Study on Nitrogen Budget in Organic, Low-Input and Conventional Cropping Systems in Greenhouse

Summary

This study was based on a long-term field trials of three different vegetable cropping systems (organic, low-input and conventional) in greenhouse which was initiated in 2002 at Quzhou Experimental Station of China Agricultural University, Hebei Province. The apparent nitrogen budget which equals to N input (nitrogen of fertilizer, transplants and irrigation) minus N output (nitrogen of the eggplants) was compared to provide the reference for the development of high yield and sustainable cropping system. The main conclusions were as follows: The total input of nitrogen in the organic, low-input and conventional systems was 1 150 kg·hm2, 1 182 kg·hm2 and 1 433 kg·hm2, respectively. The total nitrogen uptake by plants was 178 kg·hm2, 135 kg·hm2, 116 kg·hm2, respectively. The eggplant production was 93 458 kg·hm2, 93 320 kg·hm2, 90 209 kg·hm2 respectively. And the net nitrogen surplus was 971 kg·hm2, 1 046 kg·hm2 and 1 317 kg·hm2, respectively. The eggplant production in organic system was 0.1% higher than the low-input system and 3.6% higher than the conventional system. The net nitrogen surplus in organic system was 7.2% and 26.3% lower than low-input system and conventional system, respectively. These data showed that organic system tends to be higher yields and lower net nitrogen surplus leading to higher nitrogen use efficiency when compared with the low-input and conventional systems.