Advances in Nitrogen Fertigation of Citrus

Abstract

ABSTRACT Advances in micro-irrigation techniques, i.e., drip and under-the-tree sprinklers, have facilitated greater adoption of fertigation especially for perennial crops including citrus (Citrus sinensis). Fertigation can improve nutrient uptake efficiency and minimize leaching of nutrients below the root zone, and thus can contribute to an increase in crop yield as well as crop quality as compared to those with conventional dry fertilizer broadcast application. In this paper, we summarized the recent fertigation studies on citrus. Long-term studies (over five to six years) have demonstrated that fertigation was beneficial as compared with broadcast of dry granular fertilizer for: (i) increased tree canopy area of young trees; (ii) increased fruit as well as juice yield of bearing orange and grapefruit (Citrus paradisi) trees; and (iii) decreased NO3-N concentration in surficial aquifer. Citrus groves with drip or under-the-tree microsprinkler irrigation are ideal for fertigation with minimal or no extra cost for application of fertilizers. Soil area wetted by the sprinklers or drip emitters must be considered for success of fertigation. Fertigation must be avoided during heavy rainfall period to minimize leaching of nutrients and water below the rootzone.