EFFECT OF THE STOCKING RATE AND LAND SLOPE ON NITROGEN LOSSES TO WATER ON A GRAZED PASTURE OF SOUTHERN CHILE
Author
Salazar,F
Alfaro,M
Ledgard,S
Iraira,S
Teuber,N
Ramírez,L
Abstract
Most of the studies on nitrogen (N) leaching have been carried out on cut grass, and there is a lack of information on beef grazed grasslands. The objective of this study was to quantify N runoff and leaching losses in beef production systems with two different immediate stocking rates (63 and 191 Holstein Friesian steers ha-1 day-1) and two land slopes (4 and 12%). Runoff and leachate samples were analyzed from 2004 to 2006 for total N, nitrate and ammonium. No significant differences for the total N losses were found between treatments (p > 0.05), which were low ranging from 0.9 to 26.8 kg N ha-1 yr-1. The main pathway for the losses was leaching, which contributed >99% of the total N lost. The main form of N leaching was nitrate-N (>84%). Nitrate-N concentration in runoff samples was high, averaging 14 to 31 mg L-1. We suggest that these low N losses could be related the low N fertiliser inputs in the pasture and to the N adsorption properties of volcanic soils and, so that further research is required on this subject.