Nongrowing season soil surface nitrate and phosphate dynamics in a corn–soybean rotation in eastern Canada: in situ evaluation using anionic exchange membranes

Abstract

Determining how agricultural management practices affect changes in soil nitrogen (N) and phosphorus (P) could further our understanding of soil N and P cycle. The main objective of this study was to assess in situ nongrowing season soil nitrate and phosphate dynamics as adsorbed on anionic exchange membranes (AEM-N and AEM-P, respectively). The membranes were buried in the surface horizon (5 cm below the soil surface) over the nongrowing season (mid-November to mid-April) in five consecutive years (2009–2010 to 2013–2014) in a long-term corn–soybean rotation experiment established in 1992 in eastern Canada. The treatments consisted of two tillage systems, namely moldboard plow (MP) and no-till (NT), and nine combinations of fertilizer applications, namely three N rates (0, 80, and 160 kg N ha−1) and three P rates (0, 17.5, and 35 kg P ha−1) in a split-plot design with four replications. The results showed that AEM-N and AEM-P averaged 1.8 µg cm−2 d−1 and 7.4 ng cm−2 d−1 under MP, respectively, and 2.8 µg cm−2 d−1 and 67.8 ng cm−2 d−1 under NT, respectively. Nitrogen application increased AEM-N in 2010–2011, 2011–2012, and 2012–2013, but decreased AEM-P mainly under NT. Phosphorus fertilization had no effect on AEM-N, but increased AEM-P under both MP and NT. We conclude that AEM can be used as a technique to study N and P dynamics under cold winters of eastern Canada.