Perennial possibilities for increasing food and ecosystem security
Jerry Glover USAID Washington, DC [email protected]
“[agriculture]…largest threat to biodiversity and ecosystem function of any single human activity.”
Millennium Ecosystem Assessment (2005)
“[agriculture]…one of the most important drivers of…habitat change, climate change, water use, and toxic emissions.”
UN Environment Program Report (2010)
(CIMMYT, 2010)
(CIMMYT, 2010)
Model systems: Perennial grasslands harvested every year for over 75 years; only atmospheric inputs
Model systems: Perennial grasslands harvested every year for over 75 years; only atmospheric inputs How do they compare to high-input annual cereal production?
• Yields
• Carbon & nitrogen
• Ecosystem processes
Glover et al., 2010. Harvested perennial grasslands provide ecological benchmarks for agricultural sustainability.
DuPont et al., 2010. No-tillage conversion of harvested perennial grassland to annual cropland
Culman et al., 2010. Long-term impacts of high-input annual cropping and unfertilized perennial grass production
AEE, Vol. 137, Issues 1-2, 2010
Perennial grass
Annual wheat
p-value
Harvested nitrogen (kg ha-1)
47.9 47.2
0.909
Farmers are removing roughly equal amounts of nitrogen from both systems; annual crop fields
receive over 60 kg ha-1 yr-1 more nitrogen
Perennial grass
Annual wheat
p-value
Total carbon 182.2 138.8 0.027 Total nitrogen 15.4 11.7 0.013
Soil quality (0 – 1.0 m; Mg ha-1):
perennial wheat
Root C of perennial and wheat fields
Differences not simply artifacts of obsolete farming practices such as poor tillage &
fertilizer practices
Differences not simply artifacts of obsolete farming practices such as poor tillage &
fertilizer practices
DuPont et al: No-tillage conversion of native grassland using best-practices
•reductions in active carbon stocks
•reductions in water stable aggregates
•Negative impacts on soil food webs
Conservation Ag: low tillage, rotations, residue maintenance
Additional examples
•Sustained harvests of unfertilized perennial grasslands (USDA county yield data; Shortridge, 1973; Jenkinson et al., 1994, Silvertown et al., 1994)
•SOC and total soil N not reduced after decades of unfertilized grassland harvests (Jenkinson et al., 2004; Mikhailova et al., 2000, Mikhailova and Post, 2006)
(nasa.gov)
1 mm
Photo credit: Jim Richardson
(nasa.gov)
1 mm
Photo credit: Jim Richardson
Small-scale processes »» Large-scale landscape health
minutes and millimeters
Humans don’t eat hay
Global cropland (% of total area) Fruits &
vegetables 7%
Roots & tubers 4%
Tree crops 2%
Forages 11%
Other 3%
Fiber 3%
Cereals, oil seeds, legumes
68%
From Monfreda et al., 2008
Global cropland (% of total area)
Cereals, oil seeds, legumes
68%
From Monfreda et al., 2008
These are all annual crops
Global cropland (% of total area)
Cereals, oil seeds, legumes
68%
From Monfreda et al., 2008
Provide for more than 70% of our calories needs
Perennial grain crops
Sorghum
Maize
Legumes
Rice
Wheatgrass & wheat
Sunflowers
Oilseeds
Washington State University: Texas A&M:
The Land Institute: perennial sorghum, sunflower, wheat, +.
Yunnan Academy of Agricultural Sciences
CSIRO: perennial wheat
Global perennial grain programs
Mich. State Univ.: perennial wheat & wheatgrass
Swedish University Ag Sci University of Manitoba
Catedra de Cultivos Industriales: Lesquerella
(mustard family)
Nepal: perennial wheat
Cornell: perennial maize
Domestication: Intermediate wheatgrass
Wild 1 -2 cycles
3 cycles
1 m
Domestication: Intermediate wheatgrass
1 m
Domestication: Intermediate wheatgrass
X
Wide hybridization: perennial wheat
wheat/wheatgrass// wheat
wheat/wheatgrass//wheatgrass
wheatgrass
Dr. Dhruba Thapa Nepal Agricultural Research Council Khumaltar Laitpur, Nepal High altitude perennial wheat in western Nepal
“…increase food & forage security significantly in the region.”
“…minimize the workload of farmers,
especially of women in the remote areas.”
Deeper roots: “…more stable grain and biomass yields”
Deeper roots: “…higher uptake of selenium, zinc, iron and other minerals.”
“…some of the 25 lines appear highly resistant to yellow rust.”
Perennial Concerns
• Can perennials produce as much grain?
• Aren’t perennials more vulnerable to pests and disease?
• Will perennials become weeds? • How long will it take?
Perennial Concerns
Yield • Perennials have higher yield potential • Consider within context of whole system • Multifunctionality is key
Perennial Concerns
Pests and disease • Increases potential to diversify rotations,
intercrops, relay systems • Wide crosses introduce new pathways for
resistance
Perennial Concerns
Weediness • Unlike perennial forages, perennial grains are
designed to put their energy into seeds not vegetation
Perennial Concerns
Time • Farmers already use some perennial grain
legumes—pigeon peas • Perennial sorghum & rice: field trials within 5
years; farmer-ready within 15 years • Perennial wheat: farmer-ready in 20 years
Perennial Possibilities
We can transform our farms to function more like natural ecosystems
Perennial grain crops are the next step Mitigation: If agricultural soils can be
used to offset industrial emissions of GHGs, perennial crops will be key
Adaptation: Perennial crops are more resilient
Jerry Glover USAID Washington, DC [email protected]