Effects Of Straw Returning And Tillage Methods On Soil Physicochemical Properties And Crop Yield In Songnen Plain

The Songnen Plain is located in the black soil area of Northeast China.Due to the unreasonable development and utilization in recent years,the quality of cultivated land has been declining,the plough layer has become hardened and shallow,the soil nutrient loss,and the organic matter content has decreased.As a high-quality renewable organic fertilizer,straw is rich in a large amount of nutrients.Reasonable returning of these nutrients to the field can not only improve the effectiveness of soil nutrients,but also solve the problem of a large amount of straw disposal to avoid waste of resources.Appropriate straw returning and tillage methods can improve soil physicochemical properties,improve the quality of cultivated land,and then affect the growth and development of maize and soybean.This experiment began in 2017.It was a continuous positioning experiment.Five treatments were set up under maize continuous cropping and maize-soybean rotation : Traditional rotary tillage(straw leaving field)(TT)treatment was used as the control,and no-tillage sowing(total rice straw incorporation)(NT),no-tillage sowing(total rice straw incorporation)+ seedling furrow deep loosening(NTS),stubble deep loosening(total rice straw incorporation)+ seedling furrow deep loosening(SCS),ploughing(total rice straw incorporation)+ seedling furrow deep loosening(DS)four treatments were set up to systematically study the effects of straw returning and tillage methods on soil physicochemical and chemical properties and crop yield,the analysis in this paper is based on the data obtained in 2022.The results showed that :(1)Straw returning and tillage methods have an effect on soil temperature and humidity.Under the condition of maize continuous cropping,the soil moisture content at 10 cm depth was TT > DS > SCS > NT > NTS,and the soil moisture content at 20 cm depth was SCS > DS > NT >TT > NTS.Compared with TT treatment,SCS and DS treatments increased soil temperature during maize growth period,while the treatment of NT and NTS were opposite.Under the condition of maize-soybean rotation,the soil moisture content of soybean field was TT > DS > NT > SCS >NTS,and the soil temperature was DS > TT > NT > SCS > NTS.The average temperature difference of each treatment was within 1 °C.(2)Straw returning and tillage methods have an effect on soil hardness.Sowing,furrow subsoiling at seedling stage and intertillage all reduced soil hardness.Straw returning and tillage methods mainly affected the hardness of 0-15 cm soil layer,and had little effect on the hardness of15-45 cm soil layer.In the 0-30 cm soil layer,the plow tillage straw returning to the field(DS)and subsoiling stubble straw returning to field(SCS)treatment were lower than that of the treatment of rotary tillage without returning to the field(TT),and the treatment of no-tillage straw returning(NT)was higher than the TT treatment.In the 30-45 cm soil layer,the all treatments showed the opposite law.(3)Straw returning and tillage methods have an effect on soil nutrient content.In the 0-15 cm soil layer,the SCS treatment of maize continuous cropping was more conducive to soil nutrient accumulation.Compared with TT treatment,the contents of nitrogen,phosphorus,potassium and organic matter in soil were increased,and the contents of total nitrogen,total phosphorus,total potassium and organic matter were increased by 9.26 %,4.82 %,2.22 % and 14.27 %,respectively.The NT treatment of maize-soybean rotation was more conducive to soil nutrient accumulation in soybean field.The contents of total nitrogen,total phosphorus,available phosphorus and available potassium in soil were higher than those in TT treatment,and the contents of total nitrogen and total phosphorus in soil were increased by 4.57 % and 4.70 %,respectively.In the 15-30 cm soil layer,the soil nutrient contents of each treatment of maize continuous cropping was inconsistent.The NTS treatment of maize-soybean rotation increased the soil nitrogen,phosphorus,potassium and organic matter content in soybean field.(4)Straw returning and tillage methods have an effect on crop nutrient uptake.In maize grains,DS treatment had the highest total nutrient accumulation and potassium accumulation,SCS treatment had the highest phosphorus accumulation,and NT treatment had the lowest nitrogen,phosphorus and potassium accumulation.The difference between the treatments of SCS,DS and NT treatment reached a significant level.In soybean grains,the nutrient accumulation of nitrogen,phosphorus and potassium in DS treatment was the highest,which was significantly higher than that in NT treatment,and there was no significant rule among other treatments.(5)Straw returning and tillage methods have an impact on crop yield and relative benefits.Under the condition of continuous cropping of maize,the four treatments of NT,NTS,SCS and DS all increased the yield of maize,and the yield of NTS and DS treatment was 15.62 % and 22.38 %higher than that of TT treatment,and the difference was significant.Under the condition of maize-soybean rotation,the treatments of NTS,SCS and DS can increase soybean yield,and the treatments of NTS and DS have higher economic benefits.(6)Based on the comprehensive analysis of soil hardness,soil moisture and thermal regime,soil nutrient status and crop nutrient uptake and accumulation,combined with the comparison of crop yield and relative economic benefits,it is more suitable to adopt no-tillage(total rice straw incorporation)+ seedling furrow deep loosening(NTS)and ploughing(total rice straw incorporation)+ seedling furrow deep loosening(DS)in the central and southern regions of the Songnen Plain.