Evaluation of an Approach to Predict Nutrient Supply from Organic Amendments.

Organic amendments are increasingly common in agricultural production due to their ability to supply nutrients as well as improving overall soil health. In order to use organic amendments effectively, it is important to know the amount of nutrient released as well as the timing of the release in order to best match the needs of the following crop. The capacity of organic amendments to supply nutrients to crops varies widely due to differences in nutrient content, decomposability and environmental conditions.  A model was developed to predict N mineralization based on C and N mineralization from short-term lab incubations.  Published studies using PRS^TM probes (Western Ag Innovations) and plant uptake were used to evaluate the ability of the model to predict the quantity and timing of N release from a range of organic amendments.  The approach could account for much of the variation observed in N release between composts, and for the generally lower N supply from compost than manure.