Soil, Agroecosystem and Landscape Health

Martha E. RosemeyerApril 10, 2003

Rachel Corrie’s Birthday

Creating a sustainable food system: Step 1- sustainable food production

Earthfriends 1995“The Whole Story of Food”

OutlineSoil health: basis for sustainabilityAgroecosystem health: Mimicking the natural system

• Land Institute: Designing a new system• Slash Mulch System: Assessing a traditional mimic• Restoration of oak savanna with Highland cattle:

Substituting domesticated for wild

Landscape health: connecting the agroecosystems Re-wilding the farm

• Nature Conservancy Cosumnes River Project, CA

John Doran defn of soil quality or soil health (often used interchangeably)

“Quality” academics vs. “health” by non-academics

“The continued capacity for soil to function as a vital living system, within ecosystem and land-use boundaries to: sustain biological productivity promote quality of air and water environments maintain plant animal and human health”

Doran and Safley 1997

Soil provides “ecosystem functions or ecosystem services”

Cooperband: Infiltration, water retention, absorption of nutrients, degradation of pesticides, pollutants, stabilizing soil temperatures

Sequestration of carbon dioxide, decomposition of organic substrates

Other ecosystem services can be predation of insect pests and pollination (not nec. Soil)

Indicators of soil qualityPhysical

water infiltration - percolation tests texture and structure

Chemical Organic matter pH (“the master variable”)

Biological earthworm population (25/ft3)

Zimmer,G. 2000.

Soil health associated with organic matter contentOrganic matter in soil is basically the

compost that Leslie talked aboutOrganic matter is about all

that we can easily changeNeutral pH needed for

earthworms

Human health dependent on

Plant and Animal health, which is dependent on

Soil Health

Mismanagement of soil has lead to poverty, malnutrition and economic disaster

Soil, plant, human linkage:The case of SeleniumNaturally found in soil and waterIrrigation of Central Valley in CA [Se]Certain native and other plants accumulateEssential nutrient in animals and humans and can be

deficiency Cofactor in antioxidant enzymes Important in Vitamin D absorption

In large quantities is poisonous to livestock and humans causing muscle tremors, etc.

Cihacek, Anderson, Barak 1996

Soil is totally critical But there is more...

Not so linearWhat sustains plants and animals is not just

soil

Mimicking the natural systemAgroecosystem mimic the native ecosystemsOnly ecosystems that are present that

1. maintain or build their ecological capital, 2. fix and hold their nutrients, 3. are adapted to periodic stress, such as drought

and fire, and 4. manage their weed, pest and pathogen

populations.

Tropical Ecosystem mimic: Traditional slash mulch system

Pre-Hispanic, swidden (migratory)Bean, corn, root crops also sorghum and riceKey characteristic is mulch of secondary vegetation

(not primary) that is not burnedFallow part of systemSystem produces 30-40% of Costa Rica’s beans (1994)Costa Rica beans: household use 40%, commercial

60% of production (1994)

Experimental site: Farm in south Costa Rica

Finca Loma Linda Canas Gordas

Slash mulch mimic of rainforest root-litter mat

Appropriate second growth vegetation for slash mulch

system

After sowing seed, vegetation cut down and distributed to

form a mulch

Slash mulch beans

Unmulched Slash mulch

Volcanic ash soil (Andisol) with high capacity for P-fixation

The slash mulch system on steep hillsides in Costa Rica

Near Ciudad Neilly

Finca Loma Linda, Caas Gordas

No further management untilharvest and drying of the

bean plants

Threshing and winnowing

Winnowing with turkey wing on Guaymi reservation,near San Vito, Coto Brus, Costa Rica

Root systems Slash mulch Unmulched

*

*Unfertilized

Bean diseases: Effects of the mulched and unmulched systems

With Mulch Anthracnose - significantly less

(Colletotrichum lindemuthianum)

Fusarium-type root rot - significantly less

Root knot nematode -significantly less(Meloidogyne spp.)

Rhizoctonia-type root rot - significantly more

Biological impact summaryLess foliage and root disease with exception

Rhizoctonia root rot in mulched system

Different nematode communities in mulched and unmulched systems, less morphospecies diversity in soil of mulched

Greater arthropod diversity in soil of mulched systems

In summary

The traditional system appears to be sustainable because it imitated the natural system root-litter mat limiting nutrient more available avoidance of disease

Land Institute“Natural Systems Agriculture is a

new paradigm for food production, where nature is mimicked rather than subdued and ignored. Because we are located in native prairie, we look to the prairie as our model for grain crops. As a result, we are investigating the feasibility of perennial polycultures or mixtures of perennial grains.”

Ecosystem function follows structureHave identified four functional groups in prairie: cool-

season grasses, warm-season grasses, legumes and composites. Has identified perennials in all groups: cool-season grasses: wild rye, perennial wheat, warm-season grasses: bunchgrass (3x higher in protein than

corn), legumes (Fabaceae): Illinois bundleflower (38% protein), composite (Asteraceae): Maxmillian sunflower (oil)

Tall grass prairie:perennial and polyculture

Perennial polyculture at the Land InstituteMaxmillian sunflower and Monarch Butterfly (upper)

Polycultures -Land Institute

Do perennial polycultures outyield perennial monocultures?

Perennialization

Breed perennial characteristics into existing grains like wheat

Breed edible grain characteristics into perennials

Suggests genetic engineering may be a useful approach

Marty Bender and Jerry Wild (KSU) looking for sunflower moths

Genetic Engineering: what is it?

Genetically Engineering (GE): Transfer of genes from one organism-- plant, animal or microbe-- to another using biotechnology, not conventional breeding.

Genetically Modified Organism (GMO) is a term that is somewhat misleading since the process of plant adaptation or conventional breeding can be a genetic modification

Transgenic

GE is not hybridizationHybrids are conventionally bred from two inbred parentsAdvantage is the the F1 generation (the plants from the

bought seed) is uniform and recessive genes are unexpressed

Issues are the the seed saved is variable in quality so that it is not useful to save

Need to continually buy seedHas supplanted open-pollinated varieties

Assembling the agroecosystem

synthetic communities of plants, animals, and micoorganisms that are stable, productive, and close enough in form to the native community that the essential functions of pest resistance, soil stability, and nutrient cycling are preserved.

What maintained oak savanna and prairie? --fire and browsers/grazers

Can livestock substitute for natural grazers and browsers? we meet conservation goals and produce livestock too?

Scottish Highland cattleforaging on brush and grass

Can we manage the animals so thatthe rare herbaceous oak savanna plants are impacted positively?

Farming with the wildBeyond organic“We cannot have healthy farms in a degraded

landscape. Quite apart from the problem of drift-- whether chemical or genetic-- there is the fact of the biodiversity necessary to produce the ecosystem services on which our organic farms depend can only be restored and maintained on an ecosystem level”-- Kirschenmann and Gould

“The idea that organic farms are enclaves of purity-- that everything within their boundaries is God-like and everything that lies outside their boundaries is evil-- is a patch ecology perspective that must be reconsidered.” --Kirsh. and Gould identify ecological neighborhoods how can agriculture fit into them by effectively using the

ecosystem services they provide• microorganisms and soil quality; predators of insect pests

and native pollinators

The Nature Conservancy- Cosumnes River Landscape Level Project

42,000 acres Agencies -

State Fish and Wildlife EPA UC Davis

Organic rice farmers livestock grazers inbuffer areas

Egrets and cattails

Sandhill cranes in winter rice fields

Other Wild Farm pioneersWildlands corridor Coon Mt. to Split Rock

Wildway to link Lake Champlain to Adirondacks. Land trusts and Black Kettle Farm- maximizes biodiversity

Chile Parque Pumulin- viable rural economies with demonstration organic farms (800,000 acres)

Costa Rica- Palo Verde National Park- cattle used to clear vegetation

Paseo Pantera Mesoamerican corridor

Restoration of soil fertility at level of a country: case of CubaType Area

(M ha)% Rehabil.1990

Erosion 3681 86.1*Saliniz. 780 0.1Acidity 1133 26.5Poor drain 100 6.7Low SOM 3000 94.1

* principally via agronomic methods like contour plowing etc.

Methods to maintain and restore soil fertility in Cuba1) Soil Amendments

a) Organic matter- leaf-cutting ant refuse, leaf litter, compost, green manures, cover crops, worm compost (from vermiculture), urban garbage, crop residues, processing of agricultural by-products

b) Crushed rock and limec) Physically moving eroded soil and organic matter from lowlands to highlands

d) Biofertilizers

N-fixing organisms: symbiotic-Rhizobium (bacteria) Cuba- 80% N

supplied for legumes free-living-Azotobacter (bacteria) Cuba- 40-

50% of N supplied in non-legumesP-solubilizing-Bacillus (bacteria)VA Mycorrhizal Fungi-

Available commercially in Cuba (and US)

For sustainable food system- food production:We need to restore soilWe need to restore connectivity of

landscapeWork from landscape level perspective for

sustainable food production and quality of life

References

Imhoff, D. 2002. Farming with the Wild. In: Fatal Harvest.

Soule, J.D. and J.K. Piper. 1992. Farming in Nature's Image. Island Press

Jackson, L. and Jackson, D. 2002. The Farm as Natural Habitat Island Press

Cihacek, Anderson, Barak. 1996. Linkages between Soil quality and plant, animal and human health. In: Methods of Assessing Soil Quality. SSSA Spec. Pub. #49

Zimmer, G. 2000. The Biological Farmer: A Complete Guide to the Sustainable and Profitable System of Farming