The Differences Of Effects On Soil Properties Of Facilities By Two Kinds Of Hydroponic And Upland Rotations

With the adjustment of agricultural structure and the expanding of cultivation acreage, the problem of facilities salinization is becoming increasingly serious and has become an obstacle to the sustainable development of Chinese horticulture industry. Jiang Jiezeng et al.(2011) proposed a new upland-rotation mode with aquatic and xeric vegetable in facility. The new model can reduce soil salinity effctively. It is easy to both conduct and promote, not only for eliminating the need for tedious operation that depended on other treatments, but also possessing considerable economic benefits due to featured aquatic vegetables. However, because of limitations of water resources and facilities, it is difficult to maintain the aqueous layer sustainedly in some area. To explore an effective and feasible upland-rotation mode that saving water, the paper compared and analysised the different changes of ion content, soil nutrients and soil enzyme activities in0-40cm soil layer through conducting water-logging cultivation with water cress and wettish culitivation with water dropwort in two facilities. A further comparative analysis was also conducted in these two different upland-rotations with the same aquatic vegetables-Ipomoea.The article also simulated the process of govermance and remission on facilities salinization with polyethylene buckets planted water spinach in these two upland-rotation modes with conventional cultivation as CK. The main results are as follows:1. The total salt content of0-30cm soil layer decreased significantly in wettish-cultivation, and the decline was higher than that in water-logging cultivation; the content of salt in30-40cm soil layer increased, showing the infiltrated salt may remained in deep soil. And the vegetable little absorbed ions infiltrated significantly in wettish-cultivation, while NO3-as nutrient ions increased in the main root absorption layer, and the decline of K+was lower than that of water-logging cultivation. There was a decrease of salt wettish-cultivation except for the nutrient ions that vegetable absorbs a lot. The content of available nutrients and the activity of main soil enzymes all declined in the two treatments and all the declines of both treatments varied little from each other, the activities of urease and phosphatase had a great change than invertase.2. The total salt content of soil decreased significantly under treatment of both two upland rotations after two months and had a different magnitude rally after the transform to conventional cultivation for another two months, but still lower than it was before the treatment. The effect of the two modes was similar to each other. The contents of NO3-and SO42-and Cl-dropped significantly in these two modes and rebounded after the transform; the decline of SO42-was greater than that of NO3.The recovery levels of NO3-under wettish culitivation were significantly higher than that under water-logging cultivation treatment. The content of cation of each soil layers were significantly decreased after the two modes and increased after the transform. The rally of K+after wettish cultivation was obviously higher than that after water-logging treatment. The content of available nutrients and the activity of main soil enzymes had a similar decline in the two treatments.3. Through simulating conventional fertilization in facility soil wit salinization, compared and analysised the effect of remission of facility salinization by wettish-cultivation and water-lgging cultivation. The results showed that: the two cultivation modes can effectively reduce salinization and the content of NO3-in tillage layer of salt content and make it back to the suitable range (EC5:1<500μS-cm-1) for the growth of plants, and the production yield, stem diameter, height of water spinach were superior to that of conventional cultivation; The treatment of salt reduction by water-logging was significantly better than the effect of wettish cultivation, but the salt content after waterlogged soil was too low to be suitable for the growth of stubble crops as well as it was after wettish-cultivation.4. Both wettish-cultivation and water-lgging cultivation can effectively control soil salinity even in healthy soil, ease and put off the occurrence of salinization that conventional fertilization may lead to, reduce the content of nitrate in plants; Be able to handle soil salinity increases, while wettish cultivation can keep the content of NO3-in normal range, avoid excessive loss of nutrients.