Method for increasing soil nutrient content and microbial biomass nitrogen content in purple soil

Abstract

A method for increasing soil nutrient content and soil microbial nitrogen content in a Camellia oleifera plantation on purple soil, relating to the technical field of soil improvement. The planting region of the Camellia oleifera plantation is leveled, weeded, plowed and fertilized, and then ryegrass is sown between Camellia oleifera trees to form an intercropping mode of ryegrass and Camellia oleifera trees. The method can significantly increase the soil nutrient content and soil microbial nitrogen content in Camellia oleifera plantations on purple soil, effectively improve the soil environment, and promote the healthy growth of crops.

Description

Method for improving soil nutrient and microbial biomass nitrogen content of purple soil TECHNICAL FIELD

[0001] The present application belongs to the technical field of soil improvement, and particularly relates to a method for improving soil nutrient and microbial biomass nitrogen content of purple soil through intercropping of ryegrass and Camellia oleifera. BACKGROUND

[0002] Plant intercropping refers to an agricultural planting method of planting two or more different plants on the same land. This method can generally improve soil health, reduce the risk of pests and diseases, and improve crop yield and quality. Plant intercropping ultimately changes the fixation and storage of soil nutrients by promoting the improvement of soil fertility and the stability of the ecosystem. Camellia oleifera is a major agroforestry economic tree species in China and an important natural woody oil tree species. As a key component of the agroforestry complementary planting system, Camellia oleifera plays an important ecological function, and cultivating Camellia oleifera helps to improve the ecological environment and maintain soil moisture, while having broad development prospects and space. Ryegrass (Lolium multiflorum) is a common grass plant with fast growth characteristics, long growing season, strong adaptability, and not strict requirements for soil, and has a wide adaptability. At the same time, ryegrass has a relatively developed root system that can effectively retain water and soil, reduce water and soil loss, and prevent erosion of sloping land and bare soil; and can also improve the ecological environment of Camellia oleifera garden and improve the stability of the ecological system.

[0003] The purple soil hilly slope in Hengyang, central and southern Hunan Province is one of the most severe regions in terms of ecological natural environment in Hunan Province. This region has a serious problem of water and soil loss, sparse vegetation, exposed bedrock, and almost no soil layer in some areas. The natural environment is extremely severe, and it usually takes a long time, often several decades or even longer, for natural succession of vegetation. Through reasonable artificial regulation, the process of vegetation restoration can be accelerated, thereby significantly shortening the restoration time. Therefore, vegetation restoration cannot be passively waiting for natural vegetation restoration. On the contrary, we should reasonably select plants that are adapted to the local ecological environment, and under the premise of ensuring the ecological compatibility of each plant, artificially configure plant communities to influence the succession process of the community.

[0004] SUMMARY

[0005] The present application provides a planting method of ryegrass + Camellia oleifera intercropping, which effectively improves the soil nutrient and microbial biomass nitrogen content of purple soil.

[0006] The present application provides a method for improving soil nutrient and microbial biomass nitrogen content of purple soil, which specifically comprises the following steps:

[0007] (1) Select the target purple soil Camellia sinensis plantation area, carry out soil tillage and arrangement, and ensure that the soil is soft, without large pieces of soil and weeds.

[0008] (2) In December, evenly sow the rye grass seeds in the Camellia sinensis plantation, cover the soil, and irrigate.

[0009] The row spacing and spacing of the Camellia sinensis plantation in step (1) are 2m x 3m.

[0010] The rye grass sowing density in step (2) is about 60 plants / m 2 , and the row spacing is 0.3m.

[0011] The principle of the application: Purple soil is a typical soil type in some areas of southern China, and the improvement of its nutrient and microbial nitrogen content can be achieved through intercropping. Intercropping helps to improve the physical and chemical properties of the soil, while effectively increasing the ground cover rate, reducing the adverse effects of rainwater erosion and human and animal activities on the soil. The root systems of different plants have different depths and growth patterns, which can effectively utilize the nutrients in the soil. Intercropping can utilize the different growth needs and ecological niches of different plants to achieve more effective utilization of soil nutrients. At the same time, the improvement and protection of soil structure by these plant root systems also helps to reduce nutrient loss, increase soil fertility and microbial activity, and thus increase the content of microbial nitrogen. Through the mutual interaction of root exudates, nitrogen fixation and release, organic matter accumulation and decomposition, and nutrient complementation, intercropping can effectively improve the nutrient level and microbial nitrogen content of purple soil, thereby improving the soil environment and promoting the healthy growth of crops.

[0012] The application has the following beneficial effects: The intercropping of rye grass and Camellia sinensis has shown significant effects in improving the quality of purple soil. Through the organic acids and plant hormones excreted by the root systems of rye grass and Camellia sinensis, as well as their respective biomass contributions, this farming method can effectively increase the nitrogen content and microbial nitrogen in the soil. In addition, the shallow roots of rye grass and the deep root system of Camellia sinensis help to maximize the utilization of soil nutrients and reduce nutrient competition. The decomposition of Camellia sinensis branches and leaves releases abundant organic matter, further improving the soil fertility level. Overall, this complementary effect not only helps to improve soil health and structure, but also has a positive impact on crop growth and yield, providing strong support for the realization of sustainable agriculture. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a schematic diagram of the intercropping of rye grass and Camellia sinensis according to the application.

[0014] Figure 2 shows the effect of different measures on soil microbial nitrogen content according to the application. DETAILED DESCRIPTION

[0015] The present application improves the soil physical and chemical properties and the soil microbial nitrogen content of purple soil by adopting the way of ryegrass + camellia oleifera intercropping. The implementation and specific effects of the present application are further described below in combination with specific examples.

[0016] The present application takes Taoling Village of Xinhewan Town, Changning City, Hunan Province, China as an example. The dominant vegetation in this area is camellia oleifera, and the soil in this area is mainly developed from purple sandstone. Selecting camellia oleifera forests with consistent growth, adopting ryegrass + camellia oleifera intercropping planting mode can effectively improve the soil environment, improve the soil physical and chemical properties and microbial nitrogen content, and thus enhance the soil fertility and microbial activity.

[0017] The present application selects camellia oleifera forest planting areas with consistent growth, and the specific implementation method is as follows:

[0018] (1) The test area is located in Taoling Village of Xinhewan Town, Changning City, Hunan Province, and the test forest is a seven-year-old camellia oleifera forest. The planting distance of camellia oleifera forest is 2m x 3m. Before planting ryegrass, the camellia oleifera forest land is leveled and plowed.

[0019] (2) In December, ryegrass seeds are sown at a density of about 60 plants / m 2 , and the row spacing is 0.3m. After sowing, the seeds are covered with soil and watered thoroughly.

[0020] (3) In order to verify the effect of ryegrass + camellia oleifera intercropping (CR) on the improvement of soil nutrients and microbial nitrogen content, this test increases camellia oleifera monocropping + weeding (CO), camellia oleifera monocropping + no weeding (CW) and control sample (CK) for comparison,

[0021] Select areas with similar site background conditions such as altitude, orientation, slope and soil type. For the three selected measures, nine runoff plots are established. The runoff plots are made of corrosion-resistant plastic partitions, each with an area of 5m x 15m (75m 2 ), and the intervals between the plots are 0.5m. Each vegetation type is repeated three times. Three runoff plots of bare land with the same background conditions as the sampling plots and without vegetation restoration measures are selected as control plots (CK). In camellia oleifera + no weeding (CW), the main weeds are six plants, including lemongrass, chili, manzanita, abaca, sarsaparilla and saltbush.

[0022] Ryegrass was planted in December 2022, and soil samples were collected three times in April 2023 (ryegrass and weed flourishing period), July 2023 (ryegrass and weed withering period), and October 2023 (ryegrass and weed nutrient return period). Each runoff plot was divided into upper, middle, and lower slope positions, and one sampling point was randomly selected at each slope position. Surface weeds and litter were removed. A 3 cm diameter soil drill was used to collect soil samples at a depth of 0-10 cm. Three repeated soil samples were taken at each sampling point and then mixed into one sample and placed in a sealed bag. The collected soil samples were immediately sieved through a 2 mm sieve and divided into two parts, each stored in a sealed bag. One part was stored in a 4°C refrigerator for determination of soil microbial nitrogen content, and the other part was naturally air-dried to 0.149 mm sieve for determination of soil basic physical and chemical properties and alkaline hydrolysis nitrogen.

[0023] The soil nutrient determination methods are as follows: 1. Soil bulk density is determined by the cutting ring method; 2. Soil moisture content is determined by the 105°C drying method; 3. Soil organic carbon is determined by the potassium dichromate-concentrated sulfuric acid titration method; 4. Soil total nitrogen is determined by the semi-micro Kjeldahl nitrogen determination method on the HGK-99 automatic Kjeldahl nitrogen instrument; 5. Soil total phosphorus is determined by the sodium hydroxide fusion-molybdenum antimony colorimetric method. Soil microbial nitrogen is determined by the chloroform fumigation extraction-indophenol colorimetric method.

[0024] Table 1 Effects of different artificial disturbance measures on soil physical properties of purple soil

[0025] Note: CK, control plot; CO, Camellia oleifera monoculture + weeding; CR, ryegrass-Camellia oleifera; CW, Camellia oleifera monoculture + no weeding. Different lowercase letters indicate significant differences (p<0.05) among different measures at the same time, and different uppercase letters indicate significant differences (p<0.05) among different times for the same measure.

[0026] As shown in Table 1, in April, the soil moisture content under different treatments ranged from 15.4% to 22.49%, with CW>CW>CK>CR, and CW was higher than the other treatments; the bulk density ranged from 1.12 to 1.23 g·cm -3 , with CW being slightly higher than the other treatments. In July, the soil moisture content under different treatments ranged from 13.65% to 19.51%, with CW>CR>CO>CK, and CW was higher than the other treatments (p<0.05); the bulk density ranged from 1.33 to 1.46 g·cm -3 , with CW being slightly higher than the other treatments. In October, the soil moisture content under different treatments ranged from 8.93% to 12%, with CR>CW>CO>CK, and CR was higher than the other treatments (p<0.05), and the bulk density ranged from 1.35 to 1.46 g·cm -3Among them, the CR treatment is slightly higher than the other treatments. The intercropping mode improves the soil moisture content more significantly than the monoculture mode. The plant intercropping mode has a larger canopy and aboveground biomass than the plant monoculture mode, which means that plant intercropping produces more litter and dead roots, promotes the transformation of humus, and thus increases soil organic matter content and improves soil quality. In addition, a larger root biomass can secrete more adhesive substances, promoting the formation of soil aggregates, thereby improving soil structure, increasing soil porosity, and improving soil available water and water-holding capacity.

[0027] Table 2 Effects of different human disturbance measures on soil chemical properties in purple soil

[0028] Note: CK, control plot; CO, Camellia oleifera monoculture + weeding; CR, ryegrass-Camellia oleifera; CW, Camellia oleifera monoculture + no weeding. Different lowercase letters indicate significant differences (p<0.05) among different measures at the same time, and different uppercase letters indicate significant differences (p<0.05) among different times for the same measure.

[0029] As can be seen from Table 2, the soil organic carbon content of each treatment at each time period is inconsistent. The CK and CW treatments show a trend of first decreasing and then increasing, while the CO and CR treatments show a gradual upward trend. With the passage of time, the soil total nitrogen content of the 4 treatments shows different trends. In October, the total nitrogen content of the soil of each treatment increased significantly, with the CR treatment being the most obvious, with the soil total nitrogen content reaching 0.4 g·kg -1 With the passage of time, the plots treated with different measures all showed a trend of first increasing and then decreasing, but overall, only the soil total phosphorus content of the CR treatment showed an upward trend, while the other 2 treatments and the control plot showed a downward trend. It can be seen from this that the ryegrass-Camellia oleifera intercropping treatment has a more significant effect on the growth of soil organic carbon, total nitrogen, and total phosphorus content (p<0.05).

[0030] As can be seen from Figure 2, the soil microbial biomass nitrogen content of the 3 treatment measures at different times is significantly higher than that of the control plot. The soil microbial biomass nitrogen content of the 4 treatment measures shows different trends over time. The CR and CW treatments show a continuous upward trend over time. In October, the CR and CW treatments increased by 129.6 mg·kg -1 and 23.1 mg·kg -1The microbial nitrogen content of the soil was CR > CW > CO > CK. Different types of vegetation can effectively reduce surface runoff, improve soil physical and chemical properties, increase soil nutrients, and promote the growth of soil microorganisms. Planting camellia combined with ryegrass or weeds may increase soil organic matter content through deposition of fallen leaves, plant litter, and root exudates. Organic matter is an important source of nutrition for microbial growth and activity, so areas with higher organic matter content in the soil usually have a more abundant microbial community.

Claims

1. A method for improving soil nutrient and soil microbial nitrogen content of a purple soil Camellia oleifera forest, specifically comprising the following steps: (1) In the target purple soil Camellia oleifera forest planting area, leveling, weeding, plowing and fertilizing are carried out. (2) In the Camellia oleifera forest, ryegrass seeds are sown, and after sowing, the seeds are covered with soil and fully watered to form a ryegrass-Camellia oleifera intercropping planting mode.

2. The method for improving soil nutrient and soil microbial nitrogen content of a purple soil Camellia sinensis plantation according to claim 1, characterized in that, In step (1), the plant spacing of the Camellia oleifera forest is 2m x 3m.

3. The method for improving soil nutrient and soil microbial nitrogen content of a purple soil Camellia sinensis plantation according to claim 1, characterized in that, In step (2), the ryegrass seeds were sown at a density of about 60 plants / m 2 , with a row spacing of 0.3 m.

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