Biological indicators of soil quality under conventional, reduced, and no-tillage systems.

Soil microbial processes can serve as sensitive indicators of soil quality. A 2-year field experiment was conducted to determine the combined effects of tillage (conventional, CT; reduced, RT; and no tillage, NT) and residue (with or without residue removal) on soil microbial and enzyme activities under wheat (Triticum aestivum L.)- and corn (Zea mays L.) in a rotation, using a split-plot design with three replications near Shiraz, Iran. The highest microbial biomass (660.19 and 667.00 µg MBC g−1 soil in wheat and corn, respectively) was recorded under RT. Soil respiration was affected by tillage in order NT > RT > CT. The lowest microbial quotient (qCO2) was obtained under RT (15.60 in wheat and 5.94 in corn, respectively), while NT and CT either showed similar effects or NT was superior over CT. The highest acid phosphatase enzyme was obtained under RT (442.65 and 374.17 µg PNP g−1 soil h−1 in wheat and corn, respectively). Alkaline phosphatase and urease enzymes were highest under NT. Our research has shown that replacing CT with conservation tillage (especially RT) can greatly improve soil enzymes and microbial biomass and optimize qCO2 values under wheat- and corn in a rotation in a short term. [ABSTRACT FROM AUTHOR]