Quantification of seasonal soil nitrogen mineralization for corn production in eastern Canada
2008
Wu, Tian-Yun | Ma, B. L. | Liang, B. C.
Precise estimation of soil nitrogen (N) supply to corn (Zea mays L.) through N mineralization plays a key role in implementing N best management practices for economic consideration and environmental sustainability. To quantify soil N availability to corn during growing seasons, a series of in situ incubation experiments using the method of polyvinyl chloride tube attached with resin bag at the bottom were conducted on two typical agricultural soils in a cool and humid region of eastern Canada. Soil filled tubes were retrieved at 10-d intervals within 2 months after planting, and at 3- to 4-week intervals thereafter until corn harvest. Ammonium and nitrate in the soil and resin part of the incubation tubes were analyzed. In general, there was minimal NH ₄ ⁺ -N with ranges from 1.5 to 7.3 kg N ha⁻¹, which was declined in the first 30 d and fluctuated thereafter. Nitrate, the main form of mineral N, ranged from 20 to 157 kg N ha⁻¹. In the first 20-50 d, main portion of the NO ₃ ⁻ -N was in the soil and thereafter in the resin, reflecting the movement of NO ₃ ⁻ in the soil, which was affected by rainfall events and amount. Total mineralized N was affected by soil total N and weather conditions: There was more total mineralized N in the soil with higher total N, and rainy weather stimulated N mineralization. The relationship between the accumulated mineral N and accumulated growing degree-days (GDD) fitted well into first order kinetic models. The accumulated mineralized soil N during corn growing season ranged from 96 to 120 kg N ha⁻¹, which accounted for 2-3% of soil total N. Corn plants took up 110-137 kg N ha⁻¹. While the mineralized N and crop uptake were in the same magnitude, a quantitative relationship between them could not be established in this study.
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