Understanding soil biology in       commercial orchards                             Belinda Rawnsley  South Australian Res...
Introduction•   Why soil biology is important•   Tests to measure soil biology•   How and when to sample•   Improving soil...
Soil biology•   Break down organic matter and release    nutrients into plant available forms         BAM!
Soil biology•   Break down organic matter and release    nutrients into plant available forms•   Improve and maintain soil...
Soil biology•    Break down organic matter and release     nutrients into plant available forms•    Improve and maintain s...
Soil biological indicators• Tests designed to measure activity or  populations of soil organisms• Soil biology quick respo...
Microbial biomass• Total population of active microbes in the  soil at the time of sampling• Influenced by soil properties...
Microbial biomass and soil carbonLower than expected microbial biomass may indicate         a constraint to biological fer...
Seasonal variability of microbial                                   biomass under perennial crop                          ...
Fungi and bacteria•   Measured as a proportion of fungi and    bacteria in soil•   Fungi associated with decomposition and...
How to use soil biology tests• No target values for a healthy soil in  regards to soil biology• Use tests to monitor chang...
Soil Sampling• Majority of organisms live  in top rootzone• Macadamia shallow  fibrous root system                        ...
Microbial activity at depth                                  140                                        Rhizosphere soil  ...
When to sample• Coincide sampling  with periods of peak  root growth in  autumn• Avoid after  application of  fertilisers•...
Chemical use and soil biology• Soil biology decompose chemicals and  pesticides – use them as a food source• Impact of a p...
How to improve soil biology• Feed the microbes!• Organic matter must be continually supplied
How to improve soil biology•   Avoid bare soil•   Maintain grassed interrow•   Use groundcovers under trees•   Apply compo...
What about microbial inoculants?• If current practices have low microbial   7,000  populations, additions of new Nov 2009 ...
Take home message• Use soil biological tests in conjunction with  chemical and physical analysis• Monitor soil health over...
More web information• Soil health knowledge bank  Soilhealthknowledge.com.au• Victorian Resources online >soil  health vro...
Nutrition and soil health to optimize production   understanding soil biology in a commercial orchard - belinda rawnsley
Upcoming SlideShare
Loading in …5
×

Nutrition and soil health to optimize production understanding soil biology in a commercial orchard - belinda rawnsley

973 views

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
973
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
33
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Nutrition and soil health to optimize production understanding soil biology in a commercial orchard - belinda rawnsley

  1. 1. Understanding soil biology in commercial orchards Belinda Rawnsley South Australian Research and Development Institute (SARDI)
  2. 2. Introduction• Why soil biology is important• Tests to measure soil biology• How and when to sample• Improving soil biological health
  3. 3. Soil biology• Break down organic matter and release nutrients into plant available forms BAM!
  4. 4. Soil biology• Break down organic matter and release nutrients into plant available forms• Improve and maintain soil structure
  5. 5. Soil biology• Break down organic matter and release nutrients into plant available forms• Improve and maintain soil structure• Suppress soil borne diseases• Degrade chemicals• Lock up greenhouse gases in soil Soil biology is essential for the soil to function properly
  6. 6. Soil biological indicators• Tests designed to measure activity or populations of soil organisms• Soil biology quick response to soil changes• Routine soil tests do not measure soil biology• Wide range of biological indicators to measure effect of soil management  Amount (e.g. microbial biomass, plate counts)  Activity (e.g. soil respiration, enzyme activity)  Diversity (e.g. community composition)
  7. 7. Microbial biomass• Total population of active microbes in the soil at the time of sampling• Influenced by soil properties• Measured by amount of carbon, nitrogen, phosphorus and sulphur• Responds quickly to soil management• 1 to 5 % of total organic carbon (source DPIVic).
  8. 8. Microbial biomass and soil carbonLower than expected microbial biomass may indicate a constraint to biological fertility Source:Soilhealthknowledge.com.au
  9. 9. Seasonal variability of microbial biomass under perennial crop 40 HIGH 35Total microbial biomass (ugC/g) MODERATE 30 25 2 Nov 2009 20 1 Feb 2010 15 25 March 2010 10 5 0 Cultivated Biodynamic Permanent Mulch Grazing sward land (Barossa Valley, 2009/2010)
  10. 10. Fungi and bacteria• Measured as a proportion of fungi and bacteria in soil• Fungi associated with decomposition and soil structure stability  High carbon requirement • Bacteria regulate nutrient supply  transform nitrogen into a useable form
  11. 11. How to use soil biology tests• No target values for a healthy soil in regards to soil biology• Use tests to monitor changes in soil biology over time at the same time of year• Measure soil biology in relation to management and/or problem areas• Consider soil type, land use, topography and plant growth - cannot compare regions
  12. 12. Soil Sampling• Majority of organisms live in top rootzone• Macadamia shallow fibrous root system 20 cm• Sample from within 1 m of the trunk• Random sample of 8 - 20 40 cm cores bulked to give representative sample
  13. 13. Microbial activity at depth 140 Rhizosphere soil 120B -glucosidase enzyme activity (mg p -Nitrophenol/kg soil/h) 100 80 60 40 20 0 0-5 5-10 10-20 20-30 30-40 Soil depth (cm) (Rawnsley, 2008)
  14. 14. When to sample• Coincide sampling with periods of peak root growth in autumn• Avoid after application of fertilisers• Monitor at same time of the year
  15. 15. Chemical use and soil biology• Soil biology decompose chemicals and pesticides – use them as a food source• Impact of a pesticide depends upon the rate of degradation• Minimise use of heavy metals, e.g. copper
  16. 16. How to improve soil biology• Feed the microbes!• Organic matter must be continually supplied
  17. 17. How to improve soil biology• Avoid bare soil• Maintain grassed interrow• Use groundcovers under trees• Apply compost – apply early to firm up• Soil additives/amendments• Minimise compaction
  18. 18. What about microbial inoculants?• If current practices have low microbial 7,000 populations, additions of new Nov 2009 microbes 6,000 Feb 2010 or organisms are unlikely to thrive and no. free-living nematodes/200 g soil Mar 2010 persist 5,000• Products stimulate organisms already in 4,000 soil 3,000• Manage existing soil biology by feeding 2,000 the microbes 1,000 0 Conventional Biodynamic Permanent sward Undervine mulch cultivation
  19. 19. Take home message• Use soil biological tests in conjunction with chemical and physical analysis• Monitor soil health over time – will reflect changes in soil management practices• Monitor changes within a single orchard• Low microbial biomass restrains nutrient availability…build up soil biology• Healthy soils are resilient and more productive
  20. 20. More web information• Soil health knowledge bank Soilhealthknowledge.com.au• Victorian Resources online >soil health vro.dpi.vic.gov.auSoil health factsheets• soilquality.org.au

×