Wheat Straw Decomposition in the Field

Abstract Wheat ( Triticum aestivum ) varieties ‘Nugaines’ and ‘Lemhi’ were grown on Portneuf silt loam soil with three nitrogen and three irrigation treatments in 1967. After harvest, 84 kg N/ha was applied to half of each plot before plowing. Uniform straw samples were enclosed in fiberglass cloth bags and buried in the plots September 7. The straw placed in N‐treated plots received sufficient N in solution to increase the straw N from about 0.29 to 1.5%. Straw samples were recovered November 15, after the soil had cooled below 4C, and at three later sampling dates to October 3, 1968, after a bean crop ( Phaseolus spp.) was harvested. Weight loss and total N were determined on all samplings and total C on the first sampling. Decomposition was greater with N than without it for the November sampling and the March sampling for Nugaines but not at other samplings for both varieties. The weight of N in both N‐treated straw varieties decreased 55% by November 15, while in the non‐N‐treated Nugaines and Lemhi straw, N weight increased 12 and 32%, respectively, by March 22. Later, N moved out of all the straw samples when the N percentages were much lower than the theoretical equilibrium value.