Availability of soil nitrogen released from pea and lentil residue to subsequent cereal crops under reduced tillage
The release of N from legume crop residues in the field can potentially be an important nutrient source for succeeding cereal crops, particularly in soils which are N deficient. Field studies were conducted in 1996 on two soils of contrasting textures in the Dark Brown Soil Zone of Saskatchewan, a 1) Sutherland clay loam (Kernen), and a 2) Bradwell sandy loam (Goodale), which were previously cropped to pea and lentil in order to compare the effects of legume stubble type on soil N supply. Spring wheat was direct seeded in 1997 in order to compare yields and crop N uptake on pea and lentil stubble. Pre-seeding soil samples were taken and analyzed for NH, and NO,. Pre-seeding available N amounts were significantly greater at Kernen, corresponding to higher organic matter levels. Supply rates of NO, during the growing season were measured using anion exchange resin membranes (PRS- probes). Higher overall supply rates were measured at Kernen as compared to Goodale, while significantly greater supply rates on pea stubble were observed at Goodale only. Both wheat yield and N uptake were significantly greater at Kernen as a function of higher N availability. Mean N uptake and yields were generally higher under pea stubble than lentil at both sites but not significantly different at the 10% level.
anion exchange membrane
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