Factors limiting soil microbial growth and activity in wheat-based cropping systems
Date
2004-02-19
Authors
Cruz, A.F.
Hanson, K.
Hamel, C.
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Abstract
Several soil biochemical processes related to soil fertility are microbially mediated. We know
very well the factors limiting crop production but know little of the factors limiting the soil
microbial community. The goal of this study is to clarify if N, P and C limit soil microbial
growth and biochemical processes in the wheat and fallow phases of rotations receiving different
N, P and crop residue-C inputs. Soil samples were collected July 28, 2003, and brought to the
laboratory. Soils samples were treated with an N, C or P solution, with water only, or left
untreated, and incubated for 48 hours. At the end of the incubation period, soil microbial biomass
N was determined along with denitrification and nitrogenase activities. The results showed that
the microbial activities and growth were limited by soil moisture at the date of sampling.
Denitrification and nitrogenase activities were limited by N, P or C. The limiting nutrients varied
with N, P and C inputs associated with the cropping system, regardless to soil moisture. The
limitation of these elements to soil microbial activity was more frequently encountered under
fallow.
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Keywords
carbon, crop rotation, microbial, nitrogen, phosphorus
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Part Of
Soils and Crops Workshop