Organic Vegetable Gardening in the Desert

1
Organic Vegetable Gardening in the Desert

• Joran Viers
• Bernalillo County Cooperative Extension Service
• Albuquerque, New Mexico

2
Organic defined

• To chemists simply describes fact of carbon
  backbone to molecules natural and synthetic
  organic compounds exist.
• To gardeners implies a perspective favoring
  natural sources for soil fertility, and natural
  methods and materials for pest control. To some
  there is a spiritual component as well.
• Commercial agriculture process-based production
  system utilizing natural materials, and requiring
  much paperwork and verification.

3
Perspective

• Adherence to principle of feed the soil
  compost, manure, green manures, etc.
• Natural pest control cultural/physical changes
  to make habitat better for plants use of
  resistant varieties (but not GMO) judicious
  application of pest control materials acceptance
  of certain level of imperfection as indicator of
  purity.

4
Perspective

• Basic issues remain
• Soil types and their characteristics
• Climatic conditions (rainfall, temperature,
  etc.)
• Common pests (insects, weeds, diseases)
• Soil fertility plants need certain minerals in
  soil in order to grow well
• Species/variety likes/dislikes.

5
Feed the Soil

• Plants evolved getting nutrients from soil
  either mineral or from organic matter. Soil
  fauna is essential to this process
• Plants dont require a seasons worth of
  nutrients all at once
• Synthetic fertilizers are typically salts, which
  dissolve rapidly in soil solution
• Can aggravate a soil salinity problem
• Nutrients may be lost before plants use them
• Nutrient level fluctuation can negatively affect
  soil microbial ecosystem.

6
(No Transcript)
7
Synthetic Fertilizers

• Some (how many?) commercial synthetic fertilizers
  use slag and other industrial wastes as inert
  carriers
• Cases of farmers ruining fields for the
  foreseeable future by application of recommended
  rates of fertilizers.
• Heavy metals are the concern accumulation on
  farm/garden soils and the plants grown in them.

8
The Soil

• Mineral classification based on particle size
  sand, loam, clay.
• Parent material affects particle size, as well
  as
• pH measure of alkalinity (acidity) of soil most
  SW soils are pH gt 7.
• Buffering capacity high lime content makes
  changing pH next to impossible.
• Salinity, CEC, mineral nutrient levels

9
The Soil

• Organic matter humus
• Typically low levels in our soils
• Has major impact on water and nutrient
  retention/release properties
• Needs to be replenished periodically (photo-and
  biotic degradation)
• Not all OM is created equal will vary in
  nutrient levels, saltiness, pH, degree of
  decomposition,

10
Soil Preparation

• Wide-bed planting
• Reduces non-crop area relative to crop yield
• Reduces labor associated with spread-out gardens
• Plants are somewhat self-mulching
• Allows for intensive soil loosening prep work
  (double-digging)
• Easily accommodates drip irrigation.
• Add in compost or other OM and any mineral
  nutrients at time of double-digging.

11
Excerpted from How to Grow More Vegetables, by
John Jeavons.
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
Soil Building

• Organic Matter
• Compost intentionally decomposed plant and
  animal remains rich earthy smell, dark brown and
  crumbly. Use to enrich soil, as top-dress/mulch,
  in making planting mixes. Moderate N level, good
  balance of all plant nutrients.
• Manure un-decomposed animal manure may be
  easily available give it time to decompose in
  soil be aware of salt buildup potential. Higher
  N level.
• Green manure crop (often legume) grown to be
  returned to soil adds bulk carbon, may add
  nitrogen feeds soil ecosystem least loss.
• Leaves, grass clippings, etc. can have a place,
  but be aware of limitations (high carbon,
  matting, etc.).

17
Compost

• Requires right mix of dry (brown) and fresh
  (green, or manure) materials CN between 251
  and 351.
• Pile should be at least 3x3x3 to heat up
  properly.
• Turn after temperature comes down.
• Keep moist cover if necessary.
• Use a multiple bin system for easy turning.

18
(No Transcript)
19
Common Compost Problems

• Problem
• Wet, foul-smelling pile
• Dry center and little or no decomposition of
  materials
• Dampness and warmth only in middle
• Damp, sweet-smelling but no heat
• Matted, un-decomposed layers of leaves, paper or
  grass clippings
• Large un-decomposed items

• Remedy
• Turn pile, add high-carbon material
• Turn pile, soaking thoroughly cover with plastic
  to retain moisture
• Increase volume of pile and moisten well
• Add nitrogen-rich materials, turn
• Break up layers, or shred, re-layer pile avoid
  adding these materials in heavy layers
• Screen out un-decomposed items and use in next
  pile

Taken from The Rodale Book of Composting
20
You may need to add

• Nitrogen blood meal, fish emulsion, manure tea,
  alfalfa mulch (SLOW release)
• Phosphorus bone meal, rock phosphate due to
  high pH, may very quickly become unavailable
  mix 5050 with elemental sulfur at application
• Potassium greensand (also has micronutrients)
• Micronutrients often in soil but unavailable, so
  adding S can help (how much and when?)
• Humates offer an unknown level of benefit humic
  and fulvic acids, long-term stability.

21
Crop rotation limits pest/disease buildup, may
improve soil. Based on plant families and
cultivation requirements.

• Solanaceae tomato, potato, eggplant, pepper.
• Brassicaceae cabbage, broccoli, kale, turnip,
  mustard, etc.
• Cucurbitaceae squash, melon, cucumber.
• Poaceae corn, wheat, barley, rye
• Fabaceae bean, pea, medic, vetch, etc.
• Apiaceae carrot, parsley, cilantro, fennel.
• Liliaceae onion, garlic, leeks, chives,
  asparagus.

22

• Soil Solarization
• Till soil, wet up real well
• Cover with heavy-duty clear plastic, anchored
  along all edges
• Leave in the sun for several weeks to heat
  sterilize upper inches.
• Kills insects, eggs, seeds in the heated soil.

23
Direct seeding or transplanting?

• Some plants dont take transplanting well
  (cucurbits, root crops, beans and peas).
• Some do (tomato, pepper, eggplant, greens of all
  types, early corn).
• All plants that transplant well do just as well
  direct seeded.
• Can gain a week or two, depending on soil
  temperatures.
• Cost, hassle trade-offs.
• May help get ahead of weed problems.

24
Seeders for large areas.
25
Pest Control

• Pests include
• Weeds
• Insects
• Larger animals
• Diseases

26
Weeds

• Annual weeds
• Cultivate before new seed set
• Smother with mulch (before or after weed seedling
  emergence)
• Use corn gluten meal as a pre-emergent herbicide
  that breaks down into a 12 N source
• Flame weeding can work well but BE CAREFUL
  especially during the current drought.

27
Kochia scoparia
28
(No Transcript)
29
(No Transcript)
30
Cultivation tools come in all sizes and shapes.
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
Perennial Weeds

• Harder to control, as a rule
• Mulching can help
• Repeated cultivation and/or flaming can help
• For bindweed bindweed gall mite
• Crop rotation, green manuring, etc. can help.

35
Silverleaf nightshade and buffalo bur are both
relatives of tomato, potato, pepper. Both have
spines and irritating chemistry.
36
Common mallow (cheese weed) and spurred anoda are
both relatives of cotton, hibiscus. Both are
common agricultural weeds.
37

• In general
• Young weeds are easier to control by whatever
  method.
• Weeds can be composted, or used for mulch, if
  they havent set seed.
• If they have set seed, dispose of by burning,
  burying, or similar solution.
• Soil solarization can kill weeds and seeds at the
  soil surface.
• Some weeds can harbor diseases (London rocket and
  beet curly top virus).

38
Insects

• Both pests and allies.
• Most lepidopterans are pests (as larva)
• Many hemipterans are pests but some are
  predators
• Many homopterans are pests
• Most hymenopterans are allies.
• Coleopterans are found in both categories.
• It pays to know your bugs!

39
Lepidopterans moths and butterflies
Tomato hornworm
Painted lady
Corn earworm
40

• Bacillus thurengiensis a.k.a. Bt is a
  bacteria-based stomach poison specific to
  lepidopteran larva. Apply at first sign of
  activity, re-apply as needed.
• Vegetable oil plus pyrethrum on corn silk.
• Handpick the big ones and feed to the hens.

41
Hemipterans true bugs

• Squash bugs
• Plant late, plant often
• Row covers until bloom
• Rotenone on very young nymphs
• Trap cropping
• Flaming
• Disguise with buffalo gourd.
• Treat harlequin bugs with pyrethrum.

42
Predator Bugs
Damsel bug
Big-eyed bug
Assassin bug nymphs
43
Homopterans aphids their ilk

• Aphids
• Do nothing let the beneficials find them and
  establish their own populations
• Wash off with strong jet of water
• Treat with insecticidal soap
• Beauveria bassiana fungal product
• Neem, pyrethrum, etc.

44
Hymenopterans wasp, bees, ants

• Larger wasps often caterpillar predators
• Smaller wasps often parasitoids of eggs and
  larva
• Bees are key pollinators
• Ants are a mixed bag can farm aphids, can also
  help build soils and control some pests.

45
(No Transcript)
46
Coleopterans beetles

• Ladybugs, ground beetles, tiger beetles are all
  good predators.
• Weevils, Mexican bean beetles, flea beetles are
  pests.
• Bt specific to Colorado potato beetle variety
  tenebrionis

Green June beetles are opportunistic feeders.
47
For beetle control, try Neem, pyrethrum,
rotenone, Sharpshooter citric acid insecticide,
homemade tobacco extract.
Mexican bean beetle damage, adult and larva.
48
Insect Repellants

• Purchased or homemade extracts of certain plants
  may deter pests.
• Garlic
• Hot pepper
• Tobacco

49
Insect Attractants

• Pheromone traps to control codling moth
• Traps alone for small home orchards of a few
  trees
• Traps plus selective sprays (Kocide, spinosad,
  Bt) to control
• Pheromone alone for large-scale mating disruption.

50
Small-flowered plants attract adults of many
beneficial insects due to nectar. Plant along
borders, etc.
51
Got snails? Get turtles!
52
Diseases

• Our dry climate suppresses many fungal and
  bacterial disease organisms. Good garden
  sanitation will help a lot, also.
• Sulfur, neem, copper products, jojoba oil (for
  powdery mildew and whiteflies).

Curly top virus affects many plants including
squash. Beet leaf hopper is the vector, winter
annual mustards an alternate host. Prevention!!!
53
Resources

• Books
• How to Grow More Food, by John Jeavons.
• The New Organic Grower, by Eliot Coleman.
• Most anything by Rodale Press

• Other media
• Peaceful Valley Farm Supply catalog
  (www.groworganic.com).
• ATTRA (www.attra.org)
• Cooperative Extension Service offices
• Knowledgeable local gardeners.

54
(No Transcript)