Fertilization of crop systems in maize grown off-season and soybean

Abstract

It is necessary to improve the fertilization of maize grown off-season to overcame the current limited yields and to maintain the long-term sustainability of soybean and maize succession, adjusting it to the new crop technologies such as the broadcast distribution of fertilizers, the reduced spacing between plant rows and the intercropping with forage plants. The aim is optimize the fertilizer application and reduce operations. For that, it will be tested the application of all the phosphorus and potassium fertilizer required by the off-season maize-soybean succession in just one of the two crops and the fertilization of maize with nitrogen only at the V6 stage. Another objective is to study whether increased recycling of nutrients can improve K nutrition of soybean grown in succession with consortium of maize and B. ruziziensis compared to the sole crop. The study will consist of two subprojects which will be conducted under field conditions in a Red Oxisol under no till system: "Nitrogen and Phosphate Fertilizer in Maize Grown Off-season and Soybean" in Pedrinhas Paulista and Palmital (SP) and "Potassium Fertilizer in Maize Grown Off-season Consortioned with Brachiaria ruziziensis and Soybean Cultivated in Succession", in Palmital. The experimental design will be a randomized blocks in a split plot design with 4 replications. The treatments in the experiment "Nitrogen and Phosphate Fertilizers" will consist of P applied at sowing to maize or soybean and nitrogen at sowing (zero or 39 kg ha-1) and/or V6 plant stage to maize (0, 30, 60 and 90 kg ha-1. In the experiment "Potassium Fertilizer" treatments will be sole maize and maize intercropped with Brachiaria ruziziensis (at 90 cm) fertilized with potassium (maize or soybean) in combination with broadcast applied nitrogen (0, 40, 80 and 120 kg ha-1 K2O). Final plant stand, grain yields, leaf contents and nutrient extraction by both crops, and macronutrients uptake by maize and B. ruziziensis intercropped will be evaluated. (AU)