Short-term Impacts of Organic Amendments and Polyacrylamide on Soil Physical and Biochemical Properties.

ÿþIncreasing carbon (C) retention in soil is important, because SOM is a binding agent for soil structure, reservoir for plant nutrients, and a major repository of organic C (OC) pool to mitigate increase in atmospheric abundance of carbon dioxide (CO2). Application of organic amendments (OA) could increase the SOM pool. Thus, two OA [i.e. wheat straw (WS) d" 2-mm length and cattle manure (CM) each @ zero (control), 4, 8, and 16 Mg ha-1, respectively] and polyacrylamide (PAM) [@ zero (control) and 20 kg ha-1] were mixed thoroughly with a fine, mixed, mesic, Aeric Ochraqualf silt loam soil from Columbus, Ohio. This mixture of soil-OA-PAM was incubated for 80 days to asses impact on tensile strength (TS), soil moisture retention (0 to -333 kPa), aggregate stability (AS), mean weight diameter (MWD), geometric mean diameter (GMD), wettability (WA), and kinetic energy (KE) required breaking the aggregates. Both C and N mineralization were also determined. The WS, CM, PAM, and their interactions [(CM x WS), (CM x PAM), and WS x PAM)] significantly (P d" 0.05) influenced AS, MWD, TS, WA and KE, indicating improvement in soil structure. However, the effect of WS x CM x PAM interaction was non-significant on all these soil quality parameters. Organic amendments significantly (P d" 0.05) increased the OC and N contents. However, the impact of PAM on OC and N contents was non-significant. Further, PAM significantly (P d" 0.05) depressed the CO2 evolution. Field experiments are needed to assess the impact of OA on soil quality, agronomic productivity, environment quality and other ecosystem services.