Effects of Orchard Grass on Soil Fertility and Nutritional Status of Fruit Trees in Korla Fragrant Pear Orchard
1
College of Horticulture and Forestry Science, Tarim University, Alar 843300, China
2
College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
3
National and Local Joint Engineering Laboratory of High Efficiency and High-Quality Cultivation and Deep Processing Technology of Characteristic Fruit Trees in Southern Xinjiang, Alar 843300, China
*
Author to whom correspondence should be addressed.
Horticulturae 2023, 9(8), 903; https://doi.org/10.3390/horticulturae9080903
Submission received: 3 June 2023
/
Revised: 22 July 2023
/
Accepted: 3 August 2023
/
Published: 8 August 2023
(This article belongs to the Section Fruit Production Systems)
Abstract
:Grass cultivation is widely used as an effective soil management method in pear orchards. A Korla fragrant pear orchard with clean cultivation (CK) and natural grass planting for 1, 2, 3, 4, and 5 years was examined in this study. We analyzed the differences in soil fertility and shoot and leaf nutrient content under different grassing years. Compared with the clean cultivation, grass cultivation reduced the soil fertility and nutrient content of shoots and leaves at the early stage of natural grass planting (1–2 years). With the increase in grassing years, the overall level of the nutrient content of soil, shoots, and leaves gradually increased; the shallower the soil layer, the more significant the effect. Furthermore, grass cultivation significantly increased the contents of soil organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium. The nutrient contents of shoots and leaves were also significantly increased after grass cultivation. The contents of total nitrogen, total phosphorus, and total potassium in shoots were significantly increased by 7.32%, 154.84%, and 219.29% in 5, 4, and 5 years, respectively, and their contents were also increased by 69.57%, 22.86%, and 26.45% in leaves. The correlation analysis showed that there was a significant or extremely significant positive correlation among the shoots, leaves, and soil nutrient contents. In conclusion, continuous grass cultivation significantly improved the soil quality, health status, and nutritional status, and effectively solved the problem of harm to the pear orchard caused by long-term clean cultivation. This study will provide the scientific basis for the construction of a reasonable orchard soil management mode.
1. Introduction
Korla fragrant pear (Pyrus sinkiangensis Yu.), referred to as fragrant pear, belongs to the white pear system in Pomoideae of Rosasceae. As a famous, excellent and special fruit in Xinjiang, it is a geographical icon of Bazhou in Xinjiang, and also one of the pillar industries of Xinjiang’s characteristic forest and fruit industry, with good economic and social benefits [1]. Soil is the basis for the growth of fruit trees and is a basic component of the orchard ecosystem, which directly provides water and mineral nutrients for fruit trees. The physical and chemical properties of soil affect the abilities of the soil to fix fertilizer and of the trees to absorb nutrients. The relatively stable and healthy development of the soil environment is conducive to the growth and development of fruit trees and the sustainability of orchards [2,3].
Restricted by cultivation habits and local conditions, clean cultivation is the most widely used soil management method used in orchards in China. However, there is a general lack of effective soil management measures in pear orchards in Xinjiang, especially in southern Xinjiang [4]. At present, the disadvantages of clean cultivation are being gradually exposed after the long-term management mode of clean cultivation. Clean cultivation causes a series of ecological and environmental problems, such as the decline in soil quality, the decrease in fertility, and the aggravation of pests and diseases, and seriously affects the yield, quality, and economic and social benefits of fragrant pear. This restricts the healthy development of the fragrant pear industry to a certain extent.
Orchard grass is an effective method used to maintain soil fertility and increase fertilizer fixing and yield in orchards. It can create a good micro-environment for fruit trees, increase the soil organic matter and nutrients, improve the soil quality in orchards, repair the ecological environment of orchards, improve the fruit yield and quality, improve the economic benefits of planting, and solve the problem of harm caused by long-term clean cultivation [5,6,7]. Inter-row planting of vetch can improve the soil micro-ecological environment of apple orchards and increase the soil organic matter and nutrient content of orchards [8]. After grass cultivation, the contents of total nitrogen and total phosphorus in the 0–40 cm soil layers of the orchard were significantly higher than those of the clean cultivation control [9]. Moreover, natural grass between rows in orchards has a significant effect on soil organic matter and a large number of nutrient elements [10,11]. Grass cultivation reduced the nitrogen content of apple leaves, but increased the phosphorus content of leaves [12]. Until now, the studies related to the changes in soil fertility and nutritional status of fruit trees after grass cultivation in pear orchards have mostly concentrated on the short term. However, there are few reports on soil fertility and nutrient contents in shoots at different soil depths and leaves after continuous natural grass cultivation, or on the correlation among nutrient contents in shoots and leaves, and soil nutrients.
In this study, we identified the effects of different natural grassing years on soil fertility and nutritional status of Korla fragrant pear orchards, with the traditional clean cultivation method of orchards used as a control. This study determined the changes in soil fertility and shoots and leaf nutrients of Korla fragrant pear orchards after grass growing, and will provide a scientific basis for solving the series of production problems and constructing a reasonable orchard soil management model.
2. Materials and Methods
2.1. Selection of the Test Site
The experimental site is located in the Tenth Regiment of Alar City, Xinjiang Production and Construction Corps (40°61′ N, 81°32′ E) (Figure 1). It is located on the north bank of the upper reaches of the Tarim River, and has a warm temperate extreme continental arid desert climate with scarce rainfall, less snow in winter, and strong surface evaporation. The row spacing was 1.5 m × 4 m, in a north–south direction; the irrigation method was flood irrigation, the soil type was sandy loam, and the pear orchard was routinely managed.
2.2. Sample Collection
At the fruit maturity stage, the five-point sampling method was used to collect the soil samples at 0–20, 20–40, and 40–60 cm for each treatment. After natural air drying with a 100-mesh sieve, about 1 kg of mixed soil samples was retained by the quartering method and stored in self-sealing bags for determining the soil nutrients.
At the fruit maturity stage, shoots and leaves at the middle and upper parts of the tree crown and the surrounding annual growth were taken, and 60 pieces were picked for each treatment. Then, the samples were brought back to wash. The washing order was tap water, 0.1% detergent solution, tap water, and distilled water. The samples were fixed at 105 °C for 30 min, dried to constant weight at 80 °C, sieved using a 60-mesh sieve, and stored in self-sealing bags for determining the nutrient content in shoots and leaves.
2.3. Experimental Design
The experiment used a single-factor completely randomized design. Six treatments were set up, namely, clean cultivation (CK), and natural grass for 1, 2, 3, 4, and 5 years. Each treatment was repeated three times. The main types of natural grass cultivation are purslane and plantain. Purslane is a one-year-old herbaceous plant of the purslane genus. Plantagoasiatica is a two-year-old or perennial herb of Plantaginaceae. Other management measures were consistent with routine management.
2.4. Determination Items and Methods
The soil nutrient indexes were determined according to Bao [13]. Organic matter was determined by potassium dichromate capacity external heating. Total nitrogen was determined by Kjeldahl colorimetry, and total phosphorus was determined by HClO4-H2SO4 molybdenum antimony colorimetry. Total potassium was determined by flame photometry after digestion with HF-HClO4. Alkali-hydrolyzable nitrogen was determined by alkali solution diffusion, and available phosphorus was determined by 0.5 mol·L−1 NaHCO3 molybdenum antimony colorimetry. The content of available potassium was determined by COOHNH4 extraction flame photometry.
2.5. Data Processing
The data were analyzed by mean ± standard deviation of 3 replicates. DPS 7.05 software was used to analyze the data by one-way analysis of variance, and the LSD method was used for multiple comparisons (p < 0.05). SPSS 24.0 software was used to analyze the correlation of data (Pearson correlation). GraphPad Prism 9.5.0 and Origin 2021 software were used for plotting.
3. Results
3.1. Effects of Natural Grass Cultivation Years on Soil Nutrient Content in Pear Orchards
3.1.1. Effects of Grassing Years on Soil Organic Matter Content in Pear Orchards
Organic matter is an important part of soil. It is usually used as an important index of the soil fertility level, and contains nutrient elements needed for plant growth. Maintaining high organic matter in soil is an important condition for a high and stable yield of fruit trees [14]. The soil organic matter content of different grass-growing years decreased from 0 to 60 cm in the soil layer, and the soil organic matter content decreased and then increased with the increase in grassing years (Table 1 and Figure 2). The content of organic matter in each soil layer was higher than that of clean cultivation at 5 years, with increases of 12.59% (0–20 cm), 6.95% (20–40 cm), and 34.31% (40–60 cm).
3.1.2. Effects of Natural Grass Cultivation Years on Soil Total Nitrogen, Phosphorus, and Potassium Contents in Pear Orchards
The total nitrogen contents in 0–20 cm and 20–40 cm soil layers increased by 33.33% and 19.29%, respectively, at 5 years of grass planting (Table 1 and Figure 3). The total phosphorus content of 0–20 cm soil increased continuously with the increase in grass-growing years, and reached the maximum value at 5 years of grass growing, with an increase of 70.80%. The total potassium content of 0–20 cm soil was significantly higher than that of clean cultivation, indicating that grass cultivation in an orchard could significantly change the total potassium content of the soil surface. The contents of total nitrogen, phosphorus, and potassium in 40–60 cm soil were significantly higher than those in clean cultivation at 5 years of grass cultivation, with increases of 24.24%, 123.31%, and 91.38%, respectively.
3.1.3. Effects of Natural Grass Cultivation Years on Alkali-Hydrolyzable Nitrogen, Available Phosphorus, and Potassium Content in Soil
The contents of available nitrogen in 0–20 cm and 20–40 cm soil increased first and then decreased with the increase in grass age, reached the maximum at 5 years of grassing, and were significantly higher than those of clean cultivation, with increases of 48.76% and 102.32%, respectively (Table 1 and Figure 4). The content of available nitrogen in 40–60 cm soil, relative to that of clean cultivation, reached the maximum at 5 years of grassing. The content of available phosphorus in 0–20 cm soil increased by 62.78% compared to clean cultivation after 1 year, and the contents were inhibited from 2 to 5 years. The contents of available phosphorus in 20–40 cm and 40–60 cm soil decreased first and then increased. Compared with clean cultivation, the content of available potassium in 0–20 cm soil reached the maximum at 2 years and increased by 52.28%; the contents in 20–40 cm and 40–60 cm soil reached the maximum at 5 years, increasing by 98.70% and 84.24%, respectively.
3.2. Effect of Natural Grass Cultivation Years on Shoot Nutrient Content of Korla Fragrant Pear
At the early stage of natural grass (1–2 years), the total nitrogen contents of pear shoots were significantly lower than those of clean cultivation, but were 7.32% higher than those of clean cultivation at 5 years (Figure 5). Furthermore, the total phosphorus content of pear shoots increased by 154.84% at 4 years. The total potassium content of pear shoots was higher than that of clean cultivation, and reached the maximum at 5 years, with an increase of 219.29%. In conclusion, grass cultivation can increase the nutrient content in the shoots of pear, and the increase in phosphorus and potassium in the shoots of pear is more significant with the increase in the number of years of grass.
3.3. Effects of Natural Grass Cultivation Years on Leaf Nutrient Content of Korla Fragrant Pear
The quantities of mineral elements in leaves can reflect the nutritional level of fruit trees [15]. As shown in Figure 6, the total nitrogen content of fragrant pear leaves gradually increased with grass cultivation years, and reached the maximum at 5 years, with an increase of 69.57%. The total phosphorus content in the leaves was lower than that in clean cultivation in the first year, and reached the maximum of 0.43% in the third year. The total potassium content of fragrant pear leaves decreased first and then increased. It decreased by 33.06% in the first year, and reached the maximum value of 3.06% in the fifth year.
3.4. Correlation Analysis between Shoot and Leaf Nutrients and Soil Nutrients
The nutrient contents of shoots and leaves were closely related to the soil nutrient content in each soil layer (Figure 7). The total nitrogen of shoots was positively correlated with total nitrogen and alkali-hydrolyzable nitrogen in 0–20 cm soil, and the correlation coefficients were 0.598 and 0.817, respectively. It was positively correlated with total phosphorus and negatively correlated with available phosphorus. The total phosphorus of shoots was negatively correlated with the available phosphorus in 0–20 cm soil (−0.442). The total potassium of shoots was positively correlated with total phosphorus, total potassium, and alkali-hydrolyzable nitrogen in 0–20 cm soil, and the correlation coefficients were 0.695, 0.689, and 0.666, respectively. It was positively correlated with total nitrogen and negatively correlated with available phosphorus. The total nitrogen of shoots was positively correlated with soil organic matter, total nitrogen, total phosphorus, and available phosphorus in the 20–40 cm soil layer, and the correlation coefficients were 0.597, 0.799, 0.774, and 0.699, respectively. The total nitrogen of branches was positively correlated with total potassium and available nitrogen. The total phosphorus of shoots was positively correlated with organic matter and total potassium in 20–40 cm soil, and was positively correlated with alkali-hydrolyzable nitrogen. The total potassium of shoots was positively correlated with total nitrogen, total potassium, and alkali-hydrolyzable nitrogen in 20–40 cm soil, and the correlation coefficients were 0.621, 0.611, and 0.792, respectively. It was significantly positively correlated with total phosphorus and available potassium. The total nitrogen of shoots was positively correlated with total nitrogen, total phosphorus, and available potassium in 40–60 cm soil, and was positively correlated with alkali-hydrolyzable nitrogen. The total phosphorus of shoots was positively correlated with total nitrogen, total potassium, and alkali-hydrolyzable nitrogen in 40–60 cm soil, and negatively correlated with available phosphorus. The total potassium of shoots was positively correlated with total nitrogen, total potassium, alkali-hydrolyzable nitrogen, and available potassium in 40–60 cm soil, and positively correlated with total phosphorus.
Leaf total nitrogen was positively correlated with total phosphorus in 0–20 cm soil, with a correlation coefficient of 0.741. Leaf total nitrogen was positively correlated with total potassium and alkali-hydrolyzable nitrogen, and negatively correlated with available phosphorus. Leaf total phosphorus was negatively correlated with soil organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus, and available potassium in 0–20 cm soil. There was a positive correlation between total potassium in leaves and available nitrogen in 0–20 cm soil, and a negative correlation with available phosphorus. Leaf total nitrogen was positively correlated with available nitrogen and available potassium in 20–40 cm soil, and the correlation coefficients were 0.674 and 0.735, respectively. Leaf total nitrogen was positively correlated with total nitrogen, total phosphorus, and total potassium. Leaf total phosphorus was negatively correlated with soil organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus, and available potassium in 20–40 cm soil. There was a positive correlation between total potassium in leaves and total nitrogen, available nitrogen, and available potassium in 20–40 cm soil. There was a positive correlation between total potassium and organic matter and total potassium. Leaf total nitrogen was positively correlated with soil total nitrogen, available nitrogen, and available potassium in the 40–60 cm soil layer, and the correlation coefficients were 0.618, 0.709, and 0.692, respectively. Leaf total nitrogen was positively correlated with total phosphorus, total potassium, and available phosphorus in the 40–60 cm soil layer. Leaf total phosphorus was correlated with soil organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus, and available potassium in the 40–60 cm soil layer. The total potassium of leaves was positively correlated with total potassium, alkali-hydrolyzable nitrogen, and available potassium in 40–60 cm soil, and was positively correlated with total nitrogen.
4. Discussion
4.1. Effect of Grass on Soil Organic Matter Content in Orchards
Soil organic matter content is one of the key indicators of orchard soil fertility [16]. This study found that orchard grass did not have a significant effect on soil organic matter content in 0–20 cm soil. In the early stage of grass planting (1–2 years), orchard grass cultivation reduced the soil organic matter content. With the increase in grass cultivation years, soil organic matter content increased, and, the shallower the soil layer, the more obvious the effect. Related studies have shown that inter-row grass in orchards can promote the accumulation of soil organic matter [11,17,18]. Natural grass mulching in olive orchards can increase soil organic matter content [19]; the soil organic matter content decreased with the depth of the soil layer after grass cultivation [9]. The results of this study suggest that the organic matter content of soil is increased to a certain extent after grass cultivation. It may be that the quantity of natural mulch on the surface increases compared with clean cultivation after grass cultivation. Grass cultivation increases the total amount of soil microorganisms, promotes the decomposition of microorganisms involved in organic matter, and is conducive to the accumulation of organic matter.
4.2. Effect of Orchard Grass on Soil Nutrients in Pear Orchards
Soil quality is the core content of soil fertility, and soil fertility affects the soil productivity [20]. In each growth stage, the stable supply of nitrogen, phosphorus, and potassium in the soil is a prerequisite to ensure the normal growth and development of fruit trees, and their content and form of existence directly affect the growth of fruit trees. Orchard grass can change the content of soil nutrients. In this study, the decrease in soil nutrient content usually occurred in the early stage of grass cultivation (1–2 years) or in orchards with fewer grass cultivation years, which was basically consistent with the results of previous studies [21,22]. This may be due to the fierce nutritional competition between fruit trees and grass in the early stage of grass cultivation. The absorption of mineral elements by grass reduces the content of various nutrients in soil. The effects on different soil nutrients in different soil layers were different, but the overall level of soil nutrient content gradually increased with the increase in grass cultivation years. The effect of grass planting on soil nutrient content became more pronounced and the soil layer became shallower with the increase in the years of grass cultivation. The contents of total nitrogen, available phosphorus, and available potassium decreased with the increase in soil depth during the first two years of grass cultivation in kiwifruit orchards in Qinling Mountains [23]. At the third year, the nutrient contents of each soil layer increased to varying degrees, and the contents of total nitrogen, total phosphorus, available phosphorus, and available potassium increased significantly in the 0–20 cm soil layer. Compared with orchard tillage, orchard grass can increase the soil’s available nitrogen, available phosphorus, and potassium contents [24,25,26,27]. The intercropping of forage and pear trees could increase the contents of total nitrogen, available phosphorus, and available potassium in each soil layer, but the content of alkali-hydrolyzed nitrogen in the 20–60 cm soil layer decreased [28]. These results show that there may be a large difference in the effect of soil conservation caused by grasses under different cultivation years, and regional environmental conditions, soil depth, and soil type are all influencing factors.
4.3. Effect of Grass on Leaf Nutrient Content in Orchard
The quantities of mineral elements in leaves can effectively reflect the nutritional level of fruit trees [15]. Grass cultivation reduced the nitrogen content of apple leaves and increased the phosphorus content. Natural grass did not affect the nitrogen and phosphorus contents of apple leaves in arid desert areas, but increased the potassium content [29]. Furthermore, orchard grass could increase the contents of nitrogen, phosphorus, potassium, and other macro elements in apricot leaves [30]. In this study, compared with clean cultivation, different years of grass cultivation increased the total nitrogen content of fragrant pear leaves. The total phosphorus content of fragrant pear leaves decreased in the early stage of grass cultivation (1–2 years), reached the maximum at 3 years, and then decreased. The total potassium content of fragrant pear leaves was lower than that of clean cultivation at 1 year after grass cultivation, and then increased. These results may be related to the orchard soil fertility, fruit tree types and varieties, tree age, grass species, and regional climate conditions.
5. Summary
In this study, the reduction in soil nutrient content related to grass cultivation usually occurred in the early stage (1–2 years) or in the orchards with fewer years. With the increase in grass cultivation years, the contents of soil nutrients, and shoot and leaf nutrient content, gradually increased, and there was a strong correlation among the nutrient content of shoots and leaves and soil nutrients. Orchard grass cultivation is conducive to improving the soil environment, thereby making the soil environment more mature and stable, and improving the soil fertility and health status of pear orchards. This study will effectively solve the problem of the negative impact of long-term clean cultivation on orchards.
Author Contributions
Z.W. contributed to this work by designing the study, obtaining data, performing statistical analyses, writing the manuscript and interpreting the data. R.L. and L.F. performed the experiments. S.T. and J.B. participated in the conception and design of the study, interpreted the data, and reviewed and edited the manuscript. All authors have read and agreed to the published version of the manuscript.
Funding
This work was financially supported by the financial support of Bingtuan Science and Technology Program (2021CB055 and 2022CB001-11), the National Natural Science Foundation of China (31860528 and U2003121), and the Joint Foundation of Nanjing Agriculture University and Tarim University (NNTDLH 201904). These three projects are sponsored by Professor Bao Jianping from the College of Horticulture and Forestry Science, Tarim University, and the three projects have funded seven master’s degree graduate students.
Institutional Review Board Statement
Not applicable.
Data Availability Statement
Data sharing is not applicable in this paper because these data are also part of the ongoing research project.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
The location of the experimental site.
Figure 2.
Effect of natural grass cultivation years on soil organic matter content in pear orchards.
Figure 2.
Effect of natural grass cultivation years on soil organic matter content in pear orchards.
Figure 3.
Effects of natural grass cultivation years on soil total nitrogen, phosphorus, and potassium contents in a Korla Fragrant Pear orchard: (a) the content of total nitrogen; (b) the total phosphorus content; (c) the total potassium content.
Figure 3.
Effects of natural grass cultivation years on soil total nitrogen, phosphorus, and potassium contents in a Korla Fragrant Pear orchard: (a) the content of total nitrogen; (b) the total phosphorus content; (c) the total potassium content.
Figure 4.
Effect of natural grass cultivation years on soil available nutrient content in a Korla fragrant pear orchard: (a) the content of alkali-hydrolyzable nitrogen; (b) the content of available phosphorus; (c) the content of available potassium.
Figure 4.
Effect of natural grass cultivation years on soil available nutrient content in a Korla fragrant pear orchard: (a) the content of alkali-hydrolyzable nitrogen; (b) the content of available phosphorus; (c) the content of available potassium.
Figure 5.
Effect of grass age on nutrients of pear shoots: (a) the total nitrogen content; (b) the total phosphorus content; (c) the total potassium content (* p < 0.05; ** p < 0.01).
Figure 5.
Effect of grass age on nutrients of pear shoots: (a) the total nitrogen content; (b) the total phosphorus content; (c) the total potassium content (* p < 0.05; ** p < 0.01).
Figure 6.
Effect of grass age on leaf nutrients of fragrant pear: (a) the content of total nitrogen; (b) the total phosphorus content; (c) the total potassium content (* p < 0.05; ** p < 0.01).
Figure 6.
Effect of grass age on leaf nutrients of fragrant pear: (a) the content of total nitrogen; (b) the total phosphorus content; (c) the total potassium content (* p < 0.05; ** p < 0.01).
Figure 7.
Correlation analysis of leaves and shoots nutrients and soil nutrients: (a) the correlation between nutrient content of shoots and leaves of Korla fragrant pear and 0–20 cm soil nutrient; (b) the correlation between the nutrient content of shoots and leaves of Korla fragrant pear and the nutrient content of 20–40 cm soil; (c) the correlation between nutrient content of shoots and leaves of Korla fragrant pear and soil nutrients in 40–60 cm soil. The color of each color block in the heat map indicates the positive and negative correlation coefficient between soil nutrients, and the size of the color block indicates the absolute value of the correlation coefficient. The thickness of the line indicates the strength of the correlation, and the color of the line indicates the degree of significance.
Figure 7.
Correlation analysis of leaves and shoots nutrients and soil nutrients: (a) the correlation between nutrient content of shoots and leaves of Korla fragrant pear and 0–20 cm soil nutrient; (b) the correlation between the nutrient content of shoots and leaves of Korla fragrant pear and the nutrient content of 20–40 cm soil; (c) the correlation between nutrient content of shoots and leaves of Korla fragrant pear and soil nutrients in 40–60 cm soil. The color of each color block in the heat map indicates the positive and negative correlation coefficient between soil nutrients, and the size of the color block indicates the absolute value of the correlation coefficient. The thickness of the line indicates the strength of the correlation, and the color of the line indicates the degree of significance.
Table 1.
Soil nutrient content of pear orchards with different grassing years.
| Soil Depth (cm) | Grassing Years | Organic Matter (g/kg) | Total N (g/kg) | Total P (g/kg) | Total K (g/kg) | Alkali-Hydro-N (mg/kg) | Available P (mg/kg) | Available K (mg/kg) |
|---|---|---|---|---|---|---|---|---|
| 0–20 cm | Clean cultivation | 4.13 ± 0.63 aA | 1.44 ± 0.33 bAB | 1.13 ± 0.33 cB | 34.36 ± 3.20 dC | 16.59 ± 1.56 cdBCD | 59.86 ± 2.77 bB | 65.67 ± 5.69 bB |
| 1 year | 3.99 ± 0.32 aA | 1.37 ± 0.22 bB | 1.22 ± 0.27 cB | 48.09 ± 2.30 cB | 14.66 ± 3.17 deCD | 97.44 ± 11.05 aA | 81.00 ± 7.55 abAB | |
| 2 years | 4.20 ± 0.53 aA | 1.37 ± 0.02 bB | 1.34 ± 0.34 bcAB | 65.09 ± 1.39 aA | 11.59 ± 2.69 eD | 48.30 ± 0.38 bBCD | 100.00 ± 9.49 aA | |
| 3 years | 3.72 ± 0.69 aA | 1.51 ± 0.20 bAB | 1.58 ± 0.26 abcAB | 59.94 ± 2.22 bA | 19.56 ± 1.11 bcABC | 30.27 ± 5.52 cCD | 79.33 ± 11.37 abAB | |
| 4 years | 4.31 ± 1.31 aA | 1.55 ± 0.10 bAB | 1.75 ± 0.10 abAB | 61.19 ± 1.47 bA | 22.48 ± 0.98 abAB | 29.11 ± 6.03 cD | 89.33 ± 11.75 aAB | |
| 5 years | 4.65 ± 0.59 aA | 1.92 ± 0.24 aA | 1.93 ± 0.24 aA | 61.19 ± 1.42 bA | 24.68 ± 3.77 aA | 52.35 ± 0.47 bBC | 89.33 ± 4.51 aAB | |
| 20–40 cm | Clean cultivation | 3.02 ± 0.45 bAB | 1.40 ± 0.15 bB | 1.69 ± 0.32 bB | 22.38 ± 1.37 cC | 12.50 ± 2.19 dBC | 42.33 ± 6.22 abcABC | 51.67 ± 3.51 bB |
| 1 year | 2.57 ± 0.59 bB | 1.37 ± 0.06 bB | 1.48 ± 0.59 bBC | 17.84 ± 0.32 cC | 9.32 ± 0.91 dC | 37.72 ± 1.30 bcdABC | 52.33 ± 4.16 bB | |
| 2 years | 2.75 ± 0.30 bB | 1.29 ± 0.03 bB | 0.65 ± 0.23 cC | 41.33 ± 11.95 bBC | 16.49 ± 2.18 cB | 30.21 ± 9.27 cdBC | 61.33 ± 4.51 bB | |
| 3 years | 3.16 ± 0.21 abAB | 1.33 ± 0.04 bB | 1.31 ± 0.08 bcBC | 39.38 ± 7.99 bBC | 21.69 ± 2.06 bA | 20.62 ± 0.43 dC | 55.67 ± 5.86 bB | |
| 4 years | 3.99 ± 0.53 aA | 1.48 ± 0.17 abAB | 1.89 ± 0.58 bB | 69.97 ± 9.17 aA | 23.54 ± 2.00 abA | 57.03 ± 8.85 aA | 46.67 ± 9.71 bB | |
| 5 years | 3.23 ± 0.65 abAB | 1.67 ± 0.12 aA | 2.97 ± 0.01 aA | 54.92 ± 1.06 abAB | 25.29 ± 1.51 aA | 55.56 ± 7.46 abAB | 102.67 ± 9.50 aA | |
| 40–60 cm | Clean cultivation | 2.74 ± 0.16 bA | 1.32 ± 0.06 bB | 1.33 ± 0.16 bBC | 28.99 ± 0.73 cC | 11.94 ± 1.55 dD | 30.64 ± 0.28 bcB | 48.67 ± 2.89 bcB |
| 1 year | 3.50 ± 0.64 abA | 1.31 ± 0.06 bB | 1.48 ± 0.59 bB | 20.63 ± 5.93 dC | 13.31 ± 2.01 dCD | 30.95 ± 2.52 abAB | 47.33 ± 6.03 cB | |
| 2 years | 2.88 ± 0.06 bA | 1.30 ± 0.02 bB | 0.72 ± 0.31 cC | 40.22 ± 4.44 bB | 18.04 ± 2.08 cBC | 45.90 ± 26.32 abAB | 49.00 ± 7.81 bcB | |
| 3 years | 3.23 ± 0.63 abA | 1.36 ± 0.08 bB | 1.52 ± 0.16 bB | 55.06 ± 0.44 aA | 22.32 ± 3.32 bAB | 23.45 ± 4.42 cB | 58.00 ± 4.00 bB | |
| 4 years | 2.95 ± 0.16 abA | 1.63 ± 0.07 aA | 1.16 ± 0.12 bcBC | 55.76 ± 4.61 aA | 23.01 ± 2.19 bAB | 20.62 ± 1.50 cB | 57.33 ± 6.66 bcB | |
| 5 years | 3.68 ± 0.58 aA | 1.64 ± 0.06 aA | 2.97 ± 0.01 aA | 55.48 ± 4.74 aA | 27.21 ± 1.52 aA | 62.13 ± 0.47 aA | 89.67 ± 6.66 aA |
Note: Different lowercase letters indicate that there are significant differences between different grassing years in the same soil layer (p < 0.05), and different uppercase letters indicate that there are extremely significant differences between different grassing years in the same soil layer (p < 0.01) by ANOVA (mean ± SD) for the ranking test.
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MDPI and ACS Style
Wang, Z.; Liu, R.; Fu, L.; Tao, S.; Bao, J. Effects of Orchard Grass on Soil Fertility and Nutritional Status of Fruit Trees in Korla Fragrant Pear Orchard. Horticulturae 2023, 9, 903. https://doi.org/10.3390/horticulturae9080903
AMA Style
Wang Z, Liu R, Fu L, Tao S, Bao J. Effects of Orchard Grass on Soil Fertility and Nutritional Status of Fruit Trees in Korla Fragrant Pear Orchard. Horticulturae. 2023; 9(8):903. https://doi.org/10.3390/horticulturae9080903
Chicago/Turabian StyleWang, Zengheng, Rui Liu, Liang Fu, Shutian Tao, and Jianping Bao. 2023. "Effects of Orchard Grass on Soil Fertility and Nutritional Status of Fruit Trees in Korla Fragrant Pear Orchard" Horticulturae 9, no. 8: 903. https://doi.org/10.3390/horticulturae9080903
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