Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 26, 1997
Publication Date: N/A
Technical Abstract: Net carbon and nitrogen mineralization were determined from five soils (clayey, kaolinitic thermic Typic Kanhapludults) collected from the same field that had undergone differential erosion in previous decades resulting in clay contents ranging from 5 to 30%. The effect of pretreatment: (1) moist-intact, (2) dried-intact, (3) dried-crushed to pass 7.9-mm screen, (4) dried-crushed to pass 4.7-mm screen, (5) dried-crushed to pass 2-mm screen, and (6) dried-crushed to pass 0.5-mm screen was investigated on soil cores taken to depths of 0-4 and 4-8 cm. Carbon mineralization during a 24 day incubation at 50% water-filled pore space and 25 degrees C was determined at 3, 10, and 24 days by titration of excess alkali. Net nitrogen mineralization from the same samples was determined from the accumulation of nitrate-N and ammonium-N at the end of 24 days. Drying (55 degrees C, 48 h) resulted in a significant flush of microbial activity during the first 3 days. Increasing the degree of homogenization through smaller screen openings further increased the flush. However, the rate of C mineralization during 10-24 days (basal soil respiration) was similar between intact and sieved soil, whether kept moist or dried and rewetted.