1. AGRICULTURE AGENT UPDATE
NORTHERN AG. RESEARCH CENTER
HAVRE, MONTANA
JUNE 27, 2013
Soils 101
Relative to Crop Production
in Montana
Olga Walsh
Assistant Professor, Soil Nutrient Management
Western Triangle Agricultural Research Center
Montana State University

2. OUTLINE
 Soils:
 Definition
 Soil profile
 Soil texture
 MT soils
 Soil productivity:
 Soil sampling
 Nutrients ant plant growth
 Mobile vs Immobile
 MT deficiencies/toxicities
 Fertilizer Strategies

3. SOIL DEFINED
 “(i) The unconsolidated mineral or organic material on the
immediate surface of the Earth that serves as a natural
medium for the growth of land plants
 (ii) The unconsolidated mineral or organic matter on the
surface of the Earth that has been subjected to and shows
effects of genetic and environmental factors of: climate
(including water and temperature effects), and macro- and
microorganisms, conditioned by relief, acting on parent
material over a period of time.
 A product-soil differs from the material from which it is derived
in many physical, chemical, biological, and morphological
properties and characteristics.”(NRCS, 2013)

4. SOIL DEFINED
 “Soil is a natural body comprised of solids (minerals and
organic matter), liquid, and gases that occurs on the land
surface, occupies space, and is characterized by one or
both of the following: horizons, or layers, that are
distinguishable from the initial material as a result of
additions, losses, transfers, and transformations of energy
and matter or the ability to support rooted plants in a
natural environment.”(Soil Taxonomy)

5. SOIL IS A DYNAMIC BIOGEOCHEMICAL INTERFACE
BETWEEN THE EARTH’S SPHERES

6. 12 SOIL TYPES
12 basic types of soils – soil orders reflect environment in
which they form, their age, and the ecosystem they support
NRCS, 2013
Scobe
y

7. MT PREDOMINANT SOILS
 Mollisols: form in semi-
arid to semi-humid
areas, typically under a
grassland cover
 Alfisols: form in
semiarid to humid
areas, typically under a
hardwood forest cover
 Entisols: young soils, do
not show any profile
development other than an
A horizon. unaltered from
their parent material,
which can be
unconsolidated sediment
or rock.
Inceptisols: weakly developed,
one or more subsurface horizons,
contains many unweathered
minerals; form quickly through
alteration of parent material; older
than entisols; have no
accumulation of clays, iron oxide,
aluminium oxide or organic matter.
NRCS, 2013

8. SOIL PROFILE
soils.wisc.edu, 2013

9. COMPARISON OF MT’S PREDOMINANT SOILS
A – maximum
accumulation of humus
E – zone of maximum
weathering and leaching
(elluvial)
B – zone of maximum
accumulation and
alteration (illuvial)
• Bw – almost no
clay
• Bt – more clay
C – zone of minimal
accumulation, alteration
and cementation

10. SCOBEY – MT STATE SOIL
 Scobey = Mollisol
 Surface layer: very dark grayish brown clay
loam; Subsurface layer: dark brown clay;
Subsoil: dark grayish brown clay loam
 Very deep, well drained soils on till
plains, hills, and moraines in the north-central
MT
 >700,000 acres, among most productive soils in
MT Golden Triangle (Havre-Conrad-GF): dryland
winter and spring wheat
 Formed in glacial till and under prairie vegetation
 Av. annual precipitation ~ 12 in; av. annual air
temperature ~ 43 F; 115 frost free days
 Named for the town of Scobey, in NE MT.
NRCS, 2013

11. MOLLISOL
 From Latin word “Mollis”, meaning soft
 These mineral soils developed on grasslands, a
vegetation that has extensive fibrous root systems.
 The topsoil of Mollisols is characteristically dark and rich
with organic matter, giving it a lot of natural fertility
 Typically well saturated with basic cations
(Ca2+, Mg2+, Na+, and K+) that are essential plant
nutrients
 Among the most fertile soils found on Earth

12. SOIL TEXTURE
 Refers to the size of the particles that make up
the soil
2 – 75 mm
> 75mm
Rock
Very fine: 0.05 - 0.1 mm
Fine: 0.1 - 0.25 mm
Medium: 0.25 - 0.5 mm
Coarse: 0.5 – 1 mm
Very coarse: 1 -2 mm
0.002 to 0.05
< 0.002

13. SOIL TEXTURE
% Clay % Silt % Sand Texture
15 70 15 Sandy Loam
http://courses.soil.ncsu.edu/res
ources/physics/texture/soiltextu
re.swf

14. SOIL TEST
AgVise, 2013
 “Soil testing is the best tool available to determine
the amount of each nutrient needed for the
coming crop year”
 Soil testing is the best tool available to determine
the amount of each nutrient present in the soil
from the previous crop year

15. SOIL TESTING
 Soil probe allows a uniform slice of the soil profile
to any depth.
 Depths: 0-6" and 6-24", to 48“ for deep-rooted
crops (sugarbeet)
 Time:
P, K, pH, %OM, salts, Ca, Mg, Zn,Fe, Mn, and Cu -
any time of the year (minor changes)
 Time: N, S, Cl - in the fall following harvest or early
spring
 Sample storage: cool, frozen or send to the lab
immediately
AgVise, 2013

16. SOIL SAMPLING METHODS
 15-20 soil cores to
represent a field
 The cores are mixed and
a portion is sent to the lab
 Avoid non-representative
areas
 Provides average soil
nutrient level in each field
 Can result in under- or
over- estimation
 Field split into
productivity zones (satellite
canopy images, yield
maps, salinity maps, soil
type maps, topography,
etc.)
 Representative sample
(10-15 cores) from each
zone
 Soil nutrient levels in
each zone can be quite
different
 Field split into small equal
sized areas (1 - 5 acres)
 8-10 cores collected from
the center of each grid or
randomly within the grid
 Nutrient levels are
determined for each grid
 Fertilizer recommendations
– for each grid
AgVise, 2013

17. NUTRIENTS AND PLANT GROWTH
o Plant’s sufficiency range = range of nutrient necessary to
meet plant’s nutritional needs and maximize growth
o Nutrient levels outside of
a plant’s sufficiency range
cause crop growth and
health to decline due to
either a deficiency or
toxicity
Mc Cauley et al., 2009

18. MOBILE AND IMMOBILE NUTRIENTS
BLA
BLA
BLA
BLA
Roger Bray, “A Nutrient Mobility Concept or Soil-Plant
Relationships. 1954. Soil Science.

19. MT SOILS:
COMMON DEFICIENCIES /TOXICITIES
 Most common: N and P
 Sometimes – K, S
 Micronutrient deficiencies are fairly uncommon with
deficiencies of B, Cl, Fe, and Zn occurring most often
 Toxicities – uncommon, result of over-fertilization

20. ESSENTIAL PLANT NUTRIENTS
Total of 16 essential nutrients
3 Macronutrients from air and water: Carbon,
Hydrogen, Oxygen (C, H, O)
13 MACROnutrients from soil:
3 Primary nutrients - Nitrogen, Phosphorus and
Potassium (N, P, K)
3 Secondary nutrients - Calcium, Magnesium and
Sulfur (Ca, Mg, S)
7 MICROnutrients - Iron, Manganese, Zinc, Copper,
Boron, Molybdenum, and Chlorine (Fe, Mn, Zn, Cu, B,
Mo, Cl)

21. ESSENTIAL PLANT NUTRIENTS
Deficiency disrupts plant’s growth and
reproduction
Deficiency can be prevented or corrected
only by supplying the element
Nutrient is directly involved in the nutrition
of the plant

22. YIELD POTENTIAL AND FERTILIZER
Q 1. Which field has a higher Yield Potential?
Q 2. Which field needs more fertilizer?
Field A Field B

23. “BLANKET” VS PRECISION
 Conventional application of N – one rate based on
average needs of the field/fields
 Variability in production potential(natural, acquired,
spatial, temporal)
 Average rate is excessive in some parts and inadequate in
others
 Precision Agriculture = timely and precise N application
to meet plant needs as they vary across the landscape
 Sensor-Based Technologies – precision agriculture
tools, allow to account for variability and to make more
informed decisions

24. PRECISION AGRICULTURE AND NUE
• Yield Potential approach:
 No guess-work
 Minimizes producer’s risks
 Higher NUE
• Precision N Fertilization entails:
 Right time and Right rate
 They vary across the field to meet plants’ needs
• Sensor-Based Technologies – precision agriculture
tools, allow to account for all types of variability and
to make more informed decisions

25. YIELD GOAL VS YIELD POTENTIAL
 Yield Goal:
 Average yield for past 5 years + 30% (just in case we have a
good year)
 Based on past (historical data)
 Uses average N rates

 Yield Potential:
 Estimated using in-season data
 Based on current crop nutrient status
 Precise N rate (crop- and site-specific)

26. YIELD GOAL VS YIELD POTENTIAL
Yield Goal
 Sufficiency approach: to apply a fixed rate of N at a
computed sufficiency level, regardless of YP
Yield Potential:
 Estimates of YP and crop response to N provide a
physiological basis to estimate N removal and a
biologically based N application rate
Tabitha, WSU

27. YIELD POTENTIAL VARIES YEAR TO YEAR
0
20
40
60
80
100
120
140
160
180
200
1940 1950 1960 1970 1980 1990 2000 2010 2020
“Maximum Attainable Yield”
(Yield Goal)
Actual
Harvested
Yield
Should we fertilize for maximum yield every year?
Alternative to Yield Goal - Yield Potential
Source: Taylor, 2009

28. Yield Potential Prediction
 The concept of sensing biomass in various crops
 Biomass used as an indicator of nutrient need
 Knowing how much biomass is produced =>
knowing how much N is removed from the soil and
converted into biomass
 Removal of N in harvested biomass and grain is
highly correlated with yield

29. YIELD POTENTIAL AND RESPONSE TO N
YP and RI are independent from one another:
 High YP, High RI
 High YP, Low RI
 Low YP, High RI
 Low YP, Low RI
Field A Field B

30. PRECISION SENSOR’S BASICS
Emits light and measures reflectance from plants
Sensor reading - Similar to a plant physical examination
Sensor can detect:
• Plant Biomass
• Plant Chlorophyll
• Crop Yield
• Water Stress
• Plant diseases, and
• Insect damage

31. CONCEPT SUMMARY
1. How much
biomass is
produced ?
2. What Yield is
attainable without
addition of N?
3. How
responsive is
the crop to N?
4. What Yield is
attainable with
addition of N?
YPN = INSEY*RI
NDVI = (NIR-red)/(NIR+red)
INSEY = NDVI/GDD>0
RI = NDVI (NRS) /NDVI (FP)
Marty Knox is obtaining winter wheat canopy reflectance data using
GreenSeeker optical sensor, WARC, Corvallis, MT, May 2013

33. red
redNIR
NIR
30%
50%
60% 8%
NDVI = (NIR-red)/(NIR+red)
NDVI (1) = (0.60 - 0.08)/(0.60 + 0.08) = 0.76
NDVI (2) = (0.50 - 0.30)/(0.50 + 0.30) = 0.25
(1) (2)

34. CONCEPT SUMMARY
1. How much
biomass is
produced ?
2. What Yield is
attainable without
addition of N?
3. How responsive
is the crop to N?
4. What Yield is
attainable with
addition of N?
YPN = INSEY*RI
NDVI = (NIR-red)/(NIR+red)
INSEY = NDVI/GDD>0
RI = NDVI (NRS) /NDVI (FP)

35. VARIABLE RATE IN MONTANA
“Sensor-based VRT saves fertilizer
costs, improves crop production”
 By Shannon Ruckman, The Prairie Star editor; 2008
 Herb Oehlke
 Farms Wheat and Barley, since1995
 Ledger, 20 min from Conrad
 Switched from blanket to
variable-rate application
 Saved money and time
 Uses GreenSeeker on all his
wheat fields

36. VARIABLE-RATE IN MONTANA
 “I really questioned if it would work”
 “I wanted to know if it would work with the NRCS
requirements”
 “I can't under apply fertilizer, but I need to be more
efficient at it. Net return is an important number.”
 Saved 5.3 gallons of fertilizer per acre
 Achieved 8 to 10 bus/ac increase in yield
 “Had average yield- 57 bus/ac. The VRT fields
yielded 67 to 70 bus /ac. At $10/bu, that adds up
real fast. That’s $100 /ac!”

37. THANK YOU!
QUESTIONS?
ADDITIONAL SLIDES ON
NUTRIENT ROLE/ DEFICIENCY

38. MACRONUTRIENTS

39. NUTRIENTS FROM AIR AND WATER
Carbon, Hydrogen, Oxygen
Base of all organic molecules, building
blocks for growth
Absorbed as CO2
Combined with H and O
Transformed into carbohydrates in leaves
in the process of photosynthesis

40. ESSENTIAL MACRONUTRIENTS
 N, P, K
Needed in greater amounts for
growth
Lacking from soil first
Greater response

41. N DEFICIENCY
 Light green upper (young) leaves
Yellow lower (older) leaves

42. ESSENTIAL MACRO NUTRIENTS: P
 Catalyses biochemical reactions
Component of DNA (genetic memory)
Component of energy molecules
Key element in photosynthesis

43. P DEFICIENCY
 Dark purple discoloration on the leaf
tips, advancing down the leaf
Stunted plants with fewer shoots

44. ESSENTIAL MACRO NUTRIENTS: K
 Photosynthesis and movement of nutrients
Protein synthesis
Activation of plant enzymes
Regulation water use

45. K DEFICIENCY
 Marginal chlorosis and necrosis on older
leaves
Shorter internodes, stunting

46. ESSENTIAL SECONDARY NUTRIENTS
 Ca, Mg, S
Needed in moderate amounts

47. ESSENTIAL SECONDARY NUTRIENTS: CA
 Cell structure, membranes
Nutrient uptake
Reaction to negative environmental factors
Defense against disease

48. CA DEFICIENCY
Poor root growth, stunted dark rotting roots
Symptoms – in new growth (necrotic spots in young
leaves), leaves collapse before unrolling

49. ESSENTIAL SECONDARY NUTRIENTS: MG
Chlorophyll formation
Light-absorbing pigments
Amino acids and proteins
Resistance to drought and disease

50. MG DEFICIENCY
Pale green, chlorotic young leaves
Folded or twisted leaves
Symptoms similar to drought

51. ESSENTIAL SECONDARY NUTRIENTS: S
 Component of amino acids and proteins
 Component of enzymes and vitamins
 Formation of Chlorophyll

52. S DEFICIENCY
Seedlings: pale yellow
chlorosis on young
leaves
S deficient leaf (left)
normal (right)

53. MICRONUTRIENTS

54. MICRONUTRIENTS
 Fe, Mn, Zn, Cu, B, Mo, Cl
Needed in very small amounts
Involved in metabolic reactions as part
of enzymes (reused, not consumed)
Can be corrected with a fraction of
pound per acre rate

55. IRON (FE)
Respiration
Photosynthesis
Enzymatic Activator
Chlorophyll Synthesis

56. FE DEFICIENCY
 Failure to produce sufficient chlorophyll
 Interveinal chlorosis, green/yellow stripes
 New leaves turn white

57. MANGANESE (MN)
Component of various enzyme systems
for:
 energy production
protein synthesis, and
growth regulation

58. MN DEFICIENCY
Interveinal chlorosis
 Brown necrotic spots on leaves
White/gray spots on leaves
 Premature leaf drop and delayed maturity

59. ZINC (ZN)
Respiration
Photosynthesis
Enzymatic Activator
Chlorophyll Synthesis

60. ZN DEFICIENCY
First appear on middle-aged and old leaves
Muddy gray-green leaf color
Leaves appear drought stressed,
with necrotic spots

61. COPPER (CU)
 Catalyst in photosynthesis and respiration
 Constituent of enzymes
 Involved in building and converting amino
acids to proteins
 Carbohydrate and protein metabolism
 Plant cell wall constituent

62. CU DEFICIENCY
 Leaf tip die-back followed by a twisting or
wrapping of the leaves
 Delayed maturity
 Stunted, misshapen heads

63. BORON (B)
 Cell wall strength and development
 Cell division
 Fruit and seed development
 Sugar transport

64. B DEFICIENCY
 Saw tooth effect on younger leaves
Pale, “water-soaked” new shoots
Head sterility

65. MOLYBDENUM (MO)
 Conversion of nitrates (NO3 ) into amino
acids in the plant
 Conversion of inorganic P into organic
forms in the plant
 Protein synthesis
 Sulfur metabolism

66. MO DEFICIENCY
 Stunted plants
Flowering/Seed formation affected
Hollow stems
Brittle, discolored leaves

67. CHLORIDE (CL)
Photosynthesis
Stomata regulation
Gas and water balance in cells
Nutrient transport (K, Ca, Mg)
Disease resistance

68. CL DEFICIENCY
Physiological Leaf Spot Syndrome
White to brown spots on leaves
Starts in lower leaves at tillering
Similar to tan spot, smaller spots, no “halo”

69. MICRONUTRIENT DEFICIENCY
High soil pH (uptake decreases as pH
increases) – all but Mo
MT typical pH = 7-8, varies from 4.5 to 8.5
Low organic matter
MT typical OM = 1-4%
Cool, wet weather

70. MICRONUTRIENT PRODUCTS
Citri-Che Crop Mix 1 (N, S, Cu, Mn, Zn)
Gainer High Phos (N
Nitrogen, Phosphate, Potash, Sulfur, Boro
n, Copper, Iron, Manganese, Molybdenum
and Zinc