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The effect of integrated and organic management on the levels of dehydrogenase and alkalyne phosphomonosterase (EC 3.1.3.1) activities was determined in a horticultural soil during a four year crop rotation, finding no statistically-significant differences. Since soil tillage and fertilization were similar, the absence of effects suggests that the well-reasoned use of small rates of agrochemicals in the integrated management for weed and pest control may have negligible effects on soil microbiological activity.

Severe problems are caused by site burning of rice straw in Valencia, the third largest Spanish city. Removal, incorporation or composting are being tested as alternatives to burning, and the changes they produce in selected soil biological properties have been studied in two field trials. One compares removal, burning and incorporation the straw, and a second evaluates the application of straw-derived compost for rice production. No statistically-significant effects on the measured indicators of biological activity were found in either experiment, indicating that management-induced changes are small. Unexpectedly, burning did not affect negatively enzyme activities or microbial biomass contents since there were no differences between treatments, or usual levels were recovered in a few months. The changes induced by straw removal or incorporation were also not statistically significant. When straw-derived compost applications were assayed, dehydrogenase activity was slightly variable and apparently unaffected by N and compost rates or compost/mineral N combinations, but phosphomonosterase activity seems to increase parallel to compost to mineral N ratio.