Straw returning method based on corn and covered crop cultivation

Abstract

The invention discloses a straw returning method based on corn and covered crop cultivation, which comprises the following steps: grading and crushing corn straws according to soil types, carrying out zoning treatment, combining a leguminous-gramineae-cruciferae ternary mixed sowing covered crop system, and matching a decomposition microbial inoculum and controlled release nitrogen fertilizer synergistic regulation technology. The efficient decomposition of the straws and the improvement of the soil quality are realized. The method can increase soil organic matters by 0.25%, increase corn yield by 12.7% and reduce nitrogen fertilizer loss by more than 30%, and is suitable for sustainable production in dry farming areas.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural planting and soil conservation, and specifically relates to a systematic method that combines the full - amount return of corn straw to the field with the coordinated cultivation of cover crops, and is particularly applicable to the comprehensive management technology for improving the soil quality of dry - land farmland and enhancing the sustainability of the agricultural ecosystem. Background Art

[0002] 1. Analysis of Defects in the Existing Technology

[0003] (1) Limitations of Traditional Straw Returning Technology

[0004] Nutrient imbalance problem: The carbon - nitrogen ratio of corn straw (C / N = 60:1) is high. Directly returning it to the field causes competition for nitrogen between microorganisms and crops during the decomposition process, leading to chlorosis in the seedling stage of corn.

[0005] Risk of pest and disease transmission: Unrotted straw remaining in the field increases the over - wintering population of pests and diseases such as corn borer and stalk rot.

[0006] Soil structure damage: Single - plowing and returning straw to the field easily causes soil surface compaction, and the bulk density increases by 0.15 - 0.25 g / cm 3 .

[0007] (2) Bottlenecks in the Application Technology of Cover Crops

[0008] Sowing window conflict: Residual straw in the field after corn harvest hinders the sowing of cover crops, and the emergence rate is reduced by 30% - 50%.

[0009] Increased inter - species competition: The cover crops and corn compete for light and temperature resources during the symbiotic period, resulting in a 5% - 8% reduction in corn yield.

[0010] 2. Necessity for the Innovation of the Present Invention

[0011] In view of the above problems, the present invention breaks through the bottlenecks of single technologies by innovatively integrating straw spatial configuration technology, cover crop combination breeding technology, and microorganism - nutrient synergistic regulation technology, and achieves the following goals:

[0012] 1. Construct a two - level straw returning system of "surface covering - deep burial improvement" to simultaneously improve the moisture - retaining capacity and soil structure improvement effect.

[0013] 2. Develop a ternary cover crop mixed - sowing mode of "legume - gramineous - cruciferous" to achieve the multi - functional coupling of weed suppression, nitrogen fixation, and biological fumigation.

[0014] 3. Establish a dynamic monitoring and intelligent regulation system for straw decomposition to solve the problems of carbon - nitrogen ratio imbalance and low decomposition efficiency. Summary of the Invention

[0015] 1. Technical Solution

[0016] The core method of the present invention includes the following steps:

[0017] (1) Differential zoning treatment of corn straw

[0018] Crushing and grading: Dynamically adjust the straw crushing length according to soil texture:

[0019]

[0020] Spatial configuration: Adopt strip zoning technology and distribute the crushed straw in proportion:

[0021] Surface covering belt (60 - 70% mass ratio): Uniformly spread it on the 40 - 50 cm wide planting row to form a continuous covering layer;

[0022] Deep - buried improvement belt (30 - 40% mass ratio): Use a subsoiler to bury it into the 15 - 20 cm soil layer to improve the deep porosity.

[0023] (2) Selection and sowing of cover crop combinations

[0024] Construction of mixed sowing system: Configure the species ratio according to the principle of niche complementarity:

[0025]

[0026] Seed pretreatment:

[0027] Leguminous seeds: Inoculate with rhizobia (concentration ≥ 1×10 6 CFU / grain);

[0028] Cruciferous seeds: Coated with diatomaceous earth (particle size 2 - 5 μm, addition amount 3% w / w) to enhance insect resistance.

[0029] (3) Decomposition regulation and nutrient synergistic management

[0030] Dynamic monitoring and intervention:

[0031]

[0032]

[0033] (4) Synergistic tillage management

[0034] Operation of a roller - cutting root integrated machine:

[0035]

[0036] 2. Core technology innovation

[0037] (1) Construction of straw - microorganism interaction network

[0038] Inoculate with a composite microbial agent (containing white rot fungi and actinomycetes) to induce the production of:

[0039] The activity of lignin peroxidase (LiP) is increased by 2.3 - 3.5 times;

[0040] The synthesis amount of ACC deaminase ≥ 1.2 U / mg, alleviating the ethylene stress generated by straw decomposition.

[0041] (2) Root - soil interface regulation

[0042] Cover crop roots secrete flavonoids (such as daidzein ≥ 0.8 μg / g), promoting mycorrhizal fungal infection, forming a "straw - hypha bridge", and increasing phosphorus utilization rate by 18 - 22%.

[0043] 3. Technical effects

[0044] (1) Soil improvement indicators (data for 5 consecutive years)

[0045]

[0046]

[0047] (2) Production and ecological benefits

[0048] Yield increase: The average yield of maize increases by 12.7%, and the yield volatility in dry years is reduced from ±20% to ±8%;

[0049] Carbon sequestration: Annual carbon sequestration per mu is 0.82 t CO2 equivalent, of which straw decomposition contributes 0.48 t;

[0050] Emission reduction: Reduce nitrogen fertilizer loss by 4.3 kg / mu and reduce N2O emission by 1.2 kg CO2 equivalent / mu. Specific implementation methods

[0051] Example 1: Application in the spring maize area of the North China Plain

[0052] Step 1: Straw treatment

[0053] Time: October 5th (maize grain moisture content ≤ 22%);

[0054] Crushing: The vertical - shaft flow combine harvester is equipped with 3 - mm blades, and the straw length is 8 cm;

[0055] Configuration: 60% of the straw is spread on the 40 - cm planting belt, and 40% is buried 15 cm deep.

[0056] Step 2: Sowing of cover crops

[0057] Varieties: 50% hairy vetch + 30% winter rye + 20% mustard;

[0058] Aerial seeding parameters: UAV altitude 3m, row spacing 25cm, seeding rate 3.2kg / mu;

[0059] Application of microbial agents: Spraying Trichoderma agent (≥1×10 6 CFU / g) 200g / mu.

[0060] Step 3: Field management

[0061] Late November: Rolling press compaction (pressure 30kPa);

[0062] March 20th of the following year: Shallow harrowing with a disc harrow by 5cm to cut off the above-ground part.

[0063] Effect: Soil organic matter increased from 1.6% to 1.92%, and corn yield increased by 14.5%.

[0064] Example 2: Rainfed mode in the black soil area of Northeast China

[0065] Adjustment items: 100% surface coverage (slope ≤5°), mixed sowing of 60% vetch + 40% oats;

[0066] Nitrogen fertilizer optimization: Topdressing DMPP-coated urea at the 6-leaf stage (20% reduction);

[0067] Pest and disease control: Preparing 10% biological fumigant from mustard residues for furrow application.

[0068] Example 3: Water and fertilizer integration in arid areas of Northwest China

[0069] Cover crops: 70% Sudan grass + 30% chickpea;

[0070] Irrigation: The buried depth of drip irrigation tape is 5cm, and the irrigation water volume is reduced by 30%;

[0071] Returning method: Maize stubble is left at 40cm to resist wind erosion.

[0072] The above describes the present invention and its implementation manners, and this description is not restrictive. Generally speaking, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A method for returning straw to fields based on the cultivation of corn and cover crops, characterized in that The following steps are involved: (1) After corn is harvested, the corn stalks are crushed into 3-12 cm pieces according to the soil texture, and divided into a surface cover zone and a deep buried improvement zone at a mass ratio of 60-70%:30-40%; (2) Within 24 hours after corn harvest, a cover crop combination of 45-55% legumes, 25-35% grasses, and 15-25% crucifers was sown by drone at a sowing rate of 2.5-3.5 kg / mu; (3) During the growing period of the cover crop, the roller pressing and root cutting machine is used for pressing and root retention, with a roller pressing pressure of 25-35 kPa and a root cutting depth of 8-12 cm; (4) 20-30 days before corn planting the following year, crush the above-ground part of the cover crop and return it to the field, and simultaneously apply controlled-release nitrogen fertilizer and decomposing bacteria.

2. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: In the step (1), the sandy loam is crushed to a length of 3-5 cm, the clay loam is crushed to a length of 6-8 cm, and the heavy clay is crushed to a length of 9-12 cm.

3. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: In the cover crop combination, the Leguminosae family is hairy vetch or arrow pea, the Poaceae family is ryegrass or oats, and the Cruciferae family is mustard or marigold.

4. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: The decomposing bacteria agent comprises white rot fungi and actinomycetes, and the number of live bacteria is ≥ 1×10 8 CFU / g.

5. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: The controlled-release nitrogen fertilizer is sulfur-coated urea, the nitrogen release period is 50-70 days, and the application amount is 3.5-4.5% of the dry weight of the straw.

6. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: Before sowing cover crops, leguminous seeds were inoculated with rhizobia at an inoculation rate of ≥ 1×10 6 CFU / particle.

7. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: When the roller compaction-root cutting machine is in operation, the underground root length of the cover crop is retained to be ≥15 cm.

8. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: Dynamic monitoring of soil C / N ratio was conducted on the 10th, 30th and 60th days after straw was returned to the field. When the C / N ratio was greater than 25:1, urea was added by 3-5 kg / mu.

9. The method for returning straw to fields based on corn and cover crop cultivation according to claim 1, characterized in that: For plots with slopes >5°, contour straw strip mulch is used, with a 40cm strip width and 80cm strip spacing.

10. A method for returning straw to fields based on the cultivation of corn and cover crops according to any one of claims 1 to 9, characterized in that: When sowing corn, a no-till seeder is used to dig furrows in the straw mulch belt with a depth of 5-8 cm, and 40-50 kg / mu of slow-release compound fertilizer (N-P2O5-K2O=22-10-12) is applied simultaneously.

Images