Phosphorus status in some natural desert truffle stands

Little is known about the phosphorus (P) status of non agricultural soils, although some sites in drylands are potentially important for the production of desert truffles, a mycorrhizal association that may overcome the fertility deficiency. In this work we described the fertility characteristics with special emphasis on the P status of some natural desert truffle stands. The soils have poor fertility characteristics and the total P contents range from 32 to 273 mg Kg-1. The P fractionation shows fairly variable amounts of organic P, while the proportions of the other fractions are related to the soil chemical properties. The available P contents are also variable, but generally high if compared with the critical levels for optimal yields of crops. The water availability of these soils is likely to be an important factor to be kept into account when evaluating the P availability.