Cost-benefit analysis of the best combination of organic and inorganic sources to supply zinc deficiency in pecan (Carya illinoinensis [wangenh] k. Koch)

Zinc (Zn) is considered a trace element; however, this element is scarce in calcareous soils, so it is necessary to make applications to optimize performance. The objective of this study was to analyze the cost-benefit relationship of the best combination of applying organic and inorganic sources of zinc in the cultivation of walnut (Carya illinoinensis [Wangenh] K. Koch) that maximizes the yield of pecan nut. Prior to the cost-benefit analysis, five Zn application treatments were evaluated; a control treatment (T1-no application); T2 was the application of 4.5 L H2SO4 + 3 kg ZnSO4 in 100 L H2O; T3 consisted of the application of 3 Kg ZnSO4 in 20 L of worm leachate measured at 100 L of H2O; T4 was with the addition of 3 kg ZnSO4 mixed in 25 kg of solid vermicompost; and T5 was the addition of 3 Kg ZnSO4 in 25 kg of compost. A total of two applications per treatment were made. The parameters evaluated were the concentration of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) in the leaf tissue and the yield in kilograms of walnut (kg ha-1). The highest nut yield was obtained with T2 with 1,400 kg ha-1 compared to 933 kg ha-1 that were harvested in the control treatment; that is to say, a differential of 467 kg of walnut. A b/c ratio of 1.2861 was calculated for the best biological treatment, which was T2.