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Keynote ~ Soil building through microbial pathways ~ mechanisms for soil carbon sequestration ~ Christine Jones,rvd
The document discusses soil building through microbial processes and the importance of soil organic matter and carbon. It notes that original Australian topsoil carbon levels were 50-80% higher before extensive agricultural practices reduced soil carbon. The document also discusses declining mineral levels in produce since the 1940s and increasing agricultural debt levels in Australia and New Zealand since the 1990s. It argues that soil carbon is key to soil nutrient levels and plant nutrition, and outlines microbial pathways for building soil carbon through photosynthesis, exudation, and humification. The document advocates practices like pasture cropping to improve soil carbon levels and regenerate soil and agricultural productivity.
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Keynote ~ Soil building through microbial pathways ~ mechanisms for soil carbon sequestration ~ Christine Jones,rvd
- 1. Soil building through microbialprocesses Dr Christine Jones
- 4. Sir Paul EdmundStrzelecki Soil samples collected 1839 -1843 41 samples 10 highest ranking soils had OM levels from 11% to 37.75% (average 20%) 10 lowest ranking soils had OM levels from 2.2% to 5.0% (average 3.72%)
- 5. The organic carboncontent of most Australian topsoils is now 50-80% less than the original level – mostly as a result of the loss of the soil itself
- 16. Agriculture is about FOOD Butthere is something fundamentally wrong
- 17. Mineral depletion invegetables 1940 - 1991 Copper reduced by 76% Calcium reduced by 46% Iron reduced by 27% Magnesium reduced by 24% Potassium reduced by 16% Source: UK Ministry of Agriculture
- 18. Mineral depletion inmeat 1940 - 1991 Iron reduced by 54% Copper reduced by 24% Calcium reduced by 41% Magnesium reduced by 10% Potassium reduced by 16% Phosphorus reduced by 28% Source: UK Ministry of Agriculture
- 19. Australian fruit andvegetables 1948 1991 Potatoes Calcium 27 mg 3 mg 89% Broccoli Magnesium 160 mg 29 mg 82% Carrots Vit. A 25,000 IU 91 IU 99.6% Apples Vit. C 25 mg 5 mg 80% It is possible to buy an orange today that contains ZERO vitamin C.
- 20. It’s not onlythe quality of the product that has gone downhill Farmers are no longer making a profit either
- 21. Agricultural Debt Levels(AUS) 0 10000 20000 30000 40000 50000 60000 Mar- 94 Mar- 95 Mar- 96 Mar- 97 Mar- 98 Mar- 99 Mar- 00 Mar- 01 Mar- 02 Mar- 03 Mar- 04 Mar- 05 Mar- 06 Mar- 07 Mar- 08 Mar- 09 Source: RBA, Westpac Economics AUD $M $20 $40 $60 ‘94 ‘97 ‘00 ‘03 ‘06 ‘09
- 22. Agricultural Debt Levels(NZ) 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 Dec 1990 Oct 1991 Aug 1992 Jun 1993 Apr 1994 Feb 1995 Dec 1995 Oct 1996 Aug 1997 Jun 1998 Apr 1999 Feb 2000 Dec 2000 Oct 2001 Aug 2002 Jun 2003 Apr 2004 Feb 2005 Dec 2005 Oct 2006 Aug 2007 Jun 2008 Apr 2009 Feb 2010 Millions NZD 50 $50 $25 $0 1990 2000 2010
- 23. Agricultural Debt andWeighted Average Interest Rates 0 10000 20000 30000 40000 50000 60000 Mar- 1994 Mar- 1995 Mar- 1996 Mar- 1997 Mar- 1998 Mar- 1999 Mar- 2000 Mar- 2001 Mar- 2002 Mar- 2003 Mar- 2004 Mar- 2005 Mar- 2006 Mar- 2007 Mar- 2008 Mar- 2009 0.00 2.00 4.00 6.00 8.00 10.00 12.00 LHS RHS AUD - Millions % p.a ‘94 ‘97 ‘00 ‘03 ‘06 ‘09 $20 $40 $60 4% 8% 12%
- 24. SOIL CARBON isthe key driver for the nutritional status of plants – and therefore the mineral density in animals and people SOIL CARBON is the key driver for soil moisture holding capacity (frequently the most limiting factor for production) Soil carbon is the key driver for farm profit
- 25. How does carbon get intosoil???
- 32. Liquid carbon pathway Photosynthesis Resynthesis Exudation Humification
- 33. Allocation of photosynthate Shoots30 - 50% Roots 30 - 50% Microbes 0 - 40%
- 35. There would besufficient length of mycorrhizal hyphae in the top 10cm of just four square metres of healthy grassland soil to stretch all the way around the equator (Leake et al, 2004)
- 38. Soil nutrient levels(0-30cm) from between and within Gatton Panic crowns, Binnu, WA, May 2009 ________________________________________________________ Between Within Change Organic carbon (%) 0.24 1.04 433% Phosphorus (Colwell ppm) 21 71 338% Potassium (Colwell ppm) 44 150 341% Sulphur (ppm) 2.7 7.9 293% pH (CaCl) 5.8 7.1 1.3 units _______________________________________________ Source: Tim Wiley, WA Department of Agriculture and Food (increased soil C = sequestration of 123tCO2/ha)
- 39. It hasbeen widely promoted by CSIRO Division on Plant Industries that to increase levels of soil carbon requires the application of nutrients to soil and increased fertiliser costs This is contrary to what is observed in practice The carbon and nutrients MYTH
- 40. Increased C normalized pH, increased CEC Increased C increased availability of P, Ca, K, S Increased C increased availability of Cu, Zn, Fe, Mo, B Increased C reduced availability of Na, Al The carbon and nutrients TRUTH
- 41. Microbes vs fertilisers Veryfew nutrient deficiencies are absolute – most are functional (due to poor soil structure and/or lack of microbial diversity) Agrochemicals and synthetic fertilisers significantly alter microbial populations and the functional dynamics of soil
- 43. How do we getmore microbes??
- 44. 1. Stopkilling the microbes that are trying to live in your soils (use biology friendly fertilisers in place of high analysis N, P) 2. Improve plant root systems through species selection (perennial rather than annual) and above-ground management
- 47. MAP MAP +Triad Mineral Fert Root/Shoot Ratio 0.184 0.282 0.112 0.151 0.689 0.976 Biomass - Increasing Soil OM & OC F Wt - Roots vs Shoots g Fwt 31.95 29.88 27.23 30.24 30.53 31.05 21.02 4.58 3.05 8.44 5.88 31.81 0 10 20 30 No Microbes + Microbes No Microbes + Microbes No Microbes + Microbes F Wt Roots F Wt Shoots (g) % Biomass Root 17.7 22.0 10.1 13.4 40.8 49.4 Root Surface Area 302 392 127 184 978 4021 Triadimefon +/- WMF Ag blend microbe seed dressing
- 52. Soil has alwaysbeen Australia’s biggest export Even today, soil loss is greater than agricultural production For example, average wheat yield 1.2 t/ha Average soil loss on wheat farms 15 t/ha
- 53. How can weturn that around and rebuild healthy, porous, carbon-rich topsoil?
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- 65. Sowing Yarrin OatsMay 2010
- 66. Pasture Crop intolitter
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- 75. The difference inland management techniques Adjoining paddocks March 2010 Planned grazed and Pasture Cropped Continuously grazed and fertilised annually
- 83. Soil CARBON Winona 90.1tC/ha Neighbour43.4tC/ha Difference of 46.7 tC/ha = 171 t CO2/ha sequestered
- 85. Soil CARBON Since 2008,the sequestration rate has been 37 tCO2/ha/yr
- 87. Soil CARBON 0 –4” 150% 4 – 8” 243% 8 – 12” 317% 12 – 16” 413% 16 – 20” 157%
- 90. Soil Nutrients Avail Total Ca234% 270% Mg 110% 152% Zn 250% 195% Cu 185% 215% B 150% 161% Si 116% 113% N 103% 151% P 102% 155% K 198% 150% S 92% 159% Fe 87% 130% Na 45% 88% Al 28% 140%
- 91. Soil Integrity Index Accreditationsystem for soils based on Microbial diversity Soil water holding capacity Soil carbon content Simple code on food labels, eg star system (one, two or three stars)
- 92. Food quality labelling Theurban population could have a major impact on soil health through food choices, if guided by labelling based on the ecological integrity of the production system
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- 94. Relationship between totalorganic carbon and labile C in pasture cropped and conventionally cropped soils R2 = 0.99 R2 = 1.00 R2 = 0.98 R2 = 0.96 0 1 2 3 4 5 6 7 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Total organic C (%) Labile carbon (mg/g) C1 pasture cropped C3 pasture cropped C1 conventional cropped C3 conventional cropping
- 98. Decomposition pathway ends inCO2 ………………………………… Sequestration pathway produces HUMUS
- 100. CSIRO report p.42 "Apotentially troubling, but also somewhat intriguing, issue is that there is no readily apparent explanation for some of the very large SOC gains being anecdotally reported."
- 127. From Dlugokenckyet al (2009). Yearly variations in methane from 1983 to 2009. Measurements in parts per billion.