Method for improving soil nutrients and enzyme activity in camellia oleifera intercropping

Abstract

A method for improving soil nutrients and enzyme activity in Camellia oleifera intercropping, which method comprises the following steps: firstly, performing weeding and soil preparation on a young Camellia oleifera forest, then sowing Cassiae semen in holes in the young Camellia oleifera forest, and after the Cassiae semen is harvested, covering roots of Camellia oleifera trees with granular Oryza sativa straws. By means of the method, the physicochemical properties and enzyme activity of the soil in the young Camellia oleifera forest can be significantly improved, so that the fertility supply capacity of the soil is effectively guaranteed, thereby promoting the growth of a young Camellia oleifera forest.

Description

A method for improving soil nutrients and enzyme activity in oil-tea intercropping Technical Field

[0001] The invention belongs to the technical field of soil improvement, and particularly relates to a method for improving the physical and chemical properties and enzyme activity of oil-tea camellia soil through intercropping and straw mulching. Background Art

[0002] Camellia oleifera, a woody edible oil tree in the Theaceae family, is one of the four major woody oil plants in the world, along with olive, oil palm, and coconut. It is also one of the four major woody oil plants in my country, along with Chinese tallow tree, tung oil tree, and walnut.

[0003] Camellia oleifera is mainly planted in low-lying hills and ridges in the south. Its soil nutrient content is low, and its ventilation and water permeability are poor. Moreover, it can only bear fruit after 3-4 years of planting, resulting in high costs in the early stage of camellia oleifera planting and slow returns. Since there is a certain space between young camellia oleifera forests, it is suitable for planting crops with shorter growth cycles. Therefore, intercropping can improve the comprehensive benefits of young camellia oleifera forest land and increase the economic income of farmers in the early stage of planting. Cassia seed belongs to common leguminous medicinal plants. While having certain economic value, it also has a good effect on soil nitrogen supply. However, existing intercropping plants are mostly annual crops. After being harvested in autumn, their improvement effect on soil fertility will greatly decrease. At this time, if the method of artificially adding chemical fertilizers is adopted to maintain soil fertility, it will not only consume manpower and financial resources, but also pollute the soil of camellia oleifera forest land. In addition, autumn and winter are mostly dry with little rain. The structure of the soil is greatly affected by the climate, which greatly weakens the circulation of water, fertilizer and gas in the soil. The enzyme activity in the soil will also be suppressed by the influence of temperature and moisture. Therefore, how to effectively improve the physical and chemical properties and enzyme activity of oil-tea intercropping soil is an urgent problem to be solved in the process of oil-tea cultivation.

[0004] Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for improving the nutrients and enzyme activity in the oil-tea camellia planting soil by intercropping + straw covering. The method is to intercrop Cassia seeds in the oil-tea camellia young forest and cover it with granular rice straw.

[0006] The method for improving soil nutrients and enzyme activity in oil-tea camellia planting areas of the present invention mainly comprises the following steps:

[0007] (1) In March, within the target oil-tea camellia planting area, select a flat plot with a slope less than 10° and uniform oil-tea growth, and weed and prepare the land for the oil-tea camellia forest.

[0008] (2) In spring, around April, sow Cassia seeds in holes among the young oil-tea tree forests, cover with soil, water, and maintain them normally;

[0009] (3) Around September in autumn, after the Cassia seeds are harvested, crushed rice straw is covered in an area of ​​1m×1m around the roots of the tea trees.

[0010] Preferably, the planting spacing of the camellia oleifera in the camellia oleifera nursery garden in step (1) is 3m×3m.

[0011] Preferably, in step (2), when sowing Cassia seeds in holes, the main stem of the Camellia oleifera is taken as the center, and holes are dug radially outward. The horizontal distance between the first circle of holes and the main stem of the Camellia oleifera is 20 cm, and the horizontal distance between the first circle of holes and the second circle of holes is 30 cm. The holes are funnel-shaped and about 10 cm deep. 10-15 Cassia seeds are placed in each hole.

[0012] Preferably, in step (3), rice straw produced in the current season is collected from paddy fields near the test area and air-dried naturally. The straw reaches maximum dryness (moisture content of 5%-8%) after 7 days of air-drying. After air-drying, the straw is pulverized using an agricultural pulverizer and passed through a 2 mm sieve.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention involves interplanting cassia seeds in young oil-tea plantations, and then covering with rice straw after the cassia seeds are harvested. In traditional farming measures, interplanted crops and straw covering are generally used separately, but there are still many deficiencies and defects when used separately. Specifically, the crops generally interplanted are mainly annual herbaceous crops, and the harvest period is mostly in autumn or winter, and after that, the surface is mostly bare land or the interplanted crops are in a state of lodging. Bare land often causes the soil to have a decrease in fertility due to the decrease in temperature and moisture, thereby reducing enzyme activity and hindering nutrient flow. If the lodged crops are not cleaned in time, there is a risk of mildew, thereby affecting the healthy growth of crops. Traditional straw covering mostly adopts whole-section covering or chopped small-section covering, but such covering method often affects the release of nutrients due to the slow decomposition of straw. Compared with traditional soil fertility improvement methods, this method is more environmentally friendly, simple and easy to implement, and can effectively improve the physical and chemical properties and enzyme activity of the soil in the young oil-tea plantations, thereby contributing to the growth of young oil-tea trees. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic diagram of planting Cassia seeds interplanted among young oil-tea tree stands of the present invention.

[0016] FIG2 shows the crushed rice straw covered under the oil-tea camellia according to the present invention. DETAILED DESCRIPTION

[0017] The following further describes the implementation and specific effects of the present invention in conjunction with specific examples.

[0018] This invention uses the Baisha Village oil-tea camellia base in Changsha County, Changsha City, Hunan Province, as an example. Three-year-old saplings of relatively uniform growth were selected from this base in Changsha County, Changsha City, Hunan Province, to establish an oil-tea camellia-Cassia seed intercropping system. After the Cassia seeds were harvested, rice straw harvested that season was naturally air-dried, pulverized using an agricultural grinder, and passed through a 2mm mesh. After the Cassia seeds were harvested, the processed granular rice straw was applied as a targeted mulch around the oil-tea camellia roots, further improving soil fertility in the oil-tea camellia fields and promoting a healthy ecological cycle within the oil-tea camellia forests.

[0019] This experiment selected three-year-old oil-tea tree saplings with relatively consistent growth. The specific experimental methods are as follows:

[0020] (1) The experimental site is located in the Camellia oleifera base in Changsha County, Changsha City, Hunan Province. The experimental forest consists of three-year-old Camellia oleifera saplings with a planting spacing of 3m × 3m. At the end of March 2021, Camellia oleifera saplings with relatively uniform growth were selected for weeding and land preparation using a small agricultural weeder, and larger weed rhizomes were manually picked out.

[0021] (2) After weeding and land preparation in April, soak the Cassia seeds in warm water the night before sowing. The next day after germination, sow the Cassia seeds in the oil tea forest using hole sowing. When sowing Cassia seeds, dig holes radially outward from the main stem of the oil tea plantation. The first circle of holes is 20 cm horizontally from the main stem of the oil tea plantation, and the second circle of holes is 30 cm horizontally. The holes are funnel-shaped and about 10 cm deep. Place 10-15 Cassia seeds in each hole. After hole sowing, cover the surface of the holes with a thin layer of soil, water, and maintain normal management without applying additional fertilizer. Harvest in September.

[0022] (3) In order to explore the improvement of soil physical and chemical properties and enzyme activity by straw crushing treatment compared with no straw addition, the present invention scientifically designed the following experiment for comparison:

[0023] After harvesting the Cassia seeds, the experimental site was divided into plots, each measuring 3m x 7m, with three tea oil plants planted in each. A 0.5m deep trench, 7m long, was dug between the plots using a hoe. Corrosion-resistant, environmentally friendly plastic partitions, 7m long, 0.5m wide, and 3cm thick, were placed between the plots to prevent cross-contamination.

[0024] The rice straw produced in the local season was collected from the rice fields near the experimental area and naturally air-dried. Taking into account the convenience in actual production and the operability of subsequent crushing, this method found through a large number of drying experiments that in the autumn period of September when the weather is clear and the temperature is suitable, the straw can reach the maximum dryness after 7 days of natural drying, with a moisture content of 5%-8%. After drying, it is crushed with an agricultural crusher and passed through a 2mm sieve. The sieved granular rice straw is collected and used for fixed-point covering within a 1m×1m range at the root of the oil tea. The covering amount of each oil tea plant is the amount of rice straw produced per square meter in the local season: 0.8kg / m 2 , and this treatment was defined as CF; at the same time, a control group (CK treatment group) was set up without rice straw covering.

[0025] Both treatments in this experimental design were repeated five times using a randomized block design. No other fertilizers were added during the covering period. After 90 days, an S-shaped sampling method was used. First, dead leaves and straw on the surface of the soil sample were removed. Then, a ring knife with a volume of 100 cm3 and a soil drill with an inner diameter of 5 cm were used to sample the 0-20 cm and 20-40 cm layers of soil from the root area of ​​the oil-tea tree in each plot. The soil collected by the ring knife was used to determine the soil moisture content. The soil of the same soil layer in the same plot taken by the soil drill was mixed into one sample. After picking out stones and roots, the sample was passed through a 0.149 mm sieve for soil nutrient determination and a 2 mm sieve for soil enzyme activity determination.

[0026] Soil samples were tested using conventional soil methods. Soil moisture content was determined using the ring knife-drying method; soil total organic carbon was determined using the potassium dichromate hydration heating method; and soil total nitrogen was determined using the Kjeldahl digestion and distillation titration method. Soil cellulase activity was determined using the 3,5-dinitrosalicylic acid colorimetric method; soil urease activity was determined using the phenol-sodium hypochlorite colorimetric method; and soil phosphatase activity was determined using the disodium phenyl phosphate colorimetric method. Specific test results are shown in Tables 1 and 2.

[0027] Table 1 Changes in soil physical and chemical properties after 90 days of treatment

[0028] Note: The values ​​in the table are mean ± standard error (Mean ± SE) of the measured indicators. Different lowercase letters indicate statistical differences among different treatments (P < 0.05).

[0029] As shown in Table 1, rice straw mulching effectively increased soil moisture in the oil-tea intercropping system. The soil moisture content in the oil-tea-tea-cassia seed composite system (CF) treated with rice straw mulch was slightly higher than that in the CK system, with an 8% increase across all soil layers. Rice straw addition significantly increased soil organic matter content in the 0-20 cm soil layer, significantly increasing it by 41% compared to the CK system. However, the effect on organic matter content in the deeper soil layers (20-40 cm) was minimal. In contrast, rice straw mulching increased soil total nitrogen more uniformly across different soil layers, with increases of 16% (0-20 cm) and 15% (20-40 cm), respectively. As can be seen from the above, mulching with crushed rice straw effectively increased soil moisture, organic matter, and total nitrogen content in oil-tea intercropping soils.

[0030] Table 2 Changes in soil cellulase, acid phosphatase and urease activities after 90 days of treatment

[0031] Note: The values ​​in the table are mean ± standard error (Mean ± SE) of the measured indicators. Different lowercase letters indicate statistical differences among different treatments (P < 0.05).

[0032] Soil enzyme activity can be used as an important indicator of soil fertility, soil quality, and soil health. The soil enzymes we selected in this experiment are all key enzymes in the C, N, and P nutrient cycles, and therefore have good representativeness. As can be seen from Table 2, overall, rice straw mulching significantly improved soil enzyme activities in different soil layers, especially in deep soil (20-40 cm). For cellulase activity, the increase in rice straw addition compared to CK was 21% in the 0-20 cm soil layer and 41% in the 20-40 cm soil layer; for acid phosphatase activity, the increase in rice straw addition compared to CK was 67% in the 0-20 cm soil layer and 200% in the 20-40 cm soil layer; for urease activity, the increase in rice straw addition compared to CK was 42% in the 0-20 cm soil layer and 76% in the 20-40 cm soil layer. It can be seen that crushed rice straw mulch can play a strong role in enhancing the activity of soil nutrient cycling enzymes, providing an effective guarantee for the supply of nutrients required for the growth of tea oil.

Claims

1. A method for improving soil nutrients and enzyme activity in oil-tea camellia planting soil, comprising the following steps: (1) Within the Camellia oleifera planting area, select a plot with flat terrain, a slope of less than 10°, and uniform growth of Camellia oleifera; (2) Around March in spring, weeding and land preparation are carried out on the young oil-tea tree forest; (3) In spring, around April, sow Cassia seeds in holes among the young oil-tea tree forests, cover with soil, water, and maintain them normally; (4) Around September in autumn, after the Cassia seeds are harvested, crushed rice straw is covered in an area of ​​1m×1m around the roots of the tea trees.

2. The method for improving soil nutrients and enzyme activity in oil-tea intercropping according to claim 1, characterized in that: The planting spacing of the oil-tea camellia in the oil-tea camellia nursery garden in step (2) is 3m×3m.

3. The method for improving soil nutrients and enzyme activity in oil-tea intercropping according to claim 1, characterized in that: In step (3), when sowing Cassia seeds in holes, the main stem of the Camellia oleifera is used as the center and holes are dug radially outward. The horizontal distance between the first circle of holes and the main stem of the Camellia oleifera is 20 cm, and the horizontal distance between the first circle of holes and the second circle of holes is 30 cm. The holes are funnel-shaped and about 10 cm deep. 10-15 Cassia seeds are placed in each hole.

4. The method for improving soil nutrients and enzyme activity in oil-tea intercropping according to claim 1, characterized in that: Step (4) Rice straw produced in the current season was collected from paddy fields near the experimental area and air-dried naturally. After seven days of air-drying, the straw reached maximum dryness (moisture content of 5%-8%). After drying, the straw was pulverized using an agricultural pulverizer and passed through a 2 mm sieve.

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