Potassium nutrition in the first and second ratoon sugarcane grown in an Oxisol by a conservationist system

Rilner Alves Flores1*, Renato de Mello Prado2, Marcio Alexandre Pancelli2, Hilario Junior Almeida2, Leandro Rosatto Moda2, Bernardo Melo Montes Nogueira Borges2, Jonas Pereira de Souza Junior2
The presence of mulch on the soil surface after the mechanical harvesting of sugarcane (Saccharum officinarum L.) enhances the cycling of nutrients, especially K, which can decrease K fertilizer recommendations for the crop. The aim of this study was to evaluate the effect of K addition to an Oxisol, with an initial concentration 0.07 cmolc K kg-1, in first and second ratoon (no-till) sugarcane cultures by a conservationist system, i.e. rational use of fertilizers, use of alternative inputs and especially the maintenance of residues in soil that was previously burned to facilitate cutting. The following K doses were tested: 0, 32.5, 65, 130, and 195 kg ha-1, arranged in a randomized block design with five replicates. Potassium content in the soil and in the plant, as well as the yield and the quality of stalks were evaluated. Soil K application increased K concentration in soil and plant, and was reflected in the production of stems, with higher production (87.5 and 107.5 t ha-1) with the use of 120 and 123 kg K2O ha-1 in first and second ratoon sugarcane, respectively. At the first 2 yr it was not possible to reduce the K fertilization in ratoon. Therefore, with the introduction of the conservationist system there was an increase (20 t ha-1) at the second ratoon regarding the first one with the same applied rate.
Keywords: Plant nutrition, residues covering, Saccharum officinarum.
1Universidade Federal de Goiás, Campus Samambaia, Escola de Agronomia, Rodovia Goiânia/Nova Veneza, km 0, Caixa Postal 131, CEP 74690-900, Goiânia, Goiás, Brasil. *Corresponding author (rilner1@hotmail.com).
2Universidade Estadual Paulista UNESP, Faculdade de Ciências Agrárias e Veterinárias, Departamento de Solos e Adubos, Jaboticabal, São Paulo, Brasil.