Where urea is normally applied multiple times on these crops, ESN can substitute for those applications. For pasture, we would normally recommend sufficient soluble nitrogen, such as urea or ammonium sulfate, to cover about the first month of growth after application, with the balance as ESN. In the spring, the first flush of growth (first cutting) is almost always the largest with declines in successive cuttings. So if harvesting for hay or silage, it is especially important to maximize this cutting. Grass is very responsive to N, especially in the first spring growth.
It’s important to include enough soluble nitrogen to take advantage of this fast, early growth. We recommend a blend with 40 to 60% of the N coming from an immediately available source and the remainder coming from ESN. The soluble N supports immediate growth, and ESN feeds the subsequent growth. Depending on the length of growing season, total N rate and the amount of ESN, ESN should provide sufficient N supply for the second and possibly third cuttings without an additional application. If grazing and the early flush is more than can be utilized, more ESN might be used to control the early growth and better equalize growth across the summer.
Alfalfa generally does not need fertilizer N except at establishment or in conditions were N fixation may be limited by poorly aerated soils or low pH. ESN could be used in situations where some supplemental N is beneficial. In this case, we recommend a blend with minimal soluble N so as not to stimulate weeds and grasses.