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Article

Effects of Organic Substitution on the Yield and Quality of Apples and Residual Nitrate-N Leaching in Soil

by
Qian Li
1,
Yanan Chen
1,
Jingdi Zhu
1,
Lizhi Liu
1,
Jian Liu
2,
Chunzhen Cheng
1 and
Lei Li
1,*
1
College of Horticulture, Shanxi Agricultural University, Taiyuan 030031, China
2
Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, 1431 Ås, Norway
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(3), 415; https://doi.org/10.3390/agronomy14030415
Submission received: 28 January 2024 / Revised: 8 February 2024 / Accepted: 9 February 2024 / Published: 21 February 2024
(This article belongs to the Section Horticultural and Floricultural Crops)
Browse Figures
Versions Notes

Abstract

:
The substitution of chemical nitrogen (N) fertilizer with organic fertilizer (organic substitution, OS) is increasingly applied in crop production, due to its environmentally friendly characteristics, low price, and high crop and soil improvement efficacies. Here, we studied the effects of chemical N fertilizer with organic fertilizer treatment at different proportions (no organic substitution (NOS), 20% (OS-20), 40% (OS-40), 60% (OS-60), 100% (OS-100), and 200% (OS-200, double the organic fertilizer application amount of OS-100) on the yield and quality of apples in the Shanxi Province of China. The results revealed that, compared to the NOS, the total apple yields of OS treatments, especially the OS-60 and OS-100 treatments, decreased. However, all OS treatments, except OS-200, increased the yield of large-sized fruits (transverse diameter ≥ 85 mm) and the mean mass of apple fruits, and significantly decreased yield of small-sized fruits (transverse diameter < 75 mm). All OS treatments, especially OS-40, promoted the total sugar and vitamin C (Vc) contents and fruit hardness of apples, and OS-40, OS-60, and OS-200 resulted in significantly decreased titratable acid contents in apples. The influence of organic substitutions on soil quality was further investigated in a two-year field experiment. The results showed that the influence of organic substitution on soil chemical properties differed between the two years. Notably, 40% OS increased the soil organic carbon (SOC) content and the C/N ratio in the upper 20 cm of the soil in both years. Additionally, OS treatments reduced the residual nitrate (NO3−)-N (RN) content in deep soil layers, suggesting that OS has the potential to alleviate N leaching. Moreover, redundancy analysis (RDA) of the soil, fruit yield, and fruit quality parameters revealed that the SOC content in the 0–20 cm soil layer and the RN content in the 0–100 cm soil layer had the greatest impact on the fruit quality and yield variables, respectively. This study showed that the proper substitution (40%) of chemical N fertilizer with organic fertilizer could improve the yield of large-sized fruits, the mean mass and fruit quality of apples, and soil chemical properties. Our study will provide a basis for rational organic substitution in apple orchards.

1. Introduction

In the last 100 years, the application of chemical nitrogen (N) fertilizers has promoted crop production by more than four times and contributed greatly to global crop production and food security [1]. However, excessive chemical N fertilizers that greatly exceeded the normal N requirements of crops were applied by farmers for the purpose of increasing crop productions during the last two decades, resulting in decreased quality and yield of crops and excessive N accumulation in soil. Moreover, excessive N application has strongly affected the absorption of other chemicals and caused a series of environmental pollution problems [2,3,4]. As a result, excessive chemical N has been regarded as one of the most important sources of environmental contaminants. Therefore, optimizing N inputs based on crop N requirements is very necessary to reduce the adverse impacts of N fertilizer overuse [5].
Organic fertilizers are rich in nutrients, diverse organic compounds, and beneficial microorganisms [6]. Accumulating reports revealed that the applications of organic fertilizers could promote soil microbial activities [7], improve the chemical retention capacity of soil [8], increase nitrate accumulation in the root layer, inhibit nitrate movement into the deep soil layer [9], and reduce environmental N losses [10]. However, given that the release period of organic fertilizer is relatively longer than those of most chemical fertilizers [11], it is rarely applied alone, but often as a partial substitute for chemical fertilizers. Currently, the substitution of chemical fertilizer, especially chemical N fertilizer, with organic fertilizer has been regarded as a reasonable fertilization practice, which not only reduces fertilizer input but also improves soil quality and crop quality [12,13]. For example, Zhang et al. [14] reported that a combined 25% N reduction and 4500 kg ha−1 organic fertilizer substitution resulted in the highest yield of peanut. Liu et al. [15] found that a 30% substitution of organic fertilizer could increase maize yield and N utilization efficiency but reduce maize yield when the substitution rate increased to 40%. Huang et al. [16] reported that a 20% reduction in N fertilizer with a 30% organic substitution promoted dry matter accumulation enhanced the physiological resistance of banana seedlings, increased the N fertilizer utilization efficiency, and reduced N pollution. Tong et al. [17] found that a combined application of chemical and organic fertilizers could significantly promote the fruit quality of pecan by increasing the nutrient and enzyme activities in soil.
In China, chemical N fertilizers have been commonly overused (600 to 800 kg ha−1) in apple orchards [18], at a rate of more than four times those in orchards in the United States and West Europe [19]. However, the application amount of organic fertilizer in most apple orchards in China is only approximately 2–15 t ha−1 [20,21], which is far lower than those of high-quality orchards in developed countries (about 50 t ha−1). However, the amount of residual nitrate (NO3−)-N (RN) in the 0–90 cm soil layer of apple orchards in China was much higher than the RN standard (90 kg ha−1) in the European Union [22]. The low levels of organic matter and excessive application of chemical N fertilizers have severely threatened the orchard ecological environment and the sustainable development of apple production [21]. Zhu et al. [21] reported that a 25–55% chemical fertilizer reduction, with increased organic fertilizer substitutions, could improve the fruit quality of apples without reducing apple yield. Yang et al. [23] found that a 50% substitution of N fertilizer with organic fertilizer in the apple orchards in Shaanxi Province increased fruit yield, in addition to improving both fruit and soil quality. Wang et al. [24] found that the application of organic fertilizer could improve fruit quality by increasing the accumulation of soil organic matter and total N. Milosevic et al. [25] found that the application of aged cattle manure could increase the firmness and soluble solid contents of apple fruits. Although there were some reports on the influence of organic substitution on apple fruits and soil quality, research on the influence of organic substitution on the RN accumulation in apple orchards is very limited. Furthermore, given the differences in cropping systems, soil environment, and management practices, the effects of organic substitution in different areas varied greatly. In this study, we investigated the influences of organic substitutions at different proportions on apple yield and quality, as well as on soil chemical properties (including RN). The objectives of this study were to explore the optimal organic substitution proportion and to provide a basis for sound organic fertilizer management in apple production.

2. Materials and Methods

2.1. Experimental Site and Materials

The 15-year-old apple (Malus domestica Borkh. cv. ‘Red Fuji’) trees used in this study were grown in an orchard with 4 m distances between rows and 3 m planting distances within rows in Linyi County, Yuncheng City, Shanxi Province, China (110°77′ E, 35°18′ N). The estimated annual yield of this apple orchard was about 75,000 kg ha−1. This region is located in a northern warm temperate zone with a continental semi-arid monsoon climate, an average annual maximum temperature of 19.7 °C, and an average annual precipitation of 508.7 mm. The baseline physical and chemical properties of the soil at the 0–100 cm soil layer, taken at the beginning of this experiment, are listed in Table S1. The mean monthly precipitation and temperature from 2016 to 2018 are illustrated in Figure S1. The organic fertilizer, used as a base fertilizer, which was composted using sheep manure and discarded apple branches as raw materials, was provided by Shanxi Wanxingyuan Agricultural Development Co., Ltd. (Taiyuan, China). The properties of this organic fertilizer were as follows: pH, 7.1; EC, 6.7 mS cm−1; organic matter, 66.4%; total N, 1.1%; available phosphorus (AP), 0.9%; and available potassium (AK), 0.7%.
Traditional urea (N, 46%) was used as the chemical N fertilizer. Superphosphate (P2O5 16%) and potassium sulfate (K2O 52%) were used as chemical P2O5 and K2O fertilizers, respectively. These chemical fertilizers were purchased from the Shanxi Wanmufeng Fertilizer Industry Co., Ltd. (Jinzhong, China).

2.2. Organic Substitution (OS) Experiements

Organic substitution experiments were conducted from October 2016 to October 2018, using the following treatments: (1) no organic fertilizer substitution (NOS, as control), (2) 20% substitution of the chemical N with organic fertilizer (OS-20), (3) 40% substitution of the chemical N with organic fertilizer (OS-40), (4) 60% substitution of the chemical N with organic fertilizer (OS-60), (5) 100% substitution of the chemical N with organic fertilizer (OS-100), and (6) doubled organic fertilizer application amount of the 100% treatment (OS-200). For each treatment, five apple trees were used. All the apple trees were managed in the same way according to the local farming practices. Based on the total N content of the organic fertilizer, the N equivalence of the organic fertilizer to chemical N fertilizer was assessed, and the total N application amounts for all the six treatments except OS-200 (doubled) were the same (480 kg ha−1, consistent to the local N fertilization rate). For all six treatments, the same amounts of chemical P (120 kg P2O5 ha−1) and K (304 kg K2O ha−1) fertilizers were applied (Table 1). In the second year of the OS experiment, as apple trees experienced severe frost damage, the total fertilization amounts were reduced by 50% but the OS ratios were not changed. All the organic fertilizer, 50% of the chemical N and P2O5 fertilizers, and 25% of the chemical K2O were applied as basal fertilizers in October. The remaining chemical N, P2O5 and K2O fertilizers were applied as follows: 25%, 25%, and 25% for the first topdressing in March, and 25%, 25%, and 50% for the second topdressing in June, respectively. The basal fertilizers were buried in a fertilizer application band (1.0–1.5 m away from the trunk, with length of 1.2 m, depth of ~30 cm and width of ~40 cm) on both sides of the apple tree rows and fully mixed with the 0–30 cm soil depth. The topdressing fertilizers were applied in circle ditches with a radius of 30 cm and a width and depth of 20 cm around each apple tree. The apple trees were watered properly according to soil moisture contents after fertilization.

2.3. Yield Determination and Fruit Grading

In October 2017, the fruits of each apple tree were graded according to their transverse diameters (large-size fruit: diameter ≥ 85 mm, medium-size fruit: fruit diameter between 75 and 85 mm, small-size fruit: diameter ≤ 75 mm). After grading, the weights of large-size, middle-size and small-size apples were individually measured and used for yield calculations. The mean mass of apple fruits was calculated by dividing the total yield by the total number of fruits harvested from each tree. Five replicates were used for determining these variables.

2.4. Determination of Fruit Quality Parameters

Fruits were randomly selected from different parts (upper, middle, lower, inner, and outer) and different directions (east, south, west, and north) of each apple tree for fruit quality determination in October 2017. For each treatment, five biological replicates were used, each of which included 20 fruits from a given tree. Total sugar (TS) content was determined by using Fehling’s reagent reduction method [26]. Titratable acid (TA) content was determined by using the acid–base titration method [27]. The sugar/acid ratio was calculated by dividing the TS content with the TA content. Fruit vitamin C (Vc) content was determined by using the 2,6-dichlorophenol-indophenol titration method [28]. Fruit hardness was assessed by using a GY-1 hardness tester [29]. Ten replicates were used for determining these variables.

2.5. Analyses of Soil Chemical Properties

Soil samples were collected at five depths: 0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm in October 2017 and in October 2018. Five sampling sites, located 1.2–1.5 m away from the tree trunk, were selected in each treatment.
After being air-dried, ground, sieved, and thoroughly mixed, the soil samples were subjected to analyses of physicochemical properties. Soil organic carbon (SOC) and total N (TN) were measured using the potassium dichromate method and Kjeldahl method, respectively. Soil available phosphorus (AP) content was determined by using the modified molybdenum antimony anti-colorimetric method and soil available potassium (AK) by using a flame photometer [30]. Soil NO3−-N was extracted from 5 g of fresh soil with 50 mL of 1 mol L−1 KCl (Sigma-Aldrich, San Louis, MO, USA), and then measured with the hydrazine sulfate colorimetric method using a high-resolution digital colorimeter (AA3, SEAL Company, Darmstadt, Germany) [31]. The soil C and N ratio was calculated as: C/N = SOC / TN. Soil NO3−-N residue content (RN, kg ha−1) was calculated using the formula: RN content = T × B × C × 0.1, where T is the thickness (cm) of a soil layer, B is the soil bulk density (g cm−3), and C is the concentration of soil NO3−-N (mg kg−1) [32].

2.6. Statistical Analyses

The data obtained from the experiments were calculated and presented as the mean ± standard deviation of replicates. A one-way analysis of variance (ANOVA) was used for the variance analysis of the data from the six treatments using Duncan’s method at p < 0.05 and p < 0.01 levels. The OriginPro 2021 software (QriginLab Corporation, Northampton, MA, USA) was used for principal component analyses (PCA). Redundancy analysis (RDA) of fruit yield and quality and soil parameters were performed using the Canoco software (Version 5.0, Microcomputer Power Corporation, Ithaca, NY, USA).

3. Results

3.1. Influences of Organic Substitutions on the Yield and Mean Mass of Apples

After categorizing apples into large-, medium-, and small-size fruits, the yields of large-size, medium-size, small-size, and total fruits were measured (Figure 1A). Although the total yields of all OS treatments were lower than that of the NOS, the yields of large-size fruits in the ‘OS’ treatments (except OS-200) were higher than that in NOS. It is worth noting that the yields of large-size fruits in OS-40, OS-60, and OS-100 were significantly higher than that in the NOS, accounting for approximately 1.51-, 1.62-, and 1.95-fold of the NOS yield, respectively. The yield of medium-size fruits declined with the increasing organic substitution ratios (except OS-200). The NOS treatment had the highest yield (56.8 t ha−1), followed by the OS-200 treatment. Moreover, the yield of the NOS treatment was significantly higher than that of OS-100. Interestingly, the yields of small-size fruits of all OS treatments significantly reduced by 46.7–72.1% compared to the NOS treatment. Among all ‘OS’ treatments (except OS-200), the large-sized apple yields increased as the organic substitution ratio increased, in contrast to the small-size apple yield (Figure 1A).
OS also greatly influenced the mean mass of apple fruits. All the mean mass values of apple fruits of the OS treatments were higher than that of the NOS treatment. Notably, the mean mass of apple fruits from the OS-40 treatment (241.5 g) was significantly higher than that of the NOS treatment (Figure 1B).

3.2. Apple Fruit Quality under Different Organic Substitution Treatments

To investigate the influence of OS on fruit quality, the contents of TS, Vc, and TA in apples were determined in 2017. The results showed that OS significantly increased the TS content in apples (p < 0.05, Table 2). Moreover, the TS content in apples from the OS-200 treatment was significantly higher than in other OS treatments. Compared to the NOS treatment, the TA content in apples from the OS-40, OS-60, and OS-200 treatments decreased by 4.7%, 4.3%, and 7.8%, respectively. The TA content in apples from the OS-200 treatment was significantly lower than in all other treatments. The sugar/acid ratios of apples from the OS-40, OS-60, and OS-200 treatments were significantly higher than that of the NOS treatment (Table 2). The Vc contents in apples from all OS treatments except OS-20 were significantly higher than in the NOS treatment, with the highest Vc content for apples in the OS-40 treatment (Table 2). By determining the hardness of apples from all the six treatments, it was found that the fruit hardness of apples from the OS-100 and OS-200 treatments were significantly higher than in the NOS treatment (Table 2). These results indicated that one-year OS treatment influenced greatly the apple quality.

3.3. Soil Chemical Properties under Different Organic Substitution Treatments

Soil chemical properties were determined in two years after the OS treatments. The results showed that the contents of SOC declined with the increasing soil depth in all the six treatments (Figure 2A,G). In 2017, the SOC content in the upper 40 cm layer of the OS treatments increased significantly compared to that of the NOS treatment (p < 0.05), while no significant difference was identified in the 40–100 cm soil layers among all six treatments. In 2018, the SOC contents in the surface soil (0–20 cm) differed significantly among the six treatments, while no significant difference was observed in other soil layers. The SOC contents in the surface soil of the OS-40 treatment in 2017 and 2018 were both the highest (7.7 g kg−1 and 7.2 g kg−1, respectively). The SOC content in the 0–20 cm layer of all OS treatments increased by 33.5–77.7% in 2017 compared to the NOS treatment. In 2018, however, only the SOC contents in the 0–20 cm layer of the OS-20 and OS-40 treatments were higher than that in the NOS, while the SOC contents in the 0–20 cm layer of OS-60, OS-100 and OS-200 treatments were lower than that of the NOS by 18.1–23.8%.
In 2017, no significant difference in TN content was identified among the six treatments in the upper 40 cm soil layers, while a significant difference was identified in 2018 (Figure 2B,H). In 2018, the highest TN content in the 0–20 cm soil layer was found in the OS-40 treatment, and the TN contents in the 0–20 cm soil layer of the OS-20 and OS-40 treatments were higher than that of NOS by 2.3% and 59%, respectively. However, the TN contents in the 0–20 cm soil layer of the OS-60, OS-100, and OS-200 treatments were lower than in NOS by 18.1%–29.7%. Additionally, the TN content of the NOS treatment was higher than all the OS treatments in the 20–100 cm layers in 2017 and in the 40 cm–100 cm layers in 2018.
The C/N ratios in the soils at different layers were further calculated. Except in the 80–100 cm layer, the C/N ratio of NOS in all other layers was lower than in all the OS treatments in 2017 (Figure 2C). In 2017, in the surface soil (0–20 cm), a significant difference in the C/N ratio was identified among the six treatments, with the highest values in the OS-40 treatment. The C/N ratio in the surface soil of the OS treatments increased by 42.7–77.3% compared to that of the NOS treatment. In 2018, a significant difference in the C/N ratio was identified among the six treatments in the 20–60 cm layers, the C/N ratio in the high OS treatments (OS-60, OS-100, and OS-200) was lower than that of the low OS (OS-20 and OS-40) and NOS treatments, and the C/N ratio of the OS-40 treatment was the highest in all soil layers (Figure 2I).
In 2017, the soil NO3−-N contents in the 60–100 cm layers were higher than in the upper 60 cm layers. In the upper 60 cm soil layers, a significant difference was identified among the six treatments, and the NO3−-N contents in the OS treatments (especially the OS-60 treatment) were higher than in the NOS treatment. In the 60–80 and 80–100 cm soil layers, the NO3−-N content was respectively 83.6 and 71.8 mg kg−1 in the NOS treatment, which were higher than in all the OS treatments. A significant difference was observed among the treatments in the 80–100 cm soil layers (p < 0.05). Compared to the NOS treatment, the NO3−-N content in the 80–100 cm soil layer of the OS treatments decreased by 32.7–52.5% (Figure 2D). In 2018, significant differences were identified among the six treatments in the 40–60 cm and 60–80 cm layers. The NO3−-N content in the 60–80 cm soil layer of the NOS treatment was significantly higher than in all OS treatments by 62.2–80.4% (Figure 2J).
In 2017, OS also significantly influenced the AP content in all soil layers except the 60–80 cm layer (Figure 2E). In the 0–20 cm soil layer, the highest AP content was found in the OS-40 treatment (14.2 mg kg−1), accounting for 1.24–1.65 times that in the other treatments. Moreover, the AP contents in the OS-100 and OS-200 treatments were both lower than in the NOS treatment (by 31.9% and 14.1%). In the 20–40 cm soil layer, the AP content in the NOS treatment was higher than in the OS treatments (by 9.6–62.9%). In 2018, a significant difference was identified among all the six treatments only in the 0–20 cm soil layer, and the AP content in the NOS treatment was higher than in the OS treatments by 26.7–75.2% (Figure 2K).
In 2017, the AK content in the soil of all treatments declined with the increasing soil depth, and significant differences were identified in the 40–80 cm soil layers among all the six treatments (Figure 2F). In the surface soil (0–20 cm), the AK content in the OS treatments increased by 9.5–20.5% compared to the NOS treatment (178.4 mg kg−1). In 2018, significant differences were identified in the 0–40 cm and 60–80 cm soil layers among all six treatments. The AK content in the 0–20 cm soil of the OS-60 treatment (346.3 mg kg−1) was found to be the highest among all treatments (Figure 2L). Additionally, the AK content in the 60–80 cm soil layer of the OS-100 treatment was the highest and significantly higher than in the other treatments in both 2017 and 2018.

3.4. Soil RN under Different Organic Substitution Treatments

The RN contents in the soil of different treatments were determined. The results showed that the RN contents of the 40–100 cm soil layers were higher than those of 0–40 cm in both years, and the RN in the 40–100 cm layer in 2018 was higher than that in 2017, indicating that RN in different treatments obviously migrated downward (Figure 3). In 2017, the RN contents in the 0–20 cm soil layer of the OS-20, OS-60, and OS-200 treatments were higher than in the NOS treatment, and a significant difference was identified only between OS-60 and NOS. In 2018, no significant difference was identified among all treatments in the 0–20 cm soil layer, but the RN content in the OS-200 treatment was found to be higher than in the NOS treatment (Figure 3A). In 2017, the RN contents in the 20–40 cm soil layer of all the OS treatments were higher than in the NOS treatment (accounting for about 1.3-fold to 2.5-fold of the NOS treatment), and significant differences were identified between OS-60 and NOS, and between OS-200 and NOS. Interestingly, in 2018, the RN contents in the 20–40 cm soil layer of the OS-60 and OS-200 treatments were significantly lower than in the NOS treatment, while the contents in the OS-20, OS-40, and OS-100 treatments were higher than that in NOS (Figure 3B). The RN contents in the 40–60 cm soil layers of all the OS treatments were higher than in the NOS treatment, accounting for about 1.1-fold to 1.9-fold in 2017. In 2018, except OS-200, the RN contents in all the OS treatments were higher than that in the NOS treatment, accounting for about 1.3-fold to 3.4-fold of NOS (Figure 3C). The RN contents of the OS-20 and OS-100 treatments were significantly higher than in the NOS treatment. In the 60–80 cm and 80–100 cm soil layers, the RN contents in all OS treatments except the OS-20 treatment in 80–100 cm in 2018 were lower than that in the NOS treatment in both years (Figure 3D,E). In the 0–100 cm soil layer, the highest RN contents were found in the NOS treatment with 618.1 kg ha−1 and 658.3 kg ha−1 in 2017 and 2018, respectively. Compared to the NOS treatment, the RN contents of all the OS treatments decreased by 43.0–71.8% in 2017, and by 36.6–49.4% in 2018 (Figure 3F).

3.5. PCA and RDA Analysis of Soil Chemical Properties, and Fruit Quality and Yield Parameters at One Year Post OS Treatments

A PCA analysis of fruit quality and yield parameters in different organic substitution treatments explained 84.6% on the first two principals (Figure 4A). Some fruit quality parameters, such as the sugar/acid ratio, fruit hardness, and contents of TS and Vc, were positively correlated with the OS treatments (except OS-20) but negatively correlated with the NOS and OS-20 treatments, while the TA content was negatively correlated with the OS treatments (except OS-20) and positively correlated with the NOS and OS-20 treatments. The yield parameters, including the yield of medium-size fruits, total yield, and yield of small-size fruits, were positively correlated with the NOS and OS-20 treatments, while the mean fruit mass and yield of large-size fruits were negatively correlated with NOS and OS-20 treatments. Moreover, the total yield and yield of medium-size fruits were found to be positively correlated with OS-40 and OS-200 treatments. These results indicated that organic substitution resulted in significant apple fruit quality and yield changes.
The redundancy analysis (RDA) was conducted to reveal the impacts of soil chemical properties on fruit quality parameters and yield parameters in 2017 (Figure 4B,C). The RDA between the fruit quality parameters and soil chemical properties showed the first two principals of RDA accounted for 99.9% of the total variation in the fruit quality (RDA1 = 95.8%, RDA2 = 4.1%) (Figure 4B). The SOC content in the 0–20 cm soil layer, RN content in the 40–60 cm soil layer, and AP content in 40–60 cm soil layer were identified to be the three main environmental factors that significantly affected the fruit quality parameters (p < 0.05). The SOC content in the 0–20 cm soil layer, positively correlated with the fruit quality parameters (except TA), had the greatest impact on the fruit quality parameters, with an explanation rate of up to 72.8% (Figure 4B).
The RDA between the yield parameters with soil chemical properties showed that the first and second axis of the RDA explained 52.4% and 23.4% of all variations, respectively. The RN content in the 0–100 cm soil layer was the most influential factor (explaining 45.2% of the variations of yield related parameters) followed by the AK content in the 80–100 cm soil layer (explanation rate = 28.4%). The RN content in the 0–100 cm soil layer was negatively correlated with the total yield, yield of large-size fruits and the medium-size fruits, and the mean mass of apple fruits, but positively correlated with the yield of small-size fruits (Figure 4C).

3.6. PCA Analysis of Soil Chemical Properties of Differencet Soil Layers

The PCA analysis was employed to visualize the correlations between the soil chemical properties and the treatments in different soil layers. The PCA results revealed that 71.4%, 75.9%, 78.5%, 64.3%, and 73.7% of the variation in the 0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm soil layers could be explained by the first two axes, respectively (Figure 5). In the upper 40 cm soil layer, compared to 2017, the scattering degree of the OS treatments increased in 2018, indicating that organic fertilizer began to show a greater impact on the 0–40 cm soil layer in 2018 (Figure 5A,B). The distance between the OS-40 treatments in 2017 and in 2018 was smaller than in other OS treatments, indicating the soil chemical properties of the OS-40 treatment were more stable than in other treatments (Figure 5A–E). Additionally, the SOC content and C/N ratio in the 0–20 cm and 20–40 cm soil layers were positively correlated with component coordinates of the OS-40 treatment in both years (Figure 5A,B). The PCA of the RN content in different soil layers of different treatments explained 80.7% of the first two principals (Figure 5F). The RN content in the upper 60 cm soil layers was positively correlated with the OS treatments, while that in the 60–100 cm soil layer was positively correlated with the NOS treatment. Moreover, the RN content in the 0–100 cm soil layer was identified to be positively correlated with the NOS treatment but negatively correlated with all the OS treatments in both years.

4. Discussion

4.1. Organic Substitution Increased the Yield of Large-Size Fruits and Apple Quality at One Year Post Treatment

The amount of available nutrients greatly influences the yield of apples. Given chemical fertilizers can quickly provide available nutrients to apples, they have been widely used as the main nutrient source in apple orchards in China [33]. Recently, accumulated evidence has revealed that organic fertilizer substitution has great promoting effects on crop yield and fruit quality, because additions of organic fertilizers can supply organic matter and a variety of nutrients into the soil [34,35,36]. Consistently, in our present study, we found that the organic substitution improved apple quality indicators, including TS and Vc contents, sugar/acid ratio, and fruit hardness. Moreover, our study showed that high organic substitution ratios (60% and 100%) significantly reduced apple yield, which might be caused by the lack of synchronization between plant nutrient requirements and organic fertilizer nutrients release [37,38] and the suppressed symbiosis relationship between plants and soil microorganisms [39,40]. Additionally, under field conditions, crop growth relies mainly on available mineral nutrients, making a high organic substitution not ideal for increasing crop yields in the short term [41]. Although 200% organic substitution could improve the apple yield further than other OS treatments, it is not a cost-efficient fertilization plan for farmers. Notably, our study also found that 40% organic substitution significantly increased the yield of large-size fruits and the mean mass of apple fruits, and significantly reduced the yield of small-size fruits. Thus, considering both economic and environmental consequences, the 40% organic substitution is recommended in the apple orchard we studied. It is a pity that, due to the severe frost damage, the apple production was very low in 2018; thus, the effect of OS on apple yield and quality were not investigated. In the future, long-term experimental research is still needed to better demonstrate the effects of OS on apple yield and quality.

4.2. Organic Substitution Improved Soil Quality in Apple Orchards

Accumulated evidence revealed that organic fertilizers could improve soil structure, C input, and sequestration, stimulate microbial activity, and enhance the nutrient availability [42]. Chemical fertilizer substitution with organic fertilizer may adjust the C and N ratio in agricultural soils [43] and lead to better synchronization of crop N demand and N input, thus improving N fertilizer utilization efficiency and alleviating N losses [44]. The application of organic fertilizers could elevate the SOC due to the adequate contact between soil organic materials, microbes, and enzymes accelerating the organic matter decomposition [45,46,47]. Our study found that OS at all ratios could increase the SOC in 2017, but the SOC contents in high organic substitution ratio treatments (60%, 100%, and 200%) were found to be lower than in the low OS and NOS treatments in 2018. This can be explained by the fact that a high proportion of organic C inputs will increase greenhouse gas emissions, which will lead to instability in the SOC content [48]. Hou et al. [49] reported that the 0–20 cm soil layer is an effective depth for the simultaneous detection of soil fertility changes during apple production. Our study showed that the content of some soil chemical properties (especially SOC and C/N) of the 0–20 cm soil layer of the OS-40 treatment were the highest in both years, indicating that the OS-40 treatment could increase the SOC content and C/N ratio and also improve the stability of soil chemical properties in the upper 20 cm of the soil. We also found that the AP contents in the 0–20 cm soil layer of all OS treatments were lower than in the NOS treatment in 2018, indicating that the organic fertilizer application increased the downward migration of P in the soil profile [50].
Liang et al. [51] discovered that the application of organic fertilizer could achieve the purpose of improving fruit quality by modulating the balance of soil chemical properties. Consistently, our RDA analysis showed that the SOC content in the 0–20 cm soil layer had the greatest impact on the fruit quality parameters. These results indicated that organic substitution could improve the soil SOC and further improve the fruit quality.

4.3. Organic Substitution Reduced soil RN Leaching

Inorganic N in soil mainly exists in the form of ammonium N (NH4+-N) and NO3−-N. Due to the rapid conversion and easy-leaching characteristic of NO3−-N, the average utilization rate of N fertilizer is generally less than 40% [52]. Organic fertilizer can temporarily immobilize mineral N in the soil and contribute to reduced leaching losses by providing chemicals to N cycling-related soil microbial communities [53]. Chemical N fertilizer reduction combined with organic fertilizer could improve N fertilizer utilization and significantly reduce soil NO3−-N content in the depth of 0–180 cm [54]. Our study found that compared to NOS, organic substitutions increased the NO3−-N content in the 0–60 cm soil layers in 2017 and in the 40–60 cm soil layer in 2018, but decreased the RN content in the 60–100 cm layers in both 2017 and 2018, indicating that organic substitution has a potential to improve NO3−-N utilization efficiency in the root absorption zone and reduce the RN leaching into deep soils. The RN content in the 0–20 cm soil layer in 2018 was found to be lower than that in 2017, which might be explained by that the greater amount of precipitation in 2018 which accelerated nitrate leaching. Additionally, our RDA result revealed that the RN content in the 0–100 cm soil, negatively correlated with the yield of large-size fruit and the mean mass of apple fruits, was the most important environmental variable explaining the majority of apple yield variables. Furthermore, we found that organic substitutions could significantly reduce the RN content in 0–100 cm, suggesting that the organic substitution could improve the yield of large-size fruits by reducing the RN leaching in the soil.

5. Conclusions

Based on the results obtained in this study, a model describing the influences of organic substitution on the quality and yield of apples and leaching of residual NO3−-N could be summarized (Figure 6): Organic substitution with various substitution ratios considerably affected apple yield and quality indicators, as well as SOC and soil RN. Notably, organic substitution (especially the OS-40 treatment) significantly improved the yield of large-size fruits and the mean mass of apple fruits but reduced the yield of small-size fruits. Our two-year field experiments revealed that different proportions of organic substitution have different effects on the soil chemical properties. Notably, 40% organic substitution can improve and stabilize the SOC content and C/N ratio in the 0–20 cm soil layer, maintain soil NO3−-N in the root zone, and alleviate RN leaching. Our study also found that the SOC content in the 0–20 cm soil layer and the RN content in the 0–100 cm soil had, respectively, the most important impact on the fruit quality and yield parameters, indicating that organic substitution could improve apple fruit quality by increasing the SOC of the surface soil (0–20 cm) and increase the yield of large-size fruits and the mean mass of apple fruits by declining the leaching of RN. Additionally, in consideration of economic and environmental consequences, a proper ratio of organic fertilizer and chemical fertilizer (40% for the present study) is recommended for apple orchards.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy14030415/s1, Table S1: Physical properties for the soil in the apple orchard we studied before organic substitution treatments. Figure S1: The mean monthly rainfall and temperature from 2016 to 2018.

Author Contributions

Conceptualization, L.L. (Lei Li); methodology, L.L. (Lei Li) and C.C.; software, Q.L. and Y.C.; validation, Q.L., J.Z., and L.L. (Lizhi Liu); formal analysis, J.Z. and L.L. (Lizhi Liu); investigation, Y.C.; resources, L.L. (Lei Li); data curation, Q.L. and L.L. (Lizhi Liu); writing—original draft preparation, Q.L., Y.C. and J.L.; writing—review and editing, L.L. (Lei Li); visualization, L.L. (Lei Li); supervision, L.L. (Lei Li); project administration, L.L. (Lei Li); funding acquisition, L.L. (Lei Li). All authors have read and agreed to the published version of the manuscript.

Funding

This study was funded by the Basic Research Program of Shanxi (202103021223161) and the earmarked fund for Modern Agro-industry Technology Research System of Shanxi Province (2023CYJSTX07-15).

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Hou, P.F.; Deng, X.Z.; Wang, J.; Xue, L.X.; Zhang, Y.S.; Xu, T.T.; Xue, L.H.; Yang, L.Z. Fertilization and global warming impact on paddy CH4 emissions. Int. J. Environ. Res. Public Health 2023, 20, 4680. [Google Scholar] [CrossRef]
  2. Hossain, M.E.; Mei, X.; Zhang, W.; Dong, W.; Yan, Z.; Liu, X.; Rachit, S.; Gopalakrishnan, S.; Liu, E. Substitution of chemical fertilizer with organic fertilizer affects soil total nitrogen and its fractions in northern China. Int. J. Environ. Res. Public Health 2021, 18, 12848. [Google Scholar] [CrossRef]
  3. Ju, X.T.; Xing, G.X.; Chen, X.P.; Zhang, S.L.; Zhang, L.J.; Liu, X.J.; Cui, Z.L.; Yin, B.; Christie, P.; Zhu, Z.L.; et al. Reducing environmental risk by improving N management in intensive Chinese agricultural systems. Proc. Natl. Acad. Sci. USA 2009, 106, 3041–3046. [Google Scholar] [CrossRef]
  4. Chen, M.; Shao, M.A.; Wei, X.; Li, T.; Shen, N.; Mi, M.; Zhao, C.; Yang, X.; Gan, M.; Bai, X.; et al. Response of the vertical distribution of soil water and nitrogen in the 5 m soil layer to the conversion of cropland to apple orchards in the Loess Plateau, China. Agric. Ecosyst. Environ. 2022, 333, 107960. [Google Scholar] [CrossRef]
  5. Schröder, J.J. The position of mineral nitrogen fertilizer in efficient use of nitrogen and land: A review. Nat. Res. 2014, 5, 936–948. [Google Scholar] [CrossRef]
  6. De Corato, U. Agricultural waste recycling in horticultural intensive farming systems by on-farm composting and compost-based tea application improves soil quality and plant health: A review under the perspective of a circular economy. Sci. Total Environ. 2020, 738, 139840. [Google Scholar] [CrossRef] [PubMed]
  7. Li, R.; Tao, R.; Ling, N.; Chu, G.X. Chemical, organic and bio-fertilizer management practices effect on soil physicochemical property and antagonistic bacteria abundance of a cotton field: Implications for soil biological quality. Soil Tillage Res. 2017, 167, 30–38. [Google Scholar] [CrossRef]
  8. Mi, W.H.; Sun, Y.; Xia, S.Q.; Zhao, H.T.; Mi, W.T.; Brookes, P.C.; Liu, Y.L.; Wu, L.H. Effect of inorganic fertilizers with organic amendments on soil chemical properties and rice yield in a low-productivity paddy soil. Geoderma 2018, 320, 23–29. [Google Scholar] [CrossRef]
  9. Ma, C.; Liu, Y.; Liang, L.; Nian, Z.; Zhang, H.; Wang, Z. Effects of combined application of chemical fertilizer and organic manure on wheat yield and leaching of residual nitrate-N in dryland soil. J. Appl. Ecol. 2018, 29, 1240–1248. [Google Scholar] [CrossRef]
  10. Zhang, M.; Yao, Y.L.; Tian, Y.H.; Ceng, K.; Zhao, M.; Zhao, M.; Yin, B. Increasing yield and N use efficiency with organic fertilizer in Chinese intensive rice cropping systems. Field Crops Res. 2018, 227, 102–109. [Google Scholar] [CrossRef]
  11. Garzón, E.; González-Andrés, F.; García-Martínez, V.M.; DE Paz, J.M. Mineralization and nutrient release of an organic fertilizer made by flour, meat, and crop residues in two vineyard soils with different pH levels. Commun. Soil Sci. Plant Anal. 2011, 42, 1485–1496. [Google Scholar] [CrossRef]
  12. Kamran, M.; Huang, L.; Nie, J.; Geng, M.; Lu, Y.; Liao, Y.; Zhou, F.; Xu, Y. Effect of reduced mineral fertilization (NPK) combined with green manure on aggregate stability and soil organic carbon fractions in a fluvo-aquic paddy soil. Soil Tillage Res. 2021, 211, 105005. [Google Scholar] [CrossRef]
  13. Huang, R.; Wang, Y.; Liu, J.; Gao, J.; Zhang, Y.; Ni, J.; Xie, D.; Wang, Z.; Gao, M. Partial substitution of chemical fertilizer by organic materials changed the abundance, diversity, and activity of nirS-type denitrifying bacterial communities in a vegetable soil. Appl. Soil Ecol. 2020, 152, 103589. [Google Scholar] [CrossRef]
  14. Zhang, G.; Liu, Q.; Zhang, Z.; Ci, D.; Zhang, J.; Xu, Y.; Guo, Q.; Xu, M.; He, K. Effect of reducing nitrogen fertilization and adding organic fertilizer on net photosynthetic rate, root nodules and yield in peanut. Plants 2023, 12, 2902. [Google Scholar] [CrossRef] [PubMed]
  15. Liu, M.; Song, F.; Yin, Z.; Chen, P.; Zhang, Z.; Qi, Z.; Wang, B.; Zheng, E. Organic fertilizer substitutions maintain maize yield and mitigate ammonia emissions but increase nitrous oxide emissions. Environ. Sci. Pollut. Res. Int. 2023, 30, 53115–53127. [Google Scholar] [CrossRef]
  16. Huang, L.A.; Cheng, S.M.; Liu, H.L.; Zhao, Z.X.; Wei, S.X.; Sun, S.L. Effects of nitrogen reduction combined with organic fertilizer on growth and nitrogen fate in banana at seedling stage. Environ. Res. 2022, 214, 113826. [Google Scholar] [CrossRef]
  17. Tong, Y.; Wang, Z.; Gong, D.; Huang, C.; Ma, X.; Ma, X.; Yuan, F.; Fu, S.; Feng, C. Enhancing soil fertility and elevating pecan fruit quality through combined chemical and organic fertilization practices. Horticulturae 2024, 10, 25. [Google Scholar] [CrossRef]
  18. Ge, S.F.; Jiang, Y.M.; Wei, S.C. Gross nitrification rates and nitrous oxide emissions in an apple orchard soil in northeast China. Pedosphere 2015, 25, 622–630. [Google Scholar] [CrossRef]
  19. Wang, F.; Xu, X.X.; Jia, Z.H.; Hou, X.; Chen, Q.; Sha, J.C.; Liu, Z.X.; Zhu, Z.L.; Jiang, Y.M.; Ge, S.F. Nitrification inhibitor 3,4-dimethylpyrazole phosphate application during the later stage of apple fruit expansion regulates soil mineral nitrogen and tree carbon-nitrogen nutrition, and improves fruit quality. Front. Plant Sci. 2020, 11, 764. [Google Scholar] [CrossRef]
  20. Ge, S.; Zhu, Z.; Wei, S.; Jiang, Y. Technical approach and research prospect of saving and improving efficiency of chemical fertilizers for apple in China. Acta Hortic. Sin. 2017, 44, 1681–1692. [Google Scholar] [CrossRef]
  21. Zhu, Z.; Jia, Z.; Peng, L.; Chen, Q.; He, L.; Jiang, Y.; Ge, S. Life cycle assessment of conventional and organic apple production systems in China. J. Clean. Prod. 2018, 201, 156–168. [Google Scholar] [CrossRef]
  22. Wang, F.; Ge, S.; Lyu, M.; Liu, J.; Li, M.; Jiang, Y.; Xu, X.; Xing, Y.; Cao, H.; Zhu, Z.; et al. DMPP reduces nitrogen fertilizer application rate, improves fruit quality, and reduces environmental cost of intensive apple production in China. Sci. Total Environ. 2022, 802, 149813. [Google Scholar] [CrossRef] [PubMed]
  23. Yang, L.L.; Wang, Y.H.; Han, W.S. Effects of reducing nitrogen fertilizer and applying organic fertilizer on apple yield and quality and soil biological characteristics. J. Agro-Environ. Sci. 2021, 40, 631–639. [Google Scholar] [CrossRef]
  24. Wang, X.; Bao, Q.; Sun, G.; Li, J. Application of homemade organic fertilizer for improving quality of apple fruit, soil physicochemical characteristics, and microbial diversity. Agronomy 2022, 12, 2055. [Google Scholar] [CrossRef]
  25. Milosevic, T.; Milosevic, N.; Mladenovic, J. Tree vigor, yield, fruit quality, and antioxidant capacity of apple (Malus × domestica Borkh.) influenced by different fertilization regimes: Preliminary results. Turk. J. Agric. For. 2019, 43, 48–57. [Google Scholar] [CrossRef]
  26. Sankuan, X.; Cuimei, Z.; Bingqian, F.; Yu, Z.; Menglei, X.; Linna, T.; Jia, S.; Xinyi, Z.; Min, W. Metabolic network of ammonium in cereal vinegar solid-state fermentation and its response to acid stress. Food Microbiol. 2021, 95, 103684. [Google Scholar] [CrossRef]
  27. Wang, X.; Fu, X.; Chen, M.; Huan, L.; Liu, W.; Qi, Y.; Gao, Y.; Xiao, W.; Chen, X.; Li, L.; et al. Ultraviolet B irradiation influence the fruit quality and sucrose metabolism of peach (Prunus persica L.). Environ. Exp. Bot. 2018, 153, 286–301. [Google Scholar] [CrossRef]
  28. Arya, S.P.; Mahajan, M.; Jain, P. Non-spectrophotometric methods for the determination of vitamin C. Anal. Chim. Acta 2000, 417, 1–14. [Google Scholar] [CrossRef]
  29. Li, S.; Zhang, Y.; Chen, H.; Li, B.; Liang, B.; Xu, J. The effect of dwarfing interstocks on vegetative growth, fruit quality and ionome nutrition of ‘Fuji’ apple cultivar ‘Tianhong 2’-a one-year study. Plants 2023, 12, 2158. [Google Scholar] [CrossRef]
  30. Bao, S. Soil Agricultural Chemistry Analysis; China Agriculture Press: Beijing, China, 2008. [Google Scholar]
  31. He, G.; Wang, Z.; Li, F.; Dai, J.; Ma, X.; Li, Q.; Xue, C.; Cao, H.; Wang, S.; Liu, H.; et al. Soil nitrate-N residue, loss and accumulation affected by soil surface management and precipitation in a winter wheat-summer fallow system on dryland. Nutr. Cycl. Agroecosyst. 2016, 106, 31–46. [Google Scholar] [CrossRef]
  32. Dai, J.; Wang, Z.; Li, F.; He, G.; Wang, S.; Li, Q.; Cao, H.; Luo, L.; Zan, Y.L.; Meng, X.; et al. Optimizing nitrogen input by balancing winter wheat yield and residual nitrate-N in soil in a long-term dryland field experiment in the Loess Plateau of China. Field Crops Res. 2015, 181, 32–41. [Google Scholar] [CrossRef]
  33. Zhang, B.; Yan, S.; Wu, S.; Feng, H.; Siddique, K.H.M. Organic and inorganic fertilizers combined with a water-saving technique increased soil fertilities and apple production in a rainfed hilly orchard. J. Clean. Prod. 2023, 414, 137647. [Google Scholar] [CrossRef]
  34. Singh, S.R.; Singh, S.R.; Dar, H.A.; Sundouri, A.S.; Sharm, M.K. Yield and quality of apple (Malus domestica) cv. Red Delicious as effected by bio-inoculants. Indian J. Agric. Sci. 2013, 83, 1322–1326. [Google Scholar] [CrossRef]
  35. Kumar, S.; Sharma, A.; Sharma, V.K.; Ahmed, N.; Rosin, K.G.; Sharma, O.C. Integrated fertilization: An approach for higher apple (Malus domestica) productivity and ecological health of soil. Indian J. Agric. Sci. 2018, 88, 222–227. [Google Scholar] [CrossRef]
  36. Zhao, Z.; Gao, Y.; Liu, F.; Wang, X.; Tong, Y. Effects of organic manure application combined with chemical fertilizers on the leaf nutrition, quality and yield of Fuji apple. Acta Hortic. Sin. 2013, 40, 2229–2236. [Google Scholar] [CrossRef]
  37. Zhu, J.; Yu, H.; Xiong, M.; Zhu, P.; Liu, Y.; Shu, L. Mineralization of organic nitrogen in soils with contrasting fertility was regulated differently by addition of biochar and animal manures. J. Plant Nutr. Soil Sci. 2020, 51, 1227–1237. [Google Scholar] [CrossRef]
  38. Chen, R.; Chang, H.; Wang, Z.; Lin, H. Determining organic-inorganic fertilizer application threshold to maximize the yield and quality of drip-irrigated grapes in an extremely arid area of Xinjiang, China. Agric. Water Manag. 2023, 276, 108070. [Google Scholar] [CrossRef]
  39. Trivedi, P.; Leach, J.E.; Tringe, S.G.; Sa, T.; Singh, B.K. Author Correction: Plant–microbiome interactions: From community assembly to plant health. Nat. Rev. Microbiol. 2021, 19, 72. [Google Scholar] [CrossRef]
  40. Ma, L.; Li, Z.; Li, Y.; Wei, J.; Zhang, L.; Zheng, F.; Liu, Z.; Tan, D. Variations in crop yield caused by different ratios of organic substitution are closely related to microbial ecological clusters in a fluvo-aquic soil. Field Crops Res. 2024, 306, 109239. [Google Scholar] [CrossRef]
  41. Yang, X.; Zhang, C.; Ma, X.; Liu, Q.; An, J.; Xu, S.; Xie, X.; Geng, J. Combining organic fertilizer with controlled-release urea to reduce nitrogen leaching and promote wheat yields. Front. Plant Sci. 2021, 12, 802137. [Google Scholar] [CrossRef]
  42. Zhang, Y.; Li, C.; Wang, Y.; Hu, Y.; Christie, P.; Zhang, J.; Li, X. Maize yield and soil fertility with combined use of compost and inorganic fertilizers on a calcareous soil on the North China Plain. Soil Tillage Res. 2016, 155, 85–94. [Google Scholar] [CrossRef]
  43. Xue, L.H.; Yu, Y.L.; Yang, L.Z. Maintaining yields and reducing nitrogen loss in rice-wheat rotation system in Taihu Lake region with proper fertilizer management. Environ. Res. Lett. 2014, 9, 115010. [Google Scholar] [CrossRef]
  44. Zhou, J.; Li, B.; Xia, L.; Fan, C.; Xiong, Z. Organic-substitute strategies reduced carbon and reactive nitrogen footprints and gained net ecosystem economic benefit for intensive vegetable production. J. Clean. Prod. 2019, 225, 984–994. [Google Scholar] [CrossRef]
  45. Luo, G.; Li, L.; Friman, V.P.; Guo, J.; Guo, S.; Shen, Q.; Ling, N. Organic amendments increase crop yields by improving microbe-mediated soil functioning of agroecosystems: A meta-analysis. Soil Biol. Biochem. 2018, 124, 105–115. [Google Scholar] [CrossRef]
  46. Li, Y.; Feng, H.; Dong, Q.; Xia, L.; Li, J.; Li, C.; Zang, H.; Mathias, N.A.; Jørgen, E.O.; Uffe, J.; et al. Ammoniated straw incorporation increases wheat yield, yield stability, soil organic carbon and soil total nitrogen content. Field Crops Res. 2022, 284, 108558. [Google Scholar] [CrossRef]
  47. Lu, W.; Hao, Z.; Ma, X.; Gao, J.; Fan, X.; Guo, J.; Li, J.; Lin, M.; Zhou, Y. Effects of different proportions of organic fertilizer replacing chemical fertilizer on soil nutrients and fertilizer utilization in gray desert soil. Agronomy 2024, 14, 228. [Google Scholar] [CrossRef]
  48. Xu, X.; Bi, R.; Song, M.; Dong, Y.; Jiao, Y.; Wang, B.; Xiong, Z. Organic substitutions enhanced soil carbon stabilization and reduced carbon footprint in a vegetable farm. Soil Tillage Res. 2024, 236, 105955. [Google Scholar] [CrossRef]
  49. Hou, L.; Liu, Z.; Zhao, J.; Ma, P.; Xu, X. Comprehensive assessment of fertilization, spatial variability of soil chemical properties, and relationships among nutrients, apple yield and orchard age: A case study in Luochuan County, China. Ecol. Indic. 2021, 122, 107285. [Google Scholar] [CrossRef]
  50. Mohammadi, S.; Kalbasi, M.; Shariatmadari, H. Cumulative and residual effects of organic fertilizer application on selected soil properties, water soluble P, olsen-p and P sorption index. J. Agric. Sci. Technol. 2009, 11, 487–497. [Google Scholar]
  51. Liang, Z.; Jin, X.; Zhai, P.; Zhao, Y.; Cai, J.; Li, S.; Yang, S.; Li, C.; Li, C. Combination of organic fertilizer and slow-release fertilizer increases pineapple yields, agronomic efficiency and reduces greenhouse gas emissions under reduced fertilization conditions in tropical areas. J. Clean. Prod. 2022, 343, 131054. [Google Scholar] [CrossRef]
  52. Yu, X.; Keitel, C.; Zhang, Y.; Wangeci, A.N.; Dijkstra, F.A. Global meta-analysis of nitrogen fertilizer use efficiency in rice, wheat and maize. Agric. Ecosyst. Environ. 2022, 338, 108089. [Google Scholar] [CrossRef]
  53. Zhu, C.; Shen, Q.; Xu, Y. Microbial mechanism on enhancement of inorganic fertilizer use efficiency for combined use of inorganic and organic fertilizers. J. Plant Nutr. Soil Sci. 2010, 16, 282–288. [Google Scholar]
  54. Li, Y.; Hao, W.; Gong, D.; Xia, X.; Li, H. Effects of nitrogen reduction and combined application with organic fertilizer on soil nitrate nitrogen and nitrogen fertilizer utilization efficiency in summer maize and winter wheat systems. Chin. J. Soil Sci. 2019, 2, 348–354. [Google Scholar] [CrossRef]
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Figure 1. Apple yield (A) and mean mass of apple fruits (B) under different organic substitution treatments. Circles in “A” present the proportions of large-, medium-, and small-size apple yields of the total yield. Error bars represent the standard deviations of the means. Different letters above the bars indicate significant differences in the means between different treatments (p < 0.05).
Figure 1. Apple yield (A) and mean mass of apple fruits (B) under different organic substitution treatments. Circles in “A” present the proportions of large-, medium-, and small-size apple yields of the total yield. Error bars represent the standard deviations of the means. Different letters above the bars indicate significant differences in the means between different treatments (p < 0.05).
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Figure 2. Soil chemical properties under different organic substitution treatments in 2017 and 2018. (A,G) Soil organic carbon (SOC), (B,H) Total nitrogen (TN), (C,I) C/N ratio, (D,J) NO3−-N, (E,K) available phosphorus (AP), and (F,L) available potassium (AK). Error bars represent the standard deviation of the mean. * represents significant differences (p < 0.05) among samples from different treatments; “ns” represents no significant difference between different treatments.
Figure 2. Soil chemical properties under different organic substitution treatments in 2017 and 2018. (A,G) Soil organic carbon (SOC), (B,H) Total nitrogen (TN), (C,I) C/N ratio, (D,J) NO3−-N, (E,K) available phosphorus (AP), and (F,L) available potassium (AK). Error bars represent the standard deviation of the mean. * represents significant differences (p < 0.05) among samples from different treatments; “ns” represents no significant difference between different treatments.
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Figure 3. Soil RN contents in 0–20 cm (A), 20–40 cm (B), 40–60 cm (C), 60–80 cm (D), 80–100 cm (E) and 0–100 cm (F) soil layers under different organic substitution treatments in 2017 and 2018. Error bars represent the standard deviation of the mean. Different letters above the bars indicate significant differences at the p < 0.05 level. RN is the residual NO3−-N.
Figure 3. Soil RN contents in 0–20 cm (A), 20–40 cm (B), 40–60 cm (C), 60–80 cm (D), 80–100 cm (E) and 0–100 cm (F) soil layers under different organic substitution treatments in 2017 and 2018. Error bars represent the standard deviation of the mean. Different letters above the bars indicate significant differences at the p < 0.05 level. RN is the residual NO3−-N.
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Figure 4. PCA analysis of fruit quality and fruit yield parameters (A) and RDA results for fruit quality (B), fruit yield parameters (C), and soil chemical properties. ‘*’ represents statistically significant factor. ‘Exp’ represents explanation ratio.
Figure 4. PCA analysis of fruit quality and fruit yield parameters (A) and RDA results for fruit quality (B), fruit yield parameters (C), and soil chemical properties. ‘*’ represents statistically significant factor. ‘Exp’ represents explanation ratio.
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Figure 5. PCA results for soil chemical properties parameters in the 0–20 cm (A), 20–40 cm (B), 40–60 cm (C), 60–80 cm (D), and 80–100 cm (E) soil layers, and the RN content in different soil layers (F) in 2017 and 2018.
Figure 5. PCA results for soil chemical properties parameters in the 0–20 cm (A), 20–40 cm (B), 40–60 cm (C), 60–80 cm (D), and 80–100 cm (E) soil layers, and the RN content in different soil layers (F) in 2017 and 2018.
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Figure 6. Summary diagram for the effects of organic substitution on the quality of apples, nutrients, and RN leaching in soil. SOC: soil organic carbon. RN: residual NO3−-N. Orange and green arrow represents the increase and decrease in related indexes, respectively.
Figure 6. Summary diagram for the effects of organic substitution on the quality of apples, nutrients, and RN leaching in soil. SOC: soil organic carbon. RN: residual NO3−-N. Orange and green arrow represents the increase and decrease in related indexes, respectively.
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Table 1. Fertilizer application amounts in the first year of the organic fertilization experiments.
Table 1. Fertilizer application amounts in the first year of the organic fertilization experiments.
TreatmentOrganic Fertilizer
(kg ha−1)		Chemical Fertilizer (kg ha−1)
NP2O5K2O
NOS0 480 120 304
OS-2010,500 384 120 304
OS-4021,000 266 120 304
OS-6031,500 155 120 304
OS-10052,500 0 120 304
OS-200105,000 0 120 304
Table 2. Apple quality characteristics under different organic substitution treatments.
Table 2. Apple quality characteristics under different organic substitution treatments.
TreatmentsTotal SugarTitratable AcidSugar/Acid RatioVc ContentFruit
Hardness
(%)(%) (mg 100 g−1)(kg cm−2)
NOS7.15 ± 0.23 c0.29 ± 0.01 ab25.45 ± 2.17 b33.22 ± 5.55 c3.09 ± 0.37 b
OS-207.43 ± 0.22 b0.29 ± 0.02 a26.82 ± 3.51 ab34.96 ± 4.03 c3.45 ± 0.67 ab
OS-407.59 ±0.16 b0.27 ± 0.01 bc29.02 ± 3.53 a48.03 ± 3.54 a3.49 ± 0.62 ab
OS-607.65 ±0.13 b0.28 ± 0.02 bc28.77 ± 2.51 a46.20 ±4.30 ab3.42 ± 0.29 ab
OS-1007.61 ±0.13 b0.30 ± 0.01 a26.99 ± 2.46 ab45.02 ± 3.01 ab3.73 ± 0.56 a
OS-2007.97 ±0.38 a0.27 ± 0.02 c29.42 ± 2.26 a43.66 ±3.38 b3.73 ± 0.40 a
The values shown are the mean ± SD (standard deviation). Different letters within a column indicate significant differences at the p < 0.05 level among the treatments.
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Li, Q.; Chen, Y.; Zhu, J.; Liu, L.; Liu, J.; Cheng, C.; Li, L. Effects of Organic Substitution on the Yield and Quality of Apples and Residual Nitrate-N Leaching in Soil. Agronomy 2024, 14, 415. https://doi.org/10.3390/agronomy14030415

AMA Style

Li Q, Chen Y, Zhu J, Liu L, Liu J, Cheng C, Li L. Effects of Organic Substitution on the Yield and Quality of Apples and Residual Nitrate-N Leaching in Soil. Agronomy. 2024; 14(3):415. https://doi.org/10.3390/agronomy14030415

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Li, Qian, Yanan Chen, Jingdi Zhu, Lizhi Liu, Jian Liu, Chunzhen Cheng, and Lei Li. 2024. "Effects of Organic Substitution on the Yield and Quality of Apples and Residual Nitrate-N Leaching in Soil" Agronomy 14, no. 3: 415. https://doi.org/10.3390/agronomy14030415

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