Effects Of Soil Amendments And Soil Matrix Potential Regulation On Saline-Alkaline Soil Amelioration And The Yield Of Kirin Watermelon

Aiming at the problems of water shortage and soil salinization in north region of Yinchuan,the effects of different soil amendments and soil matrix potential regulation on soil water and salt in saline-alkali soil and the yield and quality of Kirin watermelon ’Meidu’ were studied by field vault experiment with Kirin watermelon ’M eidu ’ as test material.There are five treatments for soil amendments,including Sulfur fertilizer(S0(0kg·667m^-2),S5(5kg·667m^-2)and S10(10kg·667m^-2)),bio-organic fertilizer(B0(0kg·667m^-2),B40(40kg·667m^-2)and B80(80kg·667m^-2)),Soil conditioners(T0(0kg·667m^-2),T20(20kg·667m^-2),T40（40kg·667m-1）)and amendments（CK,T1（S5+B40）,T2（S5+T20）,T3（B40+T20）,T4（S5+B40+T20））;Soil matrix potential control levels were set at-10KPa and-20KPa,in order to provide theoretical basis for the improvement of sandy saline land and water saving and salt control.The main findings are as follows:（1）Single application of sulfur fertilizer,bio-organic fertilizer,soil conditioner and three kinds of amendments can enhance the salt leaching ability of 0-100cm soil layer after irrigation.Among them,S10,B40,T40,T2 and T3 had the best effect,and the soil salt content at harvest stage decreased by 14.00%-31.45%,7.76%-26.62%,12.38%-31.48%,3.02%-34.13%and 13.18%-17.46%compared with the control.After treatment,the water content of shallow soil generally increased,and the pH value decreased significantly.In addition,compared with the control,the soil nutrient content in 0-40cm soil layer changed continuously during different growth periods,and the soil nitrate nitrogen and available phosphorus contents were increased by amendments,among which S10,B80,T40 and T3 treatments had the largest increase.（2）Soil amendments promoted the growth of main vine length,stem diameter and leaf area of Kirin watermelon,increased SPAD value and photosynthesis intensity,and then increased the yield of watermelon.The yield of S10,B40,T40,T2 and T3 treatments increased by 6.32%,5.38%,8.38%,12.41%and 12.31%respectively compared with the control treatment.（3）The application of sulfur fertilizer had significant effects on soluble solids,soluble sugar,sugar-acid ratio,vitamin C and lycopene content.The reasonable application of bio-organic fertilizer had great effects on soluble solids,sugar-acid ratio and vitamin C content of melon heart.The contents of soluble solid and lycopene in melon heart were significantly affected by the application of soil conditioner fertilizer.Compared with CK treatment,the soluble solids of T2 and T3 increased by 9.84%and 9.57%respectively,and the lycopene content increased by 20.34%and 17.93%respectively.（4）Under the control level of soil matrix potential,the water content of 0-40 cm soil layer increased to a certain extent,and the water content in the vine extension period increased by 6.51%-20.70%compared with the harvest period.The soil pH value decreased with the advance of watermelon growth period,while the salt content increased by 66.10%-97.19%.The water content of 0-40 cm soil layer at harvest stage was significantly increased compared with that before sowing.Soil salt content decreased significantly in 0-40 cm soil layer.The shallow soil pH value of each treatment during the harvest period was significantly lower than that before sowing.The-20KPa treatment significantly promoted the main vine length,stem diameter and leaf area of watermelon,and significantly increased the SPAD value and photosynthesis of leaves,which was conducive to the improvement of yield and quality.（5）Soil amendments and matrix potential regulation improved the rhizosphere environment of watermelon,and reduced the types and contents of phenolic acids in root exudates.The change of root exudates may be related to the salt content of soil.In summary,the application of soil amendment significantly reduced the salt content and pH value of shallow soil,improved the soil fertility status,promoted the growth of Kirin watermelon,and improved the yield and quality.The application of 10kg·667m^-2 sulfur fertilizer,40kg·667m^-2 bio-organic fertilizer,40kg·667m^-2 soil conditioner,5kg·667m^-2 sulfur fertilizer combined with 20kg·667m^-2 soil conditioner and 40kg·667m2 bio-organic fertilizer combined with 20kg·667m^-2 soil conditioner are suitable for the growth in north region of Yinchuan and Kirin watermelon.The type and application amount of soil conditioner,-20 KPa is the soil matrix potential threshold suitable for the growth of watermelon in saline-alkali land.