Yield and Nutrition of Cotton Cultivars Under Different Potassic Fertilization Management in a Sandy Soil

Potassium (K) plays an important role in plant metabolism such as growth and development, production and quality. In addition, K is not associated with the organic structure, allowing it to be applied in the predecessor crop in the no-tillage system. The objective of this work was to evaluate the release of potassium applied in the cover crop (Urochloa ruziziensis), its uptake by cotton, and the effect on yield of cotton cultivars under different managements of potassium fertilization. The experimental design was a factorial 6x2 with five replicates. Treatments included: 1- No K and no U. ruziziensis; 2 - 140 kg ha-1 of K2O applied on cotton sowed after U. ruziziensis, 50% at 30 DAE and 50% at 50 DAE; 3 - No K and with U. ruziziensis; 4- 140 kg ha-1 of K2O applied in the U. ruziziensis; 5 - 140 kg ha-1 of K2O applied 50% in the U. ruziziensis and 50% in cotton at 30 DAE; 6 - 140 kg ha-1 of K2O applied on cotton 50% at 30 DAE and 50% at 50 DAE with U. ruziziensis. The second factor the cotton cultivars: early cultivar FM 913GLT and late cultivar FM 983GLT. It was evaluated K release of cover crop residues, boll number and weight and seed cotton yield.