Effect Of The Intercropping Between Every Two Ridges Planting Maize And Fallow On Yield,Soil Physical And Chemical Properties Under Straw Returning In Cold Region Of Northeast China

Crop stalks are one of China's most abundant renewable resources.It is one of the most economical way for straw resources to returning to field,and it can effectively mitigates the environmental problems caused by the random disposal and incineration of crop stalks.In Northeast China,however,the winter temperature is cold and dry,which is not conducive to the decomposition of straw,and even affects the normal germination of the seeds the next year.In order to fully decompose the returning straw and achieve the purpose of reducing nitrogen and stable crop yield,the experiment took maize as the research material,under different fertilizer ratios,and adopted two culture ways: one was the intercropping of two ridges dense-planted maize and two ridges fallow,the other was normal density planting.A total of 5 groups treatments were conducted: A(Low-nitrogen treatment of dense planting with coated urea)?B(Medium-nitrogen treatment of dense planting with coated urea)?C(Traditional-nitrogen treatment of dense planting with coated urea)?D(Low-nitrogen treatment of normal planting with conventional urea)?E(Traditional-nitrogen treatment of normal planting with conventional urea),to explore its effect on soil physical and chemical properties,maize growth and yield.The main results were as follows:1.In 2017,the soil bulk density of each treatment was lower than that of 2016,and the decline in soil bulk density after fallow treatment in 2016 was even more pronounced.The bulk density of A treated soil decreased the most,being 8%,and was significantly different from other treatments.2.In 2017,total nitrogen,total phosphorus,and total potassium of all treatments increased compared with 2016.Total nitrogen and total phosphorus content increased with crop growth,while total potassium showed a downward trend;after one year of fallow treatment,the total nitrogen,total phosphorus,and total potassium increments were higher than those that were not fallow.The contents of available nitrogen,available phosphorus,and available potassium increased first and then decreased with the growth of crops.In July and August,they were slightly higher than those in June and September,and the medium-nitrogen treatment of dense planting with coated urea was the highest.In 2017,the organic matter content was generally lower than 2016.In 2016,the highest content was C treatment,and in 2017,it was B treatment.3.The urease content in July,August and September was significantly higher than that in June,and the urease data of each treatment in 2017 was significantly higher than that in 2016,in which the content of urease was highest in the B treatment.The change of catalase content was basically consistent with that of urease,which behaving as it rises over time.The content of catalase in September was higher than that in June,and the content of catalase was the highest under B treatment.The soil microbial biomass carbon changes with time,showing a seasonal pattern.4.The total nutrient content of maize plants did not change significantly in two years.The 100-grain weight and length of all treatments were slightly higher in 2017 than in 2016.The heaviest 100-grain weight was the B treatment,and the highest increase was in the C treatment.The longest length was A treatment,and the largest increase in length was B treatment.The highest yield of maize is C treatment,but there is no significant difference between the yields of A and B treatments.