| Under the traditional vegetable production model,large quantities of irrigation and excessive application of nitrogen fertilizers are required for farmers to pursue high yields and high benefits,resulting in a large amount of irrigation water and soil nutrients leaking below the root layer of the crops,reducing the utilization efficiency of water and nutrients,resulting in water and fertilizer The waste of resources.Therefore,exploring the dynamic changes of nitrogen concentration and nitrogen leaching amount in soil solution under different irrigation volume and its response to different irrigation volume is of great significance for reasonable irrigation and fertilization of greenhouse vegetable production and improvement of water and fertilizer utilization efficiencyIn this study,the greenhouse cucumber was used as the research object,and the evaporation(EP)of a 20 cm diameter evaporating pan was used as the basis for irrigation.Three irrigation levels were set,11(Kcp1:0.8)and 12(Kcp2:1.0)and 13(Kcp3:1.2).With the help of a soil solution in-situ sampler in a weighing lysimeter test in greenhouse,the growth characteristics of greenhouse cucumbers under different irrigation levels were studied.Nitrogen concentration distribution and dynamic changes in soil solutions in different soil layers during growth period were studied.And nitrogen leaching situation,with a view to provide a theoretical basis for the production of reasonable water and fertilizer management of greenhouse cucumber and improve the efficiency of water and fertilizer use.The main findings are as follows:(1)Plant height,stem diameter,and biomass per plant increased with the increase of irrigation amount.Compared with the treatment I1,plant heights of 12 and 13 increased by 15.45%and 20.92%,respectively(P<0.05).The stem diameter increased by 5.95%and 16.18%(P<0.05),and the biomass per plant increased by 35.82%and 57.66%,respectively(P<0.05).The increase in irrigation volume contributes to the growth of cucumber and the accumulation of dry matter quality(2)The change of nitrate in all soil layers during the growth period of cucumber was relatively large,ranging from 50 to 1300 mg-L-1.The reduction in irrigation volume increased the nitrate concentration in 20 cm and 40 cm soil layers and decreased the nitrate content.The nitrate concentration in the 60 cm soil layer.Compared with the treatment 13,the average concentration of nitrate nitrogen in the 20 cm and 40 cm soil layers increased by 75.59%and 134.36%,while the average concentration of nitrate nitrogen in the 60 cm soil layer decreased by 18.88%.However,the change of ammonium nitrogen in all soil layers under different irrigation amounts was significantly lower than that of nitrate nitrogen,and the maximum concentration during the growth period was only 0.4 mg·L-1.The ammonium nitrogen concentration in the 20 cm soil layer was comparable to that of nitrate.Similar changes in nitrogen were observed,but there was no significant difference in treatments between 40 and 60 cm soil layers.Appropriately reducing the amount of irrigation can make the nitrogen in the soil more retained in the upper layer of soil that can be absorbed and utilized by the root system,which is conducive to the improvement of fertilizer utilization efficiency(3)The amount of leachate at 90 cm decreased with the decrease of irrigation volume.Compared with treatment 13,the total amount of leachate treated with 11 and 12 decreased by 51.1%and 33.9%,respectively,and the average concentration of nitrate nitrogen was respectively Reduced 70.35%and 40.19%.The total amount of nitrogen eluted from 90 cm soil in cucumber season was 56.08-203.13 kg·hm-2,accounting for 9.02%?32.69%of the total nitrogen application rate.Compared with treatment 13,the nitrogen leaching amount of treatment I1 and 12 Respectively reduced by 72.39%and 49.16%.With the decrease of irrigation volume,the amount of leakage liquid and nitrogen leaching at 90 cm is significantly reduced,so that more water and nutrients are retained in the soil,which is beneficial to increase water and nutrients.Utilization efficiency.(4)However,cucumber yield was the highest at 10643.33 kg-hm-2 under 12 treatment.Compared with treatments I1 and 13,the yield of cucumber increased by 24.74%(P<0.05)and 18.88%(P<0.05),respectively.Water use efficiency increased by 3.36%and 39.24%respectively(P<0.05),and partial nitrogen productivity increased by 24.74%(P<0.05)and 18.88%(P<0.05),respectively.Treatment of 12 helps to promote the growth of cucumber plants and increase the yield of cucumber,improve water use efficiency and nitrogen partial productivityConsidering the indicators of soil nitrogen concentration,leaching amount,and cucumber yield,treatment 12 is the optimal irrigation amount under the test conditions.At this time,the nitrogen concentration in the 20 and 40 cm soil layers is relatively large,while the soil layer below the root layer and The nitrogen concentration in the leakage liquid was smaller at 90 cm,and the amount of nitrogen leaching was significantly less than that of treatment 13.The cucumber yield and water and fertilizer use efficiency were the highest. |
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