Effects Of Irrigation And Biochar Application Amounts On Potato Growth And Soil Physical And Chemical Properties In Sandy Soil Of Northern Shaanxi Province

Yulin blown-sand area in northern Shaanxi province is one of the top five eugenic and high-yield potato producing areas in China due to its unique light,heat and soil conditions.However,the capacity of soil water and fertilizer retention in sandy land is low,and the utilization efficiency of water and fertilizer is low due to traditional irrigation and fertilization.Biochar has the effect of improving soil,saving water,retaining fertilizer and increasing yield.Through the field drip irrigation water and fertilizer integration experiment to explore the effects of biochar application amounts(B0（0 t/hm²）,B10（10 t/hm²）,B20（20t/hm²）,B30（30 t/hm²）and B50（50 t/hm²）and drip irrigation amounts（W1（80%ET_C）and W2（100%ET_C））on soil physicochemical characters,potato growth,physiological property and water and fertilizer utilization efficiency were studied by combining biochar with drip irrigation fertilization in 2020 and 2021.The main results were shown as below:（1）Drip irrigation amounts and biochar application amounts had significant effects on soil bulk density,soil porosity,soil water content,soil organic carbon content,the content of available potassium and the content of NO₃^--N.With the incease of biochar application amounts,soil bulk density decreased significantly,and soil porosity,soil organic carbon content and soil available potassium content increased significantly,and the maximum change occurred in the 50 t/hm².Proper biochar addition is beneficial to increase soil water content and the content NO₃^--N.With the increase of biochar application amount,soil water content and the content NO₃^--N were first increased and then decreased,and the water content was ranked as B10>B20>B0>B30>B50,however,the maximum NO₃^--N content was biochar application amount of 30 t/hm².With the increase of irrigation amount,soil bulk density was decreased,and soil porosity and water content were increased,and the available potassium and the content of NO₃^--N tended to move to deeper soil with the increase of irrigation amount.Under the same treatment,with the increase of horizontal distance,soil water content was decreased,but the available potassium and the content of NO₃^--N were decreased first and then basically remained unchanged.（2）Drip irrigation amounts and biochar application amounts had significant effects on potato growth and physiological and dry matter accumulation.The effects of biochar on potato growth index was related to the biochar addition rate and sampling time.In the early stage of potato growth in 2020,biochar application had no significant effect on potato growth indexes,but this phenomenon gradually disappeared with the progress of potato growth,around 105 days,biochar started to have a positive effects on potato growth,biochar application improved the amount of dry matter accumulation,leaf area and chlorophyll content,but which was first increased and then decreased with the increase of biochar.In the maturity stage,compared with the control group,B20 and B30 treatments had the most significant promoting effect.While in 2021,biochar has the significant effect on potato plant height,stem diameter,leaf areaindex,the dry matter accumulation during all the potato growth,which mainly manifest as B20>B30>B10>B50>B0.And the effect of biochar on dry matter accumulation of eachorgans was ranked as tuber>root>leaf>stem.In2020,due to the more rainfall,there was no significant difference in potato growth indexes between irrigation amounts,but in 2021,potato growth indexes increased with the increase of irrigation amounts.（3）Drip irrigation amounts and biochar application amounts had significant effects on potato yield,nutrient absorption and water and fertilizer use efficiency.Both different drip irrigation amounts and biochar application amounts could increase potato yield,and the potato tuber yield was first increased and then decreased with the increase of biochar application amounts,and the tuber yield was increased with the increase of irrigation amount,and the maximum tuber yield was W2B30 treatment in 2020,which was 58263.89kg/hm²,but the maximum tuber yield was W2B20 in 2021,which was 77027.73 kg/hm².With the increase of biochar application amounts,potassium concentration in potato organs was increased,and the nitrogen concentration was increased first and then decreased,while the phosphorus concentration showed no significant difference among different treatments,and the water consumption,water use efficiency and the accumulated amount of absorption of N,P and K were first increased and then decreased.The water use efficiency was decreased with the increase of drip irrigation amounts,while the water consumption and accumulated amount of absorption of N,P,and K was increased with the increase of drip irrigation amounts.Compared the fertilizer use efficiency,the Phosphorus use efficiency was significantly higher than nitrogen and potassium.（4）The effect of drip irrigation amounts and biochar application amounts to soil in Blown-sand Region of Northern Yulin was analyzed comprehensively,and then put forward the appropriate amount of biochar and drip irrigation.The application of biochar to soil mainly improved the physicochemical properties of soil,improved the ability of holding water and fertilizer,and then promotes the growth and the yield of potato.However,excessive biochar addition lead to excessive potassium,low soil water content,reduced yield and water use efficiency,and reduced plant nutrient absorption.So considering the yield,water use efficiency,potato plant nutrient absorption and economy,W1B20 treatment could be a suitable water-carbon combination under the experimental conditions.