Effects Of Fertilization Managements?Tillage And Straw Incorporation Approaches On Soil Nutrients And Spring Maize Yield

As the main production area of spring maize,there are tons of maize straw resources in Northeast China.Reasonable utilization of straw resources and improvement of the methods of returning straw to the field are of great significance to spring maize production in this area.In order to explore the feasibility of straw strip return in the main production area of spring maize in Northeast China,the field in-situ positioning experiment was started from 2017 at the experimental base of the Agronomy College of Shenyang Agricultural University in Liaoning Province for three consecutive years,setting up a total of eight treatments including soil tillage methods(rotary tillage,T1;plow tillage,T2),straw returning methods(straw stripe return,M1;full-thickness,M2)and fertilizer application methods(100% seedling line fertilization,F1;1/3 seedling line fertilization+2/3 inter-row fertilization,F2),to study the combined effects of fertilization,tillage and straw returning methods on soil microbial biomass carbon and nitrogen,available nitrogen,phosphorus and potassium,organic carbon,total nitrogen,phosphorus and potassium and spring maize yield,the main results were as follows:1.Under both plow and rotary tillage conditions,F1M1 and F2M2 significantly increased soil microbial biomass carbon content in the 0~30 cm soil layer of maize at seedling stage,and F1M1 significantly increased 0~20 cm soil microbial biomass carbon content under treatments with rotary tillage.The soil microbial biomass nitrogen content in the seedling line changed with the increase of soil depth.It was found with a trend of decreasing first and then increasing under plow tillage,while an opposite trend was showed under rotary tillage.Under plow tillage condition,F2M2 significantly increased soil microbial biomass nitrogen content in 0~10 cm and 20~30 cm soil layers.Straw strip return significantly increased soil microbial biomass nitrogen content under rotary tillage condition,compared to those under straw return to the full-thickness.2.Straw return optimized the structure of soil tillage layer,and effectively improved the spatial distribution of soil nutrients in the farmland.The soil nutrient content was mainly concentrated below the plant growth center.The farther from the plant was found,whatever in the vertical or horizontal direction,with the lower the content of soil alkalytic nitrogen,available phosphorus and available potassium.Under both tillage methods,soil available nutrients content were significantly increased by M1 or F1/F2 treatments.3.The contents of soil alkalytic nitrogen,available phosphorus,and available potassium were increased by 72.6%,36.1%,and 30.7% in different treatments during maturity stage.Under plow tillage condition,F2 significantly increased seedling line soil alkalytic nitrogen content in surface layer(0~20 cm)and available phosphorus content in all soil layer(0~60 cm)at seedling line,soil available potassium content from M1 in 0~30 cm soil layer was higher than that of M2.Under rotary condition,F2M2 significantly increased soil alkalytic nitrogen in 0~30 cm soil layer and available phosphorus content in 10~60 cm soil layer at seedling line,M1 and M2 increased available potassium content in 0~30 cm and 30~60 cm soil layer at seedling line,respectively.Under plow tillage condition,M2 significantly increased inter-row alkalytic nitrogen content in 10~60 cm soil layer and available phosphorus content of row in 20~40 cm soil layer,compared to those of M1,F2 significantly increased inter-row available potassium content in the upper soil layer(0~20 cm),but F1 was not.Under rotary tillage condition,F2 significantly increased inter-row soil alkalytic nitrogen content in 0~30 cm soil layers and available phosphorus content in 20~60 cm soil layers,and M1 significantly increased inter-row soil available potassium content in 0~60 cm soil layers,compared with M2.With the increase of straw returning years,soil alkalytic nitrogen and available potassium significantly increased,while soil available phosphorus was showed a reduction trend.4.The years of straw returning significantly affected soil organic carbon content.With the increase of straw returning years,the soil organic carbon content significantly increased during maize maturity stage.Under M2 treatment,F1 and F2 significantly increased the soil organic carbon content,especially F2M2 treatment.5.There was no significant changes in total nitrogen,total phosphorus,and total potassium content in the respective treatments from 2017 to 2018.Soil nutrients in 2017~2018 decreased with the increase of soil layer depth.Soil nutrients between treatments showed significant differences in 0~30 cm soil layer.After two-year of straw return,the total soil nitrogen and total potassium content in 0~10 cm soil layer were respectively increased by average 7.43% and 3.03%,while total soil phosphorus content was decreased by 21.56% on average.6.Maize yield is not only affected by external environment conditions,but also by the transport and distribution of its own nutrients.After first-year straw return(2017),there was no significant difference in yield and yield components between treatments,and there were slightly higher under F1T1M2 than those from other treatments.In the second year of experiment(2018),due to the increase of rainfall and years of straw returning,the gain yield under rotary tillage treatment was increased,and F1M1 treatment obtained the most increasing.except for F1T2M2,the yield of other treatments under plow tillage treatment were decreased.In the third year(2019),due to the increase of rainfall and years of straw returning,the maize yield of each treatment was showed a significant increasing trend.