| With the large-scale development of facilities and vegetables,people are blindly applying large amounts of fertilizer in pursuit of yield,and the high multiple cropping index of facilities,high temperature and high humidity,and lack of rainwater leaching have caused continuous cropping obstacles to become increasingly apparent,seriously affecting the yield and quality of vegetables.People found that after the survey,the rotation of crops with vegetables and water can effectively improve the soil properties and alleviate obstacles of continuous cropping.Rice straw is rich in nutrients.Experiments have shown that long-term straw return can effectively improve soil properties and increase soil organic matter content.People in our laboratory conducted a study to avoid the hazards of deep straw returning to farms using paddy field soil cover to cover rice straw,and found that the decomposition rate of rice straw cut into two segments was in spring and summer was 75.33%and 89.11%respectively,which was significantly higher than the rate of 49.11%in the fall of rice straw in flooded fields in autumn.Therefore,this experiment uses paddy-wheel rotation for straw-covered soil cover in the facility,and uses rice straw to cover vegetables and water to cover the surface of rice straw.This study explores the different soil specifications of rice straw and the amount of straw returned in different seasons.The rot decomposition law and its effect on soil properties,vegetable yield and quality have further explored the effect of straw returning on the salinization soil of Chinese cabbage after dry farming.The main results are as follows:1.In July-October 2015 rice straw slicing 5cm small section with 500kg/mu planted water spinch with soil surface in high temperature season;soil decomposition rate of straw is 100%,straw returned to soil treatment compared to the contrast did not return soil In terms of total phosphorus content,available phosphorus content,total potassium content,and available potassium content,the decline was smaller than that of the contrast.The early treatment of water spinch was lower than that of the contrast,and that of the later period was higher than that of the control.The total yield was higher than that of the control;Ascended,reaching the maximum value of 1584 ?S·cm-1 on the second day.The change in the contrast was relatively flat,indicating that the small section of straw can significantly increase the contact area with microorganisms to increase the decomposition rate,and the high temperature,high humidity and aerobic environment encouraged rot to explain the release of nutrients.2.From November 2015 to March 2016,rice straw was cut into 5cm segments and covered with 500kg/mu on soil surface in the low temperature season.The decomposition rate of straw was 83.3%,which was lower than the decomposition rate in hot season 100%,indicating that the temperature can significantly affect the rate of decomposition of the straw.In the low temperature season,the conductivity of the soil surface solution reached its maximum value at the third day and was only 1109?S·cm-1.The decrease in organic matter content in the treated soil was 6.5%,which was significantly lower than that in the control of 15.3%.The yield of watercress harvested twice was higher than that in the control.The nitrate content of watercress was lower than that of the control,indicating that the straw returned to the field can also be decomposed in large quantities in the low temperature season and the nutrient release rate is slower.The inhibition of vegetable growth in the early stage is small;the nitrate content can also be reduced to improve the quality of the vegetables.3.In April-October 2016,the increase of straw soil surface coverage amounted to 5 cm returning to the field with 750 kg/mu rice straw.The decomposition rate of rice straw was 100%,and the nitrate nitrogen content in the soil was significantly reduced.The comparison shows that in the decomposition process of straw,nitrate can be absorbed in the soil to relieve soil salinization;the experiment was carried out with a total of 7 harvests,and the first two post-harvest topdressing treatments were the same as the control topdressing.The top 4 post-harvesting top dressings were treated with 10 kg/mu,followed by 15 kg/mu urea,and the yields of each of the 7 treatments were higher than the control,indicating that returning straw to the field can help reduce fertilizer application.4.Increase the specifications of the straw cutting section.After about half a year,the straw will be returned to the farm from April to July 2017.After the straw is planted with 10 cm and 750 kg/mu soil cover,the straw will reach a higher level of rot.The solution rate is 90.5%,indicating that the 10cm section straw can almost completely decompose and release nutrients,and 10cm can reduce the cutting cost compared with 5cm;the total nitrogen content of the treated soil increases,the control decreases,and the total phosphorus content of treated.was no significant change from the control,and the nitrate nitrogen content in the treated soil decreased.The amaranth was harvested 3 times in total.The principle of reducing fertilization continued to be applied for harvesting and topdressing.The total yield was slightly lower than that of the control,but the content of total flavonoids from the straw planted into the field was generally higher than that of the control.5.During December 2016 to January 2017,the Chinese cabbage was treated with different fertilization levels for dry cultivation.Over-fertilization was conducted in the treatment.Compared with conventional fertilization,the soil total nitrogen content was significantly increased compared to that before planting,while the control was decreased,Nitrate nitrogen content also increased significantly,indicating that large amounts of fertilization will lead to continuous increase in soil nitrate content,soil salinization;the yield of over-fertilized cabbage was significantly higher than the control,The treatment of fiber was lower than that of the control.After over-fertilization,the content of nitrate in the treatment of Chinese cabbage was significantly higher than that of the control,indicating that excessive fertilization would cause excessive accumulation of nitrate in the vegetables and endanger human health.In April-July 2017,in the soil after the dry cultivation of Chinese cabbage,the section of 10cm rice straw was covered with 750kg/mu soil surface to cover the flooded planting water spinch,and the decomposition rate of the straw was 86.2%.The content of nitrate in soil after straw returning to treatment decreased significantly,but the change in control was not significant.This indicated that the coverage of straw soil surface had a good mitigation effect on the salinization problems that existed in the current facilities.The water spinch was harvested three times in total,and the total output of treatment is higher than the control.Therefore,the straw covers in the soil surface to plant aquatic vegetables.When the straws are covered with the same size of 5cm,the decomposition rate in the high temperature season is significantly higher than in the low temperature season;increasing the coverage of the straw surface can prolong the planting time of the aquatic vegetables and can be decomposed.straw with a 10cm section cut surface specifications can also get about 90%of the high decomposition rate.The decomposition rate of each locust was significantly higher than that of 49.11%in open field stalk flooding,and more stalks could be decomposed than the two stalks of rice stalks.The rice straw mulch covers the cultivation of aquatic vegetables,and the total vegetable output is generally higher than the control.Straw soil surface coverage can significantly reduce soil nitrate content,improve soil total potassium and other content,effectively improve soil properties,and is conducive to the reduction of fertilization. |
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