NITROGEN SOIL BUDGETS IN CONTRASTING DAIRY GRAZING SYSTEMS OF SOUTHERN CHILE, A SHORT-TERM STUDY

in recent years, the intensification of livestock production in southern chile has resulted in a high potential for environmental damage through nitrogen (n) losses, creating the need for the evaluation of n flows from these systems. the aim of the research was to determine n budgets and n use efficiency in two grazing systems in southern chile. for this, inputs and outputs were measured during one year on two grazing systems (heavy grazing, hg; and light grazing, lg). also, a control treatment with no grazing (c) was considered. the annual n soil budget was determined by the difference between all n inputs (￡ inputs) and all n outputs (x outputs). the results of the experiment indicate that hg treatments received the biggest n input (427, 359 and 288 kg n ha-1 yr-1 for hg, lg and c treatment, respectively), however this treatment also had the biggest n losses (406 kg n ha-1 yr-1), with a nitrogen recovery efficiency from fertilizer of 71%. in addition, herbage dry matter yield (dm) was greater in the hg than in the lg and c treatments (10.4; 8.1 and 7.1 t n ha-1 yr-1, respectively). also, n concentration in the forage was higher in this treatment (2.9%) than in the lg (2.7%) and c (2.5%) treatments. the results indicate that hg increases n use efficiency in pastures in southern chile, increasing the herbage production and quality, but also increasing the potential for n losses to the wider environment. farmers should consider this when choosing the appropriate grazing system.