Effects Of Different Control Measures On Production Of Cucumber And Soil Environmental Quality In Greenhouse

In recent years, cultivating vegetables in protected facilities such as sunlightgreenhouses has increased rapidly, and this cultivating method has become animportant part of modern agriculture in Chin. But in the actual production, thefertilizer and water investment excess phenomenon is very serious.Not only increase the cost of production and waste of valuable water resources, butalso result many adverse effects on soil and the environment, including the imbalanceof nutrients in soil, nitrate pollution of groundwater, and so on. These problems havebecome limiting factors to receive sustained high yield, high-quality and efficient ofvegetables in facilities vegetable production and has aroused scholars' high degree ofattention both at home and abroad.This paper choose the greenhouse soil of cucumber cultivated as the researchobject based on farmers' practical fertilization to study the effect of three differentcontrol measures, straw returning, catch crops and drip irrigation on physicochemicalproperties (soil bulk density, soil porosity, soil aggregate structure and thediversifications of carbon and nitrogen) and biological characteristics (soil microbialflora and enzyme activity) in the soil. The main results showed as follows:(1) The straw returning on the basis of farmers' practical fertilization couldreduce soil bulk density, improve the permeability and enhance the stability ofaggregate structure of topsoil significantly, especially could greatly improve thecontent of water-stable aggregate, smaller (0.5-0.25mm) water-stable aggregate. Thedrip irrigation could also reduce soil bulk density, improve the permeability, improvethe content of water-stable aggregate, increase the value of mean weight diameter (MWD) and reduce the damage rate of aggregate. But the effect is not obvious oncatch crops.(2) The catch crops and straw returning could not only improve the organicmatter content and C/N ratio of soil, improve soil fertility and slow down the fertilityfailure, but also reduce the NO3--N content of surface soil and reduce the residues andleaching of nitrogen in deep soil. The drip irrigation minimized the risk of nitrogenleaching and nitrate pollution of groundwater, but it would eventually producenegative environmental effects because of the accumulation of NO3--N to the surfacesoil, for example resulting pH decreased and EC increased in surface soil. Besides, theaccumulation of NO3--N to the surface soil may lead to the NO3--N accumulation ofthe edible parts exceeded the safety standard, so we must supply fertilizer reasonably.(3) The straw returning provided so rich sources of carbon and nitrogen formicrobial activity that soil microbial groups and the B/F ratio increased, the diversityof soil microbial strengthened, the activity of soil urease, sucrase and catalaseimproved, and so on. The catch crops could increase the B/F ratio and improve theactivity of soil sucrase. The drip irrigation elevated soluble salt content of topsoil andthis salinized environment inhibited the proliferation of the bacteria but promoted theincrease of fungal, so the B/F ratio decreased, otherwise the activity of soil urease andsucrase increased.(4)The straw returning could help to improve cucumber production and improvethe cucumber quality.The drip irrigation reduced the production of cucumber and it'snot obvious on improving the quality of cucumber. The catch crops could improve thequality of cucumber.