Controlled-release fertilizers and blends: properties and performance of the technology in the cultivation of arabica coffee

Abstract

Among the new fertilizer technologies considered strategic options to increase nutrient use efficiency in coffee cultivation are controlled-release fertilizers and their associations in the form of blends. The use of these technologies is associated with gradual nutrient release, thereby promoting favorable mechanisms that increase nutrient availability in the soil and reduce losses. In this context, the objective of this study was to evaluate the adoption of fertilizer technologies and their potential to promote agronomic and environmental gains in coffee cultivation. In the first article, blends of conventional phosphate fertilizers and controlled-release fertilizers were applied, and the dynamics of phosphorus release were modeled under field conditions. Leaf area, nutrient accumulation, and biomass of coffee plants during the establishment phase, as well as soil P availability, were quantified. Two types of phosphate fertilizers were used: conventional MAP and a blend (physical mixture of MAP with controlled-release phosphate fertilizers). Both were applied at rates of 0, 134, 268, and 403 kg ha-1 of P2O5. Phosphate fertilization increased leaf area and shoot biomass of coffee plants and raised soil P levels after 18 months. Total P accumulation in the coffee shoot was 4 kg ha-1 . For the other macronutrients, accumulation (kg ha-1 ) was: 60 (N), 46 (K), 22 (Ca), 7 (Mg), and 4 (S). For micronutrients (g ha-1 ), the values were: 657 (Fe), 160 (B), 149 (Mn), 71 (Cu), and 43 (Zn); on average, 74% of the nutrients were located in the leaves. The application of blends provided biomass gains of 18.9% in plagiotropic branches compared with conventional fertilization. In the second article, the investigation was based on the hypothesis that gradual N release is effective in mitigating losses and favorable for increasing the yield of Coffea arabica L. compared with conventional urea fertilization. Treatments consisted of conventional urea and three blends of controlled- and slow-release fertilizers (Blend Urea CRF + Urea NBPT; Blend 1; and urea-formaldehyde), which were applied at annual N rates of 0, 200, 280, and 400 kg ha-1 for three growing seasons. Ammonia volatilization losses were: 88 kg N (conventional urea) > 50 kg (Blend Urea CRF + Urea NBPT) > 34 kg (urea-formaldehyde) > 11 kg (Blend 1). These technologies reduced N2O emissions by 85% compared with conventional urea, which showed an emission factor (EF) of 0.17%. The use of Blend 1 and Blend Urea CRF + Urea NBPT resulted in yields 30% and 15% higher, respectively, than those obtained with urea. Based on the results of this study, it can be concluded that phosphate fertilization is effective in improving coffee nutrition during the establishment phase. The association of blends of conventional and controlled-release nitrogen fertilizers is a promising strategy to enhance both the profitability and sustainability of coffee production.