Long-term beef production from pastures established with and without annual crops compared with native savanna in the Eastern Plains of Colombia: A compilation and analysis of on-farm results 1979‒2016

摘要

The Eastern Plains of Colombia (“Llanos”) are made up of acid soils with low nutrient concentrations covered by tropical savannas, but they constitute a very important land resource for the country. The Llanos have traditionally supported extensive beef cattle production systems but are increasingly in demand for food, feed and oil production. The establishment of improved tropical pastures is a continuing trend as a means of intensifying beef production. Published data and the authors’ own on-farm databases were collated and analyzed to estimate commercial cattle weight gains. A total of 198 records representing pastures directly drilled into native savanna and pastures undersown with rain-fed upland rice and maize were available for the 1979‒2016 period, and were compared with savanna-based beef production. Records were available for sown paddocks 1‒15 years in age that were managed solely by ranchers or by consensus between ranchers and researchers. Performance was not affected by who made the management decisions. Pastures sown in association with maize largely out-yielded all others, but observations on these paddocks were restricted to only 3 years and there was a steep fall in production with age. Differences between conventionally established and rice-associated pastures decreased rapidly over time, and production from these pastures did not differ over the longer term. Pasture age and stocking rate during the rainy season were the major factors influencing output from all systems. Overall, adjusted, long-term weight gains per year ranged between 11 and 386 kg/ha for savanna and maize undersown pastures. The data suggest a need to document long-term planned, regular, crop-pasture rotations, but none was available. The analyses provide valuable, long-term estimates of realized beef production under commercial conditions that should assist in decision-making by graziers and policy makers.