Nitrogen uptake response of vegetable crops to organic materials

Abstract

Nitrogen (N) uptake response of pimento, Chinese radish, broccoli, cabbage, chingensai, spinach, turnip, leaf lettuce, and carrot was tested in a soil supplied with a mixture of rice bran and rice straw (RBS) with a C/N ratio of 19. Inorganic N concentration in the unplanted soil was lower but amino acid and protein concentrations were much higher in the RBS treatment than in the control soil (without additional N). N uptake by pimento and leaf lettuce was higher in the control soil than in the RBS treatment. On the contrary, N uptake by carrot, chingensai, and spinach was higher in the RBS treatment than in the control soil despite a consistently lower inorganic N status. These results suggest that the N uptake response to applied organic N depended on the crops. Similar results were obtained by using organic materials such as rapeseed cake (RC) and dried cattle feces (DCF) with a lower C/N ratio than RBS. N uptake by pimento and leaf lettuce was lower for organic N than for ammonium sulfate (AS), whereas, N uptake by carrot, chingensai, and spinach was higher for RC than for AS.