| Micro-moistening irrigation is a new high-efficiency water-saving irrigation method developed on the basis of subsurface drip irrigation mode in recent years,which has the advantages of good irrigation uniformity,high irrigation utilization efficiency and improving soil salinization degree.Micro-moistening irrigation is a good way to solve the problem of soil salinization in hetao irrigated area.At present,the research on micro-moistening irrigation is limited to the ideal test conditions such as indoor and greenhouse,while the research on the complex test environment of field is ignored,especially on the parameters such as burial depth and irrigation quota.In this study,the effects of different burial depths and irrigation rates on the growth and yield of sunflowers were studied in light saline and alkaline land of hetao irrigated area under micro-wetted irrigation conditions,and the transport law of water,fertilizer and salt in the soil was deeply studied.The effects of soil physical properties and pressure head on water infiltration were further studied in laboratory experiments.The main research results are as follows:(1)A statistical model of cumulative infiltration and time and bulk density,time and pressure head is established,and the simulation accuracy is high.(2)In 2 years,when the water treatment was at the same level,the plant height,stem diameter,dry matter,root length density,root volume density and root surface area density of the sunflower treated with the micro-moistening zone buried depth of 20cm were generally greater than that of the micro-moistening zone buried depth of 10cm.The growth index of overground and underground parts of sunflower increased with the increase of irrigation water when the burial depth of the wetted zone was constant.The comprehensive analysis showed that under micro-wetting irrigation,the burial depth was 20cm,and full irrigation was most beneficial to the growth of sunflower plants.(3)Combined with the distribution characteristics of moisture and salt in micro-moistening irrigation,the soil moisture content in the buried depth of micro-moistening belt is high,and the more the irrigation quota is,the higher the soil moisture content is,and the lower the soil salt is.The variation coefficient of water content in the growth period of the micro-moistening zone buried at a depth of 20cm was smaller at a depth of 10-60m,the soil water distribution was more unifomi,and the soil salinity of 0-60cm was significantly lower than that of the micro-moistening irrigation treatment buried at a depth of 10cm.The accumulation of salt decreases with the increase of burial depth of micro-wetting zone.(4)Under the same irrigation amount,NO3’-N and NH4+-N are easily transported to the soil layer of 10-20cm in the micro-moistening zone buried at a depth of 10cm,while NO3--N and NH4--N are easily transported to the soil layer of 20-30cm in the micro-moistening zone buried at a depth of 20cm.The accumulation of NO3--N in 0-30cm soil layer is about 3 times of that in 30-60cm soil layer.(5)Under the same burial depth,the yield and yield components showed a trend of gradual increase with the increase of irrigation water.In 2015 and 2016,fully irrigated T1 was significantly improved by 12.50%,23.93%,24.77%,7.59%,23.13%and 28.30%,respectively,compared with T2,T3 and T4 treatments.In the case of the same irrigation quota,the yield of the treatment with a buried depth of 20cm in the micro moistening zone increased compared with that with a depth of 10cm,and the difference was significant.(6)To sum up,it is recommended that the micro-moistening zone layout of sunflower farmland in hetao area should be buried at a depth of 20 cm,and the application mode of full irrigation should be adopted,and the surface soil salt should be leached by autumn irrigation. |
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