SPATIAL VARIABILITY OF SOIL PHOSPHORUS AS INFLUENCED BY SOIL TEXTURE AND MANAGEMENT

Publisher Website
Google Scholar
Abstract
The spatial variability of soil phosphorus (0–15 cm) and its relationship to management and texture was examined on an ongoing (since 1967) crop rotation study located on a Brown Chernozemic loam soil at Swift Current, Saskatchewan. Total soil P was less variable than either the total inorganic (Pi) or organic (Po) phosphorus fractions. The same was found for the sodium bicarbonate extractable P (bicarb-P) fractions, although they were more variable. The spatial variability of the measured P fractions indicated that the site was not uniformly variable. Texture varied significantly within and between treatments and replicates with sand being the most variable. Up to 90% of the variability in P could be accounted for by changes in texture. Considering this, sampling intensity could be significantly reduced in a study of temporal changes in soil P on the experimental site. Organic P (both total and bicarb-Po) and bicarb-Pi were negatively correlated to sand content. The influence of managment on soil phosphorus varied with texture. Removal of treatment effects over the textural ranges encountered and the non-uniform variability of the various soil parameters measured in this study demonstrated the importance of obtaining a complete knowledge of the spatial variability of the experimental site. Key words: Inorganic P, organic P, soil variability, bicarbonate extractable P, soil uniformity