Study of the Improvement Effects of Four Catch Crops on the Secondary Salinization of Tianjin Cucumber Greenhouse Soil
WANG Jin-long1,RUAN Wei-bin2(1.Department of Agronomy,Tianjin Agricultural University,Tianjin 300384,China;2.College of Life Science,Nankai University,Tianjin 300071,China)
Greenhouse vegetable production has been widely applied in North China due to its higher economic and social benefit. However,the special ecological environment and unreasonable irrigation or fertilizing often result in secondary salinization of greenhouse soil,that would directly do harm to crop growth,reduce crop yield and quality,and also affect human health or ecological environment. Among the methods of salt elimination,biological treatment has been paid more attention because of its predominant performance in operation and cost. Since cucumber is an important cash crop in Tianjin and the secondary salinization of cucumber greenhouse soil has been more and more severe,thus a pot cultivation experiment was designed to study the improvement effects of four catch crops on the secondary salinization in this paper. In middle July of 2007,the soil/substrate was collected from one cucumber greenhouse of Xiaobian Village,located in Nanhe Town of Xiqing District in Tianjin. Four catch crops,respectively Vicia villosa Roth.,Sorghum sudanense(Piper) Stapf.,Zea mays L. saccharata Sturt,Amaranthus mangostanus L.,were selected as experimental plants. The experiment was carried out at the campus experiment site of Tianjin Agricultural University. The seeds were sown in the pot soil on 20 July 2007,and after 10 days the seedlings were thinned to form three plant densities. A randomized block design was used with five blocks(replicates) and twelve pots(treatments) per block. On 10 September 2007,the above ground materials of each pot were harvested and the dry matter accumulation was subsequently determined. Additionally,0～20 cm soil was sampled from each pot and stored in aluminum cases after air drying for soil nutrient measurement. The results indicated that after planting these four plants,soluble salinity,Na+ content,soil nutrient and organic matter content significantly decreased compared with CK. Vicia villosa,sweet corn and Amaranthus mangostanus could significantly increase soil K+/Na+ value. Higher planting density resulted in better soil improvement effects and among these four catch crops V. villosa was strongly recommended due to its remarkable performance.