Study On Percolation Irrigation Technology Of Soil Water Control And Its Yield-Increasing And Water-Saving Mechanisms In Vegetable Protected Field

Percolation irrigation is an irrigation method of a new type, which has the advantages of other irrigation method such as furrow irrigation in vegetable protected cultivation. How to decide the percolation irrigation technology, optimize the irrigation index for soil water control according to the special conditions in protected field is the vital matter of immediate urgency for popularization and apply of this method. The field experiment on some parameters of percolation irrigation, such as irrigation maximums and minimums, the depth of percolation irrigation pipe, flume for seeping-proof, film mulching in protected cultivation of tomato was conducted in the meadow soil in the area of Liaohe Plain. The yield-increasing and water-saving mechanisms of percolation irrigation in protected field was studied out, the percolation irrigation technology fit for shelter land was put forward according to the effects of percolation irrigation technology of different parameters on soil chemical and physical properties, eco-environmental conditions, growth, development and yield of tomato and water use efficiency (WUE). The main results were as follows: 1. The essential reason why the soil eco-environment was different was the differences of soil water distribution in soil profile, which caused by the depth of percolation irrigation pipe which have significant effects on soil temperature, aeration, redox status, intensity of respiration, the availability of nutrients and salt distribution in soil profile. The results showed that under the condition that the amount of irrigation is about 30mm, the percolation irrigation with the pipe placed in the depth of 30cm is helpful to providing the best conditions for growth of crop, which the top soil is relatively dry, the wetting soil layer is in accordance with the soil layer which roots of crop is most distributed in, the soil water content could regulate the relationship of soil moisture, nutrients, air, light; the soil water of soil layer which roots of crop is most distributed in is insufficient for crop growth, and the WUE is lower because of seeping of soil water out of the soil layer of 0～100cm under conditions that the percolation pipe was placed in the depth of 40cm, while WUE is lower than that of the former because the soil aeration porosity is insufficient, soil temperature is relatively lower ,and the evaporation amount of soil water is more with the percolation irrigation pipe placed in the depth of 20cm. 2. The seepage-proofing flume and filter layer such as rice hull could not only prevent the irrigation water from seeping out of the soil layer of 0～100cm, but also avoid being blocked of percolation irrigation pipe. Furthermore, the utilization of seepage-proofing flume could apparently improve the quality of engineering of percolation irrigation. Therefore, the seepage-proofing flume for the percolation irrigation is worth being popularized in the future in vegetable protected field. It had the same effects with the plastic film of 15～20cm wide is placed under the percolation irrigation pipe.