public decimal GetAmmoniaRetention(int manureid, int seasonapplicationid)
        {
            decimal ammoniaRention = 0;

            FarmManure myManure = _ud.GetFarmManure(manureid);

            AmmoniaRetention myAmmoniaRetention = _sd.GetAmmoniaRetention(seasonapplicationid, myManure.dmid);

            ammoniaRention = myAmmoniaRetention.value.HasValue ? myAmmoniaRetention.value.Value : 0;

            return(ammoniaRention);
        }