The decomposition of wheat and barley straw buried in a coarse sand and a sandy loam soil was followed under field conditions using chopped straw enclosed in mesh bags. The straw was buried at 10 cm depth in early autumn. Plots were either kept fallow or covered in plants during the summer and autumn following straw burial. Samples were recovered on 10 dates over 15 months and were analyzed for weight loss, C, N and K content. Results obtained were corrected for organic matter and nutrients introduced to the straw by soil entering the mesh bags. Soil temperatures and soil moisture contents were determined. The plant cover reduced soil temperatures, soil moisture contents and straw weight loss rates during the summer. The overall weight loss pattern was similar for the two straw types. In both soils, the straw showed an initial weight loss of 30% during the first month after burial. After 6 months (spring), the straw had lost about 50% of its weight. The weight loss then proceeded faster in fallow than in the planted plots. Seasonal changes in weight loss rates were relatively small. The absolute weight loss rates, determined by a simple linear regression model, ranged from 0.10% day −1in planted plots of the coarse sand to 0.17% day −1 in uncovered plots of the sandy loam. For planted plots, weight losses after 15 months of exposure were 67% in the coarse sand and 78% in the sandy loam. Corresponding values for fallowed plots were 75 and 92%, respectively. Initial straw N contents differed, but overall N dynamics was less influenced by straw type than by soil type. In the sandy loam, net immobilization began just after straw burial and reached a maximum in the spring, where 3 mg N g −1 initial straw was immobilized. The N release was more rapid in fallowed than in planted plots. In the coarse sand, N was initially leached from the straw, and the immobilization of N was less extensive than in the sandy loam. Further, the release of N from the straw was grossly similar in fallowed and planted plots. For all treatments, the net release of N from the straw began when the C-to-N ratio was between 28 and 35. Most of the straw K content was leached during the first month after straw burial. Subsequent straw K content was not affected by initial K content or plant cover.