Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2011
Publication Date: 12/15/2011
Citation: He, Z., Zhang, H., Zhang, M. 2011. Irrigation-induced changes in phosphorus fractions of Caribou sandy loam soil under different potato cropping systems. Soil Science Society of America Journal. 176:676-683. Interpretive Summary: It is important to know the P transformation under different cropping systems so that farmers can manage them accordingly to sustain their production while minimizing the impact of agriculture on the environment. Sequential fractionation is a common method used in evaluating the impacts of soil management practices on soil P distribution. Even so, there is no report on evaluating the impacts of irrigation on soil P fractions using this method. This work measured sequentially-extracted P fractions in 10 potato fields of Caribou sandy loam soil that had been subjected to different three-year crop rotations with and without irrigation. Our data indicated that crop rotation and irrigation affected soil P distribution in two different patterns. The most labile water extractable P fraction was significantly impacted by crop rotation, with the highest water extractable P found in the continuous potato and soil improving cropping managements. Irrigation had greater influence on stable and recalcitrant P fractions. To our knowledge, this is the first report in using the sequential fractionation to characterize the impact of irrigation on soil P distribution. More field data from short and long experimental periods are needed to confirm these observations.
Technical Abstract: Sequential fractionation is a common method used in evaluating the impacts of soil management practices on soil P distribution. However, to our knowledge, this method has not been used in investigating the effects of irrigation on the changes in soil P fractions. In this work, we measured sequentially-extracted P by deionized H2O, 0.5 M NaHCO3 (pH 8.5), 0.1 M NaOH and 1 M HCl in Caribou sandy loam soil samples from 10 potato fields under different three-year crop rotations both with and without irrigation. As inorganic fertilizer was applied to these fields, irrigation and rotation management practices mainly affected the distribution of inorganic P fractions, with little significant changes of organic P fractions. The impact of crop rotation was mainly expressed on H2O extractable P. Irrigation had greater influence on stable or recalcitrant P in NaOH, HCl, and residual fractions. Higher levels of NaOH extractable inorganic P were observed in soil from irrigated fields, while higher levels of HCl extractable P were observed in soils under rainfed management. Our data indicate that irrigation may eventually decrease P availability and runoff potential in these potato soils over the long term due to the partial transfer of P in the sink from the functional NaOH fraction to more stable HCl and residual fractions. Whereas information and knowledge derived from this study may shed light on the dynamics of soil P fractions for sustainable agricultural production, more field data from short- and long- term experiments are needed to confirm our observations.