Study On The Fertilization Of Greenhouse Lactuca Sativa By Drip Irrigation

Fertilization by drip irrigation (hereafter as FDI) is a new technique. Once employed in green-house, it will exert better effects than the traditional irrigation in the distribution of water, saving of water and fertilizer, preserving the physical and chemical properties of soil, restraining weeds from overgrowing, providing more water and fertilizer for vegetables, ventilating the plants, reducing plant disease and pollution, accelerating the growth of plant, increasing the yield and profit, etc.The technique of ecominizing on water irrigation promises a sustained, sable development in agriculture. The abundant, but not well-distributed rainfall in Chongqing, together with the high humidity and plant disease resulted from the traditional irrigation, hindered the growth of plant. Therefore, the experiment of FDI was carried out in the typical enviroment of Chongqing for its further application in the area.By the comparison of FDI with traditional fertilization, and the analysis of the characteristics of the water-fertilizer scatter in soil, this experiment concluded a scatter pattern of water-fertilizer in soil, and worked out a program of irrigation and fertilization suitable to the greenhouse lactuca sativa in Chongqing.The above experiment showed that the quality of soil would be improved, and fertility increased, if drip irrigation was employed instead of traditional irrigation. For example, the organic substance in soil was 0.10% higher than before, total N 0.012%, available P 15.9 mg/kg, and available K 1.8mg/kg, and the production and prifit of lactuca sativa were increased by 16.74%-18.34%. In other words, drip irrigation could preserve the soil's fertility to ensure a high yield of lactuca sativa. Thus , FDI is the ideal method of preserving the soil's fertility and saving water in production.In drip irrigation, the transfer of water and fertilizer in soil is so complicated that different kinds of soil usually lead to different results. Therefore, it is necessary to acquire thelaw of the transfer of water and fertilizer in Chongqing's peculiar purple soil. The above experiment proves that in drip irrigation, the transfer pattern of water, the size and shape of wetness differ according to the soil's quality, the volume and time of water flow. Besides, the fertilizer transfers with the water, which helps the plant's nutriment assimilation.Water and fertilizer affect the yield and quality of vegetables. In drip irrigation, the water-fertilizer coupling plays an important part in the growth of lactuca saliva. Here is the pattern of water-fertilizer coupling in the experiment of lactuca sativa's drip irrigation in greenhouse:j)=2495.525+75.063xi+76.865x2+326.875xix2-31.231xi2+74.719x22And the perfect pattern of fertilization of greenhouse lactuca sativa by drip irrigation is: irrigation for 1.46 hour, fertilization of 27.31 kg/667 m2. As a result, the yield of lactuca sativa could reach 2481.119 kg/667 m2. It is a water-fertilizer coupling pattern of low cost and high yield.In FDI, water and fertilizer transfer in a limited scope with little evaporation or seepage, which effectively controls the growth of plants, improves the structure of greenhouse soil, and preserves its fertility. In other words, the FDI builds a favorable environment of water, heat, air, and fertilizer for the greenhouse lactuca sativa, and ensures a high yield and profit as well as the proper ratio between water and fertilizer.