Alternate partial root-zone drip irrigation with nitrogen fertigation promoted tomato growth, water and fertilizer-nitrogen use efficiency

Irrigation and fertilization play key roles in crop production. Scarcity of available water resources and low nutrient use efficiency calls for a need to improve water and nitrogen (N) use efficiency. This study aimed to investigate the effects of different irrigation and nitrogen treatments on the growth, yield, irrigation water-use efficiency (IWUE) and fertilizer-N utilization of tomato plants by using pre-buried soil columns (100 cm in depth) in a field. The irrigation treatments included conventional drip irrigation (CDI) and alternate partial root-zone drip irrigation (ADI) with sufficient or deficient water supply. Nitrogen fertilizer was set as high and low N input (8.30 g or 4.15 g N-15-labeled urea per plant) supplied as drip fertigation. Compared with the CDI treatment at the same nitrogen drip fertigation level, ADI promoted tomato root growth, induced more N-15 accumulation in the 0 -100 cm soil profile, facilitated the absorption of fertilizer(15)N as well as soil N by plants, thus increasing plant growth and yield as well as IWUE and fertilizer-N use efficiency, while decreased N-15 loss. Low nitrogen supply decreased plant growth, yield, N-15 absorption, N-15 accumulation in soil profile and IWUE, but increased both the N-15-use efficiency and N-15 loss percentage. Thus, ADI coupled with nitrogen fertigation has a potential to save irrigation water, increase use efficiencies of both water and nitrogen fertilizers with reduced loss of N to the environment.