Rice is one of the main cereals consumed in the world, and in this scenario upland cultivation has been highlighted by low demand of water resources for its production. Because they are less productive cultivars, cost reduction is necessary for producers to remain competitive in the market. For that, the trend has been to optimize the operations in the property, being nitrogen fertilization anticipation a possibility in cover plants or in pre-planting straw. Therefore, this work will evaluate technical and economical feasibility of earlier nitrogen fertilizer application, (15NH4)2SO4, for upland rice in succession to forage grasses under no-tillage for two consecutive years, 2017/2018 and 2018/2019. The experimental design was a randomized block design, with four replications, and treatments arranged in a 4 x 2 factorial scheme, with four treatments of nitrogen fertilization (without addition of nitrogen (0 kg ha-1) (T), with conventional nitrogen fertilization (C), with earlier nitrogen fertilization in the forage 10 to 5 days before desiccation (A1) and with earlier nitrogen fertilization in the forage' straw 5 to 1 day before rice sowing (A2) and two forages (areas previously occupied by Urochloa brizantha cv. Marandu or Urochloa ruziziensis). It will be applied in the treatments, except for the control (T), 30 kg N ha-1 at sowing and 90 kg N ha-1 in cover. The project will evaluate 1) productive performance and biometric characteristics of upland rice, 2) forage straw production, persistence and nutrient release of U. brizantha and U. ruziziensis, 3) 15N persistence and distribution in the soil-forage-rice system, 4) chemical and physical changes in the soil attributes at the end of each productive cycle, and 5) economic performance of earlier N application in upland rice during the study, in order to verify the profitability of earlier fertilization in relation to conventional application in coverage.
News published in Agência FAPESP Newsletter about the scholarship: