Effects of Ionized Water Irrigation on Organic Nitrogen Mineralization in Saline-Alkali Soil in China

The application of ionized water to irrigation, as a new type of water treatment technology, can improve the spatial distribution of water in soil and increase water utilization efficiency, which may affect the microbiological processes involved in nitrogen transformation and alter soil nitrogen supply capability. However, the effects of ionized water technology on soil organic nitrogen mineralization are still in need of further research. In this study, we investigated the soil organic nitrogen mineralization process with four different water additions: non-ionized fresh water (CK), ionized fresh water (DE), non-ionized brackish water (BCK), and ionized brackish water (BDE). By using a short-term laboratory incubation method, we monitored the changes of the inorganic nitrogen concentration in each treatment during the incubation process. We compared the net nitrogen mineralization and nitrogen mineralization rates in different treatments, and fitted the organic nitrogen mineralization process with three models (One-pool model, Special model, and EATM model). We divided the whole incubation process into three periods based on the differences of the organic nitrogen mineralization trends. The results demonstrated that when DE was compared with CK, the net nitrogen mineralization increased by 21.97% and the nitrogen mineralization rate increased by 20.42% in the latter incubation period. When BDE was compared with BCK, the net nitrogen mineralization decreased by 3.63%, and the nitrogen mineralization rate increased by 21.86% in the latter incubation period. When BCK was compared with CK, brackish water irrigation reduced the organic nitrogen mineralization intensity to a certain extent, with the net nitrogen mineralization decreased by 11.62% and the nitrogen mineralization rate decreased by 41.07% in the whole incubation process. When BDE was compared with DE, the net nitrogen mineralization decreased by 30.09% and the nitrogen mineralization rate decreased by 53.39% in the whole incubation process. The simulation model of the soil organic nitrogen mineralization process showed that the special model and EATM model are superior to the One-pool model. This study provides a theoretical basis for the popularization and application of ionized water irrigation in agricultural production.