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

Runoff and drainage losses of ammonium, nitrate, and total nitrogen during winter and early spring following hog manure application in late fall were simulated using disturbed Coaticook clay loam soil (Humic Gleysol) 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 230 kg NH4-N . ha(-1)) and two application methods (with and without incorporation) were studied. During the freezing period (winter), the soil in the boxes remained frozen and runoff was the major hydrologic process accounting for 99% of the total water collected. Total Kjeldahl-N (TKN) and ammonium-N (NH4-N) loads in runoff water increased linearly 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 application rates, respectively. Incorporation did not affect drainage water loads since infiltration in the frozen soil was low. During the thawing 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 amount of water collected. Loads of TKN in drainage water increased Linearly regard less of application methods whereas NH4-N loads increased linearly 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 rates, respectively. Rate of manure application without incorporation did not affect the loads of any form of N during the thawing period, probably due to losses which occurred during: the freezing period. Leaching produced NO3-N loads of 60 kg . ha(-1) regardless of application rate and methods indicating that the possible source of NO3-N was the soil 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, respectively. Losses due to surface-spreading were therefore 3.7 and 3% of TKN and NH4-N applied, respectively. For incorporation, total loads 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 applied. Incorporation was therefore less damaging than surface spreading.