Quantifying the effects of sawdust application on soil chemical and physical properties and corn yield

Sawdust is a wood waste containing a very rich carbonaceous component that can be used as soil amendment. However, it is also important to understand the adverse impact that sawdust might have on soil and crops. In this study, sawdust application at varying rates of nitrogen fertilizer was investigated in soils planted with two years of no-till corn and in soils planted in one year tilled and no till corn. Sawdust may be beneficial due to its rich carbonaceous nature, but it may also affect nitrogen availability for the same reason. Data on crop yield, soil physical and chemical properties such as bulk density, pH, P, K, NO₃^-, organic matter, and total soil C and N were analyzed to study the effect of sawdust on corn yield and soil quality. Three experiments were conducted including (1) two-year no-till corn with spring sawdust application (Experiment 1), (2) one-year no till corn with spring and fall sawdust application (Experiment 2), and (3) one-year tilled corn with spring and fall sawdust application (Experiment 3). Results showed no effect of sawdust on soil pH in all treatments, slight to negligible detrimental effect on corn yield which was overcome in most cases by addition of N fertilizer and significant depression on soil nitrate as a result of N immobilization. However, contrary to previous studies, no increase in soil organic matter and soil total carbon occurred. Likewise, soil total N and bulk density of the soil after two years did not differ with sawdust addition. It is probable that the short time frame of the study prevented these effects from being expressed.