Sulfur-improved manganese fertilization for sweet cassava under an overlimed organic management system

Abstract

The current farm management practices used to cultivate cassava, in a farm from Lago Oeste, Federal District, increased soil pHwater value to 7.11, lowering Mn availability to plants, leading to low root yields. The soils were overfertilized and overlimed. The objective of this work was to evaluate Mn availability for cassava plants, as well as its yield under MnSO4 and elemental sulfur (S0) fertilization, in a high pH soil. An experiment was designed for evaluating MnSO4 (0, 2.5, 5 and 10 kg Mn ha-1) and S0 (0 and 150 kg S0 ha-1) doses on cassava yield. The application of 150 kg S0 ha-1 increased cassava fresh root yield (25.7%), fresh shoot yield (17%), the number of roots (20%) and the starch percentage (7%), and decreased the cooking time (-13%), when compared with treatments without S0. The application of 10 kg Mn ha-1 increased the fresh root yield by 70% as compared to the control treatment. The highest yield was obtained when 10 kg Mn ha-1 and 150 kg S0 ha-1 were applied, rendering 20.16 t fresh roots ha-1, contrasting to the control, which produced 8.83 t ha-1. The applied treatments were essential to increase cassava yield, however, were unable to provide adequate levels of Mn to plants.