Presentation Outline. Soil Sampling. Automation and Precision. Soil Test
Management Units Use field characteristics (soil type, size, history)
Using Fertilizer and Soil Amendments by Prescription Improves Farming Practices...
Soil Testing and Reports Fertilizer Guidelines Plant nutrients (N-P-K-S…) and pH Fertilizer materials and lime Least-cost application Tracking nutrients and yield
Collect 15 – 20 subsamples randomly about the management unit. Combine into one composite sample to submit to certified lab.
Soil Test
Automation and Precision
Accurate determination of soil status 2 million lb of soil Efficient Fertilizer Program
Economics Environment
in the top 6" of an acre
Optimizes forage growth Assess property value
Cost of Improvements
1
Sampling Depth
Soil Test Report: Other items
Plow depth
Nitrogen (N) and Sulfur (S)
Root zone
6" grass-clover 12" alfalfa
Very mobile in soil & soil test results not used for fertilizer recommendations
Pastures/hay ground OSU fertilizer guide (FG 63)
Variable-depth sampling
40-60 lb/ac N (1–3 times per year) 20 – 30 lb/ac S in the spring
Nitrogen application refined
EM 9014 - Evaluating Soil Nutrients and pH by Depth http://extension.oregonstate.edu/catalog/
https://catalog.extension.oregonstate.edu/
Soil Test Report: Other items
Soil Test Report: Main items Sample
Phosphorus
Magnesium
Calcium Ca-ppm
Soil pH
33
252
614
1867
5.5
5.7
Olsen
K-ppm
Mg-ppm
Cation Exchange Capacity (CEC)
Potassium
P-ppm Weak Bray
PNW614
pH
Buffer* Index
1
15
2
12
31
298
780
2520
5.5
5.7
3
9
38
319
791
2651
5.6
5.7
Indicates potential to hold plant nutrients Capacity of soil to exchange cations (Ca, Mg, K, Na, H, Al) Highest in clay soils and high organic matter soils
Base saturation Percentage of exchange sites occupied by basic cations (Ca, Mg, K, Na) If 100%, there is no exchangeable acidity (acidic cations H and Al).
Neither used in OSU fertilizer recommendations
Not very precise Lack evidence for agronomic response
2
Fertilizer and Lime Materials (FG 52)
Cation exchange in action
https://catalog.extension.oregonstate.edu
Compare Soil Test with Crop Needs
Fertilizer Materials
Use OSU Fertilizer Guides (FG) and Pacific Northwest (PNW) bulletins http://extension.oregonstate.edu/catalog/
N-P-K-S
All values are on a percentage basis (%)
Alfalfa (FG 18, FG 60, PNW 611) Grass & Legume Pastures and Hayground (FG 22, FG 63) Soil Test Interpretation Guide (EC 1478) Other crop fertilizer guides available FG 52 - Fertilizer and Lime Materials FG 76 - Irrigation Water Quality EM 8852- Early Spring Forage Production for W. OR Pastures PNW 614 - Pasture and Grazing Management in the Northwest
Nitrogen N
Phosphorus P2O5
Potassium K2O
Sulfur S
Name
16
16
16
6
Triple-16
46
0
0
0
Urea
21
0
0
24
Ammonium Sulfate (AMS)
11
52
0
0
Mono-AmmoniumPhosphate (MAP)
0
0
60
0
Potash
16
20
0
14
Ammonium-PhosphateSulfate
Quantities of Nutrients from selected fertilizer applications
Soil Test Report: Main items
Fertilizer
lb/a applied
= lb/a N
= lb/a P
= lb/a K
= lb/a S
16-16-16-6 Triple-16
200
32
32
32
12
46-0-0-0 Urea
130
60
0
0
0
21-0-0-24 AMS
200
42
0
0
48
200
22
104
0
0
200
0
0
120
0
Example
Sample
Phosphorus P-ppm Weak Bray
Olsen
Potassium K-ppm
Magnesium Mg-ppm
Calcium Ca-ppm
Soil pH
pH
Buffer* Index
1
15
33
252
614
1867
5.5
5.7
2
12
31
298
780
2520
5.5
5.7
3
9
38
319
791
2651
5.6
5.7
percentage in fertilizer X Amount product applied = pounds nutrient applied __________
FG 63 pH is okay, Ca and Mg are good P is low, add 60 – 100 lb P2O5/ac K is good (>200)
0.16 X 200 = 32
11-52-0-0 MAP 0-0-60-0 Potash
3
Crop-specific pH
pH 5.5 – 6.5 for grass and clover
Raising pH with lime
Sub-clover and tall fescue relatively acid tolerant White clover and orchard grass less tolerant
Ag Lime CaCO3 Dolomite CaMgCO3 Not all Ca products are good liming agents
pH > 6.5 for alfalfa
Gypsum or CaSO4 does not change pH Rock dust?
Nutrient availability vs. pH Soil Amendments Ag composts Wood ash
Analyze as composts or ash (tell lab) Some increase pH (lower acidity in soil)
Lime Application Rates
Lime score (rating)
(100-score lime)
If SMP Buffer test for lime is : Under 5.5
Apply this amount of lime (t/a): 4–5
Calcium Carbonate Equivalents (cce)
5.5 – 5.8
3–4
5.8 – 6.1
2–3
Fineness Factor (ff) Moisture factor (mf) Lime score =cce x ff x mf
6.1 – 6.5
1–2
Over 6.5
0-1
pure CaCO3 = 100
Price sources and adjust tonnage applied based on lime score
4
Calculating Lime Savings
Cost Benefit Analysis
Example need of 60 lb N and 20 lb S per acre
$35 cost to test soil (mailing & Lab fee) of a 10 acre field
AMS = 21-0-0-24
60 lb N/.21 = 286 lb AMS 286 lb AMS x .24 = 69 lb S 286 lb AMS/100 X 110 acidity index
Cost
Cost
$120/T lime Guess 2 T/acre Soil test calls for 1 T/acre Difference is 1 T/acre X 10 acre X $120/T = $1200 savings in materials
Cost Benefit Analysis
Example need of 60 lb N and 20 lb S per acre
Ureasul (½ AMS + ½ Urea; 33-0-0-12)
If forage loss is 1 Ton/acre
Lime not applied
1 T/ac x 10 acre = 10 T loss Hay $200/T x 10 T = $2,000 loss
Difference
$2000 loss + $1200 not spent = $800 net loss
Acidifying Potential for Fertilizers Fertilizer Ammonium Sulfate Urea Ammonium Phosphate-sulfate
Grade 21-0-0-24
60 lb N/.33 N = 182 lb Ureasul 182 lb Ureasul x .12 S = 22 lb S 182 lb Ureasul/100 x 91 acidity index = 166 lb lime to neutralize acidity
Cost
$120/T x 10 T = $1200 not spent
286 lb AMS x $482/T = 286 lb x $482/2000 lb = $68.93 315 lb lime x $120/T = 315 lb x $120/2000 lb = $18.90 Total cost of $87.83 per acre in materials Application cost for 601 lb material Environmental cost of leached sulfur
Calculating Lime Savings
(continued)
Or add too little and suffer production loss
= 315 lb lime to neutralize acidity
182 lb Ureasul x $600/T = 182 lb x $600/2000 lb = $54.60 166 lb lime x $120/T = 166 lb x $120/2000 lb = $9.96 Total cost of $64.56 per acre in materials Application costs of 342 lb of materials
Cost Comparison AMS vs. Ureasul
*Acidity 110
46-0-0
71
16-20-0-13/15
88
Item
AMS
Ureasul
Difference
Materials cost ($/ac)
$87.83
$64.56
$23.27
Materials applied (lb)
601 lb
348 lb
253 lb
Environmental cost (lb S)
49 lb
0 lb
49 lb
Time (hrs.)
X hr.
Y hr.
$Z
*Pounds of 100 score lime needed to neutralize the acidity produced by fertilizer application of 100 lb/ac
5
Fertilizer Application to Pastures & Hay Ground
Seasonal Dry Matter Production
RESULTS
FG 63
Forage Dry Matter, lb/a
Early N application provides early-season forage
3000 2500 2000 1500 4/2 N 1000 2/5 N 500 0 25-Jan 15-Mar 4-May 23-Jun 12-Aug
Traditional Control (0) Early N
Date EM 8852 , https://catalog.extension.oregonstate.edu Early Spring Forage Production for Western Oregon Pastures
EC 1478-E Soil Test Interpretation Guide
Hay Removal Costs Nutrients
Each ton of typical forage hay removes about
12 to 15 pounds of phosphate (P2O5) 50 to 60 pounds of potash (K2O)
Also, need to provide about 30 to 50 pounds of nitrogen per acre on grassy stands (i.e. low legume component)
Kopecky, et. al (2008)
Fertilizer Application
Other Sources of Nitrogen
N2 fixation by legumes
Fall
Lime - sampling year
Ag lime (CaCO3) Dolomitic lime (+Mg)
Phosphorus (P) Potassium (K) Some Nitrogen (N)
Split applications (early & late)
Sulfur Boron – sampling year
N from urine and feces
Between hay cuttings
Amounts (20 – 300 lb N/ac) Available to grasses as legumes die
Nitrogen
Other nutrients (yearly)
Spring
Amounts vary w/ source Distribution varies w/ stock
Nitrogen (urea)
6
Fertilizer and Money
Agronomic response to inputs Improved production Spread over the cost of other inputs
Time Equipment Fuel
Animal Unit Month (AUM) = Forage
Animal Unit Month (AUM) = lb of forage required for one animal unit for one month
1000 lb cow eats
Forage Yield Measure yield (tons of hay and animal unit months carried)
Compare your yield (t/ac) with
comparable production situations soils interpretation sheets for potential
websoilsurvey.nrcs.usda.gov
Track yield over time with fertilizing according to soil test.
1000-pound cow +/- calf
Use enterprise budget sheets to track forage production costs
Animal Unit (AU)
~
2.5% body wt in feed/day
1000 lb x 0.025 = 25 lb daily feed intake 25 lb/day x 30 days/month = 750 lb/mo
Summary
Soil test and fertilize according to test Use fertilizer knowledge for least cost Know your potential yield