The Potential to Reduce Nitrogen Loss Through Rotating Different Sorghum Varieties in Greenhouse Vegetable Field

In North China plain, excessive fertilization in vegetable greenhouse always results in nitrate accumulation in soil and possible nitrogen leaching with potential environmental risk. It is necessary to rotate appropriate catch crop to absorb surplus nitrogen in fallow season and reduce rootzone nitrate level. An experiment was carried out to select suitable sorghum variety as catch crop to reduce nitrogen loss in Beijing suburb. Six common varieties were used in the experiment as conventional catch crop, sweet corn as the control. The results indicated that the biomass, root growth and nitrogen accumulation in shoots of sorghum Jinza 12 were highest in the catch crops. It demonstrated that the variety Jinza 12 was an appropriate catch crop for reducing nitrogen accumulation in surface soil layer compared with sweet corn. Meanwhile, variety Jiliang 2 maintained highest proportion of soil NH4+-N content after urea application, which might be related to the biological nitrification inhibitors (BNI) released by the root system of sorghum. It implied that sorghum could be used as catch crop to reduce nitrogen loss through plant extraction i.e. nitrogen uptake and stabilization i.e. BNI inhibition, in comparison with sweet corn