Nitrogen fertilization in pecan and its effect on leaf nutrient concentration, yield and nut quality

Several studies indicate that nitrogen fertilization is one of the main constraints in obtaining higher yields and better nut quality in pecan (Carya illinoensis [Wangenh] K. Koch). Therefore, the aim of this research was to evaluate a single and split application of nitrogen in ‘Western Schley’ variety pecan, as well as its effect on leaf nutrient concentration, yield and nut quality. A randomized complete block design with six replicates was established. N doses were 100, 150 and 200 kg∙ha-1; the single application was made in March and the split one in March and June. The leaf concentration of total N, P, K+ , Ca2+, Mg2+, Fe2+, Mn2+, Zn2+ and Cu2+, yield (kg∙tree-1), quality (nuts per kilogram and kernel percentage) and nitrogen use efficiency (NUE) were determined. Significant interaction between factors was detected for the Zn2+ concentration and the single applied dose of 200 kg∙ha-1. With the single application of 100 kg∙ha-1, the highest yield (44.60 kg∙tree-1) and nuts per kilogram (194.83) values were recorded, where the kernel percentage remained constant. The maximum NUE was obtained with 100 kg∙ha-1 applied in a single and split application (31.10 and 30.10 kg of nuts produced per kg of N applied, respectively). Increased yield and nut quality is the main objective in applying optimal N doses; however, ways of reducing the economic and environmental impact caused by its excessive application should also be sought.