The Effect Of Tillage And Straw Application On Soil Water And Water Use Efficiency Of Spring Maize

There are plenty of straw resource in China, but straw-returning rate is especially low. Straw-returning plays a significant role in improving soil fertility and has huge benefits on ecology and environment, and has a great influence not only on crop growth and crop yield, but also on the soil fertility with matching tillage methods under certain soil and climate conditions. Traditional tillage methods that plowed relatively shallow has been applied generally in China, which led to the formation of thiner plough layers and thicker plow pans, and then reduced the capability of preserving water and nutrients. Sub-soiling and deep plowing are plowing to different extent in depth,both can improve the depth of topsoil by breaking plow pans. A suitable combination of tillage method and straw-returning can not only remove crop residue, improv soil water, fertility, gas and heat conditions, increas crop yield,but also benefit to environment quality and security, ecology, society and economy, which is one of the effective measures and approaches to ensure sustainable development of agriculture.Therefore, we studied crop yield, soil water storage and crop water use efficiency under different combinations of tillage methods at various depths and straw-returningj in order to make it clear and definite the optimal combination, whatis useful to local straw resource and soil cultivation.Based on the 4-year field plot located experiment, exploring the testing method consist of different tillage which were set:Normal Plowing (P); Subsoiling 30cm without mixing the soil in different layer (S); Subsoiling 30cm with mixing the soil in different layer (SM) and 4 methods of straw-returning:No straw returning (SRO); Straw returning every other year (SRI); Straw returning year after year (SR2), what were used to study physical properties like soil bulk density, soil porosity etc, soil moisture, soil water reserving, soil moisture characteristic curve, spring corn leaf stomatal conductance, spring corn single leaf water use efficiency, spring corn yield, as well as water consumption and water use efficiency of growth stage. The major results by analyzing are as follows:1. Moderate tillage of sub-soiling and deep plowing on the basic of rotary tillage for 4 years, can effectively improve soil physical properties, such as reducing soil bulk density and enhancing soil total porosity of plough layer, plough pan and subsoil pan. A certain amount of straw returning with fertilizer also can improve soil physical properties like that given above. By analyzing the two tillage methods, deep plowing performed better on improve soil physical properties, also played a more and more important role with straw returning of gradual increasing years.2.During the growth stages of spring corn, deep plowing with annual straw-returning significantly enhanced soil water storage, improved soil moisture by 5.39% in the 0-60cm soil layer depth and soil water reserving by 32.69% in the 0-100cm soil layer depth. And deep plowing with annual straw-returning has better outstanding performance on soil water storage under precipitation less conditions.3.Sub-soiling and deep plowing with straw-returning enhanced spring corn leaf stomatal conductance of all growth stages significantly, improved leaf water use efficiency by 78.80% and 54.85% in elongation stage and tasseling stage respectively. But the difference of sub-soiling and deep plowing is not significant. Sub-soiling and deep plowing with straw-returning increased the yield of spring corn by 9.10%, and raised water use efficiency by 12.20% during whole spring corn growth stage.In conclusion, under the similar soil and climate conditions to the test district with routine fertilization and field management, taking steps to alternate sub-soiling, alternate deep plowing or sub-soiling and deep plowing in proper years on the foundation of normal plowing, meanwhile straw returning about 6000 kg/10000m2 year after year, could significantly improve soil physical properties, enhance soil water storage and spring corn water use efficiency, increase spring corn yield. Which is reasonable tillage method that is suited to the local area or the similar test conditions field.