| Excessive fertilization facilitated the loss of N, P, which caused accumulation of soil nutrition, and finally resulted in water eutrophication and pollution of groundwater. Over fertilization especially nitrogen fertilizer, N2O was released into the atmosphere through nitrification and denitrification, which led to greenhouse effect and the destruction of ozonosphere. Excessive fertilizer would also decrease the quality and competition of agricultural products. As the result, it is a great practical significance for the sustainable development of greenhouse vegetables industry to develop the study on fertilization technology, reduce fertilizer usage, increase fertilizer efficiency, improve vegetable quality, and reduce production costs.This paper came from the Science and Technology Projects:"study on balance fertilization of greenhouse vegetables and demonstation and extension", "decrement fertilization technology of greenhouse vegetables and demonstration and extension", which was supported by Wenzhou city, and based on a large number of survey and experimental datas. From 2005 to 2006, we had surveied the condition of applying fertilizer, analysised the soil environmental quality of mostly greenhouse vegetables planting based in Wenzhou. Based on analysising 1000 datas that we had got, we began the study on decrment fertilization technology of greenhouse tomato, the results are summarized below:(1) Exhaustive investigation of the condition of applying fertilizer and soil productivity in Wenzhou region. The investigation showed that fertilizer was largly plunged, the proportion of N, P2O5 and K2O was proportional imbalanced and more over, feritilizer varieties were unsuitable.(2) It has had a high fertilizer leval in the mass in Wenzhou. There was difference and imbalance in fertilizer levels in different villages and towns vegetable planting bases. Through several years of vegetabale growing, accumulation of soil nutrient had obviously changed, thereinto soil available phosphorus was the most obvious, other nutrients accumulated in different extents, such as soil available N,organic matter,available phosphorus and soil available potassium. The average value of soil PH is 5.2 that soil acidification is common. The content of exchange calcium was rich, but enchange magnesium was largely different from eath other which was lacked in generally. The content of available boron was in a low level, while the available copper and zinc was in a higher level. So, reducing or controlling application of N, P, K must be taken in greenhouse vegetables; strengthening the application of boron, and at the same time taking meatures to prevent the damage of vegetable which caused by high content of copper and zinc.(3) The yield and quality of tomato could be improved by application of the proper compound fertilizer, while it not only reduced the yield and quality of tomato, but also wasted fertilizer and directly reduced the economic interests by excess fertilization. There was a positive correlation between height and stem diameter of tomato and compound fertilization levels, which is the height and stem diameter of tomato increased with the increasing fertilization level. The nitrate content had a positive correlation increase with compound fertilization level. The recommended application rate of compound fertilizer was 1125kg/hm2, which was 28.7% reduced compared with used application.(4) The yield and quality of tomato could be improved by application of the proper phosphate fertilizer, while it could reduce the yield and quality of tomato when excess fertilization. It was unconspicuous that effects on application of the proper phosphate fertilizer on plant height and stem diameter of tomato in the rich phosphorus soil, but the average of single fruit weight will increased in proper application while it will be small in excess application. The content of nitrate was unconspicuous with phosphate fertilization. The results showed that the proper application of phosphorus fertilizer should not be more than 150kg/hm2, which was decreased by 75% compared with used application. So the phosphate fertilizer decrement application had a large space in the greenhouse tomato production.(5) Applying Sulphate-Potassium Magnesium (SPM) showed an obvious effect on the yield of greenhouse tomato, but with the increasing application of SPM fertilizer, the yield of tomato was increased then decreased. Proper SPM fertilizer could promote the growth of tomato while excessive fertilization would lead to the negative influence. Also, proper SPM fertilizer could improve the quality of tomato, while excessive fertilization lowered the quality. With the application of SPM fertilizer, the content of nitrate would be decreased. The reasonable application rate of SPM fertilizer to greenhouse tomato would be 450Kg/hm2 in Wenzhou, which was decreased by 50% compared with used application. |
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