Effects of lateral depth and layered-textural soils on water and nitrogen use efficiency of drip irrigated tomato

The effects of lateral depths and layered-textural soils on tomato yield, quality, water use efficiency (WUE), apparent fertilizer use efficiency (AFUE) and partial factor production of applied nitrogen (PFP) were investigated in a solar heated greenhouse to determine the suitable lateral depth of subsurface drip irrigation with different textured soils. The results indicated that, for the plots with uniform sandy loam soil, there was no significant influence of lateral depths, nitrogen application levels and their interactions on tomato yield and WUE. Tomato Vc contents of subsurface drip irrigation were less than those of surface drip irrigation. An increase of lateral depth resulted in a decreased tomato AFUE. Tomato PFP significantly decreased as nitrogen application level increased from 150 to 225 kg/hm2. For the treatments with uniform sandy loam soil, a lateral depth of 15 cm and a nitrogen application level of 150 kg/hm2 were recommended to obtain higher PFP. The layered-textures of soil significantly decreased tomato yield, WUE and PFP. Compared to the uniform sandy loam soil, the WUE reduced 32% for the sandy over sandy loam soil and 11% for the sandy loam-sandy-sandy loam soil, and the yield and PFP reduced 33% for the sandy over sandy loam soil and 12% for the sandy loam-sandy-sandy loam soil. It was therefore concluded that subsurface drip irrigation should be carefully used in layered textural soils, especially in the coarse over fine soils, from the view of improving water and nitrogen use efficiency.