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Soil water repellency (SWR) caused by organic coatings on soil particles can lead to serious loss in crop production and turfgrass quality. In laboratory experiments, we tested the novel concept of direct application of enzymes to alleviate SWR. In a biofuel research project on fungal pre-treatment of switchgrass (Pemicum virgatum L.) for improved saccharification, enzymatic co-products (mainly laccase mixed with other trace enzymes) were produced based on fermentation periods of 18, 36, 54, and 72 days. We characterised enzyme activities of the 18-72-day crude enzyme extracts (CEE) and applied undiluted or diluted solutions (dilutions of 5-, 10-, and 100-fold) to eight air-dried, SWR soils from several golf courses. These soils exhibited water drop penetration times (WDPT) of 345-7439 s (i.e. moderately to very strongly hydrophobic) and all showed a large decrease in SWR to WDPT Additional keywords: soil water repellency, laccase, Co-product, bioremediation., Introduction Soil water repellency (SWR) is the phenomenon in which a soil does not spontaneously wet when a drop of water is applied to the surface, indicating that the soil [...]

A pot experiment with rice under submerged condition showed that with the increase of Cd concentration, soil microbial biomass carbon (Cmic) and nitrogen (Nmic) increased initially but decreased at a certain concentration, and the turning points varied with different soil types. Soil enzyme activities had the similar variation trend with soil Cmic and Nmic, and the turning points varied with different soil types and soil enzymes. The variation coefficients were in order of dehydrogenase activity > acid phophatase activity > urease activity. Soil respiration rate and metabolic quotient increased tardily with increasing cadmium concentration. The chlorophyll content of rice increased initially but decreased then with the increase of Cd contamination, and the turning points differed with different soil types. Rice proline content and peroxidase activity were enhanced gradually with increasing cadmium concentration. The variation coefficients of rice physiological indices on paddy soils derived from silty loam and clayed red earth were in order of peroxidase activity > chlorophyll content > proline content, and peroxidase activity > proline content > chlorophyll content, respectively. Correlation analysis indicated that there was a close correlation between the variations of soil microbial biomass and enzymatic activities and rice physiological indices under Cd contamination.