’s body [34], this research aimed to reveal productivity and element concentrations in different parts of soybean and millet biomass. Owing to the lack of such information, this research also reveals appropriate practice for raising beneficial and decreasing potentially toxic elements in a sustainable way.

4.1. The Effects of Different Intercropping Patterns and Biofertilizer on Biomass Yield and Land Equivalent Ratio

The results of this study revealed that sowing pattern had a greater influence on the examined quality and quantity parameters of soybean and millet biomass compared to BF. Intercropping and BF did not significantly affect the FBY and DBY of the soybean reproductive and vegetative parts, but S1M1 and S2M2 slightly raised these values. Manjunath and Salakinkop [35] also revealed an insignificant, but negative, influence of intercropping on total dry matter accumulation in soybean, depending on millet type. Therefore, the millet used in this research, i.e., common millet, seems to be suitable for intercropping with soybean, resulting in an increase in soybean biomass yield, which could be attributed to high complementarity between the used crop types, previously reported by Namdari et al. [36]. Although intercropping of millet with leguminous crops should be advantageous for biomass productivity and quality, due to improved chemical, biological, and physical environment in the rhizosphere [37], this research indicates the importance of other factors, too. The combinations with millet on both sides of soybean (S1M1) and millet at a closer inter-row distance (S2M2) resulted in higher yield than S2M4 and the sole soybean (independently of the BF use). Thus, it can be said that the proximity of millet could support the potential of soybean biomass yield. Additionally, this research also revealed that the sowing pattern had a significant impact on millet FBY and DBY, showing the highest performance of the sole crop, while among intercrop combinations, S2M2 was the most appropriate for fresh biomass accumulation and S2M4 for dry biomass increase. PCA also revealed a high association of M1 and S2M4 with the FBY and DBY of millet, indicating the potential of alternating strips among intercrop combinations. Senghor et al. [38] revealed an insignificant impact of planting pattern on pearl millet biomass in millet–cowpea intercropping under rainfed conditions, using reduced legume density, which could support a negative correlation between millet biomass yield and the density. Nevertheless, based on the results obtained by Yang et al. [39] and Astiko et al. [40], who proved a significant association between inter-row distance and crop ratio on soybean biomass yield in soybean–maize intercropping, this research offers a basis for a significant yield increase with respect to the planting pattern.
Analyzing the integrated influence of SP and BF, it is proved that BF is not a decisive factor for soybean biomass accumulation in temperate soils [41]. Irrespective of the fact that there is a lack of data on biomass distribution between the vegetative and reproductive organs of soybean, particularly under the influence of intercropping and BF, PCA singled out S1M1 and S1M1 + BF combinations as the most effective for the FBY and DBY of soybean. In that sense, previous research revealed a positive effect of BF and intercropping integration toward the formation of reproductive organs in legumes [42], in addition to the independent positive influence of BF [43]. However, SP × BF expressed a significant impact on FBY of the reproductive part and DBY of both the reproductive and vegetative parts of millet biomass, in favor of the sole crop. The obtained results for millet grown as a sole crop are in accordance with the high millet responsiveness to arbuscular mycorrhizal fungi, which promotes millet tolerance to abiotic stresses [44].
The most commonly used index which quantifies intercropping performance is the LER index [33]. This research highlights the advantages of combining common millet and soybean in a 1:1 ratio set up as alternating strips (S2M2), emphasizing the impact of ratio and planting pattern on yield performance. In response to the fact that research on common millet–soybean forage productivity is scarce, these results provide valuable information on combining these two crop types for managing forage production. Jahanzad et al. [45] emphasized the advantage of an optimal soybean–pearl millet ratio on LER for higher exploitation when environmental resources are limited, which could be an explanation for LER>1 in the S2M2 combination, irrespective of the lower millet yield. Furthermore, the insignificant influence of BF and Y on the LER index accentuates the stability of the system when FBY and DBY are considered, while the significant impact of SP × BF interaction emphasized the potential of integrated practices for improved use of ecosystem services in regard to forage quantity. This is supported by our previous research regarding the productivity of grains, too [46]. Although a lot of research is concerned with the integrated influence of intercropping and BF on the LER index, only a few studies were focused on forage production. One of them proved the positive influence of BF on sorghum–soybean intercropping [47], while another one revealed the different effects of this integration depending on the species used in intercropping [48].

4.2. The Effects of Different Intercropping Patterns and Biofertilizer on the Absorption and Distribution of Medium and Trace Elements in the Crops

Results obtained on soybean biomass generally showed lower concentrations of some elements which are necessary to meet feed quality requirements, especially P, Zn, and Cu (depending on the animal and age), according to the Regulation on the quality of animal feed in the Republic of Serbia [49]. While there is a lack of information about the elemental composition of common millet forage, Mohajer et al. [50] revealed the insignificant impact of the growing stage and variety on ash content in millet forage, which could additionally support the fact that millet is suitable for intercropping, taking into account the connection between forage mineral quality and harvesting time.
Irrespective of the fact that seasonal influences were not the focus of this research, it should be emphasized that under stressful conditions, soybean growth is particularly affected by a decreased uptake of nutrients in general, especially P, Ca, Mg, Fe, Zn, Mn, and Cu [51]. Accordingly, all macroelements, as well as Zn, Cu, B, and Mo, were lower in soybean biomass in 2020, the year with drought occurring in July. Since the acquisition of Ca and Mg relies on water availability in the soil [52], their uptake was limited, too. In contrast, the higher accumulation of most microelements, such as Al, Cr, Mn, Fe, Co, and Ni, in soybean biomass during unfavorable meteorological conditions could be tied to their role in overcoming stress or with different rates of accumulation across growing stages. Seasonal variability in element concentrations in subtropical plants confirmed smaller macroelement and higher microelement concentrations in leaves under dry conditions [53]. Singhal et al. [54] in their review emphasized the antagonistic effect between Al and Ca, Mg, P, Mo, and B, explaining it with restricted root growth and microbial activity necessary for nutrient acquisition, while simultaneously highlighting the role of Al, as well as Co, in alleviating drought through different mechanisms. A possible mechanism can be connected to the research by Lei et al. [55] who revealed the role of abscisic acid in Fe homeostasis, while Hasan et al. [56] indicated synergism between microbial symbiosis and plant metabolic pathways to explain mechanisms involved in Fe homeostasis under combined Fe and drought stress in soybean. Regarding millet, it should be emphasized that Cu was the only microelement with a greater concentration in both the vegetative and reproductive parts in 2020, as a year with a dry period in July. The explanation can rely on the role of superoxide dismutase in overcoming stress [57], since Cu presents an essential cofactor for this enzyme [58]. Considering Al, its significantly lower accumulation in millet biomass in 2020 (as opposed to soybean) could signify a higher secretion of carboxylates by millet roots in this year. This could be supported by higher P accumulation, since it is known that carboxylate efflux is responsible for plant P acquisition, too [59]. Although the majority of research has focused on reduced mineral uptake under stress conditions, this research provides new insights in this field regarding macro-and microelement acquisition and partitioning by different intercrop combinations, and paves the way for future research endeavors. This could be of particular importance, taking into account climate change and the rational use of agroecosystem services toward increased forage and food quality.
It was shown that sowing pattern had a greater influence on the accumulation of microelements in the reproductive part than the vegetative part of millet, as well as concentrations of macroelements in both parts, simultaneously. The S1M1 combination seems to be the most appropriate for raising macroelement accumulation in millet biomass, in general. This combination (without BF) is also suitable for the greater accumulation of Fe and Mn in the vegetative part, opposite to the results obtained by Htet et al. [60] with maize and soybean, where a positive influence of intercropping on Ca concentration and a negligible effect on Mg and P accumulation in fodder was observed. In addition, realizing that Ca concentration in common millet is lower than in other cereals, as well as other millet types [61,62], the importance of soybean presence for Ca accumulation in common millet biomass is emphasized. Analyzing the reproductive and vegetative parts of soybean, concentrations of Ca, P, S, and Cr in both parts were significantly affected by planting pattern. The S2M2 combination proved to increase the accumulation of Ca, B, and Zn in the vegetative part of biomass, especially in combination with BF. These results are of the utmost importance considering that B deficiency in plants is considered the second most important micronutrient constraint, after Zn, especially in alkaline calcareous soils where B and Zn deficiencies are common [63]. An increased uptake of these two elements by soybean was probably connected with different requirements across the growing stages of both crops, supported by research on the maximum accumulation rate of elements in relation to the growing stage, which are different for soybean and millet [64,65,66]. The enhanced Zn uptake by soybean could be a result of the ability of millet as a gramineous plant to exudate phytosyderophores, especially in calcareous soil [67]. However, detailed study is needed to explain possible mechanisms, as Lytle and Jolley [68] in their research showed the low ability of phytosiderophore secretion by common millet. Although the antagonistic effect between P and Zn is widely known [69], the obtained results revealed that intercropping decreased this effect when the vegetative part was considered, as high concentrations of both P and Zn existed in soybean grown in alternating strips (S2M2 and S2M4). It is important to emphasize that Cao et al. [70] revealed dynamic changes in the soil bacterial community between mono-cropped and millet intercropped with soybean, which could affect the availability of mineral elements from soil. Zhang et al. [71] also noticed an increase in root exudates and the availability of N and P together with decreased soil pH under maize–soybean intercropping. Such a mechanism can explain the reduced accumulation of Al and the increased absorption of other microelements in intercropped millet. Namely, the solubility of most microelements is enhanced by reducing soil pH to a certain extent [72], while the enhanced production of organic acids by soybean could bind Al, making it unavailable for root uptake [73]. Considering the sowing pattern further, the S2M2 combination had a significant and positive effect on Fe and Mn accumulation in the vegetative part, as well as on Cr, Mn, Fe, and Ni accumulation in the reproductive part of millet biomass, simultaneously reducing Zn accumulation in both parts.
PCA additionally proved soybean’s importance for managing element accumulation in common millet biomass, emphasizing S2M2 and S1M1 combinations in general. Wiche et al. [74] also showed increased amounts of Fe and Mn in a barley shoot when intercropped with lupin, highlighting the inconsistency between increase in lupin ratio and element accumulation, while Selim [75] revealed a reduced accumulation of Fe, Mn, and Zn in maize intercropped with cowpea. The independence of P and Zn in total soybean biomass was also emphasized. Additionally, the S2M2 combination resulted in the greatest accumulation of Cr and Mn in the reproductive part of soybean, which are known to be essential for animals [76], thus complementing the nutritional value of soybean. Accordingly, S2M2 could be emphasized as promising for boosting forage quality, because soybean harvest was carried out in the R5 growing stage, after the highest uptake of elements occurred [15]. On the other side, the S1M1 combination without BF could be applied when a higher concentration of Cr and Cu in the vegetative part of soybean biomass is needed, in parallel with increased Co in the reproductive part. This indicated S1M1 to be adequate for increasing soybean forage quality also, since most of the boosted elements are essential for animals [77] and are significantly lower than maximum tolerable levels in the feed [78]. S2M2 + BF is highlighted by PCA, too, as this combination grouped most elements among tested combinations, emphasizing the advantages of this combination in managing element accumulation in soybean biomass. These findings pointed to the importance of spatial separations in order to achieve complementarity rather than competition in overall mineral uptake.
Although the integration of intercropping and BF influenced significant changes in the accumulation of minerals in both parts of soybean, the independent effect of BF was not observed when the vegetative part of soybean was considered. A similar trend was observed with millet, where BF was insignificant for the accumulation of the majority of the examined elements, despite the fact that AMF improves nutrient acquisition by plants in general. This could be explained by environmental conditions and the specific interrelations of plant and fungi which drive the symbiosis between mycorrhiza and the responsiveness of plants [79]. Regarding the reproductive part of soybean, BF significantly raised the concentrations of macroelements only, i.e., Mg, P, and S. This is especially important for P, as limited P absorption is one of the uttermost productivity limitations in calcareous soils [80]. Previous research conducted by Qin et al. [81] proved the positive effect of dual inoculation with AMF and rhizobium on P availability from the soil of intercropped maize and soybean. Also, Qin et al. [82] explained the beneficial effect of AMF on P uptake by soybean through activating the mycorrhizal P uptake pathway in the presence of a high Mg concentration [83]. However, regarding millet, a reduced accumulation of P, Cr, and Zn in the vegetative part, as well as Al in the reproductive part of biomass is in line with the results of Deepika et al. [84], who revealed the crucial role of soil characteristics in shaping interactions between common millet and AMF, emphasizing that nutrient acquisition is not entirely reliant on symbiosis with AMF. Nevertheless, this claim could not directly explain the significantly higher level of B, Mn, and Mo in the reproductive part of BF-treated millet, but a possible explanation might be a greater translocation rate for Mn and a lower translocation rate for Cr [85]. While Ingraffia et al. [86] revealed the insignificance of the interaction of intercropping and AMF for element accumulation in faba bean shoots (when intercropped with wheat), it is important to emphasize intercropping and BF integration on element distribution in soybean plants. In this context, it is noticed that S2M2 + BF had the greatest impact on increasing the effectiveness of Ca and B accumulation in the vegetative part and Mg, B, Cr, and Mo accumulation in the reproductive part, with significant impact only in the case of Ca and Cr.

5. Conclusions

This study revealed that intercropping and biofertilizing were not decisive factors for soybean biomass accumulation on calcareous soil, whereas the sowing pattern was the major determinant influencing millet biomass accumulation. The obtained results highlighted the S2M2 combination as the most promising for a more efficient exploitation of environmental resources, supported by the insignificant impact of BF and year on the LER value. The S2M2 combination was also identified as the most effective for enhanced element accumulation in different parts of soybean and millet biomass. B and Zn were greatly accumulated in the vegetative part of soybean, while Cr and Mn were more prominent in the reproductive one. Similarly, Mg, S, Mn, and Fe showed increased accumulation in the vegetative part of millet, followed by enhanced accumulation of most microelements in its reproductive part. BF had a minor impact on element accumulation (specifically increasing the concentration of Mg, P, and S in soybean pods, and B, Mn, and Mo in the millet panicle, while it decreased the concentration of P, Cr and Zn in the millet vegetative part). These results suggest that nutrient acquisition is not entirely reliant on symbiosis with mycorrhiza.
Therefore, soybean–common millet intercropping is considered a feasible and sustainable solution for forage production enriched with essential elements, while also promoting the efficient utilization of agroecosystem services. This study further supports continued research in this area, as it may contribute to the development of an optimal intercropping pattern that enhances both forage yield and quality.

Author Contributions

Conceptualization, V.D. and M.S.; methodology, M.Š., D.M.M.-O., J.T. and V.D.; validation, M.S., D.M.M.-O., M.B., J.T., V.P. and V.D.; formal analysis, M.Š., J.T. and V.D.; investigation, M.Š., M.S., M.B., J.T., V.P. and V.D.; resources, M.S. and D.M.M.-O.; data curation, M.B., J.T. and V.P.; writing—original draft preparation, M.Š. and V.D.; writing—review and editing, M.S., D.M.M.-O., M.B., J.T. and V.P.; visualization, M.B. and V.D.; supervision, M.S. and D.M.M.-O.; funding acquisition, M.S. All authors have read and agreed to the published version of the manuscript.

Funding

Research was funded by the Ministry of Education, Science and Technological Development, Republic of Serbia, grant number 451-03-136/2025-03/200040 and 451-03-136/2025-03/200168. The work contributes to key visions and strategies in Europe, the UN SDG 2: Zero hunger (End hunger, achieve food security and improved nutrition and promote sustainable agriculture) and UN SDG 12: Responsible consumption and production (Ensure sustainable consumption and production patterns).

Institutional Review Board Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

The authors are grateful to Igor Kodranov (Faculty of Chemistry, University of Belgrade) and Slađana Đurđić (Faculty of Chemistry, University of Belgrade) for their tremendous efforts in conducting the chemical analysis of the experimental material. The authors are grateful to Biljana Noro, Branka Radovanović, Milan Kostić, Miroslav Maksimović and other colleagues for their dedication in conducting the experiment.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Abbreviations

The following abbreviations are used in this manuscript:
FBYFresh (green) biomass yield
DBYDry biomass yield
S1M1Alternating rows of soybean and millet
S2M2Alternating strips of two rows of soybean and two rows of millet
S2M4Alternating strips of two rows of soybean and four rows of millet
S1Sole crop of soybean
M1Sole crop of millet
YYear
SPSowing pattern
BFBiofertilizer
BFƟWithout biofertilizer

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Figure 1. PCA model based on fresh (FBY) and dry (DBY) biomass yields and concentration of macro- and microelements in soybean biomass collected from different sowing patterns (S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer).
Figure 1. PCA model based on fresh (FBY) and dry (DBY) biomass yields and concentration of macro- and microelements in soybean biomass collected from different sowing patterns (S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer).
Agriculture 15 02029 g001
Figure 2. PCA model based on fresh (FBY) and dry (DBY) biomass yields and concentration of macro- and microelements in common millet biomass collected from different sowing patterns (M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer).
Figure 2. PCA model based on fresh (FBY) and dry (DBY) biomass yields and concentration of macro- and microelements in common millet biomass collected from different sowing patterns (M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer).
Agriculture 15 02029 g002
Table 1. Elemental composition of a 30 cm soil layer, prior to sowing, for 2018 and 2020.
Table 1. Elemental composition of a 30 cm soil layer, prior to sowing, for 2018 and 2020.
YearNPKCaMgSBAlCrMnFeCoNiCuZnSe
(kg ha−1)(mg kg−1)
201871.932.7258.14002299.572.414.1263.00.17185.463.21.52.24.74.30.03
2020117.941.2359.73856338.770.311.1257.10.33207.637.11.74.34.42.90.08
Table 2. Experimental design.
Table 2. Experimental design.
Experimental Crop CombinationSowing Density (Plants ha−1)Inter-Row Distance (cm)
CombinationSoybeanMilletSoybeanMilletSoybean–SoybeanSoybean–MilletMillet–Millet
S1/S1 + BFSole crop 440.000-50--
M1/M1 + BF Sole crop-2640.000--25
S1M1/S1M1 + BF1 row1 row220.000660.000-50-
S2M2/S2M2 + BF2 rows2 rows352.0001056.000502525
S2M4/S2M4 + BF2 rows4 rows195.5561173.333505025
S1—sole crop of soybean, M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer.
Table 3. Average temperatures and precipitation amount at Zemun Polje during the growing seasons of 2018 and 2020, together with the 2008–2017 average.
Table 3. Average temperatures and precipitation amount at Zemun Polje during the growing seasons of 2018 and 2020, together with the 2008–2017 average.
MonthsAverage Temperature (°C)Precipitation Amount (mm)
201820202008–2017201820202008–2017
April18.014.414.224.64.737.4
May21.716.918.539.079.976.7
June22.721.322.5150.1125.968.4
July23.623.324.661.934.851.8
August25.725.224.444.066.338.2
Aver./Sum22.320.220.863.962.354.5
Table 4. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in fresh biomass yield (FBY), and dry biomass yield (DBY) of the vegetative and reproductive part of soybean and common millet (expressed in t ha−1), as well as on variation in land equivalent ratio (LER) for fresh (FB) and dry biomass (DB).
Table 4. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in fresh biomass yield (FBY), and dry biomass yield (DBY) of the vegetative and reproductive part of soybean and common millet (expressed in t ha−1), as well as on variation in land equivalent ratio (LER) for fresh (FB) and dry biomass (DB).
Source of VariationSoybeanCommon MilletLERLER
FBYDBYFBYDBYFB DB
VegetativeReproductiveVegetativeReproductiveVegetativeReproductiveVegetativeReproductive
S1/M134.21 ns5.77 ns9.73 ns1.41 ns17.77 a8.56 a5.51 a5.23 a
S1M142.21 ns8.54 ns12.95 ns2.10 ns12.23 b5.90 b3.23 b3.10 b0.94 b0.93 b
S2M241.38 ns8.21 ns12.47 ns2.05 ns16.15 a,b7.77 a4.00 b4.12 a,b1.10 a1.12 a
S2M432.56 ns5.94 ns9.94 ns1.50 ns15.81 a,b7.47 a,b4.59 a,b4.27 a,b0.91 b0.90 b
BF38.33 ns7.13 ns11.26 ns1.79 ns15.68 ns7.37 ns4.41 ns4.14 ns0.95 ns0.95 ns
BFϴ36.85 ns7.11 ns11.28 ns1.74 ns15.30 ns7.48 ns4.35 ns4.22 ns1.02 ns1.02 ns
201848.20 a12.81 a15.35 a3.26 a12.63 b7.07 ns4.35 ns4.85 a0.99 ns0.96 ns
202026.98 b1.42 b7.20 b0.27 b18.35 a7.78 ns4.41 ns3.51 b0.98 ns1.00 ns
p value
SP0.0630.4340.1090.4920.0050.0010.0000.0010.0000.000
BF0.6470.9890.9870.9010.7510.8260.8640.8470.1220.164
Y0.0000.0000.0000.0000.0000.1650.8690.0000.7980.444
SP × BF0.3340.8910.5020.9190.0820.0340.0010.0310.0000.001
SP × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
BF × Y0.0000.0000.0000.0000.0000.5820.9830.0070.4540.365
SP × BF × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
S1—sole crop of soybean, M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer. Different letters indicate significant difference at p < 0.05, ns—not significant.
Table 5. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the vegetative part of soybean biomass.
Table 5. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the vegetative part of soybean biomass.
Sources of VariationCaMgPSBAlCrMnFeCoNiCuZnMo
(g kg−1)(mg kg−1)
S115.37 c5.85 ns3.45 a1.98 a30.92 a,b84.69 ns0.89 b75.88 ns107.31 ns0.08 ns1.37 ns6.00 a22.32 b0.51 ns
S1M116.71 a,b5.25 ns3.06 b1.92 a29.40 a,b73.80 ns1.29 a76.13 ns99.53 ns0.09 ns0.91 ns5.89 a,b27.19 a,b0.57 ns
S2M217.70 a5.77 ns3.29 a1.76 b35.56 a65.36 ns1.01 a,b80.34 ns113.57 ns0.09 ns1.06 ns5.79 b29.19 a0.46 ns
S2M416.53 b5.90 ns3.43 a1.97 a26.88 b77.11 ns1.28 a67.84 ns119.82 ns0.09 ns1.18 ns5.35 c30.78 a0.35 ns
BF16.77 ns5.72 ns3.27 ns1.90 ns30.08 ns74.30 ns1.02 ns72.49 ns112.15 ns0.09 ns1.14 ns5.72 ns26.91 ns0.48 ns
BFϴ16.39 ns5.67 ns3.35 ns1.92 ns31.30 ns76.18 ns1.21 ns77.60 ns107.96 ns0.09 ns1.12 ns5.79 ns27.83 ns0.47 ns
201816.94 ns6.43 a3.44 a1.88 ns35.54 a45.18 b0.90 b60.59 b75.28 b0.08 b0.71 b5.71 ns28.22 ns0.72 a
202016.22 ns4.96 b3.17 b1.94 ns25.84 b105.30 a1.33 a89.50 a144.84 a0.10 a1.55 a5.80 ns26.52 ns0.22 b
p value
SP0.0000.1910.0000.0000.0140.5610.0130.4040.5790.9350.1160.0000.0020.279
BF0.3340.8380.2140.6730.5480.8450.0840.3350.6950.9760.8530.4810.6010.920
Y0.0610.0000.0000.0830.0000.0000.0000.0000.0000.0000.0000.3150.3320.000
SP × BF0.0010.5570.0000.0000.0800.9510.0240.7900.9400.7210.5220.0000.0000.701
SP × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
BF × Y0.2170.0000.0000.3550.0000.0000.0000.0000.0000.0000.0000.3470.0490.000
SP × BF × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer. Different letters indicate significant difference at p < 0.05, ns—not significant.
Table 6. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the reproductive part of soybean biomass.
Table 6. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the reproductive part of soybean biomass.
Sources of VariationCaMgPSBAlCrMnFeCoNiCuZnMo
(g kg−1)(mg kg−1)
S18.53 a3.82 ns4.56 a1.94 a27.47 ns133.56 ns1.95 b36.79 b161.77 ns0.16 b4.42 b7.62 ns38.14 ns0.74 ns
S1M17.96 b3.74 ns4.38 a,b1.99 a30.73 ns111.20 ns3.17 a39.39 a,b145.80 ns0.21 a5.14 a8.46 ns37.67 ns0.70 ns
S2M27.35 c3.84 ns4.19 b1.93 a36.39 ns102.17 ns4.19 a44.39 a159.28 ns0.17 b4.97 a,b8.34 ns40.94 ns0.75 ns
S2M47.93 b3.91 ns4.22 b1.76 b33.06 ns123.46 ns3.34 a37.86 b177.80 ns0.15 b4.52 a,b7.69 ns37.37 ns0.66 ns
BF8.01 ns3.91 a4.49 a1.98 a31.67 ns113.58 ns3.11 ns38.74 ns159.30 ns0.17 ns4.79 ns7.99 ns39.36 ns0.73 ns
BFϴ7.88 ns3.75 b4.18 b1.84 b32.15 ns121.61 ns3.22 ns40.48 ns163.03 ns0.18 ns4.73 ns8.06 ns37.70 ns0.69 ns
20188.21 a4.02 a4.37 ns2.00 a41.24 a36.49 b2.48 b35.45 b97.21 b0.15 b4.31 b9.23 a45.22 a1.05 a
20207.68 b3.64 b4.30 ns1.81 b22.58 b198.70 a3.84 a43.76 a225.12 a0.20 a5.21 a6.82 b31.85 b0.37 b
p value
SP0.0000.4680.0010.0010.2140.8200.0010.0030.7270.0040.0200.3560.6210.930
BF0.4600.0290.0000.0010.8760.7450.7820.2920.8500.6180.7670.8800.4340.716
Y0.0030.0000.3660.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
SP × BF0.0000.1270.0000.0000.7310.9740.0060.0330.9760.0270.0600.7460.8970.998
SP × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
BF × Y0.0200.0000.0000.0000.0000.0000.0030.0000.0000.0000.0000.0000.0000.000
SP × BF × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer. Different letters indicate significant difference at p < 0.05, ns—not significant.
Table 7. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the vegetative part of common millet biomass.
Table 7. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the vegetative part of common millet biomass.
Sources of VariationCaMgPSBAlCrMnFeCoNiCuZnMo
(g kg−1)(mg kg−1)
M15.21 b3.87 b2.16 ns1.86 b2.01 ns113.44 a2.34 ns33.43 b79.81 b0.08 ns1.89 ns3.04 ns15.57 a0.24 ns
S1M15.96 a4.68 a2.18 ns2.28 a2.11 ns72.82 b4.35 ns43.03 a89.41 a0.08 ns1.54 ns3.17 ns13.31 a,b0.31 ns
S2M25.38 a,b4.58 a2.42 ns2.26 a3.31 ns99.07 a,b3.11 ns42.74 a89.14 a0.08 ns1.89 ns3.56 ns10.35 b0.27 ns
S2M45.74 a,b4.04 b2.27 ns1.84 b1.98 ns58.70 b3.78 ns44.05 a83.61 a,b0.09 ns2.43 ns3.36 ns17.25 a0.25 ns
BF5.55 ns4.28 ns2.09 b2.00 ns2.65 ns81.58 ns2.51 b41.26 ns85.19 ns0.08 ns1.78 ns3.40 ns12.00 b0.25 ns
BFϴ5.59 ns4.31 ns2.43 a2.12 ns2.05 ns90.44 ns4.28 a40.36 ns85.80 ns0.09 ns2.09 ns3.17 ns16.24 a0.28 ns
20185.13 b4.47 a2.09 b1.95 b3.38 a107.54 a5.14 a37.93 b81.32 b0.10 a2.72 a2.50 b12.50 b0.34 a
20206.01 a4.12 b2.43 a2.17 a1.33 b64.47 b1.65 b43.69 a89.67 a0.07 b1.15 b4.06 a15.74 a0.20 b
p value
SP0.0410.0000.1240.0000.0530.0000.2150.0000.0260.8000.1710.5740.0020.283
BF0.8650.7660.0000.1110.1440.4000.0110.6460.8250.1100.2690.4010.0020.339
Y0.0000.0030.0000.0040.0000.0000.0000.0020.0010.0000.0000.0000.0200.000
SP × BF0.3070.0000.0000.0000.0520.0040.1230.0010.0320.4790.3580.7020.0000.631
SP × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
BF × Y0.0000.0300.0000.0060.0000.0000.0000.0160.0000.0000.0000.0000.0000.000
SP × BF × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer. Different letters indicate significant difference at p < 0.05, ns—not significant.
Table 8. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the reproductive part of common millet biomass.
Table 8. Multivariate analysis of variance for the effects of sowing pattern (SP), biofertilizer (BF), year (Y), and their interactions on the variation in macro- and microelement concentration in the reproductive part of common millet biomass.
Sources of VariationCaMgPSBAlCrMnFeCoNiCuZnMo
(g kg−1)(mg kg−1)
M10.98 ns1.58 b3.04 b1.16 c3.49 a37.22 a2.25 b23.57 d55.24 b0.07 ns2.28 b5.66 ns26.92 a0.19 a
S1M11.08 ns1.76 a3.28 a1.42 a1.85 b15.51 b1.84 c25.40 c46.81 b0.07 ns2.34 b5.83 ns21.37 b0.15 b
S2M21.01 ns1.58 b3.02 b1.26 b1.59 b18.78 a,b2.92 a30.65 a66.06 a0.07 ns2.85 a5.63 ns24.26 a,b0.18 a
S2M41.21 ns1.58 b3.03 b1.31 b2.15 b31.65 a,b1.74 c27.75 b62.87 a,b0.08 ns2.26 b5.38 ns21.51 b0.19 a
BF1.13 ns1.65 ns3.12 ns1.30 ns2.98 a18.78 b2.28 ns28.12 a55.84 ns0.07 ns2.37 ns5.54 ns23.24 ns0.19 a
BFϴ1.01 ns1.60 ns3.07 ns1.27 ns1.55 b32.80 a2.09 ns25.56 b59.65 ns0.07 ns2.50 ns5.71 ns23.79 ns0.16 b
20180.85 b1.74 a3.02 b1.29 ns2.60 ns37.99 a2.26 ns26.67 ns63.07 a0.08 a2.25 b4.85 b25.43 a0.19 a
20201.29 a1.51 b3.17 a1.29 ns1.94 ns13.59 b2.11 ns27.01 ns52.42 b0.07 b2.61 a6.40 a21.60 b0.16 b
p value
SP0.1650.0120.0000.0000.0010.0380.0000.0000.0000.2450.0000.6310.0000.001
BF0.1380.3200.3950.4310.0000.0240.2700.0040.3030.2010.2610.4810.6390.001
Y0.0000.0000.0030.9650.0820.0000.3770.7070.0030.0130.0010.0000.0000.000
SP × BF0.3340.0810.0000.0000.0000.0130.0000.0000.0010.3230.0000.9520.0040.000
SP × Y0.0000.0000.0000.0000.0010.0000.0000.0000.0000.0000.0000.0000.0000.000
BF × Y0.0000.0000.0170.4370.0000.0000.5700.0210.0010.0470.0010.0000.0000.000
SP × BF × Y0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000
M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer. Different letters indicate significant difference at p < 0.05, ns—not significant.
Table 9. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the vegetative part of soybean, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Table 9. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the vegetative part of soybean, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Measured
Parameters
BFBFϴ
S1S1M1S2M2S2M4S1S1M1S2M2S2M4
FBY (t ha−1)36.14 ± 4.73 ns42.10 ± 6.11 ns40.41 ± 6.10 ns34.66 ± 3.93 ns32.28 ± 2.67 ns42.31 ± 5.17 ns42.35 ± 2.00 ns30.47 ± 4.18 ns
DBY (t ha−1)10.00 ± 1.33 ns12.51 ± 2.02 ns12.11 ± 1.73 ns10.43 ± 1.29 ns9.45 ± 0.67 ns13.39 ± 1.78 ns12.84 ± 1.07 ns9.45 ± 1.38 ns
Ca (g kg−1)15.20 ± 0.45 c17.04 ± 0.39 a,b17.85 ± 0.48 a16.97 ± 0.41 a,b15.53 ± 0.33 b,c16.39 ± 0.24 b17.54 ± 0.24 a16.09 ± 0.53 b,c
Mg (g kg−1)5.73 ± 0.03 ns5.24 ± 0.05 ns6.01 ± 0.03 ns5.89 ± 0.03 ns5.98 ± 0.02 ns5.26 ± 0.03 ns5.53 ± 0.06 ns5.91 ± 0.03 ns
P (g kg−1)3.31 ± 0.02 b3.09 ± 0.02 c3.29 ± 0.01 b3.37 ± 0.01 b3.60 ± 0.01 a3.04 ± 0.01 c3.29 ± 0.01 b3.48 ± 0.02 a,b
S (g kg−1)1.88 ± 0.01 c,d1.93 ± 0.00 c1.83 ± 0.01 d1.96 ± 0.02 b,c2.07 ± 0.01 a1.91 ± 0.01 c1.69 ± 0.00 e1.99 ± 0.01 b
B (mg kg−1)30.01 ± 2.36 ns29.03 ± 4.07 ns36.84 ± 4.15 ns24.45 ± 2.96 ns31.83 ± 2.55 ns29.76 ± 3.57 ns34.28 ± 2.68 ns29.32 ± 2.24 ns
Al (mg kg−1)86.47 ± 4.16 ns73.16 ± 1.03 ns61.94 ± 2.34 ns75.62 ± 3.26 ns82.92 ± 4.40 ns74.44 ± 3.90 ns68.78 ± 2.49 ns78.59 ± 1.43 ns
Cr (mg kg−1)0.87 ± 0.01 b1.16 ± 0.12 a,b0.82 ± 0.01 b1.25 ± 0.02 a0.91 ± 0.02 b1.41 ± 0.03 a1.21 ± 0.01 a,b1.31 ± 0.03 a
Mn (mg kg−1)72.79 ± 0.41 ns73.24 ± 0.64 ns79.77 ± 1.51 ns64.18 ± 0.46 ns78.97 ± 0.92 ns79.01 ± 1.47 ns80.91 ± 1.02 ns71.49 ± 0.73 ns
Fe (mg kg−1)114.43 ± 1.34 ns99.31 ± 0.60 ns114.12 ± 1.27 ns120.75 ± 0.59 ns100.19 ± 1.02 ns99.75 ± 1.77 ns113.02 ± 1.42 ns118.89 ± 1.62 ns
Co (mg kg−1)0.09 ± 0.00 ns0.09 ± 0.00 ns0.08 ± 0.00 ns0.08 ± 0.00 ns0.08 ± 0.00 ns0.08 ± 0.00 ns0.09 ± 0.01 ns0.09 ± 0.00 ns
Ni (mg kg−1)1.40 ± 0.02 ns0.99 ± 0.03 ns1.05 ± 0.03 ns1.13 ± 0.03 ns1.33 ± 0.03 ns0.83 ± 0.02 ns1.08 ± 0.02 ns1.22 ± 0.03 ns
Cu (mg kg−1)6.03 ± 0.04 a5.66 ± 0.06 b5.80 ± 0.05 b5.42 ± 0.04 c5.97 ± 0.06 a6.13 ± 0.05 a5.78 ± 0.07 b5.28 ± 0.06 c
Zn (mg kg−1)22.80 ± 0.30 b22.51 ± 0.38 b29.69 ± 0.19 a32.65 ± 0.43 a21.85 ± 0.27 b31.86 ± 0.42 a28.69 ± 0.45 a28.91 ± 0.54 a
Mo (mg kg−1)0.47 ± 0.01 ns0.62 ± 0.01 ns0.50 ± 0.01 ns0.32 ± 0.01 ns0.55 ± 0.01 ns0.51 ± 0.02 ns0.43 ± 0.01 ns0.38 ± 0.01 ns
S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer; different letters indicate significant difference at p < 0.05, ns—not significant.
Table 10. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the reproductive part of soybean, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Table 10. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the reproductive part of soybean, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Measured
Parameters
BFBFϴ
S1S1M1S2M2S2M4S1S1M1S2M2S2M4
FBY (t ha−1)5.87 ± 0.90 ns8.78 ± 1.17 ns7.52 ± 1.43 ns6.33 ± 0.78 ns5.66 ± 0.50 ns8.30 ± 0.89 ns8.90 ± 0.31 ns5.55 ± 0.69 ns
DBY (t ha−1)1.46 ± 0.22 ns2.18 ± 0.33 ns1.91 ± 0.35 ns1.63 ± 0.22 ns1.37 ± 0.09 ns2.03 ± 0.26 ns2.20 ± 0.18 ns1.37 ± 0.18 ns
Ca (g kg−1)8.56 ± 0.32 a8.01 ± 0.32 b7.35 ± 0.21 c8.14 ± 0.14 a,b8.51 ± 0.44 a7.92 ± 0.41 b7.35 ± 0.19 c7.73 ± 0.07 b,c
Mg (g kg−1)3.98 ± 0.04 ns3.80 ± 0.03 ns3.98 ± 0.03 ns3.89 ± 0.03 ns3.67 ± 0.02 ns3.68 ± 0.03 ns3.70 ± 0.02 ns3.94 ± 0.01 ns
P (g kg−1)4.76 ± 0.01 a4.58 ± 0.02 b4.36 ± 0.02 c4.26 ± 0.03 c,d4.35 ± 0.01 c4.18 ± 0.02 d4.01 ± 0.02 d4.18 ± 0.02 d
S (g kg−1)2.02 ± 0.01 a,b2.05 ± 0.02 a2.00 ± 0.01 a,b1.83 ± 0.01 b1.85 ± 0.01 b1.93 ± 0.02 b1.86 ± 0.01 b1.69 ± 0.01 c
B (mg kg−1)26.57 ± 5.31 ns30.80 ± 0.72 ns36.84 ± 4.73 ns32.47 ± 3.00 ns28.37 ± 2.21 ns30.66 ± 3.42 ns35.93 ± 2.23 ns33.65 ± 3.02 ns
Al (mg kg−1)132.18 ± 1.97 ns121.34 ± 1.61 ns97.37 ± 5.17 ns103.45 ± 3.69 ns134.93 ± 5.36 ns101.07 ± 2.70 ns106.97 ± 2.98 ns143.48 ± 4.99 ns
Cr (mg kg−1)1.98 ± 0.08 c3.06 ± 0.04 b,c4.52 ± 0.03 a2.86 ± 0.03 b,c1.92 ± 0.02 c3.28 ± 0.04 b3.86 ± 0.02 a,b3.82 ± 0.05 a,b
Mn (mg kg−1)35.79 ± 0.36 b38.94 ± 0.44 b42.68 ± 0.05 a,b37.53 ± 0.32 b37.78 ± 0.46 b39.84 ± 0.52 b46.11 ± 0.64 a38.19 ± 0.26 b
Fe (mg kg−1)167.85 ± 2.29 ns145.58 ± 1.10 ns157.36 ± 0.92 ns166.41 ± 0.34 ns155.69 ± 2.20 ns146.02 ± 0.86 ns161.21 ± 1.73 ns189.20 ± 1.72 ns
Co (mg kg−1)0.17 ± 0.01 b0.21 ± 0.00 a0.15 ± 0.00 b0.15 ± 0.01 b0.16 ± 0.00 b0.21 ± 0.00 a0.19 ± 0.00 a,b0.15 ± 0.00 b
Ni (mg kg−1)4.29 ± 0.06 ns5.39 ± 0.15 ns5.13 ± 0.09 ns4.35 ± 0.05 ns4.54 ± 0.07 ns4.88 ± 0.03 ns4.81 ± 0.06 ns4.69 ± 0.03 ns
Cu (mg kg−1)7.31 ± 0.29 ns8.27 ± 0.20 ns8.45 ± 0.12 ns7.95 ± 0.06 ns7.92 ± 0.10 ns8.66 ± 0.29 ns8.22 ± 0.15 ns7.43 ± 0.09 ns
Zn (mg kg−1)40.21 ± 0.81 ns38.10 ± 0.88 ns40.79 ± 0.08 ns38.35 ± 0.59 ns36.08 ± 0.32 ns37.25 ± 0.66 ns41.09 ± 0.45 ns36.40 ± 0.11 ns
Mo (mg kg−1)0.73 ± 0.02 ns0.69 ± 0.03 ns0.79 ± 0.01 ns0.71 ± 0.01 ns0.74 ± 0.01 ns0.70 ± 0.01 ns0.72 ± 0.02 ns0.61 ± 0.00 ns
S1—sole crop of soybean, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer; different letters indicate significant difference at p < 0.05, ns—not significant.
Table 11. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the vegetative part of common millet, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Table 11. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the vegetative part of common millet, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Measured
Parameters
BFBFϴ
M1S1M1S2M2S2M4M1S1M1S2M2S2M4
FBY (t ha−1)18.25 ± 1.55 ns12.33 ± 3.90 ns15.93 ± 3.26 ns16.19 ± 1.67 ns17.28 ± 1.35 ns12.12 ± 2.35 ns16.37 ± 4.62 ns15.43 ± 0.87 ns
DBY (t ha−1)5.62 ± 0.65 a3.26 ± 1.12 b4.13 ± 1.00 b4.63 ± 0.62 a,b5.39 ± 0.55 a,b3.20 ± 0.80 b4.26 ± 1.31 b4.56 ± 0.63 a,b
Ca (g kg−1)5.29 ± 0.20 ns5.90 ± 0.36 ns5.30 ± 0.37 ns5.73 ± 0.28 ns5.13 ± 0.24 ns6.02 ± 0.19 ns5.45 ± 0.39 ns5.74 ± 0.21 ns
Mg (g kg−1)3.94 ± 0.03 c4.67 ± 0.03 a,b4.45 ± 0.04 b4.05 ± 0.05 c3.81 ± 0.02 c4.70 ± 0.02 a4.72 ± 0.02 a4.02 ± 0.02 c
P (g kg−1)1.96 ± 0.00 c1.97 ± 0.04 c2.20 ± 0.02 b2.22 ± 0.01 b2.36 ± 0.01 b2.39 ± 0.02 b2.64 ± 0.01 a2.32 ± 0.02 b
S (g kg−1)1.85 ± 0.01 c2.18 ± 0.02 b2.14 ± 0.01 b1.82 ± 0.02 c1.87 ± 0.02 c2.38 ± 0.01 a2.38 ± 0.01 a1.86 ± 0.02 c
B (mg kg−1)2.79 ± 0.21 ns2.37 ± 0.18 ns3.03 ± 0.32 ns2.41 ± 0.23 ns1.22 ± 0.17 ns1.85 ± 0.19 ns3.60 ± 0.14 ns1.55 ± 0.34 ns
Al (mg kg−1)103.71 ± 3.59 a73.23 ± 2.97 b92.89 ± 0.86 a,b56.48 ± 3.30 b123.17 ± 3.89 a72.41 ± 1.17 b105.24 ± 1.78 a60.93 ± 3.68 b
Cr (mg kg−1)1.43 ± 0.01 ns3.16 ± 0.06 ns2.55 ± 0.00 ns2.91 ± 0.03 ns3.25 ± 0.03 ns5.55 ± 0.04 ns3.67 ± 0.04 ns4.65 ± 0.04 ns
Mn (mg kg−1)34.92 ± 0.49 b41.61 ± 0.60 a44.05 ± 0.53 a44.46 ± 0.53 a31.93 ± 0.07 b44.44 ± 0.63 a41.43 ± 0.19 a43.65 ± 0.30 a
Fe (mg kg−1)81.44 ± 0.99 b83.72 ± 0.65 b89.83 ± 1.37 a,b85.78 ± 1.79 b78.19 ± 1.68 b95.10 ± 0.90 a88.45 ± 1.07 a,b81.46 ± 1.62 b
Co (mg kg−1)0.08 ± 0.00 ns0.07 ± 0.01 ns0.08 ± 0.00 ns0.09 ± 0.00 ns0.08 ± 0.00 ns0.10 ± 0.00 ns0.09 ± 0.00 ns0.09 ± 0.00 ns
Ni (mg kg−1)1.46 ± 0.02 ns1.44 ± 0.06 ns1.71 ± 0.03 ns2.49 ± 0.02 ns2.32 ± 0.02 ns1.63 ± 0.02 ns2.06 ± 0.03 ns2.37 ± 0.03 ns
Cu (mg kg−1)2.98 ± 0.07 ns3.07 ± 0.05 ns3.90 ± 0.07 ns3.64 ± 0.04 ns3.10 ± 0.03 ns3.28 ± 0.06 ns3.21 ± 0.04 ns3.08 ± 0.07 ns
Zn (mg kg−1)13.56 ± 0.28 b,c10.84 ± 0.38 c8.98 ± 0.16 c14.61 ± 0.33 b,c17.58 ± 0.30 a,b15.77 ± 0.10 b11.73 ± 0.11 c19.89 ± 0.45 a
Mo (mg kg−1)0.21 ± 0.01 ns0.30 ± 0.01 ns0.25 ± 0.01 ns0.25 ± 0.01 ns0.27 ± 0.01 ns0.31 ± 0.00 ns0.28 ± 0.00 ns0.25 ± 0.01 ns
M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer; different letters indicate significant difference at p < 0.05, ns—not significant.
Table 12. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the reproductive part of common millet, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Table 12. Integrated influence of sowing pattern and biofertilizer (BF) on yields of fresh biomass (FBY) and dry biomass (DBY) of the reproductive part of common millet, and concentrations of macro- and microelements in it, presented as a mean ± standard deviation.
Measured
Parameters
BFBFϴ
M1S1M1S2M2S2M4M1S1M1S2M2S2M4
FBY (t ha−1)8.66 ± 0.72 a5.81 ± 1.88 b7.62 ± 1.71 a,b7.39 ± 0.76 a,b8.46 ± 0.63 a5.99 ± 1.16 b7.93 ± 2.24 a7.56 ± 0.44 a,b
DBY (t ha−1)5.32 ± 0.62 a3.02 ± 1.08 b4.02 ± 1.12 a,b4.20 ± 0.62 a,b5.14 ± 0.48 a3.18 ± 0.80 b4.22 ± 1.31 a,b4.34 ± 0.62 a,b
Ca (g kg−1)1.07 ± 0.07 ns1.13 ± 0.10 ns1.02 ± 0.09 ns1.31 ± 0.07 ns0.90 ± 0.06 ns1.04 ± 0.09 ns1.00 ± 0.10 ns1.11 ± 0.05 ns
Mg (g kg−1)1.61 ± 0.01 ns1.82 ± 0.02 ns1.59 ± 0.01 ns1.58 ± 0.02 ns1.55 ± 0.02 ns1.70 ± 0.02 ns1.58 ± 0.02 ns1.57 ± 0.01 ns
P (g kg−1)3.09 ± 0.02 b3.25 ± 0.01 a3.08 ± 0.02 b3.05 ± 0.01 b2.99 ± 0.02 b3.32 ± 0.01 a2.96 ± 0.01 b3.02 ± 0.01 b
S (g kg−1)1.20 ± 0.01 c1.40 ± 0.01 a1.28 ± 0.01 b,c1.32 ± 0.01 b1.13 ± 0.04 d1.44 ± 0.01 a1.24 ± 0.01 c1.30 ± 0.01 b
B (mg kg−1)4.35 ± 0.52 a2.50 ± 0.47 b,c2.04 ± 0.45 c3.05 ± 0.43 b2.63 ± 0.53 b,c1.20 ± 0.14 c,d1.15 ± 0.34 d1.24 ± 0.54 c
Al (mg kg−1)20.96 ± 1.10 b13.52 ± 1.38 b14.33 ± 1.71 b26.30 ± 2.23 b53.48 ± 2.09 a17.51 ± 1.28 b23.22 ± 1.39 b37.00 ± 2.01 a,b
Cr (mg kg−1)2.65 ± 0.05 b2.06 ± 0.03 c2.73 ± 0.04 b1.69 ± 0.04 d1.84 ± 0.02 c,d1.62 ± 0.01 d3.10 ± 0.03 a1.79 ± 0.02 c,d
Mn (mg kg−1)24.85 ± 0.33 d27.04 ± 0.43 c31.61 ± 0.53 a28.96 ± 0.31 b22.28 ± 0.17 f23.75 ± 0.12 e29.68 ± 0.42 b26.54 ± 0.47 c
Fe (mg kg−1)56.49 ± 0.83 b47.79 ± 0.72 b,c61.63 ± 2.10 a,b57.45 ± 1.39 b53.99 ± 0.79 b,c45.82 ± 0.55 c70.48 ± 1.30 a68.28 ± 0.75 a
Co (mg kg−1)0.08 ± 0.00 ns0.07 ± 0.00 ns0.07 ± 0.01 ns0.08 ± 0.00 ns0.06 ± 0.00 ns0.06 ± 0.00 ns0.07 ± 0.00 ns0.08 ± 0.00 ns
Ni (mg kg−1)2.33 ± 0.04 b,c2.40 ± 0.03 b,c2.55 ± 0.04 b2.20 ± 0.05 c2.23 ± 0.02 c2.29 ± 0.03 b,c3.16 ± 0.02 a2.31 ± 0.01 b,c
Cu (mg kg−1)5.56 ± 0.11 ns5.77 ± 0.13 ns5.55 ± 0.07 ns5.28 ± 0.10 ns5.77 ± 0.11 ns5.90 ± 0.05 ns5.72 ± 0.07 ns5.47 ± 0.04 ns
Zn (mg kg−1)27.05 ± 0.39 a22.24 ± 0.21 b23.09 ± 0.38 b20.59 ± 0.18 b26.79 ± 0.28 a20.50 ± 0.24 b25.43 ± 0.33 a,b22.43 ± 0.55 b
Mo (mg kg−1)0.21 ± 0.01 a0.16 ± 0.01 b,c0.19 ± 0.00 a,b0.20 ± 0.00 a,b0.17 ± 0.00 b0.13 ± 0.01 c0.17 ± 0.01 b0.18 ± 0.00 b
M1—sole crop of millet, S1M1—alternating rows of soybean and millet, S2M2—alternating strips of two rows of soybean and two rows of millet, S2M4—alternating strips of two rows of soybean and four rows of millet; BF—biofertilizer, BFƟ—without biofertilizer; different letters indicate significant difference at p < 0.05, ns—not significant.
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MDPI and ACS Style

Šenk, M.; Simić, M.; Milojković-Opsenica, D.M.; Brankov, M.; Trifković, J.; Perić, V.; Dragičević, V. Intercropping of Soybean and Common Millet—A Rational Way of Forage Biomass Quality Enhancement. Agriculture 2025, 15, 2029. https://doi.org/10.3390/agriculture15192029

AMA Style

Šenk M, Simić M, Milojković-Opsenica DM, Brankov M, Trifković J, Perić V, Dragičević V. Intercropping of Soybean and Common Millet—A Rational Way of Forage Biomass Quality Enhancement. Agriculture. 2025; 15(19):2029. https://doi.org/10.3390/agriculture15192029

Chicago/Turabian Style

Šenk, Milena, Milena Simić, Dušanka M. Milojković-Opsenica, Milan Brankov, Jelena Trifković, Vesna Perić, and Vesna Dragičević. 2025. "Intercropping of Soybean and Common Millet—A Rational Way of Forage Biomass Quality Enhancement" Agriculture 15, no. 19: 2029. https://doi.org/10.3390/agriculture15192029

APA Style

Šenk, M., Simić, M., Milojković-Opsenica, D. M., Brankov, M., Trifković, J., Perić, V., & Dragičević, V. (2025). Intercropping of Soybean and Common Millet—A Rational Way of Forage Biomass Quality Enhancement. Agriculture, 15(19), 2029. https://doi.org/10.3390/agriculture15192029

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