Effects Of Combined Application Of Organic And Inorganic Fertilizers On Yield And Quality Of Spinach And Soil Nutrient Content

Overspending inorganic fertilizer causes environmental pollution and decreases quality of vegetables.Combined application of organic and inorganic fertilizers could not only solve the questions caused by inorganic fertilizers,but also avoid the pollution caused by the livestock and poultry manure.We took spinach(Spinacia oleracea) as the test material.The test was conducted on alluvial soil.We set up 4 application levels of pure nitrogen:150,300,450,600kgN/ha.Under each application level,we set up 4 combined proportion:100%M,75%M+25%N,50%M+50%N,100%N.By the test,we want to seek the best combination point between the yield and quality of spinach and the protection of environment.The main test results were as follows:1.Adequate supply of nitrogen was an important factor to high yield of spinach,but excessive nitrogen supply could decrease the yield of spinach.Combined application of organic and inorganic fertilizers could increase the yield of spinach.2.The nitrate content of spinach and nitrogen were significantly correlated.Compared with the single application of organic fertilizer and combined application of organic and inorganic fertilizers,the single application of inorganic fertilizer could increase the nitrate content of spinach.Differences of nitrite content of spinach among different fertilizer treatment were not obvious.Adequate supply of nitrogen was an important factor to the Vitamin C Content of spinach,but excessive nitrogen supply could decrease the Vitamin C Content of spinach.Combined application of organic and inorganic fertilizers could increase the Vitamin C Content of of spinach.3.The single application of organic fertilizer and combined application of organic and inorganic fertilizers could increase soil organic matter content,total nitrogen and total phosphorus content after harvest of spinach.4.The content of nitrate nitrogen in soil increased with nitrogen application rate.Comparatively,the law of nitrate nitrogen in soil is 100%N>50%M+50%N>75%M+25%N>100%M.The influence on content of nitrate nitrogen decreased with the deepening of the soil gradually,particularly significant in 0-40cm,insignificant in 40-100cm.At early growth stage of spinach,the content of nitrate nitrogen in soil profile increased firstly and then reduced with the deepening of the soil gradually.At middle growth stage and after harvest,the content of nitrate nitrogen in soil profile decreased with the deepening of the soil gradually.5.The law of available phosphorus in soil was 100%M>75%M+25%N>50%M+50%N>100%N. The effect on content of available phosphorus decreased with the deepening of the soil gradually, particularly significant in 0-20cm.The content of available phosphorus in soil profile decreased with the deepening of the soil gradually.6.Taking a comprehensive consideration between the yield and quality of spinach and nitrate nitrogen accumulation,we concluded that the optimal nitrogen application level was 300kg/ha,while 75%nitrogen provided by organic fertilizer and 25%by inorganic fertilizer.