| As the warming of global climate,the worsening of drought and the severe shortage of water resources,dryland agriculture plays an important strategic role in ensuring the sustainable development of food in the future.It is crucial that effective conservation and efficient utilization of natural precipitation for the sustainable development in dryland agriculture.How to implement water conservation and water storage and water use is of great scientific significance and practical value for improving crop yield and water productivity in farmland.Based on the field experiment at the same location,this study was carried out various water regulation patterns such as rain-gathering and preservation by mulching,increase soil density and water storage by tillage and straw-returning,regulating soil water by planting density and supplementary irrigation in dryland of Shanxi province in the central of loess plateau in 2013-2017.The purpose of the study was to explore the relationship between efficient water harvesting,water conservation by reducing transpiration consumption,crop water use and crop growth and development,yield and water use efficiency.And the mechanism of increasing yield and water use efficiency under different water-regulating patterns is analyzed.The main results were as follows:1.Through the study on the technology of water collecting and preservation by mulching in dryland maize,it showed narrow film + straw mulching(MS)treatment increased significantly 0-160cm horizontal and vertical water storage,Compared with CK,soil water storage increased 30.8 mm improved 10.1%for three average years.Mulching raised effectively raised soil temperature of 0-15 cm topsoil layers,compared to CK,MS,WM and NM increased correspondingly 0.91?,0.64?Cand 0.63 ?.And soil accumulation temperature during the whole growth period was increased 12.5%,6.4%and 7.9%.Soil mulching provided suitable water and temperature conditions,and promoted the growth and development of the ground and underground parts of maize plant.Mulching reduced the amount of water consumption during the reproductive period.In the same test year,the ET value of narrow film + straw mulching was always lower than that of the other two mulching treatments.Compared with CK,the grain yield in MS treatment increase 21.3%and the average water use efficiency for 3-year(WUE = 30.9 kg ha-1 mm-1 M-1)increase 30.4%.Especially in drought and normal years,MS increased significantly WUE.Because of the combined effect of straw and mulching,narrow film + straw mulching was better than that of single mulch.And it is an effective water-regulating measure for dryland agriculture.2.The rational tillage and straw returning can improve the soil structure and soil water storage capacity.The Study showed that no-tillage(NT)and sub-soiling(SS)increased the horizontal and vertical water content of 0-200cm soil layers,and increased the soil effective storage capacity.The no-tillage and straw-returning and sub-soiling and straw-returning increased by 69.12 mm and 68.89 mm water storage contents of 0-200 cm during the fallow period,respectively,by 16.6%and 17.0%.And the soil storage capacity of 0-200 cm on average during the maize growth period also increased.According to fitting analysis of daily rainfall and daily water storage in the different tillage treatments,no-tillage treatment can intercept effective rainfall and improve rainfall infiltration when the daily precipitation was>5mm.Sub-soiling treatment increased soil porosity which can effectively collect<5 mm ineffective rainfall.The relevance analysis between daily water consumption and yield showed that soil water consumption patterns of no-tillage and sub-soiling treatments were more favorable to grain yield increasing in maize.There were significant differences in water use efficiency between different tillage and straw-returning(P<0.05).Therefore,no-tillage and straw returning treatment(NT+SR100)and sub-soiling and straw returning(SS+SR100)improved soil stucture and increased soil water infiltration,maintenance and even improved WUE,which were the best combination patterns for storing soil water in dryland maize.3.Appropriate population density and supplementary irrigation can also effectively regulate soil moisture.The results showed that the grain yield of maize with full irrigation and limited irrigation was higher than that of non irrigation,and the increase rate is 4.83?11.88%.However,there was no significant difference in yield under different irrigation levels.There were significant differences in WUE between different irrigation and density treatment.From the point of WUE at different irrigation levels,limited irrigation improved water utilization in deep soil layers and reduced daily water consumption and improved the soil water efficiency.From the point of WUE at different planting density treatments,WUE in D6.0 was the highest(WUE = 28.46 kg/hm2.mm).Compared with D4.5?D7.5 and D9.0 treatments,WUE in D6.0 increased 9.4%,2.7%and 9.1%,respectively.Therefore,full irrigation was difficult to achieve in arid and semi-arid areas,limited irrigation could be an effective way to increase yield and WUE when the planting density was D6.0.4.The increase in yield potential is also a prerequisite for achieving WUE improvement.The study showed that the yield difference between the optimized pattern and the conventional pattern was 3549.9 kg/hm2,and the yield potential was influenced by rainfall and environmental factors between different years.The variation of yields was 27.4%?39.8%in five years.The quantitative analysis of each factor showed that the contribution to yield of film mulching and density was larger,which were the key factors limiting the yield increase,while the contribution to yield of nitrogen fertilizer factor was the least.Compared with the conventional pattern,the optimized pattern improved maize yield and WUE. |
PDF Full Text Request