Detailed Explanation of the Technical Key Points for Returning the Full Amount of Wheat Straw to the Field

Crop straw is an important by-product of crops. It is also an important production resource for agriculture and industrial production. Returning crop straw to the field not only avoids the environmental pollution problems caused by rotting and burning, and achieves feeding the land with the land itself, but also consolidates the foundation of soil fertility for greatly increasing soil organic matter content, improving soil structure, building up soil fertility, strengthening the quality construction of cultivated land, and raising crop yield and quality. In every agriculturally developed country in the world, great attention is paid to the scientific rationality of the fertilization structure and the return of most crop straw to the field. The results of a large number of scientific experimental studies also show that returning crop straw to the field is one of the most economical and effective measures for building up soil fertility. The reason why returning wheat straw to the field is difficult to promote and apply is that the straw is hard to bury and tends to cause seedling stunting. In 2005, while organizing and implementing the Ministry of Agriculture's "Soil Organic Matter Improvement Subsidy Pilot" project, the author and others summarized the experimental and demonstration application research on straw return carried out in recent years, and distilled the technical key points for returning the full amount of wheat straw to the field, for everyone's reference in the process of promotion and application.

1 Chopping the wheat straw

The local @#@245@#@ yield per mu is generally 300-400 kg, and the amount of wheat straw per mu is also above 300 kg. In production, during mechanical rotary tillage, more than 80% of the wheat straw must be buried into the soil. Only then can the quality of sowing and planting of the next crop be guaranteed, and only then will farmers accept it. In practice, the author and others found that wheat straw with a stubble height of less than 10 cm is relatively easy to bury in the soil. When it is less than 15 cm, stubble cleaning is better, so when mechanically harvesting wheat, the spacing of the straw chopping blades of the harvester should be adjusted to 5-8 cm, so that 90% of the wheat straw is less than 10 cm in length. The resulting wheat straw is suitable for the operation of various tillage machines, and only then is the straw-burying effect very ideal.

2 Adjusting nitrogen and increasing fertilizer

First, increase the application of nitrogen fertilizer. When the full amount of wheat straw is returned to the field, the amount of straw is large, and the carbon-to-nitrogen ratio of the straw itself is about 100:2, while the ratio required for decomposition is about 100:4. Therefore, in the process of decomposing into organic fertilizer, the straw needs to absorb nitrogen and other elements from the soil, and a certain amount of nitrogen fertilizer must be supplemented in production. Generally, when 300 kg of straw per mu is returned to the field, about 10 kg of urea should be applied as base fertilizer, and after 5-7 days about 15 kg of urea should be applied as seedling fertilizer. Second, increase the application of bio-organic fertilizer. Experiments show that increasing the application per mu causes phenomena such as mud sticking to the knife roller and drag plate and excessive operating load on the machinery; when the water layer is too deep, the straw separates from the mud, and the straw is prone to floating, the straw-burying effect is poor, and the stubble-burying rate decreases, which will bring certain adverse effects on both artificial rice transplanting and mechanical rice transplanting. Therefore, before the operation, the water layer should be controlled at a depth of 3-4 cm, soaked for 3-4 hours, and shallow-water rotary tillage should be adopted. Second, the two-pass operation method should be adopted. In the first pass, the forward speed of the machinery should be slow, and the rotary tillage depth should be more than 20 cm; in the second pass, the speed can be slightly faster, and the rotary tillage depth should be more than 25 cm, ensuring that more than 80% of the wheat straw can be buried into the soil.

4 Controlling water and regulating air

The fundamental reason why wheat straw produces toxic substances during the rotting and fermentation process that inhibit the occurrence and absorption function of rice seedling roots and cause rice seedling stunting is this. More than 5 days after the rice seedlings are transplanted, they have basically taken root and become established, and after about 10 days they clearly resume growth. If the straw is soaked in water for a long time during the fermentation process, the toxic substances produced by straw decomposition cannot be discharged in time and become concentrated in large amounts in the root-layer soil, and the growth of the rice seedlings will be obviously inhibited. Therefore, water should be drained in time for aeration to promote root growth. Therefore, the water and slurry management of rice fields where straw is returned to the field must adopt an alternating dry-wet mode, soaking in water for 1-2 days and aerating for 2-3 days. Deep-water long-term retting and poor aeration must be avoided. This affects rice growth.

To make it easier to apply, the author and others summarized a jingle to help everyone remember: Returning straw to the field is really good, cultivated land quality gradually improves, chopping the wheat straw is the key, rational fertilization promotes tillering, shallow-water rotary tillage provides a guarantee, controlling water and regulating air prevents seedling stunting, combining land use with land nurturing, increased yield and income are guaranteed.