WINTER AND EARLY SPRING LOSSES OF NITROGEN FOLLOWING LATE FALL APPLICATION OF HOG MANURE

Runoff and drainage losses of ammonium, nitrate, and total nitrogen du ring winter and early spring following hog manure application in late fall were simulated using disturbed Coaticook clay loam soil (Humic Gl eysol) contained in 0.26 m(2) boxes. A factorial treatment combination of three hog manure application rates (0, 27.3, and 54.6 m(3) . ha(-1 ), which represented 0, 150, and 300 kg TKN . ha(-1), or 0, 115, and 2 30 kg NH4-N . ha(-1)) and two application methods (with and without in corporation) were studied. During the freezing period (winter), the so il in the boxes remained frozen and runoff was the major hydrologic pr ocess accounting for 99% of the total water collected. Total Kjeldahl- N (TKN) and ammonium-N (NH4-N) loads in runoff water increased linearl y with surface application rates. Loads were 3.2, 8.0, and 12.7 kg TKN . ha(-1) and 1.7, 5.3, and 9.0 kg NH4-N . ha(-1) for increasing appli cation rates, respectively. Incorporation did not affect drainage wate r loads since infiltration in the frozen soil was low. During the thaw ing period (early spring), snow-melt produced both runoff and drainage water until the soil had thawed completely at which time infiltration increased sharply. Drainage then accounted for 80% of the total amoun t of water collected. Loads of TKN in drainage water increased Linearl y regard less of application methods whereas NH4-N loads increased lin early for incorporation only. Loads were 5.4, 6.3, and 7.3 kg TKN . ha (-1) and 1.0, 1.4, and 2.0 kg NH4-ha(-1) for increasing application ra tes, respectively. Rate of manure application without incorporation di d not affect the loads of any form of N during the thawing period, pro bably due to losses which occurred during: the freezing period. Leachi ng produced NO3-N loads of 60 kg . ha(-1) regardless of application ra te and methods indicating that the possible source of NO3-N was the so il itself. Total loads were 9.5, 15.1, and 20.8 kg TKN . ha(-1); 3.2, 6.7, and 10.4 kg NH4-N ha(-1) for the three surface spreading rates, r espectively. Losses due to surface-spreading were therefore 3.7 and 3% of TKN and NH4-N applied, respectively. For incorporation, total load s were less; 9.5, 10.5, and 11.5 kg TKN . ha(-1): 3.2, 3.7, and 4.3 kg NH4-N . ha(-1), representing only 0.7% of TKN and 0.5% of NH4-N appli ed. Incorporation was therefore less damaging than surface spreading.