| The drought is a key factor of crop yields in dry farming areas in Weibei dryland which is a semi-humid area liable to drought with uneven distribution of rainfall.The study set up different amount of straw mulch and the cover time in the dry agricultural land of Weibei dry plateau, and analysed the effect of straw mulching on spatial distribution dynamic of soil water, soil physical and chemical properties and maize growth and development index two-year located experiment. The main conclusions are as follows:1. Straw mulch improve the soil moisture.t was showed that soil moisture increased with the increasing amount of coverage.The most apparent effect on soil moisture was above the layer of60cm. and the effect of full coverage was better than the growth period coverage.2.Compared with bare land, straw mulch reduced0～25cm soil temperature in seedling stages.The same coverage period. the rate of temperature decreased with the increasing amount of coverage and gentle changes with soil depths.The highest value in daily changes of soil temperature delayed with soil depths.In the same amount of coverage, the soil temperature of full coverage was lower than the growth period covered.Covering straw treatments affected the growth process of corn greatly and postponed rate increased with the increasing amount of coverage.3.Straw mulching reduced soil bulk density and reduced with the increasing amount of coverage. The soil bulk density was less different between the full coverage and growth stages coverage mode in the same amount of coverage.There was no significantly different between all treatments and the control and among the treatments.After dry sieving and wet sieving, the order of the content of>0.25mm soil aggregates in0～10cm soil layer was middle and high coverage>low coverage>CK and10～20cm soil layer was high and middle coverage> low coverage>CK.We found that in0～20cm soil layer, straw mulch significantly increased the content of>0.25mm aggregates. the amplitude of soil mechanical aggregates was2.66%～6.24%(P<0.01) and soil water-stable aggregates was13.80%～39.27%(P<0.05). the content of full coverage was higher than the growth period.The straw mulch improved the water stable aggregates ration in0～40cm soil layer. The water stable aggregates ration increased with the increasing amount of coverage and gradually stabilized in deeper layer.4. Straw mulch infuluenced the total nutrient of0～40cm soil layer and improved organic carbon and available nutrient content of0～60cm soil layer. The straw mulch had most influence on soil nutrient content of0～20cm soil layer. Effects on soil nutrient under different straw mulching treatments decreased with deeper layer and increased with years of mulching. In the same coverage period, the soil nutrient content of full coverage was higher than the growth period covered, the middle coverage was better to improve the soil nutrient.5. The application of straw mulching affected soil enzyme activity obviously of0～10cm soil layer. Effects on soil enzyme activity under different straw mulching treatments decreased with deeper layer. In the same amount of coverage, the soil enzyme activity of full coverage was higher than the growth period covered, but the difference was not significant. The soil urease activity increased with the increasing amount of coverage. The tendency of soil alkaline phosphatase and invertase was different with the soil urease activity and the middle coverage had a maximal increase slope to the control.6. The two years study showed that straw mulch significantly improved the corn yield. The straw mulch increased yield mainly by added kernels per row and hundred-kernels weight. Compared with the control, the yield amplitude of full cover was7.74～22.94%and the growth cover was3.90～18.84%(P<0.01). the water use efficiency in full coverage increased by4.54～12.92%and in growth coverage increased by2.61～10.09%(P<0.01).The yield amplitude of full coverage was larger than growth coverage, the largest yield amplitude was with middle coverage.Integrated2-year results. full coverage with the middle amount improve soil moisture, nutrients, yield and water use efficiency, and it is the best scheme to implement in Weibei plateau. |
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