Effects of different water and nitrogen amounts on nitrate leaching in sunlight greenhouse during cucumber growing season

The study was conducted to determine the effects of water and nitrogen amounts on nitrate leaching during cucumber growing season in a greenhouse in Xinji,Hebei province in 2010.The results indicate that the water-saving treatment which maintains soil moisture contents at 18.7%-22.1% in the whole period can fully meet the demand of water for cucumber growth.The highest value of soil nitrate nitrogen content is achieved in the water-saving and conventional nitrogen rate treatment,and the lowest value is achieved in the conventional water rate and nitrogen-saving treatment.The nitrate nitrogen leaching amount in the depth of 95 cm is closely related to soil moisture and nitrate nitrogen contents during cucumber growing season,especially of the primary fruit stage and full fruit stage.Comprehensive analysis shows that the optimal treatment is W2N2 with 30% reduction in water and 25% reduction in nitrogen compared with the conventional treatment,and the nitrate nitrogen leaching amount is reduced by 35.0% in the whole period.In this study,the yields between the water-saving and nitrogen-saving treatment and the conventional treatment are not significantly different.There are water-saving and nitrogen-saving approaches compared to the conventional treatment of farmers.According to fertilizer demand and soil moisture in different periods,we can gain obvious water-saving and nitrogen-saving effect through the control of water and nitrogen.