EFFECT OF COMPOST AND BRASSICA COVER CROPS ON SOIL MICROBIAL BIOMASS AND ASPARAGUS PERFORMANCE

The decomposition of plant residues is a biological process mediated by soil fauna, but few studies have been done evaluating its dynamics in time during the process of disappearance of straw. This study was carried out in Chapecó, in southern Brazil, with the objective of monitoring modifications in soil fauna populations and the C content in the soil microbial biomass (C SMB) during the decomposition of winter cover crop residues in a no-till system. The following treatments were tested: 1) Black oat straw (Avena strigosa Schreb.); 2) Rye straw (Secale cereale L.); 3) Common vetch straw (Vicia sativa L.). The cover crops were grown until full flowering and then cut mechanically with a rolling stalk chopper. The soil fauna and C content in soil microbial biomass (C SMB) were assessed during the period of straw decomposition, from October 2006 to February 2007. To evaluate C SMB by the irradiation-extraction method, soil samples from the 0-10 cm layer were used, collected on eight dates, from before until 100 days after residue chopping. The soil fauna was collected with pitfall traps on seven dates up to 85 days after residue chopping. The phytomass decomposition of common vetch was faster than of black oat and rye residues. The C SMB decreased during the process of straw decomposition, fastest in the treatment with common vetch. In the common vetch treatment, the diversity of the soil fauna was reduced at the end of the decomposition process.

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Effects of Cover Crops on Soil Microbial Biomass in Vegetable Cropping Systems

HortScience ◽

10.21273/hortsci.39.4.871a ◽

2004 ◽

Vol 39 (4) ◽

pp. 871A-871

Author(s):

Mohan Selvaraj* ◽

Mathieu Ngouajio

Keyword(s):

Microbial Biomass ◽

Cover Crops ◽

Cover Crop ◽

Soil Microbial Biomass ◽

Cropping Systems ◽

Soil Microbial Activity ◽

Soil Microbial ◽

Winter Cover ◽

Winter Cover Crops ◽

Sorghum Sudangrass

The inclusion of cover crops into cropping systems may influence soil microbial activity which is crucial to sustained crop production. A study was conducted to measure short term effects of summer and winter cover crops on soil microbial biomass carbon (MBC) in a cucumber-tomato rotation system. The experiment was established in Summer 2002 as a factorial of summer cover crops (planted either as fallow or after harvest of cucumbers) and winter cover crops (planted in September). The design was a split-block with four replications. The main plot factor was summer cover crop and consisted of five treatments; sorghum sudangrass fallow (SGF), cowpea fallow (CPF), sorghum sudangrass after cucumber (SGC), cowpea after cucumber (CPC) and bareground fallow (BGF). The sub-plot factor was winter cover crop and consisted of three treatments including cereal rye (CR), hairy vetch (HV) and bareground (BG). In spring of 2003, soil samples were collected in each treatment at 30 days before (30 DBI), 2 days after (2 DAI) and 30 days after (30 DAI) cover crop incorporation. MBC was measured using the chloroform fumigation-incubation method. Both summer and winter cover crops affected soil microbial activity. MBC in the summer cover crop treatments at 30 DBI was 47.7, 51.4, 49.2, 43.7 and 42.5 μg·g-1 soil for SGF, CPF, SGC, CPC and BGF, respectively. At 30 DAI, 113.1, 88.9, 138.5, 105.6, and 109.3 μg·g-1 soil was obtained in SGF, CPF, SGC, CPC, and BGF plots, respectively. Soil MBC was similar at 2 DAI in the summer cover crop treatments. Among winter treatments MBC was similar at 30 DBI and 30 DAI, but significant at 2 DAI with values of 62.8, 53.3, 59.3 μg·g-1 soil for CR, BG, and HV, respectively.

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