Stop the BS!

Report
WIB Demonstration Projects
• categories (including but not limited to):
– School and Community Gardens
– Permaculture/Biointensive Gardening
– Traditional Dryland Farming
– Food Preservation
– Food Justice
– The Business of Food
• awards will be presented at 2014 Conversations
• tell us about your idea!
Stop the BS!
Or, more kindly…
Thanks for coming to our
workshop on soil health.
Desert Difficulties
• alkalinity
– high pH reduces availability of some
nutrients
• salinity and sodicity
– salt levels affect nutrient and water
uptake
• poor drainage
– affects plant growth and makes
leaching of salts impossible
Dessert Difficulties
• pH of rainwater ~ slightly acidic
– desert soils tend towards alkalinity
• ocean now desert
– salt in water  salt in soil  salt on soil
• clay compounds the problems
• gardening methods also contribute
– amendments
– irrigation techniques
Sodic Soils
• definition: high level
exchangeable NA, low total level
salts
• characteristics: high pH, poor
drainage, crusted when dry,
brown film on top of soil
• effects on plant growth: reduced
nutrient uptake, sodium toxicity
Sodic Soils
• miracle cure for sodic soil: gypsum
• time and correct treatments can help soil
recover structure
• BUT adding gypsum to saline soil will only
increase salinity…
Saline Soils
• definition: high level of salts dissolved in soil and water
• characteristics: salty crust often visible on soil as low rainfall and clay prevent
salts from being flushed out
• effect on plant growth: reduced water uptake
• Salt-affected soils may inhibit seed germination, retard plant growth, and
cause irrigation difficulties.
• Saline soils cannot be reclaimed by chemical amendments, conditioners or
fertilizers.
• Saline soils are often reclaimed by leaching salts from the plant root zone.
• Soils high in salt and/or sodium may limit crop yields. Periodic soil testing and
treatment, combined with proper management procedures, can improve the
conditions in salt-affected soils that contribute to poor plant growth.
Factors Contributing to Salt Problems
•
•
•
•
Drainage
– A common sign of salt problems is the accumulation of salts at the soil surface due
to limited percolation in compacted and/or clayey soils. Soluble salts move with
the soil water. Deep percolation of water down through the soil profile moves salt
out of the rooting zone. Surface evaporation concentrates the salts at the soil
surface. Salt deposits may or may not be seen as a white crust on the soil surface.
– In some areas, salt naturally accumulates, due to limited rainfall to leach the salt
out. Here, corrective measures are limited to improvements in soil drainage.
Legumes.
Soil Amendments
– Manure, biosolids, and compost made with manure or biosolids may be high in
salt. When using manure or compost made with manure, routinely monitor salt
levels.
– Excessive or Unnecessary Fertilizer Applications
• Unwarranted application of fertilizers (such as phosphate or potash) increases
the salt level. On soils marginally high in salts, potash fertilizers should be
avoided unless a potassium deficiency is identified by soil tests.
– Pet Urine
• Damage by pet urine is also a salt problem. Water moves by osmotic pressure
from the roots to the high salt concentration in the soil, dehydrating and killing
roots.
http://www.ext.colostate.edu/pubs/crops/00503.html
http://aces.nmsu.edu/pubs/_circulars/CR656.pdf
Saline Soil Management
• Residue Management
– Crop residue at the soil surface reduces evaporative water losses, thereby limiting
the upward movement of salt (from shallow, saline groundwater) into the root
zone. Evaporation and thus, salt accumulation, tends to be greater in bare soils.
Fields need to have 30 percent to 50 percent residue cover to significantly reduce
evaporation. Under crop residue, soils remain wetter, allowing fall or winter
precipitation to be more effective in leaching salts, particularly from the surface soil
layers where damage to crop seedlings is most likely to occur.
– Plastic mulches used with drip irrigation effectivly reduce salt concentration from
evaporation. Sub-surface drip irrigation pushes salts to the edge of the soil wetting
front, reducing harmful effects on seedlings and plant roots.
• Irrigation Frequency Management
– Salts are most efficiently leached from the soil profile under higher frequency
irrigation (shorter irrigation intervals). Keeping soil moisture levels higher between
irrigation events effectively dilutes salt concentrations in the root zone, thereby
reducing the salinity hazard.
– Most surface irrigation systems (flood or furrow systems) cannot be controlled to
apply less than 3 or 4 inches of water per application and are not generally suited
to this method of salinity control. Sprinkler systems, particularly center-pivot and
linear-move systems configured with low energy precision application (LEPA) nozzle
packages or properly spaced drop nozzles, and drip irrigation systems provide the
best control to allow this type of salinity management.
• Don’t use city water, very salty
Stop the BS, err Manure!
• manure and compost made from manure
contain salts
vs.
Working with Saline Soils
• salt tolerance of different crops
• irrigation techniques
• garden and bed design
Salt Tolerance of Different Crops
High
{}
Medium
{} Low
High
{}
Medium
{} Low
Irrigation Techniques
• consider pH and salt content
of irrigation water
– hint: rainwater is best!
• sub-surface drip is best choice considering
efficiency and salt management
Garden and Bed Design
Garden and Bed Design
• wisdom of ancestors: waffle gardens
Desert Difficulties:
The Long View
•
•
•
•
miracle cure for sodicity = gypsum
but no miracle cure for salinity 
if we can’t fix it, let’s not make it worse
manure? no! or at least test and monitor your
salinity levels, and apply in moderation
• Organic Matter we love you!
– compost!
– cover crops!
Your Ideas!
• Sid: soil swapping and garden tours,
worms, garden wide compost, cover tarp,
sand from mcgaffey exit, acidic peat
moss
Bo-whatty? Bokashi!
• What You Need
– Bucket with leachate valve (or no valve…more labor in
end)
• 2 buckets that stack inside each other (fairly tight fit)
• Valve/Spigot, Rubber Washers, Nut
• Buying everything new about $20 (ACE)
– Microbe-innoculated bran
• recipe: 12 lb. bran + 3 oz. molasses + 3 oz. mother + 1 gal water
• $34 + $2 + $2 = $38 = enough bran for several months
• the method
– scraps* + bran + time
• *even animal products!
– anaerobic decomposition in 2-4 weeks
And Bokashi for All
• scale up for big gardens and institutions
– remember, NO sorting of scraps (perfect for kids)
• try it out and spread the bran, I mean, word!
Cover the World with Cover Crops
• aka ‘Gone Legumin’
• primary benefit (for desert gardens):
increase OM content of soil
–water infiltration and retention
–nutrient cycling
–soil microecology
–etc etc etc
The Goodie Bag
• Summer Alfalfa
– annual (not very winter hardy)
– makes loads of biomass
– taproot breaks up hard soil
• Sweet Clover
– needs only 16 inches precip/year
– great forage for bees and other pollinators
– mines nutrients and brings to surface
Let’s Go Legumin’
• plant your alfalfa and sweet clover in April or
May (depending on how warm it is)
• work up ground, broadcast, and rake over
(recommendation is to plant ¼” deep)
• you may have to irrigate to get cover crop
established, but remember…
• the goals is to improve the soil so that it can
retain water in the future

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