Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
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Soils 101 for High Tunnels 2012
1. Soils 101:
Soil Physical & Chemical Properties
Peter Bierman and Carl Rosen
Department of Soil, Water, and Climate
University of Minnesota
MFVGA Beginning Grower Workshop
January 18, 2012
2. Physical Properties
l Texture, structure, organic matter
l Controls drainage, water-holding capacity
l Suitability for vegetable/fruit production
l Often the most difficult to manage
3. Soil Testing and Soil Fertility
l Essential plant nutrients
l Managing fertility
l Soil acidity and liming
l Types of soil tests
l Soil sampling/sample handling
l Fertilizer sources
4. Soil Composition
Soil is composed of solids, water, and air
ďŽ Solids (50%)
ďŽ Sand, silt, clay (90-99%)
ďŽ Organic matter (1-10%)
ďŽ Water (25%)
ďŽ H 2O
ďŽ 100-1000 ppm soluble salts
ďŽ Air (25%)
ďŽ High CO2 (10-20 times as high
as the atmosphere)
5. Importance of Soil Physical Properties
l Healthy crop root growth
q roots require both air and water
l Determines infiltration, drainage,
aeration, water-holding capacity
q control the balance
between air and water
in the root zone
6. Soil Texture
l Relative proportions of sand-, silt-, and
clay-sized particles
q sand > silt > clay
l Soil âtextural classâ
q loamy sand, silt loam, clay
l Texture is a fixed
soil property
q not altered by management under ordinary
conditions
7. Soil Texture
l Coarse-textured soils
q dominated by sand
⢠well-drained/aerated
⢠low water and nutrient holding capacity
l Fine-textured soils
q dominated by clay
⢠poorly drained/aerated
⢠high water and nutrient holding capacity
l Loams
q intermediate texture and properties
9. Soil Structure
l Sand, silt, clay combined into
aggregates
l Aggregates arranged with pore spaces
between them
l âGoodâ structure
q ~50% solids and 50% pore space
q pore space evenly distributed
⢠large, air-filled pores (drain readily)
⢠smaller, water holding pores
10. Soil Structure
Soil Air & Water
Tightly Held
Water Film
Water-filled
Pore Space
Air-filled
Macropore
Soil
Aggregate
11. Soil Structure
l Soil structure can be altered by
management
q improved or degraded
Granular aggregation promoted Compaction reduces pore space
by organic matter
12. Soil Organic Matter
Organic matter affects most soil properties
ď§ Forms of organic matter
⢠Plant/animal residues
⢠Various stages of
decomposition
⢠Humus
⢠Decomposition by-product
⢠Resistant to further
degradation
13. Soil Organic Matter
l Can improve aggregation and structure
l High water-holding capacity
l Improves physical condition of both
coarse- and fine-textured soils
l Retains and cycles
nutrients
l Drives soil biology
14. Soil Depth
l Determines potential rooting depth
l Zone of water and nutrient uptake
l Drainage restriction
l Gravel, bedrock, compacted layers
15. Finding Soil/Site Information
l County Soil Surveys
q soil maps
q soil types
q texture
q drainage
q topography
q water-holding
l NRCS, SWCD, Extension
l SoilWeb App
l http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx
18. Site Preparation/Modification
l Ideally begins well before planting the
first vegetable crop Subsurface Drainage and
Crop Root Growth
l Drainage
improvements
Free water level
Free water level
Free water level Free water level
Spring Summer Spring Summer
Undrained Land Tile Drained Land
20. Soil Testing and Soil Fertility
l Essential plant nutrients
l Soil sampling/handling
l Types of soil tests
l Soil acidity and liming
l Cation exchange capacity
l Organic/inorganic fertilizers
l Value of soil testing
q example field
21. Essential Plant Nutrients
Nutrients derived from the soil and/or fertilizer
Macronutrients Micronutrients
Primary Zn â Zinc
N - Nitrogen B â Boron
P â Phosphorus Fe â Iron
K â Potassium
Mn â Manganese
Secondary
Cu â Copper
S â Sulfur
Mg â Magnesium Mo â Molybdenum
Ca â Calcium Ni â Nickel
Cl â Chlorine
22. Soil Sampling
l Collect representative samples
q Soil tests are only as accurate as
the samples you submit
q Sampling is often the weakest link
in a soil testing program
l Follow sampling and handling
guidelines of the laboratory you
submit samples to
23. Sampling Guidelines
l Divide fields into uniform areas
q soil type, slope, crop history, tillage,
previous lime, fertilizer, manure, compost
applications
l No more than 20 acres for a single
sample
l Collect 20-30 soil cores
q random, zig-zag pattern across the field
l Standard depth 6-8 inches
q 2 feet for soil nitrate test
24. Soil Sampling
l Thoroughly mix sub-samples in a clean,
plastic container
q submit about a pint of this composite
sample to a laboratory for analysis
l If soil is wet
q air dry
⢠spread in a thin layer on a
clean surface before mixing
q oven dry at <97° F
25. Soil Tests
l Standard series
q do on a regular basis
q P, K, soil pH, buffer pH, OM, texture
⢠lime requirements are based on a Buffer Index
l Additional tests
q first time a new site is sampled
⢠or when a problem is suspected
q Ca, Mg, Zn, B
⢠Cu and Mn on organic soils
28. Soil Acidity
l Soil pH measures acidity/alkalinity
l Mineral soils
q pH 5.8 to 7.0
⢠optimum range for most vegetables
q pH of 5.4 or less reduces scab on potatoes
l Organic soils (peats and mucks)
q optimum pH is lower, 5.2 to 6.0
29. Soil pH
l Microbial
activity
l Nutrient
availability
q optimum pH
about 1 unit
lower for
organic
soils/media
Mineral soils
30. Liming
l Soil acidification
q rainfall and leaching, N fertilizers
l Western MN vs. eastern MN
l Soil pH
q do you need lime?
l Buffer index
q reserve acidity
q how much lime?
31. Nitrogen
l Recommendations based on
q crop grown
⢠expected yield
q soil organic matter level
q preceding legume crops
q manure or compost applications
q nitrate soil test
⢠measures residual N
⢠standard in western MN
32. Phosphorus and Potassium
l Recommendations based on
q crop grown
⢠expected yield
l Soil test level for P and K
33. Relative Nutrient Mobility
l Nitrogen moves much faster than
phosphorus and potassium in the
soil
l Phosphorus has very limited
mobility in the soil
l Implications:
q P and K should be
incorporated before planting
q Nitrogen can be topdressed or
sidedressed during the
growing season
34. Soil Cation Exchange Capacity
CEC is the amount of positively charged ions a
soil can hold â reduces leaching and buffers
the soil solution
Soil Solution
K+ Mg2+
Ca2+
H+
35. Sources of Plant Nutrients
Plant nutrients come from both organic and
chemical sources
36. Organic vs. Inorganic Fertilizers
l Organic
q Nutrients slowly released
q Low burn potential
q Improve soil structure
q May contain weed seeds
q Usually higher cost
q Acceptability for certified organic crop
production depends upon the certifying agency
l Inorganic (manufactured soluble fertilizers)
q Nutrients quickly available
q High burn potential
q Lower cost/unit of nutrient
41. Sweet Corn Tissue Analysis
Element Conc. Interp. Element Conc. Interp.
(%) (ppm)
N 1.72 Def. Fe 79 Suff.
P 0.16 Def. Mn 860 Excess
K 2.01 Low Cu 8 Suff.
Ca 0.28 Def. Zn 22 Suff.
Mg 0.15 Def. B 4 Low
S 0.09 Def.
42. Sweet Corn Soil Test
pH P K Mg Ca S Zn Salts
------------------------ ppm ------------------- mmhos/cm
3.8 96 90 16 106 3 0.8 0.2
L H M L L L M L
44. Recommendation
l Lime to pH 6 in the fall with dolomitic lime
l Apply potassium-magnesium sulfate in the
spring preplant
l Soil test yearly to
monitor changes
45. Additional Information
l Nutrient Management for Commercial Fruit
and Vegetable Crops in Minnesota
BU-5886-E - 2005
ď§ University of Minnesota Extension Service
q http://www.extension.umn.edu/
l University of Minnesota Soil Testing Lab
q http://soiltest.cfans.umn.edu/
q Phone: 612-625-3101