Effects Of Potassium Fertilizer Types And Irrigation Amount On Potato Growth And Water And Fertilizer Utilization Under Drip Irrigation In Northern Shaanxi

Yulin,Shaanxi province is one of the main potato producing areas in China,but there are some unreasonable problems in irrigation and fertilization in actual planting,such as"chlorine should not be avoided in potatoes","potassium nitrate burning seedlings"and others,so that potassium fertilizer can not fully play its nutritional role.Potato is a potassium-addicted crop.Reasonable management of potash fertilizer is the key to increase production and efficiency of potato industry.In this study,under the drip irrigation and fertilization system,"Qingshu No.9"was used as the experimental material to carry out experiments in the Yulin sandstorm area of northern Shaanxi province in 2020 and 2021.Three irrigation levels（W1-60%ET_c,ET_c is the water requirement of crops,W2-80%ET_c and W3-100%ET_c）and four potassium fertilizers（K0-no K fertilizer control,KCl-chloride,K₂SO₄-potassium sulphate and KNO₃-potassium nitrate）were set.The potato’s birth period growth index,dry matter accumulation,yield and its components in mature,quality and soil water distribution index were observed.The potato fertilizer use efficiency and economic benefits were calculated.The effects of different combinations of potassium fertilizer and irrigation on potato yield,quality and utilization of water and fertilizer were analyzed.The following conclusions are drawn:（1）Potassium fertilizer types and drip irrigation amount and their interaction had significant effects on potato growth,dry matter accumulation,yield,its components and economic benefits.Increasing irrigation was beneficial to leaf growth and significantly increased dry matter accumulation,yield and net income at maturity.Potassium fertilizer significantly promoted potato growth and tuber enlargement.At W1 level,the yield of KCl treatment was lower than that of K₂SO₄ and KNO₃.At W2 and W3 levels,the potato yield,commercial tuber and net income of KNO₃ treatment were significantly higher than that of KCl and K₂SO₄,and there was no significant difference between K₂SO₄ and KCl treatment.In terms of the interaction between water and potassium,the dry matter accumulation,yield and economic benefit of W3+KNO₃ treatment at maturity were significantly higher than those of other treatments.（2）Potassium fertilizer type and irrigation amount had significant effects on starch and reducing sugar content.With the increase of irrigation amount,starch content increased significantly,while reducing sugar content showed a decreasing trend.At the W1 level,the starch content of KCl treatment was significantly lower than that of K2SO4 and KNO3,and irrigation was increased,but there was no significant difference among the three potassium fertilizer types,and the trend was K₂SO₄>KNO₃>KCl.At W1 and W2 levels,the reducing sugar content of KCl treatment was significantly higher than that of K₂SO₄ and KNO₃.At W3level,there was no significant difference among the three potassium fertilizer types,and the changing trend was K2SO4<KNO3<KCl.In terms of the interaction between water and potassium,W3+K₂SO₄ had the highest starch content and the lowest reducing sugar content.（3）Potassium fertilizer types and irrigation amount had significant effects on plant nitrogen accumulation and potassium accumulation.Potassium fertilizer was beneficial to plant nutrient absorption,increased soil available potassium content at harvest stage,and reduced soil residual nitrate nitrogen.The more dry matter accumulated in potato mature stage,the higher the nutrient content absorbed by plant,and the less the residual nutrient content in soil.The nitrate accumulation of KNO3 was lower than that of KCl and K2SO4.In terms of the interaction between water and potassium,W3+KNO3 treatment had the highest nutrient uptake and the lowest soil nitrate nitrogen content.Sufficient water and potassium nitrate treatment promoted plant growth and increased nutrient uptake.（4）Irrigation amount,potassium fertilizer type and their interaction had significant effects on potato nutrient utilization efficiency.With the same potassium fertilizer,the nutrient utilization efficiency increased with the increase of drip irrigation,increasing irrigation promoted the uptake and utilization of nutrients by plants,and the effectiveness of fertilizer was different under different water conditions.In general,the nutrient utilization efficiency of potassium nitrate treatment was higher.（5）Potassium fertilizer types,irrigation and their interactions had significant effects on potato water use efficiency（WUE）.Under the same potassium fertilizer treatment,WUE decreased with the increase of irrigation amount in 2020,and increased with the increase of irrigation amount in 2021.At the same irrigation amount,potassium fertilizer application significantly increased WUE.In terms of potassium fertilizer treatment,KNO₃ was generally higher than that of K₂SO₄ and KCl,and there was no significant difference between K₂SO₄and KCl.Taking potato growth,yield,economic benefit,quality and utilization of water and fertilizer into consideration,by combining entropy weight method and TOPSIS,the study concluded that W3+KNO₃（potassium nitrate application,irrigation amount is 100%ET_c）can obtain high yield,quality and efficient potato with high utilization efficiency of water and fertilizer under high economic benefit.The study can provide scientific basis for potato drip irrigation potassium management in northern Shaanxi.