Abundancia de trébol rojo y trébol blanco en pasturas del centro y norte de la provincia de Buenos Aires

The abundance of legumes in grasslands is a key factor for the supply of nitrogen to associated grasses andthe contribution to the quality of the diet of ruminants. Based on the above, a study was conducted at the levelof production systems in the northern of Buenos Aires province with the aim of estimating the abundance ofwhite and red clovers in pastures and the biotic, abiotic and anthropogenic factors that may affect them. 140pastures of 2-3 years old were surveyed in 68 farms of 9 de Julio, Bolivar and Lobos counties in which red clover plant density and white clover content were estimated. For each pasture, the occurrence of diseasesand the damage due to insects on red clover roots, chemical soil properties, the technology used by the farmer in the establishment, production and pasture management were determined. The data were systematized and analyzed statistically using descriptive and inferential statistics with the SAS software. The average density of red clover plants was 6.9 plants m-2 and the average white clover coverage was 2.0%. The abundance of clovers that have been found is insufficient to support a competitive and sustainable productivity of grassland in the northern portion of Buenos Aires province. Technology of establishment and soil type were the factors most related to the density of red clover whereas technologies of production and management were the most relevant for white clover content. The factors to reverse the low abundance of legumes in pastures were identified.