LAUSR

ABSTRACT Understanding the spatial characteristics of soil properties would be helpful in recognizing their relationship and the development of site-specific management techniques. The paper aims to identify any spatial heterogeneity of the P-related properties in a plot scale and to explain the main mechanisms influencing this variability in the upper layer of arable Luvisols. Samples were collected from the upper soil horizon in April and August 2008. The content of the total (PTOT), available (PAVAIL), inorganic (PINORG) and organic (PORG) form of P and the acid (ACP) and alkaline (ALP) phosphatase activity were assessed. The ALP was significantly higher in April than in August, while the ACP did not differ between the sampling dates. The PINORG was significantly higher in August than in April, while the other P forms did not differ seasonally. The PORG content, PAVAIL concentration and ALP activity in April revealed a moderate spatial variability, while the PAVAIL content and ACP in August showed a strong variability. No significant relationship was found between any P form and the phosphatase activity. The results are essential to predict the contribution of internal factors in the total variability of soil properties that can interfere with the influence of soil management practices.