Microbial biomass under various soil- and crop-management systems in short- and long-term experiments in Brazil

Management and cropping systems varying in soil mobilization rates and plant-residue inputs may have profound effects on the biological properties of soil. Therefore, the objective of this study was to quantify soil microbial biomass carbon and nitrogen (MB-C and MB-N)—by means of the fumigation-ext...

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Bibliographic Details
Published in:Field crops research 2010-10, Vol.119 (1), p.20-26
Main Authors: Silva, Adriana Pereira, Babujia, Letícia Carlos, Franchini, Julio Cezar, Souza, Rosinei Aparecida, Hungria, Mariangela
Format: Article
Language:English
Subjects:
Biomass
carbon
crop management
crop residues
Crop rotation
Crop sequence
crop yield
cropping sequence
field crops
field experimentation
grain crops
green manures
long term experiments
Maize
Microbial biomass
nitrogen
no-tillage
seasonal variation
soil biological properties
soil management
soil microorganisms
Soil quality
Soil tillage
Soybean
species differences
tillage
Triticum aestivum
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Summary:Management and cropping systems varying in soil mobilization rates and plant-residue inputs may have profound effects on the biological properties of soil. Therefore, the objective of this study was to quantify soil microbial biomass carbon and nitrogen (MB-C and MB-N)—by means of the fumigation-extraction method—under varied soil-management and crop-rotation/succession systems in southern Brazil, correlating the results with yields of soybean and maize crops. The microbial biomass and grain yields were examined at the 0–10 cm layer in four short- to long-term field experiments. Experiment 1 was a 26-year trial consisting of four soil-management systems: (1) no-tillage (NT), (2) conventional tillage [(CT) with disc plough], (3) field cultivator (FC) or (4) heavy-disc harrow (DH), each with a crop succession (CS) of soybean (summer) and wheat (winter). Experiment 2 was a 21-year trial consisting of one CS, soybean/wheat every year) and seven crop rotations (CRs) comprising soybean, maize, wheat and green manures (lupine, radish and black oat), under the NT system. Experiment 3 comprised a 14-year CT trial, and 4-year and 14-year NT trials, with both one CS and two CRs. Experiment 4, a 10-year trial consisted of CT and NT and three CRs. Analyses were performed during the summer and winter croppings. Differences in microbial parameters, as a function of crop succession and rotation, were not easily detected as they varied as a function of a complex combination of plant species and time of implementation of the experiment. In contrast, MB-C and MB-N values were consistently higher—up to more than 100%—under NT in comparison to CT and were associated with higher grain yields. Our results—from this wide range of experiments—suggest that MB-C and, particularly, MB-N are sensitive indicators of the effects of soil- and crop-management regimens.
ISSN:0378-4290
1872-6852
DOI:10.1016/j.fcr.2010.06.012