Nitrogen (N) dramatically increases the yield of grass stands, as well as forage protein levels. Optimum rates depend on the cost of N, anticipated value of the hay, thickness of stand, moisture conditions, and whether it is pasture or hay. Good grass stands with less than one-third legume, can generally benefit from at least 70 kg/ha (63 lbs/acre) of actual N (Table 3-6, OMAFRA Publication 811, Agronomy Guide). The first application of N for hay should be made at green-up, as soon as possible in the spring when soil conditions are suitable. If you have not already done so, walk alfalfa fields and dig some plants to assess winterkill, heaving, frost damage and plant health. Watch for crown and root rots, brownish discoloration, spongy texture and lack of secondary roots and nodulation. Plant health can be more significant than plant density to get a good yield. For more information on Alfalfa Stand Assessment refer to the following article.