The cycle of nutrient from animal feed to manure to soil and than to crops is an efficient and environmentally sound practice for surface and groundwater if it is done properly done. Good manure management should include all the steps from storage to spreading. The document deals with proper ways to valorize manure particularly in determining the land surface needed for manure application. Two methods for such evaluation and optimization of the manure in order to maximize returns from the nutrients in the manure and avoid environmental consequences from over application are presented. The first method is for a new facility by evaluating the land needed and the second one is for an existent facility by fine tuning the operations. The first step is to set realistic yields goal, as yields goal that are too high will lead to over application of manure and nutrients wastes that could cause leaching and goal that are too low will result in less manure applied and less yield. The subsequent steps are presented for all the calculation for the two possible situations. For soils presenting a P concentration in the soil lower than 30 ppm, the application rate should be done according N requirements. For soil with high P content or if required by regulation, the application rate can be calculated considering P as the limiting element. Commercial fertilizer can than be used to complete the fertilizer requirements of certain elements in order to maximize the yield. Manure and soil sample should be taken every year to evaluate the situation and in order to make appropriate evaluations of the application rates needed.

This document is very interesting and contains a good tool to evaluate the land needed to maximize the nutrients value in manure and to make sure that environmental impacts from manure application are as low as possible.