| Huang-Huai-Hai River Valley is the main producing area of high-protein soybean in China, wherethe preceding crop is winter wheat. Lots of wheat straw in the field would affect the sowing quality ofsoybean. Due to the lack of convenient and efficient straw returning technology and no-tillage sowingtechnology, straw processing has been an important factor restricting yield and benefit of soybean, soilfertility and environmental protection. In recent years, the National Soybean Industry R&D Systemdeveloped a new technology called “No-tillage with Straw Mulching and Precise Sowingâ€, which is anew way to resolve the problems of straw treatment and sowing quality in Huang-Huai-Hai region. Inthe current study, the main factors are no-tillage with straw mulching precise sowing (NS), conventionalmechanical sowing (CS) and rotary-tillage artificial sowing (RS), and two minor factors are totallystraw returning and half straw returning, six treatments totally. We studied the effects of different strawreturning ways on soybean yields and soil physical and chemical properties, the key points of no-tillagesowing technology, and assessed the utilization value of no-tillage with straw mulching precise sowingtechnology. The main results are the followings:Compared with the CS and RS, the NS technology caused higher sowing quality and betteremergence evenness, faster and earlier emergence and higher emergence rate. The emergence rate washigher than97%in two years. The amount of straw returning had no significant effect on sowing andemergence quality.The growth and development of soybean in no-tillage sowing treatments (NS and CS) were fasterthan RS, the VE stage and R1stage were0.6-3.4days and0.1-2.3days earlier respectively. In dry years,the superiority of NS was more obvious, the VE stage was0.6-1.2days and the R1stage was0.6-1.4days earlier than that of CS. The growth of soybean in NS treatment is the fastest, and leading to alongest duration between the VE stage and the R7stage, which is good for soybean yield. The amountof straw returning has no significant effect on soybean growth and development.Compared with the CS and RS, soybean seedling in NS was stable, strong, and vigorous. NS hadreasonable yield structure, on which there was not significant effect of the amount of straw returning.Because of the missing seedling and low plant density, the number of branch, pods and seeds per plantand100-seed weight of RS were higher than the other two sowing ways. NS had the highest yield giventhe amounts of straw returning is the same. The treatment of half straw returning has higher yield thanthe totally straw returning.No-tillage sowing treatments would increase the soil volume weight, but straw returning can slowthe rate of increase. With the years of straw returning, it may play a more important role than tillagemethod on the soil volume weight. Effects on soil temperature and moisture by straw returning occur inthe period between sowing date and VE stage. No-tillage sowing treatments would reduce thetemperature of soil surface, increase the soil moisture, and has a much more significant effect than RStreatment which would increase the soil temperature and reduce the soil moisture.Straw returning treatments would increase the soil organic matter, the content of available phosphorus and available potassium, reduce the soil pH value and the content of NH＋4-N and NO3--N.No-tillage with straw mulching precise sowing with totally straw returning treatment caused the biggestreduction of pH value and increase of organic matter and available phosphorus. It can improve soilchemical properties which can facilitate soybean to absorb and utilize soil nutrient.Wheat straw maturity degree increases as the soybean grows. Before soybean harvest, wheat strawmaturity degree is the largest in RS, it can reach58.6%. The straw maturity degree can reach50%in NStreatment, and do no harm to the next wheat sowing.No-tillage with straw mulching precise sowing with totally straw returning is a convenient andefficient straw returning technology and no-tillage sowing technology as well. It is suitable forpopularization in summer soybean production of Huang-Huai-Hai region, and it has very broadapplication prospect. |
