Study On Soil Fertility Status And Technology Of Reduced Fertilization And Increased Efficiency In Greenhouse Vegetable Production Of Baoding

Fertilization is an important means to improve the yield and quality of vegetables.However,the excessive and unbalanced fertilization is becoming more and more serious in vegetable production,which may potentially restricts the sustainable development of vegetable industry.In this study,the main vegetable production areas in Baoding were taken as the research area.The soil fertility of vegetable field was investigated and analyzed.Furthermore,field experiments were conducted to investigate the effects of fertilization management(i.e.reduced fertilization rate)as well as application of nitrogen(N)regulators on yield,quality and nutrient use efficiency of greenhouse vegetables.The main results are summarized as follows:(1)The comprehensive evaluation parameters of soil fertility in greenhouse vegetable field was significantly higher than that in open field and grain field.But the contents of organic matter,total N and alkali-hydrolyzed N in greenhouse vegetable field were generally lower than the content of fertile soil standards,only 17.1%(>30.0 g/kg),19.4%(>1.5 g/kg)and 40.3%(>120.0 mg/kg)of the total samples reached fertile soil standards,respectively.The available phosphorus(P)and potassium(K)content in vegetable soil were significantly enriched.The content of micro-elements(iron,manganese,copper,zinc)were generally at the medium to high level.(2)Under the condition of high soil fertility,there was no significant effect on the yield of cucumber without applied N,P or K or no fertilizer.However,the yield of violet cabbage decreased significantly after two consecutively rotation without N application while was not affected without P or K application.In terms of vegetable quality,the nitrate content of cucumber was not changed by no N application compared with N application or no fertilizer due to the sufficient N supply from soil.But the nitrate content of violet cabbage decreased significantly in the second rotation.The soluble sugar content of cucumber without N,P,K or no fertilizer application decreased significantly,but the sugar-acid ratio was not affected significantly because of the decrease of organic acid content.No K application significantly reduced the Vc content in cucumber.Therefore,at a higher level of available nutrients in the soil,an appropriate amount of fertilizer should be applied in order to balance the yield,quality and enhancing efficiency of vegetables.(3)Under the condition of high soil fertility,the yield and profit of cucumber and violet cabbage could be increased by 2.1%-18.5% and 4.0%-20.7%,respectively,due to the reduction of N by 44.0%-58.6%,P2O5 by 52.0%-80.5% and K2 O by 21.9%-84.3% compared with conventional fertilization.Meanwhile,the content of Vc and the sugar-acid ratio were increased by 4.8%-28.0% and 13.2%-25.4%,respectively.The accumulations of N,P and K in violet cabbage were increased by 16.4%,13.7% and 7.4%,respectively,and the fertilizer partial productivity were increased by 1.1-1.5,1.2-4.4 and 0.4-5.5 times,respectively.The results indicated that the fertilizer application rate in conventional fertilization was obviously high at present.Consequently,there is a great potential of simultaneously achieve high yield and nutrient use efficiency as well as optimal economic benefit with the rationally reduction of N,P and K fertilization rate.(4)At the same fertilization rate,the yield and economic benefit of vegetables were increased by 3.2%-8.6% and 3.7%-21.3%,respectively,with the combined application of N regulators,i.e.urease inhibitor or nitrification inhibitor.Besides,the application of urease inhibitor or nitrification inhibitor can improve the quality of vegetables as well.Compared with control,the nitrate content of violet cabbage was decreased by 10.1%-11.7% at harvest,and at early-fruit stage and mid-fruit stage the soluble solids content of cucumber,tomato fruit-bearing stage and cucumber of mid-fruit stage the content of soluble sugar and the sugar-acid mid-fruit stage cucumber were increased,respectively.Moreover,the application of urease inhibitor and nitrification inhibitor increased N,P and K accumulation of cucumber by 7.6%-11.9%,0.7%-22.6% and 2.0%-6.6%,respectively.The accumulation of N,P and K in violet cabbage was increased by 17.9%-21.4%,1.3%-11.6% and 1.6%-6.1%,respectively.The apparent efficiency,agronomy efficiency and partial factor productivity of N,P and K were also enhanced.Therefore,the application N regulators such as urease inhibitor or nitrification inhibitor is an important measure to increase yield,improve qualities and increase efficiency on greenhouse vegetables through regulation of N transformation.Based on the results from the present study,under higher soil fertility,the reduction of fertilizer application rate and combined application of N regulators can synergistically improve economic and environmental benefits,reduce nutrient losses and improve nutrient use efficiency in vegetable production.