Effects Of Straw Returning On Physical&Chemical Characteristics Of Brown Soil And Growth Of Corn

Investigation to corn stover incorporation effect on soil fertilization and maize yield is crucial forimproving the straw returning cultural technology, increasing the soil storage and capacity, andestablishing the soil organic fertilization system. The main objective of this work was to study theeffects of corn stover incorporation on soil physical properties including soil moisture content, bulkdensity, porosity and aggregate compositions, on soil chemical properties including soil total nitrogen,total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium andorganic matter, and on growth characteristics of maize including plant height, stem diameter,chloroplast of ear-leaf and yield. In the rain-fed agricultural area of Liaoning Province, a nine-yearfield location trial from2005to2014consisted of five treatments, which was a split plot design withfive (5) straw returning treatments as follows:(1) conventional tillage without organic residue andfertilizer (CK),(2) fertilizer recommendation (OPT),(3) fertilizer recommendation+straw4500mg/hm2(OPT+L),(4) fertilizer recommendation+straw7500mg/hm2(OPT+M),(5) fertilizerrecommendation+straw10500mg/hm2(OPT+H). Three main results of current study are summarizedas follows:(1) Corn stover incorporation increased the topsoil moisture content after the bell-mouthed period,but decreased the topsoil moisture content in earlier maize growth period, and the same as tendency inthe soil water storage and capacity in soil layer depth of0-100cm. Compared with single applicationof chemical fertilizer, OPT+M treatment increased the soil water storage and water use efficiency by11.78%and0.10kg/(mm·hm2) under medium amounts of straw returning, and OPT+L treatmentincreased soil water storage and water use efficiency by5.92%and0.18kg/(mm·hm2) under smallamounts of straw returning. Furthermore, corn stover incorporation for9years, soil bulk densitydecreased by3.81%～9.16%, soil field water capacity increased by8.32%~9.31%, and total porosityincreased by6.61%~7.13%, while, in the depth of soil layer from0~10cm and from10~20cm, soilmechanical stable aggregates of diameter above0.25mm increased by3.45%~7.13%and4.96%~10.62%, water-stable aggregates increased by6.29%~9.44%and10.33%~19.32%, the meanweight diameter of mechanical stable aggregates increased by10.81%,9.46%and7.87%,7.86%, andthe mean weight diameter of water-stable aggregates increased by7.01%~7.64%and2.87%~4.66%.(2) Compared with OPT, corn stover incorporation for9years, soil organic matter increased2.53～3.39g·kg-1(P<0.05), which was in the order large>medium>small straw returning; there wasno difference in soil total nitrogen, total phosphorus, and soil total potassium (P>0.05); there wassignificant in soil available nitrogen that increased by12.20%~26.72%(P<0.05), which was in theorder large=medium>small straw returning; soil available phosphorus under small straw returningamounts, available phosphorus with medium and large amounts increased4.28mg·kg-1,5.54mg·kg-1and5.85mg·kg-1, respectively; there was significant in available potassium that increased25.35~32.47mg·kg-1(P<0.05).(3) Compared with OPT, both OPT+M and OPT+H treatment decreased emergence rate of maize; OPT+L treatment was conductive to increase plant weight and stem diameter of maize, butOPT+M and OPT+H treatment had little effect on that; Corn stover incorporation slow down therate of decline of chlorophyll in the ear position leaf, though the content of chlorophyll in the earposition leaf decrease when the maize was in tasseling stage; chemical fertilizer plus straw returningincreased obviously corn grain yield by4.24%~10.26%, in which OPT+L treatment was the best.