IMPACT OF TEMPORAL AND SPATIAL PATTERNS OF POTASSIUM ON PRECISION MANAGEMENT IN PERMANENT PASTURES

Abstract

Alto Alentejo region in Southern Portugal has over 200,000ha of permanent pasture. Here, the soil is relatively rich in potassium (K) due to its presence in the bedrock, and thus it is not usually applied in fertilizers. On the other hand, cycling of K in grassland systems has received relatively little attention in research and practice in recent years (Kayser and Isselstein, 2005). Given its importance in the quality of crops and since uniform application of fertilizers in areas with spatial variation in soil properties could result in points of fertilizer application above or below the required doses (Bernardi et al., 2011), it is important to evaluate the potential for implementation of variable rate technologies (VRT). The transfer of technology traditionally used for cereal crops, to pastureland may encourage extensive livestock in areas with shallow and rocky soil, where animal husbandry is the predominant activity. The general objective of this study was to evaluate the specificity of the dynamics of soil K, over ten years, in a complex system: a bio diverse pasture installed on a shallow soil, grazed by sheep, in Mediterranean conditions.