Fertilization recommendation for Brassica oleracea using Bulletin 100 is still valid after more than two decades

Abstract

The 4R Nutrient Stewardship is a concept that aims to optimize fertilization of agricultural crops, encompassing social, economic and environmental aspects. This concept involves 4 scientific principles (the right source of fertilizer, the right rate, the right timing and the right place) that should be defined based on local conditions and knowledge. This study aimed at determining best fertilization practices for broccoli in the region of Tatuí-SP in Brazil, using the 4R nutrient stewardship principles. Four experiments were installed, each one referring to a 4R principle, comparing the standard fertilization applied in the region with different management options. The recommended rate by the fertilization bulletin outperformed other rates we tested. An increase or decrease by 25% in the bulletin recommended rate led to a reduction in broccoli productivity. Mineral fertilizer source promoted highest growth, followed by a combination of mineral and organic. In regard to timing, the standard practice applied in the region, which is applying 100% of N and K at planting, did not differ from splitting the dose in 3 parcels. Lastly, applying the fertilizer in the planting row promoted better growth than broadcasting on the soil surface. The standard fertilization practiced in the region promoted the highest growth, although there are other possibilities in terms of timing and placement that also resulted in similar growth, and the decision should be made according to the reality of each farmer.