02135nam a2200157 a 450000100080000000500110000800800410001910000170006024501030007726000880018052016520026865000130192065000130193370000160194670000150196210525802016-09-16       2015    bl uuuu     u01u1 u    #d1 aDO CARMO, M.  aMeasurement of campos rangelands herbage mass by simple methods. [Resumen].h[electronic resource]  aANNUAL MEETING OF THE SOCIETY FOR RANGE MANAGEMENT, SRM, 68., Sacramento, USAc2015  aAccurate and precise estimation of herbage mass is essential for livestock management, because herbage allowance depends on it estimation. Difficulties in estimation arise because of great variability in herbage mass in grassland and rangeland situations. Measuring yield directly by cutting is costly and destructive; but herbage height is highly correlated with herbage mass, thus could be a substitute of the cutting. Based on measurement of herbage mass in a large experiment (EEBR) and in four farms across Uruguay (MICN), we analyzed the relationship between herbage height and dry weight of the quadrat in kg/ha. Analysis was performed  with PROC MIXED and PROC CORR of SAS. On the other hand, the sample size to be taken in each paddock is of great importance and was estimated from the data population described above by resampling and estimating the coefficient of variation (CV) between means. A CV of 10% was defined as the limit to consider the estimation precise enough. The general relationship was y = 224 (±36) + x * 339 (±4), R2 = 0.84. Sample size to maintain the average with a CV error below 10% varied with mean, because it change the variance, however as a general rule, with a sample size between 60 to 100 only one estimation from 198, was above 10% error of the mean. We conclude that estimations based on herbage height are accurate enough (R2 = 0.84) to estimate the herbage mass and a sample size from  60 to 100, give as confidence to estimate herbage mass with precision in paddocks from 5 to 190 ha. That methodology should be extended to Campos rangeland manager for decision making to control grazing intensity.  aFORRAJES  aPASTURAS1 aCARDOZO, G.1 aSOCA, P.M.