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Article

Effects of Tillage Methods on Carbon and Nitrogen Sequestration and Soil Microbial Stoichiometric Equilibrium in a Black Soil Farmland with Full Return of Straw to the Field

by
Meiren Rong
1,
Zhigang Wang
1,*,
Xiangqian Zhang
2,3,*,
Zhanyuan Lu
2,3,
Lanfang Bai
1,
Zhipeng Cheng
1,
Tianhao Wang
1,
Yajing Zhang
1,
Hongwei Liang
2,
Tiantian Meng
2,3,
Lingyue Liu
4 and
Fang Luo
4
1
College of Agronomy, Inner Mongolia Agricultural University, Hohhot 010019, China
2
Inner Mongolia Academy of Agriculture and Animal Husbandry Sciences, Hohhot 010031, China
3
Key Laboratory of Black Soil Protection and Utilization, Ministry of Agriculture and Rural Affairs, Hohhot 010031, China
4
Arongqi Agricultural and Career Development Center, Hulunbuir 162750, China
*
Authors to whom correspondence should be addressed.
Agronomy 2025, 15(7), 1664; https://doi.org/10.3390/agronomy15071664
Submission received: 11 May 2025 / Revised: 29 June 2025 / Accepted: 8 July 2025 / Published: 9 July 2025
(This article belongs to the Section Agroecology Innovation: Achieving System Resilience)
Browse Figures
Versions Notes

Abstract

Long-term irrational farming practices and low return of organic materials to the fields in the black soil area have led to reduced soil carbon and nitrogen stability and nutrient imbalance, which in turn affect soil fertility and crop yields. Straw return is an effective way to enhance soil organic matter and crop productivity, but the effects of long-term straw return under tilling practices on carbon and nitrogen sequestration and soil microbial stoichiometric equilibrium in black soil need to be further investigated. This study investigated the physical, chemical and biological properties of the 0–60 cm soil layer under deep tillage with straw return to the field (DTS), deep harrow with straw return to the field (DHS), rotary tillage with straw return to the field (RTS), no tillage with straw return to the field (NTS), and conventional tillage with straw removal (CT) on the basis of seven consecutive years of tillage pattern location trials in the black soil area of eastern Inner Mongolia. The results showed that DTS and NTS significantly increased the soil organic carbon (SOC), soil total nitrogen (TN), soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN) contents, and the SOC/TN ratio in the 0–40 cm soil layer, enhancing soil carbon and nitrogen sequestration capacity, while the concomitant increase in the average MBC/MBN ratio in the plow layer from 6.8 to 8.2. The soil microbial quotient increased by 29.0% and 26.2%, respectively, and the stoichiometric imbalance ratio decreased by 7.9% and 5.7%, respectively. Meanwhile, in terms of maize yield from 2018 to 2024, DTS showed the most stable and significant yield increase with 41.53%. Whereas NTS showed a higher yield increase potential with a 27.36% increase in yield as the number of years of straw return increased. Therefore, DTS and NTS are superior tillage methods to improve the quality of the black soil tillage layer, to promote soil microbial carbon and nitrogen balance, and to increase crop yields.

1. Introduction

As one of the four major black soil belts in the world, the type of soil in northeastern China is Chernozems, which have a very dark mollic horizon [1]. This region is an important grain and livestock production base in China, with its arable land accounting for about 10% of the country’s total arable land [2]. With its high organic matter content and superior fertility characteristics, black soil plays an irreplaceable role in ensuring national food security. However, under the long-term intensive agricultural production model, irrational farming practices and excessive removal of crop residues have led to soil degradation, such as a significant decrease in the organic matter content of northeastern black soils, a dysfunctional microbial community structure, and increased fluctuations in crop yields [3,4]. In recent years, as an important soil conservation measure, the effects of straw return to the field to improve soil structure, enhance soil organic matter content, and supplement soil nitrogen and phosphorus [5,6]. Zhao et al. [7] found in their meta-analysis that, compared with straw removal, straw return could increase the soil organic carbon (SOC) content in the 0–30 cm soil layer by 0.81 g kg−1 on average. However, the enhancement effect of straw on farmland ecosystem functions was dependent on tillage methods. The study further confirmed that tillage combined with straw return can effectively improve soil quality and increase crop yield in black soil areas [8]. Recent work by Liu et al. [9] showed that for different tillage methods, no-tillage (NT) management showed the greatest increase in crop yield at 6.2%. Although a large number of studies have been conducted to investigate the effects of straw management practices on crop yield and soil fertility [10,11], soil microorganisms play a central role in regulating biogeochemical cycles and maintaining carbon and nitrogen nutrient balances [12]. It has been shown that the increase in organic matter and nutrient availability caused by the return of straw to the soil increases the amount of fungal, bacterial and microbial carbon and nitrogen in the soil [8,13]. However, the research on the mechanism of carbon and nitrogen sequestration and soil microbial system carbon and nitrogen balance in black soil under different tillage methods under long-term straw return conditions is still insufficient. Therefore, it is of great significance to investigate in depth the mechanism of the effect of straw return on the soil microbial system under different cropping methods to optimize the farmland management strategy in the black soil area.
The result of an experiment conducted by Chu et al. [14] in 2018 indicates that no-tillage combined with straw return is an effective management measure to alleviate carbon limitation of soil microbial metabolism and enhance soil multifunctionality in the Northeast Plains. However, the effects of straw return on soil microbial communities were tillage method-dependent and spatially and temporally heterogeneous. Liu found that although deep turning of maize straw to return it to the soil was beneficial to maintain the stability of the microbial network [15], it had a limited effect on the enhancement of microbial diversity and function. Soil microbial quotient (MBC/SOC), as a key indicator characterizing the ratio of microbial biomass to soil organic carbon, reflects the ability of microbial communities to regulate organic matter decomposition and nutrient cycling processes, which play an important role in maintaining ecosystem function, promoting plant growth, and maintaining soil fertility [16]. Studies have shown that higher MBC/SOC ratios are generally indicative of better soil quality and more active microbial communities, which may accelerate the decomposition process of organic matter [17]. In addition, the soil microbial stoichiometric imbalance ratio, as an important parameter to quantify the difference in chemical composition between microorganisms and resources, provides a new research perspective to reveal the dynamic balance of nutrients in the soil microbial system [18,19].
Although a large number of studies have demonstrated that straw return to the field can significantly improve soil fertility, microbial biomass and its activity, there is still a lack of systematic research on the equilibrium characteristics of the synergistic changes in carbon and nitrogen contents of soil microbial systems and their regulatory mechanisms under different tillage methods. In this study, based on a 7-year field trial in the black soil area of eastern Inner Mongolia, we systematically investigated the dynamic changes in soil physical structure, carbon and nitrogen sequestration, and microbial biomass in black soil farmland under the condition of full straw incorporation into the field by tillage. Based on the previous research, the following scientific hypotheses were put forward: (1) Long-term straw return to the field enhances soil organic carbon and total nitrogen content and promotes the continuous accumulation of microbial biomass; (2) long-term straw return to the field affects the structure of the soil microbial community, and the accumulation characteristics of microbial biomass are regulated by tillage methods; and (3) straw return to the field effectively promotes the carbon and nitrogen sequestration capacity of the soil microbial system of the agricultural fields in the black soil area and maintains the dynamic balance of carbon and nitrogen in the system. The aim of this study was to elucidate the mechanism of the influence of tillage methods on the variation of carbon and nitrogen contents and their balance characteristics in soil microbial systems at the background of straw return to the field. It can provide a theoretical basis and practical guidance for the regulation of carbon and nitrogen cycling and the optimal selection of straw return methods in the black soil area.

2. Materials and Methods

2.1. Study Site

This experiment was conducted in Najitun Township, Arong Banner, Hulunbuir City, Inner Mongolia Autonomous Region (49°19′ N, 122°02′ E) in 2018. The test site is located at the eastern foot of the Greater Khingan Mountains, which is a temperate continental semi-humid climate zone. According to the long-term observation data of the local meteorological station, the annual average temperature of the area is 1.7 °C, the annual effective cumulative temperature of ≥10 °C is 2394.1 °C d, the annual average precipitation is 458 mm (of which more than 60% is concentrated in June-August), the annual average sunshine hours are about 2600 h, and the frost-free period is 110–120 days. The climatic conditions during the maize growth period in the experiment are presented in supplementary materials (Figure S1). Before the experiment, the experimental area was planted with maize for a long time, and unified field management was implemented, and the soil type for the test was Chernozems [1], and the basic physicochemical properties of the different soil layers with soil bulk density (SBD), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), available potassium (AK) and pH value (pH) are shown in Table 1.

2.2. Experimental Design

The field experiment was established in 2018 using a one-way completely randomized block design with five tillage methods: (1) deep tillage with straw return to the field (DTS); (2) deep harrow with straw return to the field (DHS); (3) rotary tillage with straw return to the field (RTS); (4) no tillage with straw return to the field (NTS); and (5) conventional tillage with straw removal (CT). CT was considered as the control, and the specific tillage methods are shown in Table 2. All treatments maintained their specific tillage and straw management practices annually throughout the seven-year study period to ensure treatment consistency and long-term comparability. There are three replicated plots (30 × 30 m) for each method. The maize variety in the experiment was Fengyu 8, and the planting density was 75,000 seeds ha−1. The experimental area is rain-fed agriculture; there was no irrigation during the entire growth period of maize. The types of fertilizer were compound fertilizer (N-P2O5-K2O:19-19-19) and urea (N ≥ 46%). At sowing, a compound fertilizer (N-P2O5-K2O:19-19-19) was applied as basal fertilizer at a rate of 450 kg ha−1. Additional urea (N ≥ 46%) was top-dressed during the jointing stage at 225 kg·ha−1.
The field experiment was conducted over seven consecutive years (2018–2024) with consistent straw return practices for all treatments. The residues were returned to the field annually after post-harvest. The amount of straw returned to the field from the 2018 harvest to the 2023 harvest is shown in Table 3. To quantify straw return amounts, aboveground biomass was sampled from 5 m × 2 rows of plants per plot at physiological maturity in the preceding season. Samples were collected in triplicate, oven-dried at 80 °C to constant mass, and weighed to determine dry biomass. This value was scaled to plot-level straw yield (kg ha−1) to establish precise straw return quantities for each tillage treatment. Following maize harvest, all residual straw was uniformly returned to respective plots.

2.3. Soil Sampling and Physicochemical Analysis

Soil samples were collected from the 0–10 cm, 10–20 cm, 20–40 cm, and 40–60 cm soil layers using a soil auger after the maize harvest in October 2024, and mixed soils were collected from each plot using the five-point sampling method. The samples were sieved through a 2 mm sieve to remove plant residues and debris. The collected soil samples were divided into two portions: one portion was stored at 4 °C for the determination of soil microbial carbon and nitrogen (MBC, MBN), and the other portion was air-dried for the determination of soil organic carbon (SOC) and soil total nitrogen (TN). MBC and MBN were determined by chloroform fumigation [20], SOC was determined by combustion analysis [21], and TN was determined by semi-micro Kjeldahl nitrogen determination [22]. The soil carbon and nitrogen stoichiometric ratios were all mass ratios in this experiment. The soil microbial quotient and stoichiometric imbalance equations were as follows [23].
Soil microbial quotient carbon (QMBC) = (MBC/SOC) × 100%.
Soil microbial quotient nitrogen (QMBN) = (MBN/TN) × 100%.
Stoichiometric imbalance ratio = (SOC/TN)/(MBC/MBN).
Soil bulk density (SBD) and soil porosity (SP) were determined using the ring knife method [24]. In each plot, the corresponding planned surface was dug, and soil samples were taken from 0 to 10 cm, 10 to 20 cm, 20 to 40 cm, and 40 to 60 cm for a total of four soil layers, with three replicates for each layer. SBD and SP were calculated based on the weight of the soil dried at 105 °C, calculated as follows:
SBD (g cm−3) = (W1 − W2)/V,
SP (%) = [1 − (W1 − W2)/particle density] × 100%.
where SBD denotes soil bulk density (g·cm−3), SP denotes total soil porosity (%), W1 is the weight of the soil after drying plus the weight of the ring cutter, W2 is the weight of the ring cutter, and V is the volume of the ring cutter (100-cm3) with a particle density of 2.65 g cm−3.
Maize yield was measured at the physiological maturity stage by harvesting 2 rows of plants in the middle of the measured production. Grain was dried to calculate yield at 14% moisture. Twenty plants with uniform ear growth were selected for the determination of ear rows, row grains, and 1000-grain weight.

2.4. Data Analysis

The data were statistically analyzed using SPSS 25.0 (IBM, Inc., Armonk, NY, USA) with a mixed-model approach to account for both fixed and random effects. For soil parameters across different depths, soil depth was used as a fixed effect. For interannual yield variation analysis, year was included as a random effect. ANOVA with LSD post hoc tests (p < 0.05) was used to compare tillage methods, while Tukey’s HSD test (p < 0.05) was applied for depth comparisons. Structural equation modeling (SEM) was performed using Amos 26.0 (IBM, USA). All figures were generated using Origin 2024 (Origin Lab, Northampton, MA, USA).

3. Results

3.1. Effect of Tillage Methods on the Physical Parameters of Soils

As shown in Table 4, different tillage methods had significant effects on soil bulk density (SBD) and porosity (SP) in the 0–60 cm soil layer. Overall, SBD showed an increasing trend with increasing soil depth, while SP showed a gradual decrease. From 0 to 10 cm, SBD was lowest in the DTS at 1.09 g cm−3, while it was higher in the NTS and CT at 1.21 g cm−3 and 1.19 g cm−3, respectively. SBD was 8.4% lower under the DTS compared to CT. The 10–20 cm soil layer soil bulk density showed the same performance as the 0–10 cm soil layer. And the SBD was 5.5% lower under the DTS compared to CT; in the 40–60 cm soil layer, the SBD was significantly lower under the DTS compared to CT by 5.8%. The DTS had lower soil bulk density than other methods in all soil layers, indicating that straw return to the field can effectively reduce soil bulk density and improve soil structure.
The trend of soil porosity was opposite to that of soil bulk density, decreasing gradually with soil depth (Table 4). In the 0–10 cm soil layer, the DTS had the highest SP of 58.89%, while the NTS had the lowest SP of 50.81%. Compared with CT, the SP of DTS was significantly increased by 6.0 percentage points. In the soil layers of 10–20 cm, 20–40 cm and 40–60 cm, the SP of DTS was significantly higher than that of other methods, and it was increased by 7.0, 4.9 and 6.1 percentage points compared with that of CT, respectively. On the whole, the porosity of the DTS was higher than that of the other methods in all the soil layers, which indicated that the deep tillage with straw return to the field could significantly improve soil porosity and enhance soil aeration and water retention capacity. The lowest soil porosity was found in the 0–60 cm soil layer under the NTS, with an average of 47.2%, and the difference with the CT was not significant. It can be seen that under the condition of long-term straw return to the field, the degree of soil disturbance by the tillage method is the main factor affecting the soil bulk density and porosity of the black soil farmland.

3.2. Effect of Tillage Methods on Soil Organic Carbon, Total Nitrogen Content and Carbon to Nitrogen Ratio

Tillage methods significantly affected the soil organic carbon (SOC) and total nitrogen (TN) content of the black soil farmland under straw return (Figure 1). SOC showed a decreasing trend with the increase of soil depth, and the SOC contents of DTS and NTS were significantly higher than those of other methods in the 0–10 cm soil layer, with an increase of 29.3% and 26.4%, compared with that of CT. SOC contents of the DTS were significantly the highest in the 10–40 cm layer, while the difference of NTS is not significant, with an increase of 34.7% and 32.3%, respectively, compared with CT on average. In the 40–60 cm soil layer, the differences in SOC content under the four straw return methods were not significant, but all of them were significantly higher than CT. TN content showed a decreasing tendency with the increase in the depth of the soil layer; DTS and NTS were significantly higher than that of the other methods (Figure 1). Among them, NTS had the highest TN content in the 0–10 cm and 10–20 cm soil layers, which was 19.6% and 26.6% higher than CT, respectively. And the difference between DTS and NTS was not significant, which were 16.0% and 23.4% higher than CT, respectively. In the 40–60 cm soil layer, the TN content of DTS and NTS was 8.1% and 11.1% higher, respectively, compared with that of CT. Overall, NTS and DTS were outstanding in enhancing TN content, especially in the topsoil layer.
As can be seen from Figure 1, compared with CT, straw return significantly increased the soil organic carbon to total nitrogen ratio (SOC/TN) in the 0–60 cm soil layer of the black soil farmland. In the 0–40 cm plow layer, the SOC/TN values under DTS and NTS were higher than those of other methods, with an average increase of 12.3% and 10.8% compared with CT. However, SOC, TN and SOC/TN ratios under different tillage methods did not show significant differences in the 40–60 cm soil layer, which indicated that the enhancement of soil carbon and nitrogen ratios by straw return to soil was mainly concentrated in the middle and upper layers of the soil, and the influence on the deeper layers of the soil was relatively limited.

3.3. Effect of Tillage Methods on Soil Microbial Biomass Carbon, Microbial Biomass Nitrogen and Microbial Biomass Carbon to Nitrogen Ratio

As shown in Figure 2, straw returned to the field significantly enhanced the microbial biomass carbon and microbial biomass nitrogen (MBN) contents in the 0–60 cm soil layer of the black soil farmland. The MBC and MBN showed a tendency to increase and then decrease with soil depth. The highest MBC and MBN contents were reached at 10–20 cm and were significantly higher in the DTS, with significant increases of 45.4% and 33.5% compared to CT. The difference between NTS and DTS was not significant, with an average increase of 42.4% and 31.6% compared to CT, respectively. The values of MBC/MBN are key indicators to represent the nutritional status and growth limitation of microorganisms. Compared with non-returned straw, long-term straw return significantly increased the MBC/MBN in the 0–60 cm soil layer by an average of 19.8%. In the 0–40 cm plow layer, the MBC/MBN of straw return methods ranged from 7.0 to 8.3. Among them, the MBC/MBN of DTS and NTS were significantly higher than the other methods, from 6.8 to 8.2, which was 19.8% and 20.2% higher than that of CT, respectively.

3.4. Effect of Tillage Methods on Soil Microbial Quotient

Compared with CT, long-term straw return significantly affected the soil microbial quotient of carbon (MBC/SOC), showing a tendency of increasing and then decreasing (Table 5). MBC/SOC reached greatest values at 10–20 cm and 20–40 cm, with an average of 1.4%, 0.2 and 0.4 percentage points higher than CT, respectively. The lowest MBC/SOC was found in the 0–10 cm and 40–60 cm soil layers, and the differences between methods were not significant. Within the 0–40 cm plow layer, MBC/SOC under DTS and NTS were significantly higher than the other methods, by 0.3 percentage points on average, compared to CT. The soil microbial quotient of nitrogen (MBN/TN) showed a tendency to increase gradually with soil depth, reaching a maximum value at 40–60 cm, with an average of 2.2%, an increase of 0.3 percentage points compared to CT. There was no significant difference in MBN/TN at 10–20 cm and 20–40 cm, with an average of 1.9%. It reached the minimum value at 0–10 cm (Table 5), with an average of 1%, but it was 0.2 percentage points higher than CT. In general, the MBC/SOC of DTS and NTS in the 10–40 cm soil layer increased significantly, indicating that they had a strong promoting effect on soil microbial activity.

3.5. Effect of Tillage Methods on Soil Microbial Stoichiometric Imbalances

In order to further analyze the effects of long-term straw return on the dynamic balance of soil and microbial nutrients, the present study assessed the state of soil carbon and nitrogen balance in black soil farmland through the soil microbial stoichiometric ratio. As can be seen in Figure 3, the soil stoichiometric imbalance ratio (C/Nimb) increased with soil depth under long-term straw return conditions. The C/Nimb in the 0–10, 10–20, 20–40 and 40–60 cm soil layers of different tillage methods could be reduced by an average of 7.7% as compared with that of CT. Within the 0–10, 10–20 and 20–40 cm tillage layers under different tillage methods, the NTS had the lowest C/Nimb, which was on average 7.9% lower than CT, followed by the DTS, which was on average 5.7% lower than CT. It can be seen that straw return can effectively improve the balance of soil stoichiometry, especially under DTS and NTS.

3.6. Effect of Tillage Methods on Maize Yield Under Successive Years of Straw Return

From the analysis of Table 6, it can be seen that DTS, DHS, RTS and NTS showed a trend of increasing yields year by year compared with CT. Maize yields of CT were relatively stable but significantly lower than those of the straw return methods. In terms of inter-annual trends, the DTS showed the most outstanding yield performance, with a sustained increase from 7514.79 kg ha−1 in 2018 to 10,635.75 kg ha−1 in 2024, with a 41.53% increase in yield. In contrast, DHS and RTS showed higher yield competitiveness in the early years. But maize yield in NTS increased significantly with increasing years of straw return, from 7921.03 kg ha−1 in 2018 to 10,087.91 kg ha−1 in 2024, with an increase in yield of 27.36% as the years of straw return increased. In summary, different tillage methods under long-term straw return were able to significantly increase maize yields, with the DTS showing the most stable and significant yield increase in the multi-year experiment, while the NTS showed higher yield increase potential with the increase in the number of years of straw return.

3.7. Structural Equation Modeling of the Effect of Tillage Methods on the Structure, Fertility, Microbiology, Nutrient Sequestration, Soil Quality and Yield Characteristics of Black Soils

The direct and indirect effects of different tillage methods on soil structure, fertility, microbial properties, carbon and nitrogen sequestration, and soil quality and maize yield of the black soil farmland under straw return conditions were analyzed by structural equation modeling SEM (Figure 4). It was found that all the predictor variables contributed 79% to the soil quality and 36% to the maize yield. Tillage methods had a highly significant negative effect on soil fertility (p < 0.001), while soil fertility highly significantly and positively affected soil microbial characteristics (p < 0.001) with an explanation of 54%. At the same time, microbial characteristics showed a highly significant positive effect on carbon and nitrogen sequestration in black soil farmland (p < 0.001) with an explanation of up to 86%. There was a significant positive correlation (p < 0.05) between microbial characteristics, soil carbon and nitrogen sequestration and soil quality, with 86% and 96% (p < 0.05) degree of explanation, respectively. Soil quality had a significant positive effect on maize yield (p < 0.05) with a degree of explanation of 79%. Thus, it can be seen that the long-term straw returning conditions of farming methods mainly through the improvement of soil fertility and structure to promote microbial activities, improve the black soil farmland soil carbon and nitrogen sequestration capacity, and then improve the soil quality, so that the soil to achieve carbon and nitrogen balance, and ultimately to achieve the increase in maize yield.

4. Discussion

4.1. Influence of Tillage Methods on Soil Physical Properties Under Long-Term Straw Tillage

After seven consecutive years of straw returning to the field, different returning methods significantly affected the soil bulk density and porosity in the 0–60 cm soil layer of the black soil farmland, in which the DTS significantly reduced the soil bulk density and increased the soil porosity in the plow layer (Table 4). This suggests that DTS is an effective way to improve the physical structure of black soils by increasing their aeration and permeability, and that the reduction in soil bulk density and increase in porosity facilitate the growth and development of maize roots and improve soil fertility and productivity [25,26]. These findings align with global conservation agriculture trends, where reduced tillage intensity combined with residue retention improves soil pore characteristics [27]. In addition, increased soil porosity improves the microbial ecosystem of the soil and promotes microbial growth and activity [28]. Carbon and nitrogen cycling processes in soil are closely related to soil organic matter (SOM) turnover and nutrient utilization, and the dynamics of SOC and TN levels are crucial for optimizing soil organic matter turnover mechanisms and straw management practices [29]. In a Brazilian farming experiment, soil carbon content in the 0–5 cm layer measured 30–45 g kg−1 after 4.5 years. But the lowest values were observed under CT soil, lower than reduced tillage and no-tillage, regardless of the winter cover crop used [30]. The results of this study showed that continuous years of straw return significantly affected the SOC and TN contents of the black soil, and the SOC and TN contents under different straw return methods showed a gradual decrease with the deepening of the soil layer (Figure 1). This result is consistent with the findings of Zhao et al. [31] and Yang et al. [32].
The SOC and TN contents were higher and not significantly different between DTS and NTS within the 0–40 cm tillage layer; this result confirms scientific hypothesis 1 of this study. The higher SOC and TN in the 0–40 cm tillage layer under DTS may be attributed to the lower soil bulk density, increased porosity and improved biological conditions (increased microbial biomass) in the soil structure, which prompted sufficient mixing of straw with the tillage soil, accelerated the decomposition of straw, and released a large amount of nutrients, such as carbon and nitrogen, into the soil [8]. Typically, the 0–20 cm soil layer contains high carbon and nitrogen content; however, the increase in carbon and nitrogen content under the deep tilling and deep pine and shallow tilling measures may be due to the soil disturbance by the tillage measures that redistributes nutrients from the topsoil of the 0–20 cm to the 20–35 cm tillage layer, which enhances the supply of nutrients to the 20–40 cm tillage layer [33]. However, Yuan et al. concluded that straw return to the field and without severe soil disturbance could result in better carbon and nitrogen retention capacity of the soil [34], while in this study, NTS also effectively increased the SOC and TN content of the soil, which was analyzed as the reason might be that no-tillage reduced the disturbance of the soil by tillage. This aligns with global trends observed in conservation agriculture systems, where surface residue retention under no-till consistently enhances topsoil SOC stocks [35]. And at the same time, straw mulching in the topsoil increased the temperature of the tillage layer, which promotes microbial activity [36], increasing the accumulation of microbial biomass [37]. This activation process promotes nutrient cycling and soil health [38].

4.2. Influence of Tillage Methods on Soil Microbial Biomass Under Long-Term Straw Reclamation

Soil microorganisms are drivers of soil function [39] and contribute to soil function by regulating microbial function, community composition and succession [40]. Microbial biomass is the active soil nutrient reservoir, which plays a key role in soil material transformation and nutrient cycling, while MBC/MBN can characterize the community composition and structural information of soil microorganisms [41,42].
Previous studies concluded that a suitable environment with sufficient nutrient supply can promote the proliferation of soil microorganisms and increase biomass accumulation [37]. The results of this study showed that straw return significantly increased the MBC and MBN contents and their ratios in the tillage layer of the soil. Moreover, the microbial biomass carbon-to-nitrogen ratio, as an effective indicator for assessing soil productivity, is closely related to the microbial-mediated C and N content [43], and the ratio of fungi to bacteria in the soil determined by the PLFA method was found to increase with the increase in soil microbial carbon-to-nitrogen ratio [44]. It is generally accepted that microbial biomass C/N is dominated by soil bacteria in the range of 3 to 6 and fungi in the range of 7 to 12 [45]. Bradford found that higher microbial biomass C/N ratios may promote fungal abundance and reduce bacterial/fungal [46] and that fungi have a stronger carbon utilization efficiency compared to bacteria [47]. Song et al. [48] found that the mean value of MBC/MBN in the Guanzhong Plain was 5.63, suggesting that the area was mainly dominated by bacteria. The study in black soil showed that the MBC/MBN ratio in the tillage layer from 0 to 40 cm under straw return was 7.0 to 8.3, while that of CT was 6.8. Therefore, the soil microbial community may be changed from the bacterial type to the fungal type after successive years of straw returning to the soil. This shift towards fungal dominance under organic input regimes is increasingly recognized as a key mechanism for enhanced decomposition and stabilization in agricultural soils worldwide [49]. But these microbial transitions may vary under different climatic and soil conditions; for example, at high temperature and moisture, microbial turnover is faster, which may alter the fungi-to-bacteria ratio and the associated nutrient cycling effects [50].
The MBC/MBN ratios of the DTS and NTS were significantly higher than those of the other methods under different tillage methods, and the reasons for this may be closely related to the increase in soil organic carbon input and the enrichment of the fungal community under the straw return condition. Because fungi have higher carbon use efficiency than bacteria and can decompose complex organic matter (e.g., lignin and cellulose) more efficiently, thus promoting soil organic carbon mineralization and nutrient release [51]. This process not only improves soil carbon and nitrogen sequestration capacity but also may enhance the stability of soil aggregates and further improve soil structure through the expansion of fungal mycelial networks [52], and this result confirms the scientific hypothesis of study 2. However, the long-term ecological effects of microbial community transition from bacterial to fungal types, such as functional complementarity between fungi and bacteria in nutrient cycling, bacterial dominance accelerating nutrient mineralization, and fungal dominance increasing stability, may affect the soil ecosystem’s multifunctionality [53,54]. There are inherent limitations in inferring shifts in soil microbial community composition based solely on MBC/MBN ratios. Future studies should validate these inferences with metagenomic data, as fungal dominance may vary with straw quality and climatic conditions [55].

4.3. Effects of Straw Return on Soil Microbial Quotient and Soil Microbial Stoichiometry

Soil microbial quotient is the ratio of soil carbon, nitrogen and other elements in soil microbial biomass, and it is a sensitive indicator to characterize changes in soil organic matter and nutrient cycling [56,57]. In the process of the soil organic carbon cycling, the soil microbial quotient amount of carbon (MBC/SOC) is an important indicator for assessing soil health and reflecting the microbial uptake of carbon [58], and a larger ratio indicates a higher degree of soil health and a more active microbial community [17]. Soil microbial quotient nitrogen (MBN/TN) indicates the proportion of nitrogen in the soil bound to microbial biomass, reflecting the importance of microbial biomass to the soil nitrogen cycle [59]. Yan et al. [60] showed that traditional agricultural production causes a decrease in soil microbial biomass carbon and nitrogen in black soils, which in turn reduces soil microbial entropy. But the results of this study indicated that straw return significantly affected soil microbial quotient carbon in the tillage layer, and MBC/SOC showed an increasing and then decreasing trend with the increase of soil depth and reached the peak value within the soil layer of 10–40 cm, indicating that straw return provides a better environment for soil microbial activities and that there is a positive effect between the two, which promotes the accumulation of soil organic matter, which is consistent with the results of the study by Song [48]. In addition, soil microbial entropic nitrogen (MBN/TN) showed a tendency to increase gradually with the deepening of the soil layer, which may be attributed to the scarcity of SOC and TN in the deeper soils, and the microorganisms overcame the imbalance between organic matter stoichiometry by adjusting their own biomass [19]. Soil microbial stoichiometric imbalance can reflect microbial adaptation to soil nutrient fluctuations and the relationship between the two in the synergistic regulation of nutrient dynamic balance in ecosystems [61]. Zhou et al. [18] demonstrated that the larger the value of soil microbial stoichiometric imbalance, the worse the quality of the soil, and the lower the growth and utilization efficiency of microorganisms. In this study, the soil microbial stoichiometric imbalance values of the straw-returned methods were found to be smaller than those of the no-returned methods, suggesting that straw returned for several years improved soil quality and increased microbial growth and utilization efficiencies, which confirmed the scientific hypothesis of the present study 3. The soil microbial stoichiometric imbalance was minimized under NTS, while there was no significant difference between DTS and NTS, indicating that the two straw-returning methods, deep tilling and no-tillage, were effective in balancing synergistic changes between the carbon and nitrogen contents associated with soil microbial systems of the black-soil farmland.

4.4. Effect of Straw Return on Maize Yield in Black Soil Farmland

Tillage methods influence maize yield and nutrient accumulation through multiple mechanisms [62]. The 7-year study demonstrates that continuous straw return practices, particularly deep tillage with straw return (DTS) and no-tillage with straw return (NTS), significantly enhance maize yield through multiple interconnected mechanisms. In terms of soil structure, 7 years of straw return improved soil physical properties, with DTS significantly reducing bulk density (by 5.5–8.4%) and increasing porosity (by 4.9–7.0 percentage points) in the 0–60 cm soil layer, consistent with findings by Blanco-Canqui et al. [63] regarding enhanced soil aggregate stability under long-term straw management. In terms of soil fertility, 7 years of straw return substantially elevated soil organic carbon (SOC) and total nitrogen (TN) contents, with DTS showing 34.7% higher SOC in the 10–40 cm layer compared to conventional tillage (CT), aligning with long-term experiments by West et al. [64]. In terms of soil microbes, continuous straw return stimulated microbial activity, increasing microbial biomass carbon (MBC) and nitrogen (MBN) by 45.4% and 33.5%, respectively, over CT after 7 years, corroborating Geissler’s [65] observations on microbial substrate availability under sustained organic inputs. Results from a long-term positioned experiment (initiated in 2018) in Heilongjiang Province’s black soil region show that both straw incorporation and reduced-till mulching significantly increased corn yield compared to conventional tillage with straw removal [66]. It is basically consistent with the results of this study. However, from the perspective of the structural equation model (SEM), we predicted the possible mechanisms for the increase in the yield of DTS and NTS. It was constructed by integrating various soil indicators from the 0–40 cm soil layer under different straw return methods, elucidating a sequential pathway where enhanced soil fertility promoted microbial properties, which in turn facilitated carbon and nitrogen sequestration, ultimately leading to improved soil quality that determined maize yield (explanatory degree 79%). These findings corroborate the studies by Chao et al. [67] and Xu et al. [68] on the synergistic improvement of soil health and crop productivity through straw return. Notably, although both DTS and NTS demonstrated yield improvements through this pathway, Pittelkow et al. [69], through meta-analysis, emphasize the importance of considering regional adaptability, as climatic factors may influence the effectiveness of different straw return methods in the topsoil layer. These context-specific yield responses to tillage and straw management are constrained by climatic and regional factors and further limited by the use of a single maize genotype and fixed fertilization regime in this study. Therefore, subsequent studies should incorporate diverse genotypes and graduated input levels to validate the transferability of these management practices across heterogeneous agroecosystems.

5. Conclusions

Long-term straw return, particularly through deep tillage (DTS) and no-tillage with straw to the field (NTS) methods, significantly enhances soil quality and maize yield in black soil farmland. DTS optimally improves soil physical structure by reducing bulk density and increasing porosity, while both deep tillage and no-tillage methods elevate soil organic carbon, nitrogen content, and microbial activity, fostering nutrient sequestration, improving soil quality, and ultimately increasing crop yield. For agricultural practice, maize production in black soil areas recommended to alternate the use of deep tillage and no-tillage to balance soil nutrients, improve the structure of the plow layer, and achieve the dual effects of soil protection and utilization. Future research should explore the long-term ecological impacts of microbial community shifts and the regional adaptability of these methods under varying climatic conditions to refine sustainable management strategies.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy15071664/s1, Figure S1: Solar radiation, daily average temperature and total precipitation during the maize growing season in 2018 to 2024.

Author Contributions

Conceptualization, M.R., Z.W., X.Z., and Z.L.; methodology, Z.W., X.Z., Z.L., and L.B.; software, L.B., T.W., and H.L.; validation, Z.C., T.W., and Y.Z.; formal analysis, M.R., L.B., Z.C., and T.M.; investigation, L.L., F.L., T.W., Y.Z., H.L., and T.M.; resources, Z.C., T.W., and L.B.; data curation, M.R., Z.C., T.M., and Y.Z.; writing—original draft preparation, M.R., H.L., L.L., and F.L.; writing—review and editing, Z.W., X.Z., Z.L., and L.B.; visualization, M.R., Z.C., Y.Z., and T.M.; supervision, T.W., Y.Z., L.L., F.L., and H.L.; project administration, Z.W., X.Z., Z.L., L.B., L.L., F.L., and T.M.; funding acquisition, X.Z. and Z.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Black Soil High-Quality Conservation Standard System Project, grant number NMGGZLBZTX-02; National Key Research and Development Program Projects, grant number 2022YFD1500703-03; National Natural Science Foundation of China, grant number 32060450; Inner Mongolia Agricultural and Livestock Innovation Fund, grant number 2023CXJJN18; National Natural Science Foundation of China, grant number 32460534; and National Key Research and Development Program Projects, grant number 2022YFD1500902-04.

Data Availability Statement

The data reported in this study are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Agronomy 15 01664 g001
Figure 1. Effect of tillage methods on soil organic carbon (SOC), total nitrogen (TN) and carbon-to-nitrogen ratio in different soil horizons. Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
Figure 1. Effect of tillage methods on soil organic carbon (SOC), total nitrogen (TN) and carbon-to-nitrogen ratio in different soil horizons. Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
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Figure 2. Effect of tillage methods on microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and microbial biomass carbon to nitrogen (MBC/MBN) ratio in different soil horizons. Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
Figure 2. Effect of tillage methods on microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and microbial biomass carbon to nitrogen (MBC/MBN) ratio in different soil horizons. Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
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Figure 3. Effect of tillage methods on soil stoichiometric imbalance ratios in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
Figure 3. Effect of tillage methods on soil stoichiometric imbalance ratios in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
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Figure 4. Structural equation modeling (SEM) of the effect of tillage methods on the structure, fertility, microbiology, nutrient sequestration, soil quality and maize yield of black soils under straw return. Note: (1) The values next to the arrows represent standardized path coefficients; * indicates significances of * p < 0.05, ** p < 0.01, *** p < 0.001. (2) Red represents positive correlation, blue represents negative correlation, solid lines indicate significant correlations, dashed lines indicate non-significant correlations, and the thickness of the line represents the magnitude of the path coefficient.
Figure 4. Structural equation modeling (SEM) of the effect of tillage methods on the structure, fertility, microbiology, nutrient sequestration, soil quality and maize yield of black soils under straw return. Note: (1) The values next to the arrows represent standardized path coefficients; * indicates significances of * p < 0.05, ** p < 0.01, *** p < 0.001. (2) Red represents positive correlation, blue represents negative correlation, solid lines indicate significant correlations, dashed lines indicate non-significant correlations, and the thickness of the line represents the magnitude of the path coefficient.
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Table 1. Physical and chemical properties of 0–60 cm soil layer before the test started in 2018.
Table 1. Physical and chemical properties of 0–60 cm soil layer before the test started in 2018.
Soil Initial PropertiesSoil Depth (cm)
0–10 cm10–20 cm20–40 cm40–60 cm
SBD (g cm−3)1.401.421.421.44
SOC (g kg−1)19.2517.3713.1513.28
TN (g kg−1)1.951.921.430.74
AP (mg kg−1)47.922.37.710.4
AK (mg kg−1)62.741.338.732.2
pH (H2O)7.978.058.108.29
SBD: soil bulk density; SOC: soil organic carbon; TN: total nitrogen; AP: available phosphorus; AK: available potassium; pH (H2O): pH value, soil: water ratio, 1:5.
Table 2. Design of field experiments with different tillage methods under straw return to field.
Table 2. Design of field experiments with different tillage methods under straw return to field.
Tillage MethodsField-Specific Implementation Plan
Deep tillage with straw to the field (DTS)After the maize harvest, all the stalks are crushed and returned to the field, the soil is deeply tilled (tillage depth 30–35 cm), the soil is re-harrowed in the spring of the following year, and then maize is sown.
Deep harrow with straw return to the field (DHS)After the maize harvest, all the stalks are crushed and returned to the field, and then the soil is re-harrowed 2 times (re-harrowing depth of 10–15 cm) in the spring of the following year, and then the maize is sown.
Rotary tillage with straw return to the field (RTS)After the maize harvest, all the stalks are crushed and returned to the field, and then the soil is harrowed twice by rotary plowing (rotary plowing depth of 10–15 cm), and the soil is re-harrowed in the spring of the following year, and then the maize is sown.
No tillage with straw return to the field (NTS)After the maize harvest, all the stalks are crushed and evenly covered on the surface to be returned to the field; no-till seeders are used directly in the spring of the following year to complete sowing, fertilization and compaction.
Conventional tillage with straw removal (CT)After the maize harvest, all the stalks are removed, the soil is shallowly turned (tillage depth 15–20 cm), the soil is re-harrowed in the spring of the following year, and then the maize is sown.
Table 3. The amount of post-harvest straw returned in different tillage methods from 2018 to 2024.
Table 3. The amount of post-harvest straw returned in different tillage methods from 2018 to 2024.
YearsTillage Methods (kg·ha−1)
DTSDHSRTSNTS
20189586.7210,608.889827.759912.26
201910,789.7610,661.049581.059517.37
202012,093.0512,355.0112,116.599940.43
202113,599.9211,222.9112,134.2610,247.58
202213,705.6912,913.5312,851.9910,521.00
202313,365.8012,306.3111,490.4211,152.77
DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field.
Table 4. Effect of tillage methods on soil bulk density and porosity in the 0–60 cm soil layer.
Table 4. Effect of tillage methods on soil bulk density and porosity in the 0–60 cm soil layer.
IndexDepth (cm)Tillage Methods
DTSDHSRTSNTSCT
Soil bulk density
(g·cm−3)		0–10 cm1.09 ± 0.02 c1.16 ± 0.01 b1.10 ± 0.01 c1.21 ± 0.02 a1.19 ± 0.01 a
10–20 cm1.21 ± 0.01 c1.28 ± 0.01 b1.29 ± 0.01 b1.37 ± 0.02 a1.28 ± 0.03 b
20–40 cm1.26 ± 0.02 d1.31 ± 0.02 c1.35 ± 0.03 b1.40 ± 0.01 a1.37 ± 0.02 ab
40–60 cm1.30 ± 0.02 c1.34 ± 0.02 c1.32 ± 0.02 c1.42 ± 0.02 a1.38 ± 0.02 b
Soil porosity
(%)		0–10 cm58.89 ± 1.03 a55.01 ± 0.55 bc56.21 ± 0.83 b50.81 ± 0.78 d52.88 ± 0.80 c
10–20 cm55.91 ± 0.51 a50.77 ± 0.76 bc50.95 ± 0.64 b47.01 ± 0.83 d48.91 ± 0.75 c
20–40 cm52.11 ± 0.90 a47.55 ± 0.54 b48.00 ± 0.72 b45.77 ± 0.21 c47.22 ± 0.68 b
40–60 cm50.58 ± 0.52 a44.63 ± 0.63 b45.66 ± 1.03 b45.01 ± 0.95 b44.45 ± 1.03 b
Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
Table 5. Effect of tillage methods on microbial quotient of soil in 0–60 cm soil layer.
Table 5. Effect of tillage methods on microbial quotient of soil in 0–60 cm soil layer.
IndexDepth (cm)Tillage Methods
DTSDHSRTSNTSCT
Soil microbial quotient MBC/SOC
(%)		0–10 cm1.20 ± 0.05 a1.08 ± 0.01 b1.11 ± 0.02 b1.08 ± 0.04 b0.93 ± 0.01 c
10–20 cm1.52 ± 0.03 a1.29 ± 0.02 b1.46 ± 0.06 a1.48 ± 0.05 a1.23 ± 0.04 b
20–40 cm1.42 ± 0.05 ab1.25 ± 0.05 c1.36 ± 0.02 b1.47 ± 0.03 a1.06 ± 0.03 d
40–60 cm1.26 ± 0.02 a1.11 ± 0.03 c1.09 ± 0.03 b1.11 ± 0.02 b0.93 ± 0.02 d
Soil microbial quotient MBN/TN
(%)		0–10 cm1.51 ± 0.03 a1.44 ± 0.07 b1.40 ± 0.04 bc1.35 ± 0.04 c1.23 ± 0.03 d
10–20 cm1.84 ± 0.01 a1.81 ± 0.06 ab1.84 ± 0.05 a1.85 ± 0.06 a1.71 ± 0.07 b
20–40 cm2.08 ± 0.06 a1.81 ± 0.02 c1.91 ± 0.08 bc1.99 ± 0.02 b1.74 ± 0.06 d
40–60 cm2.34 ± 0.04 a2.14 ± 0.05 b2.15 ± 0.10 b2.10 ± 0.05 c1.90 ± 0.06 d
Data are expressed as the mean ± SE. Lower case letters indicate statistical differences (p < 0.05) between different tillage methods in the 0–60 cm soil layer. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
Table 6. Effect of different tillage methods on maize yield (2018–2024).
Table 6. Effect of different tillage methods on maize yield (2018–2024).
YearsTillage Methods (kg·ha−1)
DTSDHSRTSNTSCT
20187514.79 ± 52.79 c8440.47 ± 120.05 a7115.04 ± 95.07 d7921.03 ± 62.48 b7998.76 ± 13.68 b
20198952.35 ± 107.06 a9169.41 ± 192.15 a8329.82 ± 118.88 b7836.04 ± 92.43 c7885.40 ± 103.30 c
20209843.05 ± 207.67 a9561.35 ± 176.22 b9719.92 ± 157.71 ab8245.16 ± 63.35 c8102.96 ± 50.26 c
202110,477.06 ± 254.58 a9117.25 ± 318.43 c9784.26 ± 154.46 b8779.49 ± 314.44 cd8348.90 ± 49.16 d
202210,301.51 ± 182.39 a9261.72 ± 292.12 b9594.61 ± 287.04 b9240.28 ± 293.81 b8552.92 ± 115.10 c
202310,469.52 ± 385.82 a9469.56 ± 456.28 b9613.56 ± 179.48 b9622.30 ± 173.35 b8679.86 ± 126.51 c
202410,635.75 ± 90.68 a9756.71 ± 143.73 b10,099.87 ± 240.96 b10,087.91 ± 436.02 b8630.14 ± 49.91 c
Average9742.00 ± 1094.359253.78 ± 460.449179.58 ± 1025.628818.89 ± 850.078314.14 ± 312.59
Data are expressed as the mean ± SE. Lower case letters indicate statistically significant differences (p < 0.05) between different tillage methods. DTS: deep tillage with straw return to the field; DHS: deep harrow with straw return to the field; RTS: rotary tillage with straw return to the field; NTS: no tillage with straw return to the field; CT: conventional tillage with straw removal.
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Rong, M.; Wang, Z.; Zhang, X.; Lu, Z.; Bai, L.; Cheng, Z.; Wang, T.; Zhang, Y.; Liang, H.; Meng, T.; et al. Effects of Tillage Methods on Carbon and Nitrogen Sequestration and Soil Microbial Stoichiometric Equilibrium in a Black Soil Farmland with Full Return of Straw to the Field. Agronomy 2025, 15, 1664. https://doi.org/10.3390/agronomy15071664

AMA Style

Rong M, Wang Z, Zhang X, Lu Z, Bai L, Cheng Z, Wang T, Zhang Y, Liang H, Meng T, et al. Effects of Tillage Methods on Carbon and Nitrogen Sequestration and Soil Microbial Stoichiometric Equilibrium in a Black Soil Farmland with Full Return of Straw to the Field. Agronomy. 2025; 15(7):1664. https://doi.org/10.3390/agronomy15071664

Chicago/Turabian Style

Rong, Meiren, Zhigang Wang, Xiangqian Zhang, Zhanyuan Lu, Lanfang Bai, Zhipeng Cheng, Tianhao Wang, Yajing Zhang, Hongwei Liang, Tiantian Meng, and et al. 2025. "Effects of Tillage Methods on Carbon and Nitrogen Sequestration and Soil Microbial Stoichiometric Equilibrium in a Black Soil Farmland with Full Return of Straw to the Field" Agronomy 15, no. 7: 1664. https://doi.org/10.3390/agronomy15071664

APA Style

Rong, M., Wang, Z., Zhang, X., Lu, Z., Bai, L., Cheng, Z., Wang, T., Zhang, Y., Liang, H., Meng, T., Liu, L., & Luo, F. (2025). Effects of Tillage Methods on Carbon and Nitrogen Sequestration and Soil Microbial Stoichiometric Equilibrium in a Black Soil Farmland with Full Return of Straw to the Field. Agronomy, 15(7), 1664. https://doi.org/10.3390/agronomy15071664

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