Durum Wheat Productivity in Response to Soil Water and Soil Residual Nitrogen Associated with Previous Crop Management

Green manure may have potential uses in dryland agroecosystems. This study determined the effect of green manure on residual soil water and soil N and the subsequent durum wheat (Triticum turgidum L.) performance in comparison with the effect of preceding dry pea (Pisum sativum L.), silage pea (Pisum sativum L.), and spring wheat (T. aestivum L.). Three green manures [black lentil (Lens culinaris Medik.), chickling vetch (Lathyrus sativus L.), and forage pea (Pisum sativum L.)] were grown in 2006, 2007, and 2008, along with pea, wheat, and a summerfallow (check) in Saskatchewan, Canada. Durum wheat was grown the year after these treatments. At durum wheat planting, the green manure treatments had the same amount of water in the 0- to 1.2-m soil profile as the summerfallow in 2007 and 2009 but less water compared with the summerfallow in 2008. Summerfallow provided highest soil N among all treatments in 2007 and 2008 but lower soil N than green manure treatments in 2009. Green manure treatments increased subsequent durum wheat grain yield by 19% compared with preceding silage pea or dry pea and by 54% compared with preceding spring wheat but decreased yield by 12% compared with summerfallow treatments. The green manure with late planting and termination enhanced soil-water conservation and offered input-saving advantages compared with the early- and mid-planting and termination treatments. Overall, green manure treatments enhanced soil water storage, provided N benefits, and increased subsequent durum wheat yield compared with crops harvested for grain.