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ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #99966
Title: MICROBIAL ACTIVITY IN AGRICULTURAL SOIL AFFECTED BY FERTILIZATION LEVEL

Author
item Carpenter Boggs, Lynne
item Pikul Jr, Joseph

Submitted to: Soil Ecology Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/26/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Continuous corn, corn-soybean, and corn-soybean-wheat/alfalfa-alfalfa crop rotations have been maintained since 1990. Each plot was split into three fertilizer treatments: N0 subplots received no nitrogen fertilizer, N1 subplots received N fertilizer sufficient for an 85 bu/acre corn yield, and N2 subplots were fertilized for a yield goal of 135 bu/acre. All plots received equal applications of P and K, and were chiseled after harvest. Fertilization level not only affected crop yields, but also the level of soil microbial activity and available substrate. Dehydrogenase activity, basal respiration, microbial biomass (SIR), and total readily mineralized carbon declined with increasing N fertilizer application. Effects were most dramatic in continuous corn. These results could be due to "priming" effects of fertilizers, i.e. the stimulation of resource mineralization. Priming would, over time, reduce the pool of available substrates and thereby reduce microbial biomass and activity.