Changes of Soil Nitrate-Nitrogen and Denitrification as Affected by Nitrogen Fertilizer on Two Quebec Soils
1994
Liang, B. C. | MacKenzie, A. F.
Corn (Zea mays L.) production may result in NO⁻₃-N accumulation in soils because of high N fertilizer applications. Nitrate-N in soil may be lost by denitrification and leaching. Prediction of the amount lost would be helpful in minimizing these losses. Field experiments were conducted to investigate the effects of N fertilizer rates on soil NO⁻₃-N under corn on two soils of contrasting texture from 1988 to 1991 in southwestern Quebec. Denitrification as affected by previous N fertilizer rates was estimated for the nongrowing season of 1990–1991. Soil NO⁻₃-N levels in the fall increased linearly with increasing N fertilizer rates above the normal N rate both on clay and sandy clay loam soils. However, NO⁻₃-N could have been leached out of the rooting zone on the coarser Chicot soil (fine-loamy, mixed, frigid Typic Hapludalf) in the late growing season, depending on rainfall. The changes in soil NO⁻₃-N over winter were a function of both soil NO⁻₃-N levels the previous fall and over-winter precipitation. Denitrification losses varied from 7 to 24 kg ha⁻¹ during the nongrowing season, increasing with N fertilizer rates only on the Ste. Rosalie clay soil (fine, mixed, frigid Typic Humaquept). In comparison with total NO⁻₃-N disappearance over the same period, losses of NO⁻₃-N due to denitrification were relatively small. Thus, significant portions of NO⁻₃-N losses were probably due to leaching both on clay and sandy clay loam soils.
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