Nutrient value of animal manures in front of environmental hazards

The increment of the industrial farms in the Southeast of Spain represents an opportunity to reuse animal manures in and and semiarid soils, as a source of nutrients and organic matter. However, there are diverse components in their composition potentially dangerous for the environment from the different management activities in the industrial farms, especially heavy metals and salinity. In this experiment, 48 different types of manures from horse, cow, calf, pig, sheep, goat, rabbit, fowl, chicken, ostrich, turkey and earthworm were evaluated on total nutrient content, specially N and P. We also monitored the salt content and the presence of the heavy metals Cd, Hg, Pb, Cr and Ni as main environmental hazards for agricultural soils. We tested a nitric acid digestion for a rapid sample preparation using electro thermal energy (microwave), with very good efficiency on metal recovery.