We investigated the N turnover in compost based on wheat straw and clover-grass hay. Postponing the addition of some of the nutrient rich material was expected to influence the microbial succession and thereby the mineralisation pattern. After the initial bacterial degradation of soluble carbohydrates, more recalcitrant compounds are decomposed by less N demanding fungi. Thus, when the additional clover-grass hay was added less immobilisation was anticipated and more mineralised N would be available. After 7% weeks of composting almost twice as much N was mineralised after the postponed addition. 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.
Keywords: Composting; Nitrogen mineralisation; Growing medium; Plant residues; Decomposition
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