david montgomery - soil
TRANSCRIPT
Twitter: @dig2grow
Invention of the plow fundamentally altered the balance between soil production and soil erosion, dramatically increasing soil erosion…
Archaeological studies show that soil erosion played a key role in the demise of ancient civilizations.
The world’s agricultural soils have already lost 66 to 90 billion tons of carbon, mostly due to tillage.
- Lal, 1999
430 million ha of arable land lost to soil degradation, an area equivalent to
about one third of all present cropland.
- Pimental et al., 1995
Losses caused by soil erosion
On-site• Nutrient loss• Loss of organic matter• Reduced fertility• Reduced water holding capacity• Yield drop• Reduced planting area
Off-site• Sedimentation in lakes and rivers• Impaired water quality• Loss of biodiversity• Reduced food supply• Inflated food prices
Long-term cost…
Estimated cost of soil erosion in US
$ 44 B Pimental et al., 1995$ 37 B Uri, 2000$ 20 B Troeh et al., 1991$ 2.2 to 13 B Tegtmeier and Duffy, 2004$ 1.1 – 13 B Clark, 1985$ 1.1 – 3.1 B Hitzhusen et al., 1984$ 1.7 – 1.8 B Crosson, 1986$ < 1.2 B Colacicco et al., 1989$ 0.5 – 1.1 B Larson et al., 1983$ 0.6 – 0.8 B Crowder, 1987
Telles et al., 2011, The Costs of Soil Erosion, Revista Brasileira de Ciencia do Solo, v. 35, p. 287-298.
Varies 100 fold…up to $44 B per year
(from: FAO, 2014. Food Wastage Footprint, p. 76).
Annual global cost of soil erosion from water: $ 33 Billion
Per hectare on-site cost of soil erosion
Telles et al., 2011, The Costs of Soil Erosion, Revista Brasileira de Ciencia do Solo, v. 35, p. 287-298.
$ 27 – 1500 Brazil Marques et al., 1961$ 60 EU Riksen and Graaff, 2001$ 38 – 166 Brazil Rodrigues, 2005$ 15 – 25 Brazil Bertol et al., 2007$ 5 – 67 Spain Hein, 2007$ 28 – 73 Brazil Sarcinelli et al., 2009$166 – 409 EU Kuhlman et al., 2010
Highly variable $ 5 to $1500 per hectare per year
Is Soil Restoration Possible?
Can we reverse the historical pattern?
Forthcoming spring 2017, Montgomery, D. R., Triple Harvest (W. W. Norton)
Principles of Conservation Agriculture (FAO)
• minimal or no disturbance (e.g., no-till)
• permanent ground cover (cover crops)
• complex rotations (reduce pathogen carryover)
** livestock in intensive rotational grazingReduced input costs + similar yield = higher farm profits
Societal value of soil organic carbon is about $120/ton.*
At global average sequestration rate of 0.77 tons/ha/yr for conservation agriculture (no-till + complex rotation)** that comes to $40/acre/yr.
* Lal, R., 2014, Journal of Soil and Water Conservation, v. 69, p. 186A-192A.** West, T. O,. And Post, W. M., 2002, SSSA Journal, v. 66, p. 1930-1946.
Societal Value of Soil Carbon
Cost to farmer of 1% loss in soil organic matter translates to an indirect of about $66/acre per year.*
* Tsiafouli, M. A., et al., 2015, Global Change Biology, v. 21, p. 973-985.
Value of Soil Carbon
Rattan Lal
Rattan Lal estimates that conservation agriculture could put enough carbon back into soils to offset 5 to 15% of global fossil-fuel emissions.
The Rodale Institute suggests that carbon sequestration in soils could fully offset fossil fuel emissions.
Carbon Sequestration Potential of Agricultural Soils
Twitter: @dig2growWeb: dig2grow.comEmail: [email protected]/thehiddenhalfofnature
Connect with us…. WE