Agriculture's influence on native grassland microflora Amy Vaira

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Agriculture's influence on native grassland
microfloraAmy Vaira
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Questions

• Name an agricultural influence on soil microflora
  and how the practice specifically affects the
  microbial biomass.
• What are some suggestions made by researchers to
  minimize the effects on the native microflora?
• Why is soil microflora important?

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Importance of microflora

• Degradation of organic matter
• Release of Nitrogen
• Soil aggregation
• Protection against plant pathogens
• Diversity Soil ecosystem health

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Influences on soil flora

• Soil type
• Crop type
• Age of plant
• Agricultural practices (i.e. tilling, irrigation,
  wheel traffic, crop rotation)

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Crop type

• Crop has influence on rhizosphere flora
• More important factor than soil type
• Crop type vs. soil type vs. developmental stage
• Complex interaction

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Fertilizers Pesticides

• Overall increase of organic matter
• Farmyard manure
• Higher soil quality microbial biomass
• Compost and disease suppression
• Positive affects
• Higher soil carbon content
• Increased microbial biomass

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Conventional Tillage

• Better biological condition of soil
• Increased amounts of ammonia-oxidizing bacteria
• Results in temporary higher soil biomass
• No till greater diversity
• Increased number of pathogens root rot
• Increase in CO2 released
• More mature bacteria found in tilled plots

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Traffic-induced soil compaction

• Reduction in rhizosphere area
• Restriction in root growth
• Higher soil-water content
• Reduction in soil porosity
• Impacts decomposition nutrient cycling
• Affects plant growth
• Increase in biomass activity in no tilled-areas
• More residue higher water content

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Others

• Irrigation
• Increased carbon
• Increased biomass
• Crop rotation
• Affects pathogen densities
• Organic farming
• Improved soil quality
• Increased biomass
• Higher pest resilience

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• Arithmetic mean of soil chemical properties. (a)
  soil pH (b) organic carbon content (C org) (c)
  and total nitrogen content (N tot), the latter
  two expressed in of the soil dry mass in
  different farming systems BIODYN, organic
  farming with composted manure BIOORG, organic
  farming with rotted manure CDNFYM, conventional
  farming with manure CONMIN, stockless
  conventional farming. Significant differences are
  indicated by contrast analysis P lt 0.05, P lt
  0.01, P lt 0.001. Error bars indicate standard
  errors. From Birkhofer et. al. 2008

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Suggestions by Researchers

• Eliminate tillage
• Increase overall soil quality
• Organic farming
• Decrease in crop yield
• Irrigation
• Elimination of wheel-traffic
• Problems?

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  and yield of snap beans, 1991. Biol. Cultivation
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• 2. Birkhofer, K., T.M. Bezemer, J. Bloem, M.
  Bonkowski, S. Christensen, D. Dubois, F. Ekelund,
  A. Fliebach, L. Gunst, K. Hedlund, P. Mader, J.
  Mikola, C. Robin, H. Setala, F. Tatin-Froux, W.H.
  Van der Putten, and S. Scheu. 2008. Long-term
  organic farming fosters below and above ground
  biota implications for soil quality, biological
  control and productivity. Soil Biol. Biochem.
  402297-2308.
• 3. Clegg, C.D., R.D.L. Lovell, and P.J. Hobbus.
  2003. The impact of grassland management regime
  on the community structure of selected bacterial
  groups in soil. FEMS Microbiol. Ecol. 43263-70.
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  Microbial biomass and soil enzyme activities in
  compacted and rehabilitated skid trail soils.
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