K dynamics in the soil-plant system for sugarcane crops: a current field experiment under tropical conditions

Abstract

Sugarcane stands out as the most used renewable energy source in Brazil. Its yield and adaptation respond perfectly to tropical edaphoclimatic conditions. This study evaluates the K dynamics in the soil–plant system for sugarcane crops under tropical conditions. Treatments were arranged in randomized blocks design with five doses of K2O (0, 50, 100, 150, and 200 kg ha−1) and five replications. The following analyses were performed: K content in the soil, plant uptake, availability and decomposition of sugarcane straw, and K balance in the soil–plant system. Data on response variables were subjected to the analysis of variance and F test at 5% probability. Quantitative factors were subjected to polynomial regression analysis by selecting the model of higher significance. The potassium dose of 200 kg ha−1 increased K levels at 0.8 m by 20% relative to the control. After 70 days, 50% of the 79 kg K ha−1 was available from sugarcane straw mineralization. The treatment that improved K in soil was 150 kg ha−1 of K annual application. This dose causes a positive balance of K in the soil with 133.32 kg ha−1 year−1.