Chloride Nutrition Influences the Nitrogen Use Efficiency in Coffee.

Abstract

Chloride (Cl-) is applied in coffee in rates as a “macronutrient” due that potassium (K+) is one of the most demanded nutrients by the coffee plant, and the potassium muriate (KCl) bases fertilizer is one the most used by the coffee growers. Does not exist scientific evidence that addresses the question regarding with which is the influences of the Cl- applied in the K fertilization base on MOP on coffee growth, nutrient uptake, and nitrogen use efficiency (NUE). Over four years, two trials were conducted on greenhouse and field conditions to address these questions. The trials set up were designed to test the influence of increased Cl- and reduced S rates on biomass accumulation, nutrient uptake, and NUE. A significant effect of the Cl- rates on growth was observed under greenhouse conditions but a non-significant effect on yield under field conditions. Cl- and S significantly influence the NUE in coffee. The result allows us to conclude that Cl- rates need to be balanced with S rates and that Cl- applied as a macronutrient can improve the NUE in coffee when those rates do not exceed 180 mg. L-1 Cl- and 80 mg.L-1 S in the greenhouse and 150 kg.ha-1.year-1 Cl- and 50 kg. ha-1.year-1 S in field conditions. In practical terms, coffee farmers need to balance the K base fertilizers sources to improve the nutrient use efficiency, especially the NUE.