Decomposition of crop residue in the landscape

Abstract

Decomposition of spring wheat (Triticum aestivum L.), flax (Linum usitutissimum L.) and pea (Pisum sativum L.) residue placed at the soil surface, was measured at four slope positions: upper, upper-middle, lower-middle and lower, in the landscape. Slope position did not significantly affect decomposition or microbial populations in crop residue placed at the surface under a cereal leaf canopy. Decomposition of pea residue was significantly higher than for wheat and flax, due to differences in carbon to nitrogen ratios. Over-winter loss of crop residue varied considerably between crops. Microbial populations in residue were highest in pea residue compared to wheat and flax, and were independent of slope position. Microbial populations in the soil were affected by slope position but not residue. The most active phase of residue decomposition occurred from late, spring to early summer, and was correlated with high yeast populations.