Abstract
Water and nitrogen (N) are two key limiting factors for citrus production. Reported effects of water and N inputs on citrus yield, water use efficiency (WUE) and N use efficiency (NUE) vary greatly, mainly due to differences in cultivars, tree age, climate, soil types, and water and N input levels. So far, no systematic analysis has been performed, and as a result, the interactive effects of water and N inputs on yield, WUE and NUE of citrus orchards are unknown. Also, gaps between attainable and actual yields, WUE and NUE have not been established yet. Here, we report on a global meta-analysis of yields, WUE and NUE of citrus production systems, using 1009 observations from 55 studies, conducted in 11 countries. Median citrus yields ranged from 30 to 60tha1, which were in between average global yields (range 1030tha1) and attainable yields (range 6090tha1). Median WUE ranged from 2.5 to 5kgm3 and median NUE from 150 to 350kgkg1. Citrus yields were related to water and N inputs and tree age. Relationships between water and N inputs and yield, WUE and NUE were also analysed for sub-datasets and quantiles, to examine the relationships near the extremes. There were statistical significant interactions between water and N inputs in yield and NUE, but not in WUE. This indicates that studies aiming at the optimization of water and N inputs must consider interactions and optimize water and N inputs simultaneously. Based on our analyses, we estimated that reducing over-optimal irrigation to optimal irrigation may increase citrus yield by 20%, WUE by 30% and NUE by 15%. Similarly, reducing over-optimal N fertilization to optimal N fertilization may increase yield by 10%, WUE by 15% and NUE by 40%. We concluded that there is room for a significant increase in yield, WUE and NUE through the simultaneous optimization of water and fertilizer N inputs via precision fertigation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have