| The declining soil water storage capacity, soil quality and productivity, caused by such factors as dry climate, little precipitation, soil erosion, were a crucial bottleneck of the sustainable development of agriculture in China’s arid and semi-arid region. How to improve the straw incorporation technology, dig latent capacity of crops straw on improving soil structure, fertility and quality, continuously improve farmland productivity, was worth to pay close attention as an important research subject in the arid agricultural production. This thesis analyzed three measures (i.e. cut, aminated or mixed with inorganic soil amendment) on soil water characteristics, soil structure as well as the biological effects by indoor simulated tests and field trials respectively. The main conclusions are as follows:(1) The long straw apparently decreased soil water infiltration in the preliminary studies. The soil with pulverized straw can improve soil stable infiltration rate, but the increase was lower. The pulverized and ammoniated straw could significantly improve soil infiltration capacity. Inorganic soil amendment had a significant effect on soil stable infiltration rate and cumulative infiltration.(2) The soil with different straw utilization had a different water-holding capacity in the low suction. The pulverized straw can improve water-holding ability of Lou soil after short time straw-incorporation, and showed a higher immediate effect. The pulverized and ammoniated straw showed more significant effect on improving water-holding capacity. After adding inorganic soil amendment to soil, the soil showed a superior water-holding capacity, compared with the control. When the inorganic soil amendment was incorporated with pulverized and/or ammoniated straw respectively, it has little interaction with straw. Difference on the treatments for soil water-holding capacity reduced in the later period of test. The results on Loessial soil test showed that the different straw utilization had no obviously effect on soil water-holding ability the short term. Soil water-holding capacity cannot be improved until continuous straw-incorporation significantly. The different straw utilization had a very slow and long shelf life on soil water-holding capacity, compared with the inorganic soil amendment.(3) The different straw utilization had great influence on soil water release capacity under the low suctions in Lou soil and Loessial soil respectively. The water release capacity of different treatments showed a "high-low-high" tendency. The reduction of water release capacity mainly occurred after16weeks of incubation. The water release ability would be enhanced effectively after continuous straw utilization, but the ascension range was not too much, in which the pulverized straw’s is higher than other treatments, so it can improve the soil drought resistance effectively. The different straw utilization was not obvious effect on soil water release capacity in single Loessial soil test. The different straw utilization could improve soil water release capacity in double straw-incorporation. The pulverized and ammoniated straw worked best with the water release capacity, compared with other treatments.(4) The soil cumulative evaporation with different straw utilization were increased in the early test in Lou soil and Loessial soil, compared with the control. Soil evaporation performance of the treatment was greatly affected by the manners of straw-incorporation.The pulverized straw could significantly improve soil evaporation rate, compared with long cut straw. The pulverized and ammoniated straw could effectively reduce soil evaporation capacity, compared with the pulverized straw. The pulverized and ammoniated straw mixed inorganic soil amendment (calcium sulfate, aluminum sulfate) respectively could inhibit soil evaporation capacity effectively, while they still had a higher soil cumulative evaporation, compared with inorganic soil amendment.(5) When the pulverized straw was incorporated in the Lou soil and Loessial soil, it could significantly increase the soil structure indexes R0.25, MWD and GMD, further improve soil structure stability. When it mixed with inorganic soil amendment, it had a significant effect on soil structure stability. The long straw, pulverized and ammoniated straw showed a late-effectiveness on soil water-stable aggregates, however, it effectively improved the stability of soil water stable aggregates structure after16weeks of incubation. Inorganic soil amendments (calcium sulfate, aluminum sulfate) had no obvious improvement to the water stable aggregates content and soil structure stability.(6) The soil porosity fractal dimension in soil low suction showed a "high-low-high" tendency under different straw utilization in Lou soil test. The treatments with different straw utilization all were strongly effective to improving the soil porosity fractal dimension after16weeks of incubation in single and double test respectively. The pulverized and ammoniated straw showed stability and a long-term characteristic to uniformity and connectivity of the soil pore. While straw reduced uniformity and connectivity of soil pore in the early Loessial soil test. With the decomposition of straw, soil pore connectivity was improved gradually. Compared with pulverized and ammoniated straw, Long straw was poor in improving soil pore connectivity. When the pulverized and ammoniated straw were mixed with inorganic soil structural amendment, the effect was more obvious on improving soil pore fractal dimension. The different straw utilization could more effectively improve the uniformity and connectivity of soil pores compared with inorganic soil amendment used alone.(7) The pulverized straw could significantly increase the proportion of decomposed straw, compared with long straw. While the effect of the pulverized and ammoniated straw on the proportion of decomposed straw reached the significant level significantly. The inorganic soil amendments (calcium sulfate, aluminum sulfate) would respectively reduce organic carbon mineralization rate.(8) The different straw utilization had late-effectiveness on vigorous growth period of summer maize. The pulverized and ammoniated straw mixed with calcium sulfate amendment could improve summer maize growth rate significantly compared with other treatments. The effect of the different straw utilization on cumulative dry matter of summer maize was a fluctuant process, in which the promoting functions of the pulverized and ammoniated straw occurred mainly in seedling stage and milk stage. There was not obvious influence on grain yield among treatments. The long and ammoniated straw could increase the grain yield, and the pulverized and ammoniated straw was more significant than other treatments on biomass yield among the treatments.(9) The results of water use efficiency test show:Compared with the control, crop water consumption coefficient of long ammoniated straw、pulverized and ammoniated straw、long ammoniated straw pulverized and ammoniated straw、pulverized and ammoniated straw pulverized and ammoniated straw decreased by4.31%,1.91%,3.11%,2.01%respectively, and WUE of these treatments respectively increased by3.29%、3.64%、2.25%、0.87%. When ammoniated straw were added into soil, it played a positive role in increasing crop yield, water use efficiency.This study showed that the effects of different straw incorporation manners on soil physical properties, the recommended way to select the comminuted incorporation manners could be preferable in the long run. |
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