When calculating the manure application rates, the residual levels of nutrients from the previous crops and manure should be taken into consideration. Legumes and manure are sources of residual nitrogen. A good stand of alfalfa can supply 112 kg/ha (100 lbs/ac) of nitrogen to the following crop (Ontario Ministry of Agriculture, Food and Rural Affairs 1997). In most operations the residual nitrogen is small and not practical to consider when making general nitrogen recommendations. Most fertilizer recommendations take into account previous crop credits.