Technical points of returning full amount of wheat straw to field

Crop straw is an important byproduct of crops. At the same time, it is also an important production resource for agricultural and industrial production. Returning crop straws to fields not only avoids environmental pollution caused by decay and burning, but also realizes land cultivation by land, and increases soil organic matter content in large areas, improves soil structure, fertilizes soil fertility, strengthens cultivated land quality construction, and improves crop yield and quality. All countries with developed agriculture attach great importance to the scientific rationality of fertilizer structure and the return of most crop straws to fields. A large number of scientific experimental results also show that crop straw returning to the field is the most economical and effective soil fertility improvement measures. The reason why wheat straw returning to field is difficult to popularize and apply is that grass is difficult to bury and easy to stiff seedlings. In 2005, while organizing and implementing the project of "soil organic matter promotion subsidy pilot" of ministry of agriculture, the author summarized the experimental demonstration and application research of straw returning to field in recent years, and extracted the technical points of wheat straw returning to field for reference in the process of popularization and application.

1 Chopped wheat straw

Local@#@245@#@yield per mu is generally 300~400kg, wheat straw per mu is also more than 300kg. In production, more than 80% of wheat straw should be buried in the soil during mechanical rotary tillage. Only in this way can the quality of the next crop be guaranteed and recognized by farmers. In practice, the author found that wheat straw with stubble height less than 10 cm was easier to bury in soil. When the stubble is less than 15cm, it is better to clean the stubble. Therefore, when harvesting wheat mechanically, adjust the blade spacing of the harvester to 5~8cm, so that 90% of the wheat straw length is less than 10 cm, and the wheat straw produced is suitable for various tillage machinery operations. The effect of burying grass is very ideal.

2. Nitrogen regulation and fertilizer increase

One is to increase nitrogen fertilizer application. The proportion of carbon and nitrogen in straw itself is about 100:2, and the proportion required for decomposition is about 100:4. Therefore, nitrogen and other elements need to be absorbed from soil during the decomposition of straw into organic fertilizer, and a certain amount of nitrogen fertilizer should be applied in production. Generally, when 300kg straw is returned to the field per mu, about 10 kg urea should be applied as base fertilizer, and about 15 kg urea should be applied as seedling fertilizer after 5~7 days. The second is to increase the application of biological organic fertilizer. The results showed that the soil sticking on the carriage and the heavy load of machinery appeared when the fertilizer was added per mu; when the water layer was too deep, the grass and soil separated, the straw floating easily appeared, the effect of grass burying was poor, and the rate of stubble burying decreased, which would bring certain adverse effects on artificial transplanting and mechanical transplanting. Therefore, before operation, the water layer should be controlled at a depth of 3~4cm, soaked for 3~4 hours, and shallow water rotary tillage should be achieved. Second, it is advisable to adopt the method of two operations. The speed of the first machine should be slow, and the rotary tillage depth should be more than 20cm; the speed of the second time can be slightly faster, and the rotary tillage depth should be more than 25cm to ensure that more than 80% of the wheat straw can be buried in the soil.

4. Water control and gas regulation

Toxic substances produced by wheat straw in the process of decay and fermentation inhibit the formation and absorption of rice seedling roots, which is the basic reason for rice seedling stiffness. After 5 days, rice seedlings basically took root and survived, and recovered obviously in 10 days. If the straw fermentation process is soaked in water for a long time, the toxic substances produced by straw decomposition cannot be discharged in time, and a large amount of them are concentrated in the root layer soil, and the growth of rice seedlings will be obviously inhibited, so dehydration and ventilation should be carried out in time to promote root growth. Therefore, it is necessary to adopt the mode of alternate wet and dry water slurry management in paddy field with straw returning, soaking in water for 1~2 days and aeration for 2~3 days, avoiding long retting in deep water and poor aeration. Affect rice growth.

For the convenience of application, the author summed up a formula to help everyone remember: straw returning is good, cultivated land quality is gradually improved, wheat straw shredding is the key, reasonable fertilization to promote tillering, shallow water rotary tillage has guarantee, water control and gas regulation to prevent seedling stiffness, land use and land maintenance combination, yield increase and income guarantee.