| China is the country with the largest cultivation area and the highest yield of watermelon and muskmelon.Because of its advantages of short cultivation cycle,strong adaptability to production and remarkable economic benefits,it has become the main source of farmers’economic income in some major producing areas.The problem of blind excessive fertilization in watermelon and muskmelon production is prominent,and the fertilization method of one shot dose fertilization is widely used,which is easy to cause nitrogen loss and environmental pollution.Slow and controlled release fertilizers can effectively control the release rate of nitrogen,reduce the loss of nitrogen fertilizer caused by volatilization,leaching,etc.,thereby increasing the utilization of fertilizers and reducing the pollution caused by fertilization to the environment;and after a one-time application,it can basically meet the nutrient demand of crops in the whole growth period.Because of the different fertilizer controlled release principles and manufacturing processes,the nutrient release characteristics of slow and controlled release fertilizers are different.Meanwhile,soil properties and environmental conditions will also affect the nutrient release of slow and controlled release fertilizers,and the nutrient demand characteristics of different crops are also different.In production,it is necessary to screen and adapt according to crop nutrient demand laws and nutrient release characteristics of slow and controlled release fertilizers.Therefore,this study uses four kinds of resin-coated controlled-release fertilizers and two kinds of stable fertilizers with release period of 90-120 days,then analysis the nutrient release rate of different types of slow and controlled release fertilizers in different soils of chernozems,cumulated irrigated soils,fluvo-aquic soils,sierozems,red earths by indoor culture experiment,and screening the slow and controlled release fertilizer suitable for watermelon and muskmelon application in different soil.On the basis of indoor culture experiment,study the effects of controlled-release fertilizer and chemical fertilizer reduction on yield,quality and nutrient utilization of muskmelon in Hetao Irrigation District of Inner Mongolia were studied under the traditional planting mode of water film,with a view to reduce the application of chemical fertilizer and increase efficiency,and to provide a scientific basis for reducing the environmental risk of non-point source pollution caused by farmland water withdrawal under the mode of water film planting and scientific application of slow and controlled release fertilizers in other regions.Through research,the following main results were obtained:(1)Nutrient release characteristics of slow and controlled release fertilizers in different soil of watermelon and muskmelon show that:the nutrients transformation of fertilizer and the form of nutrients in soil are affected by soil physiochemical properties.After culturing for 15days,the nitrate nitrogen were the major forms of inorganic nitrogen in alkaline soils of chernozems,cumulated irrigated soils and fluvo-aquic soils.However,the ammonium nitrogen showed an increasing trend in alkaline sierozems,and the ammonium nitrogen content was significantly higher than that in other alkaline soils.And the ammonium nitrogen were the major forms of inorganic nitrogen in acid soils of red eraths.There are differences in production technology and materials used by different company.The nutrient release rates of RU2 and RCP2 are higher than those of RU1 and RCP1,which are both coated with resin,andthey are less affected by soil.The nutrient release rate of the same fertilizer is significantly different in different soils and different stages,and the nutrient release of slow and controlled release fertilizer is slow in chernozems and cumulated irrigated soils.The results of matching the nutrient release rate of different fertilizers in different soils with the nutrient absorption characteristics of muskmelon showed that,RUI and SF1 were suitable for application in chernozems,RU1,RU2,RCP2 and SF1 were suitable for application in sierozems,RCP2 was suitable for application in fluvo-aquic soils,RU1,RU2 or RCP2 were suitable for application in red earths,RU2 were suitable for application in cumulated irrigated soils.(2)The result of field experiment of muskmelon with water film planting in Hetao irrigation area of Inner Mongolia shows that:compared with no fertilization(CK),the dry matter quality,yield and nutrient uptakes of muskmelon in all fertilization treatments increased significantly.The yield of controlled release fertilizer and organic fertilizer treatment(RSF+OM,chemical fertilizer reduced nitrogen by 46%,phosphorus by 62%,combined with organic manure by 15 t/hm~2)was significantly higher than that of CF treatment.Compared with CF,the yield and quality of optimized reduced fertilization(RF,fertilizer reduced nitrogen by 46%and phosphorus by 62%),controlled release fertilizer(RSF)and optimized reduced fertilization and organic manure(RF+OM)did not decrease.Compared with CF treatment,RF and RSF treatments increased the nitrogen use efficiency by 15.1%and 21.5%,respectively.Compared with CF,RF and RSF treatments increased the phosphate use efficiency by 20.4%and 18.8%,respectively.(3)Treatments added with manure(RF+OM、RSF+OM)maintained the level of soil organic matter,therefore increased soil fertility,as compared to the treatments only added the chemical fertilizers.The soil mineral nitrogen content of CF treatment was significantly higher than that of other treatments in sowing date.There is no significant difference in soil mineral nitrogen content between conventional fertilization(CF)and controlled release fertilizer(RSF)treatments during harvest period,and these treatments are significantly higher than other treatments.Reducing the application of chemical fertilizer and applying controlled release fertilizer have important ecological and environmental significance for reducing nitrogen loss from muskmelon field in the Hetao area into the Wulangsuhai Lake. |
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