Excellence in Ag Sciences Day 2011
Educators connecting Agriculture to Research,
In-Field Tests for
Soil Quality & Health
John W. Doran
Editor: Renewable Agriculture & Food Systems,
Co-founder Renewing Earth and Its People Foundation,
USDA-ARS Cooperator, Former President SSSA,
Agronomy & Horticulture, Univ. Nebraska, Lincoln, NE
Continuing education : Appalachian School of Life
THREATS to SUSTAINING
EARTH & ITS PEOPLE
POVERTY- - - - - of Affluence - - - - - WAR
• Population Growth
Adequate Food and
Standard of Living
• Fossil Fuel Dependence
$ and environmental Costs
ENVIRONMENT
HEALTH/AIDS
Early settlers plowing the prairie – To survive in a
seemingly hostile environment
2-3 fold grain yield increases from industrial
agriculture have come at a fairly high cost and
always subsidized by oil
Green revolution scientists shocked to discover
that feeding the world could impair the environment
People who farmed sustainably for over 40
centuries now lose 18 lbs of farmable soil
for every 1 lb of food eaten
For the first time since the dawn of civilization we
now have the technological capacity to change the
global environment
Need Soil Management to economically meet food production needs
and maintain quality of essential soil, water, and air resources
Renewable Agriculture & Food Systems
SUSTAINABLE AGRICULTURE
An agriculture that can EVOLVE toward:
• Greater human UTILITY
• Greater EFFICIENCY of RESOURCE use
• Favorable BALANCE with the
ENVIRONMENT
(Richard Harwood, MSU, 1990)
Sustain. Strategies & Indicators
• Conserve soil organic matter
Change in time/space (Color chart/Density)
• Minimize soil erosion
Infiltration/compaction/runoff (Ring & Probe)
• Balance production with environment
Seasonal soluble N & P, leaching and loss of
greenhouse gases (EC probe & Strips)
• Better use of renewable resources
EC, pH, Nitrate, Respiration/temperature
USDA Soil Quality Test Kit
“Helped translate science into practice.”
“Test kit has facilitated partnerships between
farmers and ag specialists”
Methods for Assessing Soil Quality
Edited by: J.W. Doran and A.J. Jones
Soil Science Society of America, Special Pub. No. 49
(Harvey Gaynor- Australian Cotton Producer)
“I need help from Scientists with
TOOLS for MANAGEMENT
more than
INDICATORS of SOIL QUALITY”
We need PARTNERSHIPS to get
KNOWERS working with DOERS
Measuring Agricultural Sustainability at the
Farm Level
Farmer/Society
Needs
Acceptable
• Yields
• Profits
• Risk
• Energy($) Ratio
Output/Input
Resource/Environmental
Conservation
Adequate/Acceptable
• Soil organic matter
• Soil depth
• Soil cover
• Leachable Salts (NO3)
Electrical Conductivity
(After Gomez et al., 1996)
Intensive Soil Quality Assessment on a Field Scale
Irrigated Field Near Gibbon, in Central Platte Region of Nebraska
Organic Matter (%
Northing
3.3
2.9
2.5
2.1
1.7
1.3
Easting
Soils Map
Aerial
Photograph
Intensive Grid
Sampling
(40’ x 80’ Grid)
1.3
1.7
2.1
2.5
2.9
Organic Matter (%)
3.3
Breaking New Ground
C management at the
Farm Scale
SQ Vest- Ring of many uses
Infiltration
Soil Compaction
Water-holding Capacity
Bulk Density & WFPS
Respiration (3h Solvita)
(field temp. & WFPS)
Potential N Mineralization
SQ INDICATORS for PRODUCERS
• Direction of CHANGE in SOIL OM with TIME
Visual or Remote Sensing of Soil Color, Soil Analysis
• Visual : DUST, RUNOFF, RILLS, SEDIMENT
Soil Properties: Depth, OM, Texture, % Cover, Infiltration
• CROP and VEGETATION Characteristics
Yields, Color, N content, Rooting (Visual/Remote Sensing)
Soil Physical State / Compaction (Dig a Hole)
• Input / Output Ratios of COSTS and ENERGY
Soil & Water Nitrate Levels to indicate Efficient N Use
Soil Acidification (leaching with inefficient N fertilizer use)
Soil Electrical Conductivity (EC) :
Indicator of Soil Health and activity of
Plants, Microorganisms, and Nematodes;
Range of units (dS/m) in wet soil:
0 to 1 units: best soil health
1 to 2 units: Caution, problem for:
• Sensitive plants
(d.e. bean, cowpea, pepper, orchardgrass, berseem
clover, and potatoes)
• Nitrogen bacteria
(more Nitrous Oxide evolved offsets benefits of tieup of atmospheric CO2 in SOM; 1 N2O = 300 CO2)
• Plant parasitic nematodes
(may have a selective advantage at EC>1)
Rapid estimator of Soil Nitrate-N
(low lime soils, pH < 7.2)
140 X EC <= ppm Nitrate-N
Late Spring Nitrate-N Test for
non-limited corn yield
(Early June, top 12” soil, corn 12” tall 4-6 leaves)
EC differential of 0.15 units (21 ppm nitrate-N) in fertilized corn
or 0.10 units (14 ppm nitrate-N) with manure or after soybean or
alfalfa.
Nitrate loss after heavy rain and water logging
If soil EC is 0.01, the Nitrate-N content is < 1.4 ppm
Single Most Valuable
Soil Quality Indicator
“Dig A Hole”
OUR CHALLENGE
Charting a course
towards Sustainability
by
Translating Science into Practice
The End
of the
Beginning
Achieving Global
Sustainability
• What can I do,
I’m only one person?
• Change must come
from within ourselves.
• We must be the change that we want in
the world! (Mahatma Gandhi)
Love One Another
Care for the Earth
Thank
You!
Post-Millennium Agriculture
“Returning to Basics”
Thank You for Your Attention
100
NO3-N (ppm)
pencil probe
80
NO3-N = -1.7 + 105.6(EC)
r2 = 0.77
60
40
20
0
0.0
0.1
0.2
0.3
0.4
0.5
EC (dS m-1)
0.6
0.7
S. Gommes, 172 NE
& IA Sites, 2003
Measured Check
Measured Inorganic Fertilizer
Measured Manure
Estimated Check
Estimated Inorganic Fertilizer
Estimated Manure
-1
N-Mineralization (kg N ha )
80
60
40
20
0
0
4
8
12
Time (weeks)
16
Figure 3. In situ N-mineralization and net mineralization predicted from
Bulk Soil Electrical Conductivity.
20
Lincoln EI CC-M2 soil
0.030
0.0030
60 % WFPS
N2O
EC 0.40
EC 0.50
EC 1.0
EC 1.5
EC 2.0
0.0025
g N2O-N m-2
0.0020
90 % WFPS
0.43
0.025
0.89
0.53
0.020
0.93
0.0015
0.015
0.84
1.63
0.0010
0.010
1.94
0.51
0.0005
0.005
0.39
0.37
0.0000
0.000
0
2
4
6
8
10
Time, d
EC0
0.38
0.53
1.02
1.54
2.04
Nitrate-Nitrogen, ppm
day 0
day 10
27
60
27
50
27
1
27
1
27
1
12
0
2
4
6
8
Time, d
EC0 Nitrate-Nitrogen, ppm
day 0
day 10
0.38
27
0
0.53
27
0
1.02
27
1
1.54
27
0.5
2.04
27
1
10
12
1.4
y = 0.241 + 0.820
r ² = 0.997
Bad Boy II Field EC dS m-1
1.2
1.0
0.8
0.6
Control
200 kg N ha-1
300 kg N ha-1
Regression
0.4
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
Markson1 Laboratory EC1:1 dS m-1
1.2
1.4
55 *
45
40
JD193, Corn 1.5m tall
193
a Fertilizer applied to NCK plots only Julian
b Fertilizer applied to NCK, CP and MP plots
*
*
*
Day of EM survey, 1999
334
*
313
*
JD263, Cover crop
JD251, Corn harvested
JD238, Corn ear filled
80
279
250
236
JD215, Corn silked, 3m tall
b
*
*
215
JD180, Corn 0.7m tall
180
a
*
JD201, Fertilizer applied
JD165, Fertilizer applied
154
159
165
60
JD134, Field planted
75
144
50
**
JD121, Field disked
65
JD110, CN & MN applied
70
133
75
82
89
97
102
110
119
Conductivity, mS/m
Electrical Conductivity
Cover
No Cover
Significant (P <0.05)
*
*
*
*
*
*
Soil Sampling Map of a Full Section in NE
Colorado
Based Upon Measurements of Electrical
Conductivity
- Sampling
Site
N
1999 Wheat Yields vs.
ECa
100
(bu ac-1)
Yield
80
60
40
20
0
5
10
15
20
Veris EC
(mS m1)
25
30
35
Glomalin
-1
(mg g soil)
Glomalin ECa Class Means
0.8
ECaClass
Low
Med. Low
Med. High
High
0.6
0.4
0.2
0.0
Wheat Corn
Millet Fallow
“Worldwide changes are transforming
American agriculture into an endeavor
focused not only on efficient food and fiber
production but also on delivering
improved public health, social well-being, and
a sound environment”
(FRONTIERS IN AGRICULTURAL RESEARCH:
Food, Health, Environment, and Community, NRC,
NAS, Washington, D.C.2002)