The hypothesis that delayed addition of nutrient rich material to compost would influence the mineralisation pattern was investigated by studying N turnover in compost based on wheat straw and clover-grass hay. After 7(1)/(2) weeks of composting almost twice as much N was mineralised when the addition of some of the N-rich clover-grass hay was postponed, suggesting that this influenced the microbial succession. The delayed addition resulted in a second temperature peak and a decline in the pH. Despite the altered conditions no significant effect was observed on the weight loss or loss of C and N. In conclusion, compost processes can in a simple way be affected by delayed substrate application leading to a higher nutrient availability without altering other parameters significantly. (c) 2004 Elsevier Ltd. All rights reserved.