Nutritional responses to soil drying and rewetting cycles under partial root-zone drying irrigation.

Abstract Repeated soil drying and rewetting (DRW) cycles occur in rainfed and irrigated agriculture. The intensity and frequency of DRW cycles regulate both microbial physiology and soil physical processes, hereby affecting the mineralization and immobilization of soil nutrients and their bioavailability. Partial root-zone drying irrigation (PRI) irrigates half of the soil zone, while the other half is allowed to dry, and the two halves is alternately irrigated. PRI outweighs conventional deficit irrigation in further improving water use efficiency (WUE) by enhancing the root-to-shoot chemical signaling that regulates stomatal aperture. PRI induced soil DRW cycles and more soil water dynamics in the root zone enhance soil nutrient mineralization process and thus increase the bioavailability of soil nutrients, resulting in improved nitrogen (N) and phosphorus (P) uptake, in which soil microbial processes play a key role. Studies investigating how soil DRW cycles and water dynamics under PRI on nutrient transport in soil solution, soil microbe mediated P transformation, interactions between phytohormones and nutrient uptake, root morphological and architectural traits for nutrient acquisition, and PRI-integrated fertigation are still lacking. In addition, the positive nutritional effect may be varied in terms of climatic conditions and intensity and frequency of precipitation or irrigation, and these merit further in-depth studies.