Canopy responses of signal grass cv. Basilisk pastures subjected to three fertilization regimes at two stubble heights

Abstract

The impacts of fertilization regimes and stubble heights in signal grass cv. Basilisk pastures were evaluated during late spring and summer in Brazil. Liming and N, P and K fertilization were applied to generate gradients in soil fertility to maintain soil base saturations around 35%, 50% and 65%, increase soil P concentration and the proportion of K in soil cation exchange capacity, combined with two stubble heights of 10 and 15 cm. Herbage accumulation was not affected by fertilization regimes and stubble height reaching 10 t/ha of dry matter during the growing season. Cutting at 10 cm maximizes the leaf mass and leaf area index and decreases dead material mass without the need of high soil base saturation and NPK fertilization rates to sustain plant growth. However, this stubble height required longer regrowth periods to attain 95% of light interception (LI95%). A stubble height of 15 cm is preferred when short regrowth periods are required. The canopy height at the point of LI95% does not change with fertilization regimes, but the LI95% is reached at different canopy heights in late spring and summer in signal grass pastures. The adoption of a moderate fertilization regime is recommended as a strategy to obtain an equitable forage distribution between late spring and summer.