Abstract
Residue management in cropping systems is useful to improve soil quality. However, the studies on the effects of residue management on the enzyme activities and microbial community of soils in South China are few. Therefore, the effects of incorporating winter cover crop residue with a double-cropping rice (Oryza sativa L.) system on soil enzyme activities and microbial community in Southern China fields were studied. The experiment has conducted at the experimental station of the Institute of Soil and Fertilizer Research, Hunan Academy of Agricultural Science, China since winter 2004. Four winter cropping systems were used: rice–rice–ryegrass (Lolium multiflorum L.) (R-R-Ry), rice–rice–Chinese milk vetch (Astragalus sinicus L.) (R-R-Mv), rice–rice–rape (Brassica napus L.) (R-R-Ra) and rice–rice with winter fallow (R-R-Fa). The result indicated that the enzyme activities in the R-R-Ry, R-R-Mv and R-R-Ra systems were significantly higher (P<0.05) than in the R-R-Fa system during the early and late rice season. The β-glucosidase activities reached peak values at the tillering stage after residue application, and alkaline phosphatase activities reached peak values at the booting stage after residue application, respectively, the activities of β-glucosidase and alkaline phosphatase gradually decreased after this. Arylsulfatase activities reached peak values at the maturity stage. Arylamidase activities reached peak values at the maturity stage. The numbers of aerobic bacteria, actinomycete and fungus of residue treatments were significantly higher (P<0.05) than that the R-R-Ra system. However, the number of anaerobic bacteria under the R-R-Ry and R-R-Mv systems was significantly lower (P<0.05) than that under the R-R-Fa system during early rice and late rice growth stage. Thus, incorporation of winter cover crops into rotations may increase enzyme activities and microbial community in soil and therefore improve soil quality.
Highlights
Enzymes play an important role in the cycling of nutrients in nature, and soil enzyme activity can be used as an index of soil microbial activity and fertility [1]
The RR-Ry had the highest b-glucosidase activity and the rice with winter fallow (R-R-Fa) had the lowest activity (Fig. 2), and the activity decreased in the following order: rice–rice– ryegrass (R-R-Ry).rice– rice–rape (R-R-Ra)
In the late rice season, the highest activity was the treatment that the rape was used as residues, and the activity trend was as follows: R-RRa.R-R-Ry
Summary
Enzymes play an important role in the cycling of nutrients in nature, and soil enzyme activity can be used as an index of soil microbial activity and fertility [1]. Enzyme activity profiles reflect soil functional diversity, which is influenced by the genetic diversity of soil microorganisms, plants and animals and is closely related to environmental factors and ecological interactions [4]. Among the different enzymes in soils, arylamidase, alkaline phosphatase, b-glucosidase and arylsulfatase are important for the transformation of plant nutrients. B-glucosidase catalyzes glucose formation and is an important enzyme in the terrestrial carbon cycle, glucose being an important energy source for microbial biomass [3]. Phosphatases play an important role in transforming organic phosphorus into inorganic forms that are suitable for plants. Arylsulfatase is an extracellular enzyme that catalyses the hydrolysis of organic sulphate esters, releasing SO2 that can be used by plants
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