Optimum combination of soil amendments under drip irrigation with different water sources in coastal areas of East China

The effects of drip irrigation (DI) with fresh water (FW) and brackish water (BW) on saline-alkali soil improvement were compared under treatments of five amendment combinations. The experiment was designed using the orthogonal test method and performed using an indoor DI system. Soil electrical conductivity (EC), pH, sodium adsorption ratio and soil nutrients were analyzed after DI both before evaporation and after one month of evaporation. The results showed that after one month of evaporation, soil EC increased by an average of 97.26% and 27.76% for the FW and BW treatments, respectively. Furthermore, it was shown that soil nutrients increased greatly under the BW treatment and that cow dung proved to be a leading agent influencing soil nutrients except available soil potassium ( p <0.05). Consequently, the optimum combination of soil amendments was determined as 0.03 m 3 /m 2 of straw, 3 kg/m 2 of phosphogypsum, 0.04 m 3 /m 2 of cow dung, 0.6 kg/m 2 of humic acid and 0.18 kg/m 2 of microbial fertilizer under the BW treatment.