Canopy structure and forage nutritive value of elephantgrass subjected to different stocking rate and N fertilization in the "Mata Seca" ecoregion of Pernambuco

Dourado, Diego LoiolaDubeux Junior, José Carlos BatistaMello, Alexandre Carneiro Leão deSantos, Mércia Virginia Ferreira dosLira, Mário de AndradeFreitas, Erinaldo Viana deApolinário, Valéria Xavier de OliveiraSantos, Erick Rodrigo da Silva

The objective was to evaluate the effect of three stocking rates (2, 3.9, and 5.8 animal units ha−1) and three fertilization levels (0, 150, and 300 kg N ha−1 yr−1) on herbage mass and nutritive value of elephantgrass (Pennisetum purpureum Schum.) cv. IRI-381. The experiment was conducted from May to August of 2009 and 2010 in Itambé, PE, Brazil, during the rainy season. Treatments were allocated in a split-plot arrangement in a completely randomized block design. The variables measured included leaf mass (pre- and post-grazing), botanical composition, soil cover, leaf area index, light interception, leaf angle, and concentrations of dry matter, organic matter, N, and in vitro digestible dry matter. When fertilized with 300 kg N ha−1 yr−1, leaf mass reached 18,560 kg ha−1. Leaf area index decreased with increasing stocking rate. The relationship between sward height and light interception was R2 = 0.0126. Increased stocking rate resulted in greater contribution of signalgrass [Brachiaria decumbens (Stapf.) R.D. Webster] in the botanical composition, with a contribution up to 29% in 2010. Elephantgrass nutritive value is directly affected by the fertilization levels and stocking rate, with highest nutrient concentrations observed with 2 AU ha−1 and 300 kg N ha−1 yr−1.(AU)

1. grazing
2. Pennisetum purpureum
3. pasture
4. livestock
5. nitrogen