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 latespring and summer in Brazil. Liming and N, P and K fertilization were applied to generate gradients in soil fertility tomaintain soil base saturations around 35%, 50% and 65%, increase soil P concentration and the proportion of K in soilcation exchange capacity, combined with two stubble heights of 10 and 15 cm. Herbage accumulation was not affectedby fertilization regimes and stubble height reaching 10 t/ha of dry matter during the growing season. Cutting at 10cm maximizes the leaf mass and leaf area index and decreases dead material mass without the need of high soil basesaturation and NPK fertilization rates to sustain plant growth. However, this stubble height required longer regrowthperiods 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.

Canopy leaf area and leaf mass in the upper stratum of Urochloa hybrid ‘Mavuno’ grass subjected to nitrogen fertilisation

“…The greatest proportion of the total herbage mass of Mavuno grass was retained in the lower stratum (HM < 20), a common response observed in tropical perennial grasses (Passos et al, 2022), and N fertilisation did not affect this trait. Nevertheless, the herbage mass in the uppermost stratum (HM > 20) was highly variable between regrowth cycles and years.…”

“…Pastures of ‘Mulato II’ ( Urochloa brizantha × U.decumbens × U. ruziziensis ) receiving 250 kg N ha −1 year −1 expressed higher leaf area index (LAI) and daily herbage accumulation rates compared with the application of 50 kg N ha −1 year −1 , whereas all pastures maintained similar herbage mass (Yasuoka et al, 2018). In U. decumbens ‘Basilisk’, simulating a rotational grazing management under cuttings, Passos et al (2022) observed that the total herbage mass, leaf mass and LAI at the pre‐cutting stage were not affected by different fertilisation regimes but, instead, were positively associated with defoliation severity.…”