We would typically describe the release of ESN to be about 50 to 70 days, but temperature and moisture can alter the timing of its release.
The attached figure shows the effect of temperature on the release as measured in the laboratory in water. This is not to be interpreted as a prediction of exactly what will happen in the field, but it will give you an idea of the temperature effect.
Moisture has little effect on the rate of release as long as there is adequate moisture to maintain the process. If ESN is incorporated into the soil and there is sufficient moisture to grow a crop, there would be little effect of moisture. Moisture only becomes a concern when it is surface applied and not incorporated in areas with limited or infrequent rainfall.
As an example, let’s compare a couple of different environments. In the Midwest US, we have many no-till corn growers who use ESN as a top dress with no incorporation with great success. Rainfall in these areas is typically sufficient to provide intermittent moisture to continue the release. By comparison, in the Great Plains, we would not recommend top dress applications for dryland cropping because rainfall is too infrequent.