Soil water infiltration after oilseed crop introduction into a Pacific Northwest winter wheat–fallow rotation

Abstract

Rapid water infiltration is important for improving water storage and reducing erosion potential in arid and semiarid areas. Taprooted crops are sometimes credited with improving water infiltration. In a study repeated over three years, we tested whether adding a single brassica crop year to the traditional wheat (<i>Triticum aestivum</i>)–summer fallow rotation would improve water infiltration. We found significantly faster rates of ponded water infiltration in subsequent wheat crops following canola (<i>Brassica napus</i>; 29.68 ± 19.83 mm h^–1 [1.17 ± 0.78 in hr^–1], <i>n</i> = 24) and mustard (<i>Brassica carinata</i>; 25.27 ± 17.32 mm h^–1 [0.99 ± 0.68 in hr^–1], <i>n</i> = 19) as compared to wheat following winter wheat (21.14 ± 15.78 mm h^–1 [0.83 ± 0.62 in hr^–1], <i>n</i> = 24). The greater infiltration rates measured following brassicas compared to wheat were not attributed to root channels due to the lack of visible channels. Crop diversification with oilseeds can increase water infiltration after only a single crop year.