Effects Of Different Irrigation Amount And Nitrogen Rate Combination Treatments On Potato Growth And Soil Water And Nitrogen Transport And Distrbution

Aiming at the problems of strong evaporation,shortage of water resources,low utilization efficiency of irrigation water and nitrogen fertilizer,and extensive planting management in the arid region of Ningxia,The experiment was conducted by random block test to study the effects of membrane under drip irrigation different irrigation amount and nitrogen amount treatments on potato growth index,tuber yield,water consumption rate,water and nitrogen utilization efficiency and soil water and nitrogen transport and distribution.The main research conclusions are summarized as follows:(1)Potato plants grow fastest in tuber formation period(6.26-7.25)and have the highest chlorophyll content in their leaves at seedling stage(6.6-6.25).Nitrogen had a significant effect on plant height at the beginning of growth(P<0.05),and irrigation water had a significant effect on plant height at the end of growth(P<0.05).Both irrigation water and nitrogen had significant effects on stem diameter at the late growth stage(P<0.05),while the irrigation water,nitrogen and interaction effects of water and nitrogen had no significant effects on leaf area and chlorophyll content(P>0.05).Among them,the effect of irrigation water on plant height and leaf area growth was greater than that of nitrogen,while the effect of nitrogen on stem diameter and chlorophyll content was greater than that of irrigation water.The combination of water and nitrogen with the irrigation quota of 1800 m3-hm-2 and the nitrogen application amount of 120 kg·hm-2 was the most favorable for the above-ground growth of potato plants.(2)Influenced by irrigation,rainfall,evaporation,root activity and other factors,water consumption,water consumption rate and modulus coefficient of potatoes all presented single-peak curve changes with the progressive growth period,and water consumption,water consumption intensity and water consumption modulus of tuber growth period(7.26～20)were the maximum.The critical water requirement period for potatoes is between late June and late August.Water consumption,rate of water consumption and water consumption modulus all increase with the increase of irrigation quota and decrease with the increase of nitrogen application.In different water and nitrogen combinations,the irrigation quota is 1800 m3·Uhm-2,the nitrogen application amount is 120 kg·hm-2,and the water consumption is 4020.82 m3·hm-2,showing the maximum.When the irrigation quota is 900 m3·hm-2 and the nitrogen fertilizer is 240 kg·hm-2,the water consumption is 2940.95 m3·hm-2,which is the minimum.(3)When the irrigation quota was in the range of 900～1350 m3·hm-2,increasing nitrogen application could significantly increase potato yield.The nitrogen application amount was within the range of 120～180 kg·hm-2.Among them,the irrigation amount and nitrogen rate combination with the irrigation quota of 1350 1m·hm-2 and the nitrogen application amount of 240 kg·hm-2 produced the maximum yield of 58509.36 kg·hm-2.The combination of irrigation amount and nitrogen rate with an irrigation quota of 1800 m3·hm-2 and a nitrogen rate of 120 kg·hm-2 produced the largest yield of large potatoes,reached 41147.73 kg·hm-2.The combined yield of irrigation amount and nitrogen rate with an irrigation quota of 900 m3·hm-2 and a nitrogen rate of 240 kg·hm-2 was the next highest,56008.49 kg·hm-2.The output reached the expected ideal level.(4)Under the same irrigation quota treatment,the water use efficiency increases with the increase of nitrogen application,while the nitrogen use efficiency decreases with the increase of nitrogen application.When the irrigation quota was 1800 m3·hm-2,the water use efficiency decreased with the increase of nitrogen application.Under the same nitrogen treatment,the water use efficiency decreased with the increase of irrigation quota,and the nitrogen use efficiency increased with the increase of irrigation quota.When the amount of nitrogen was 240 kg·hm-2,the utilization efficiency of nitrogen fertilizer first began to increase and then decrease with the increase of irrigation quota.The water use efficiency of the combination of irrigation amount and nitrogen rate with an irrigation quota of 900 m3·hm-2 and a nitrogen rate of 240 kg·hm-2 was the highest.IWUE was 62.23 kg·m-3 and YWUE was 19.04 kg·m-3.The combination of irrigation amount and nitrogen rate with an irrigation quota of 1800 m3·hm-2and a nitrogen rate of 120 kg·hm-2 had the highest nitrogen use efficiency.AEN was 95.96 kg-kg-1,PFPN was 437.47 kg·kg-1.(5)There is no deep water leakage in the observation layer(0-100 cm),when the irrigation amount are 900 m3·hm-2 and 1800 m3·hm～2.Under the irrigation treatment of 1350 m3·hm-2,deep seepage was observed in soil(0-100 cm).Under the influence of irrigation,meteorological factors and crop root activities,the soil moisture content and nitrogen in soil layer 0-60 cm changed dramatically.With the increase of soil depth,the changes of soil moisture content and nitrogen in soil layer of 60～100 cm are relatively stable.Soil nitrate nitrogen content was mainly accumulated in the surface layer(0-20 cm)and the middle and lower layer(60～100 cm).Due to the weak leaching ability of ammonium nitrogen to the subsoil,the content of ammonium nitrogen in the surface soil(0-20cm)is generally higher than that in the subsoil.Tuber growth period is the period when the potato absorbs the most nitrogen.Hydrus-1D software can accurately simulate soil moisture distribution in soil layer of 0-60 cm in potato growing period.