02526naa a2200241 a 450000100080000000500110000800800410001910000180006024500870007826000090016552018440017465000210201865000120203965000200205165000240207165000210209565000090211665300240212570000190214970000160216870000210218477300790220515679042004-09-30       1999    bl uuuu     u00u1 u    #d1 aMENDES, I. C.  aMicrobial biomass and activities in soil aggegates affected by winter cover crops.  c1999  aWiter cover may increase soil organic matter (SOM) and improve soil structure in intensively managed summer vegetable croping systems. Our study examined the influence of three cover crop treatments ( fallow, cereal, and legume within a summer crop rotation of sweet corn and broccoli) on microbiological properties associated with five soil aggregate-size classes (&lt0.25,0.25 to 0.5 0.5 to 1.0, 1.0 to 2.0, and 2.0 to 5.0 mm) of a willamentte silt loam ( Pachic Ultic Argixerolls). The distribuitions of total organic C ( TOC), total Kjeldahl N (TKN), soil microbial biomass c (SMBC), readily mineralizable Cand N, and two enzyme activities (B-glucosidade and fluorescein diacetade [FDA] hydrolysis) were compared among aggregate-size classes of surface (0-20 cm) soils at seedbed preparation (June 1996) and after harvest of either brocoli (September 1995) or sweet corn (September 1996). Although cover croping did not significantly influence aggregate - size distribuition, TOC, nor TKN on any sampling date, it did significantly (P&lt0.05) influence SMBC in September 1995, mineralizable C and N and FDA hydrolisys and B- glucosidade activites in june 1996, and levels of mineralizable C and N and B-glucosidade activiy in september 1996. Significant(P&lt0.01) interactions occurred among the cover crop treatments and aggregate-size classes for SMBC in September 1995, an among mineralizable C and N FDA hydrolisys in june and september 1996. Mineralizable C and N and FDA Hydrolisys differed ( P &lt 0.01) among aggregatesize classes between june and september 1996: These changes were significantly (P&lt0.01) sffected by cover crop treatment. these studies identified focal pints for further research on the effects of aggregatesize classes and cover croping on activities and dynamics of their respective microbial communities.  aAnálise do Solo  aCerrado  aFísica do Solo  aPlanta de Cobertura  aQuímica do Solo  aSolo  aBiomassa microbiana1 aBANDICK, A. K.1 aDICK, R. P.1 aBOTTOMLEY, P. J.  tSoil Science Society of America Journal, Madisongv. 63, p. 873-881, 1999.