The effect of available carbon and nitrogen in straw on soil and ash aggregation and acetic acid production

Abstract

Aerobically decomposed straws containing various contents of available C and N were tested for resultant aggregating effect on Mt. St. Helen's ash and Palouse silt loam. Aggregation decreased when straw N content increased in the range 0.25–1.09% w/w. These results suggest that microbial extra-cellular products are very important for stabilizing soils. Microbial production of acetic acid, which can be phytotoxic to wheat plant seedlings, was greatest initially from the 1.09% N w/w straw. After the first three days of aerobic decomposition, acetic acid production was not linked to the straw N content. The potential of barley and wheat straw to serve as a substrate for acetic acid production was greater than that of the remains of the flowering heads (chaff). However, the chaff might pack more tightly than the straw in the field, which would increase effectively its acetic acid concentration over that of the straw.