Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
MIRANDA, Mario et al. Dry matter production and nitrogen use efficiency of giant missionary grass in response to pig slurry application. R. Bras. Zootec. [online]. 2012, vol.41, n.3, pp. 537-543. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982012000300009.
This study assessed the effect of successive applications of pig slurry on the dry matter (DM) production and the nitrogen use efficiency of giant missionary grass along two years. A total of 55, 110, 165, 220 and 275 m3 of pig slurry/ha/year were applied in order to supply 100, 200, 300, 400 and 500 kg of total N/ha/year, respectively. These treatments were compared with the ammonium nitrate (200 kg of N/ha/year) source of N and with a control (no nitrogen application). Annually, nitrogen was applied in four divided doses, after the cutting of forage grasses, which takes place five times a year. The total DM yield did not differ between years and increased linearly as a function of pig slurry application, ranging from 2,698 kg of DM/ha/year (control) to 11,371 kg of DM/ha/year (275 m3 of pig slurry/ha/year). There was an increment of 32.3 kg of DM/m3 of pig slurry/ha or 17.7 kg of DM/kg of N/ha. The highest average daily DM accumulation rate (66.8 kg of DM/ha/day) was achieved with the highest pig slurry rate, from February/2007 to April/2008. Nitrogen use efficiency did not differ across pig slurry rates (19.0 kg of DM/kg of N), but it was lower than that obtained with ammonium nitrate (30.3 kg of DM/kg of N). The efficiency index of pig slurry ranged from 0.52 to 0.72.
Keywords : A. jesuiticus × A. scoparius; organic fertilization; pasture.