Glover et al., 2010. Harvestedperennial grasslands provideecological benchmarks foragricultural sustainability.DuPont et al., 2010. No-tillageconversion of harvestedperennial grassland to annualcroplandCulman et al., 2010. Long-termimpacts of high-input annualcropping and unfertilizedperennial grass productionAEE, Vol. 137, Issues 1-2, 2010
PerennialgrassAnnualwheat p-valueHarvestednitrogen (kg ha-1)47.9 47.2 0.909Farmers are removing roughly equal amounts ofnitrogen from both systems; annual crop fieldsreceive over 60 kg ha-1 yr-1 more nitrogen
perennialwheatRoot C of perennial and wheat fields
Differences not simply artifacts of obsoletefarming practices such as poor tillage &fertilizer practices
Differences not simply artifacts of obsoletefarming practices such as poor tillage &fertilizer practicesDuPont et al: No-tillage conversion of nativegrassland using best-practices•reductions in active carbon stocks•reductions in water stable aggregates•Negative impacts on soil food webs
Additional examples•Sustained harvests of unfertilized perennialgrasslands (USDA county yield data; Shortridge, 1973;Jenkinson et al., 1994, Silvertown et al., 1994)•SOC and total soil N not reduced afterdecades of unfertilized grassland harvests(Jenkinson et al., 2004; Mikhailova et al., 2000, Mikhailova andPost, 2006)
Washington State University:Texas A&M:The Land Institute: perennialsorghum, sunflower, wheat, +.Yunnan Academy of AgriculturalSciencesCSIRO: perennial wheatGlobal perennial grain programsMich. State Univ.: perennialwheat & wheatgrassSwedish University Ag SciUniversity of ManitobaCatedra de CultivosIndustriales: Lesquerella(mustard family)Nepal: perennial wheatCornell: perennial maize
Dr. Dhruba ThapaNepal Agricultural Research CouncilKhumaltar Laitpur, NepalHigh altitude perennial wheat in western Nepal“…increase food & forage securitysignificantly in the region.”
“…minimize theworkload of farmers,especially of women inthe remote areas.”
Deeper roots: “…more stablegrain and biomass yields”
Deeper roots: “…higheruptake of selenium, zinc,iron and other minerals.”
“…some of the 25 lines appearhighly resistant to yellow rust.”
Perennial Concerns• Can perennials produce as muchgrain?• Aren’t perennials more vulnerable topests 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 forresistance
Perennial Concerns Weediness• Unlike perennial forages, perennial grains aredesigned to put their energy into seeds notvegetation
Perennial Concerns Time• Farmers already use some perennial grainlegumes—pigeon peas• Perennial sorghum & rice: field trials within 5years; farmer-ready within 15 years• Perennial wheat: farmer-ready in 20 years
Perennial Possibilities We can transform our farms tofunction more like natural ecosystems Perennial grain crops are the next step Mitigation: If agricultural soils can beused to offset industrial emissions ofGHGs, perennial crops will be key Adaptation: Perennial crops are moreresilient
Jerry GloverUSAIDWashington, DCjglover@usaid.gov
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