Soil Nutrient Accumulation, Water And Fertilizer Management In The New-built Greenhouse

Sunlight greenhouse is one of special ways to grow vegetable crops under cold climate innorth China in winter. It successfully solves the problems of supplying vegetables in northChina, and makes a significant contribution to increase the farmers,income and improve theliving standards of urban residents. Therefore, since1980s, it has developed rapidly.However, the prominent phenomenon of blind excessive fertilization during the production process brings about a series of problems, which seriously restricts the sustainable developmentof sunlight greenhouse in China. Many researchers have conducted a lot of studies in thisaspect, however, their researches mainly focus on old greenhouse, the research on nutrientand water management on new greenhouse are rarely reported. Therefore, studyingfertilization status, dynamics of soil nutrient accumulation, water and fertilizer integratedcontrol status, phosphate fertilizer and potash fixed position of different types of soil, canpromote the sustainable development of sunlight greenhouse, and has important theoreticaland practical significance to the development of China’s agriculture. Therefore, this researchhad chosen the new greenhouse in Yangling, Shaanxi as research objects, to survey thefertilization status through continuous field survey, analyze the nutrient accumulationcharacteristics through soil nutrient determination, use field fertilization trials to explore theeffects of tomato yield and soil nutrient under different ration of water and fertilizerprocessing, and evaluate the characteristics of different types of new greenhouse soil inphosphate and potash fixation through incubation method. The main conclusions are:（1） The excessive fertilization was very common in the newly-built greenhouses. Theaverage application rates of organic manure in the greenhouses in the region was121t.hm^-2.The ratioes of N, P₂O₅and K₂O nutrients from organic manures accounted for52%,48%, and44%of the total amount of nutrients added into the greenhouses. The average applicationrates of N, P₂O₅and K₂O fertilizers used in the greenhouses in the region were690kg.hm^-2,720kg.hm^-2and915kg.hm^-2, respectively. Excessive fertilization, especially excessiveapplication of P-fertilizer and K-fertilizer was a very severe problem.（2） The excessive fertilization exists from the beginning of planting in the newgreenhouses, excessive organic fertilizer and chemical fertilizer input lead to a large surplus of nutrients, and the total amount of the apparent surplus of soil nitrogen, phosphorus andpotassium nutrient （in N, P₂O₅, K₂O） in the first three years reaches3784,4097,2727kg/hm².Organic matter, total nitrogen in soils increased linearly, with an average annual increase4.25,0.25g/kg in the3years. The increases of soil available phosphorus, potassium accumulationwere more significant; and2years after planting, available P and K in topsoil reached to avery high level. With the increase of years of cultivation, nitrate accumulation in soil profilesincreased significantly; and available phosphorus, available potassium under topsoil soil alsoincreased. Soil nitrate accumulation in0^-200cm after three years of planting increased to1380kg/hm²; available phosphorus, available potassium in topsoil was169.3mg/kg,366mg/kg, respectively, they were significantly higher than before planting.（3） Compared with the conventional water and fertilizer treatment, the two formulafertilizer and water treatments got similar fruit yields; however, they saved35-46%ofnitrogen fertilizer,40-54%of phosphorus fertilizer,20-35%of potassium fertilizer,respectively. The two formula fertilizer and water treatments saved14.6%-21.2%ofirrigation water; and they also slow down the accumulation of phosphorus, potassium in soil.It indicates that there is a great potential to save water and fertilizers in farmers,greenhouse.（4） The incubation method indicated that to increase soil1mg/kg of availablephosphorus, it needed to added8.04kg/hm²of phosphate fertilizer （P₂O₅） for Lou soil, and6.81kg/hm²phosphorus fertilizer （P₂O₅） for Aeolian sandy soil. And to increase soil1mg/kgof potassium available, it needed to add8.3kg/hm²potash （K₂O） for Lou soil, and5.9kg/hm²potash （K₂O） for Aeolian sandy soil.