Nitrogen Mineralization for Three Compost Fraction Sizes.

The rate of nitrogen mineralization from composted materials may be affected by fraction size. This study was conducted to evaluate nitrogen mineralization from 3 size fractions (< 1.0 mm, 1.0 to < 2.0, and 2.0 to 4.0 mm) of 5 different composted materials.  Each experimental unit consisted of 10 g of soil mixed with 1 g of compost for each size fraction (5 sampling dates x 3 replications each).  The experimental units were incubated at 30C for 7, 14, 28, 56, and 116 days  Three of the composts showed the smallest nitrogen mineralization from the finest fraction (<1 mm) and the greatest mineralization from the coarser fraction (2-4 mm).  These results suggest that sieving composted materials may have an impact on nitrogen mineralization.