Overcoming Productive Limitations in Nevada’s Soils: the importance of pH, salts and organic matter

1. Overcoming the productive
limitation of Nevada’s soils: the
importance of pH, salts, and
organic matter
David Howlett, Ph.D.
Nevada Division of Forestry
July 17, 2013 UNCE

2. overview
1. good and bad soils
2. soil-related limitations to
production
3. low organic matter
4. high pH
5. salts
6. tools to help you
overcome these limits
(web soil survey demo)

3. a “good” soil…
Physical
Chemical
Biological

4. Nevada
soils…
and
landscapes
State Soil: Orovada Series

5. soil formation: the five soil forming factors
Hans Jenny, 1949
1. parent material
(metamorphic, volcanic,
sedimentary)
2. topography/landscape
(hill or bottom)
3. climate (47°, 8-9 in rain)
4. organisms (including us)
5. time (varied)
Reno- Sparks area
what factors can we control???

6. soil services
• nutrient storage and
delivery system for
plants (food, fuel, and fiber)
• storm water control,
pollutant storage
• structural support for
roads and buildings

7. soil texture, or particle size distribution
Soil Fraction Size, mm Feel in hand Surface area,
cm3/g
Sand <0.05- 2 gritty 21-210
Silt 0.02-0.05 smooth, silky 2,100
Clay <0.02 sticky 23,000
soil chemistry
dominated by clay
Why?
surface area!

8. the soil solution
• all nutrient
uptake by
plants occurs
in aqueous
solution
(water is
solvent)
• charge
matters!
uptake mechanisms: mass flow, diffusion, and interception

9. soil characteristics that limit production
1. low organic matter
2. high salt content
3. high pH
others…
 texture (distribution of particle sizes)
 depth to bedrock
 structure (erosion)
 hardpans
 compaction
 disturbance (mining, urban)
 toxicity (spills, mining, natural)
 high water table

10. 1. organic matter in the soil
• nutrient reservoir
(fertilizer use enhanced)
• helps with structure
• increases soil organisms
• improves moisture status
• helps prevent erosion
• moderates soil temp
• ~0-4% in N Nevada

11. organic matter diagnostics
• soil color, darker the better
• plants, duff layer presence
indicator
• soil test

12. how to increase organic matter?
• add well-decomposed compost
• grow cover crop or other
plants, mix in
• anything that helps plants grow
will increase OM (irrigation,
fertilizer, mulch)
• combine with aeration
treatments in turf

13. 2. soil pH or acidity
• concentration of H+ and OH-
ions in solution
• expressed in log scale:
pH 7 is 100 times more acidic than pH 9
major role in determining soil nutrient
status…

14. pH and soil nutrient availability

15. What can you do about pH?
• test pH- easy and cheap !!
• lower pH with acidic material (S, or OM),
watch for free carbonates (buffer)
• grow plants tolerant to high pH

16. 3. accumulation of salts
Source: http://www.fusion360inc.com/sections/benefits/FusionGallery
>2,900 ppm Na Cl
Fallon NAS

17. how does salt accumulate?
•occurs naturally in
‘playas,’ dry lake bed
•irrigation water contains
salts that remain after
water evaporates
•poor drainage
exacerbates

18. effects of high salt on soil?
• salts reduce water uptake by plants
• sodium (Na+) competes with other cations for
exchange sites, disperses clay
• reduced soil structure = lower infiltration,
crusting on surface

19. how to deal with salt
• on newly developed site, leach with irrigation
(needs good drainage, check with probe)

20. how to deal with salt II
• gypsum application, CaSO4
.2H2O
(Ca replaces Na, difficult, must be repeated)
• plant salt-adapted plants
(talk to expert, UNCE publication 12-04)
http://www.unce.unr.edu/publications/files/ho/2012/sp1204.pdf
• maintain, improve drainage
(install pipes, French drain, etc.)

21. soil test!
• Chemical extraction of soils
• Provides information on ‘plant available’
nutrients, salts, pH
• Helps determine what your soil needs, or does
not need to be productive
does NOT test: pesticides, toxics, soil biology,
total available nutrients
Soil testing labs:
http://www.growyourownnevada.com/resourc
es/private-soil-testing-labs/

22. tools to help you
• good observation, above and
below ground
• local nursery staff, UNCE
• soil tests!
• USDA Soil series
web soil survey

23. review
limitation diagnosis remedy caveat
low organic
matter
light colored soil add OM, grow
plants
well-
decomposed
high pH test lower pH, amend,
plant adapted
species
difficult to do on
large scale, with
free carbonates
very hard
high salts Crusting, plant
symptoms (similar
to water stress)
Leach, amend,
plant adapted
species
must have good
drainage, keep
up amendments

24. thank you!
David Howlett, PhD
Urban and Community Forester
Nevada Division of Forestry
(775) 684-2506
dhowlett@forestry.nv.gov
http://forestry.nv.gov/