Livestock manure contains most nutrients that crops require and is frequently used as a fertilizer. This paper looks at its usefulness in relation to forages. The results showed that in general the application of hog manure resulted in significant forage yield increases when compared to the control plots in all cases. Forage stands that are kept in good condition will have a greater response to manure application than stands contaminated with weed or poorly productive grasses.
Soil type, nutrient demand of various crops and nutrient content of manure will affect the manure application rate. In order to calculate this rate correctly, nutrient analysis of the manure and soil test recommendations should be done. Factors that need to be considered when applying manure are 1) application methods, such as low-disturbance injection which provides a low-cost alternative to fertilization, 2) application timing, where spring application seems to be the most beneficial and 3) application frequency where applications made to meet a two year nutrient requirement result in good responses.
A study by PAMI (2000) indicated that application of high rates of manure resulted in a carryover of nutrients in the years following application that have contributed to a concentration of nitrates in the forage. A number of factors can influence this accumulation and it is recommended that forages (cut for hay or grazed) that have received nutrients should be tested to determine nitrate and potassium levels.