Abstract
In order to improve the utilization rate of nitrogen fertilizer and reduce the environmental pollution risk of the nitrogen accumulation in the vegetable field, this study was carried out in the summer leisure period of the greenhouse vegetable production. This experiment designed different planting density treatments in 2017 and 2018, i.e. for catch waxy corn, 3300 plants/667m2 (WCD1), 5000 plants/667m2 (WCD2), 6600 plants/667m2 (WCD3), for forage sweet sorghum, 4500 plants /667m2 (FSS4), 7000 plants/667m2 (FSS5), 9000 plants/667m2 (FSS6) in 2017; and for catch waxy corn, 4500 plants/667m2 (WCDI), 7000 plants/667m2 (WCDII), 9000 plants/667m2(WCDIII), for forage sweet sorghum, 7000 plants/667m2 (FSSIV), 10000 plants/667m2 (FSSV), 14000 plants/667m2 (FSSVI) in 2018. The results showed that the biomass and nitrogen absorption of the two catch crops began to improve and then decreased with the increase of planting density. The nitrogen absorption amount of the catch waxy corn and forage sweet sorghum was 22.36~28.68 kg/667m2,21.67~24.39 kg/667m2, respectively. Different planting density of catch waxy corn and forage sweet sorghum could significantly reduce the total nitrogen content of 0~30cm soil layer and the nitrate nitrogen content of 0~90cm soil layer, for catch waxy corn and forage sweet sorghum, the reduction rate of total nitrogen content in 0~30cm soil layer was 9.6%~27.0%, 5.7%~23.5%, the reduction rate of nitrate nitrogen content reached 50.0%~90.8%, 80.1%~96.4%, respectively, which effectively controlled the nitrate nitrogen leaching to soil deep layer. Planting catch crops could increase soil urease activity, regulate soil nitrogen transformation. Compared with other treatments, WCDII and FSSV treatment can reduce the initial urease activity and soil nitrate nitrogen content of next crops, which is consistent with the nutrient requirements of broccoli in the early stage of growth. These catch crops planting could reduce the nitrogen environmental risk in the greenhouse soil. Finally, the study proposed that the suitable planting density of catch waxy corn and forage sweet sorghum planted was 6600~7000 plants/667m2, and 9000~10000 plants/667m2, respectively, in the greenhouse summer leisure period. It is more advantageous to improve soil nitrogen absorption and reduce soil nitrogen environmental risks for catch waxy corn.
Highlights
Nitrogen is an important necessary nutrient element for the growth and development of crops, and is an element that causes eutrophication of water bodies in the ecological environment[1,2], especially in the production system of intensive greenhouse
In 2017, the total biomass and aboveground biomass of the catch waxy corn were increased with the increase of planting density, and the aboveground biomass accounted for more than 88.2% of the total biomass
Root biomass decreased with the increase of planting density, and WCD1 treated root biomass was significantly higher than WCD2 and WCD3 treatment; The nitrogen uptake trend of catch waxy corn was the same as that of biomass
Summary
Nitrogen is an important necessary nutrient element for the growth and development of crops, and is an element that causes eutrophication of water bodies in the ecological environment[1,2], especially in the production system of intensive greenhouse. In 2015, China's facility vegetable fields area reached 5.35 × 106 ha, accounting for 23.6% of total vegetable acreage[3]. The input of nitrogen fertilizer in the greenhouse production system is several times higher than the nitrogen demand of vegetable crops. Peng et al[4] pointed out that the nitrogen fertilizer input amount was even more than 10 times the recommended amount in the vegetable fields in the North China Plain. When the nitrogen application rate in the vegetable plots was 240 kg/ha and
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
