good nutrient management begins with routine soil testing
TRANSCRIPT
Good nutrient management begins with
routine soil testing
Soil testing helps farmers control higher input costsAuthor: TOM C. DORAN AgriNews Publications Date: October 10, 2008 Publication: Illinois AgriNews (La Salle, IL) Page: A1
DECATUR, Ill. - Rising fertilizer costs magnify the importance for growers to make sound agronomic decisions. "We really need to set realistic yield goals. These new hybrids have a much better yield potential," Dan Froehlich, director of agronomy at Mosaic Co., said at the recent Illinois Society of Professional Farm Managers and Rural Appraisers.
Soil testing is key to optimizing yields while not over-applying fertilizer.
PHOSPHOROUS
Goals of routine soil testingRapid
Cheap
Predictive
Widely applicable
Very different from research analysis of soil
Routine soil testing starts with the collection of "representative" soil samples in the field
followed by sample processing and analysis at a high throughput lab.
.
Routine soil testing – key steps
Routine soil testing concludes with formulation of fertilizer recommendations
based on interpretation of analytical results
Routine soil testing – key steps
At the lab (or sometimes before delivery to the lab), soil samples are dried and pulverized. Both of these processes can alter nutrient status.
Routine soil testing – key steps
Small sub-samples of the soil that arrives in the lab are isolated (gravimetrically or
volumetrically) and extracted with a selected mixture of chemicals.
Historically, different extracting solutions have been used for specific nutrients and different
kinds of soils.
Routine soil testing – key steps
By themselves, extractable nutrient levels are not informative.
Extractable nutrient levels provide an index of nutrient availability that can be interpreted
using results from field experiments.
Extractable nutrient levels are not directly related to most of the factors controlling nutrient availability during
a growing season.
moisture temperature microbial activity
rooting depth root health
The optimum number of soil samples is a
compromise between what should be done (to accurately represent the field) and what can be
done (cost).
How many samples should be collected from
a particular field ?
120 acre field
The U of I currently recommends collecting 1 composite sample per 2.5-
acres.
Some day soon soil testing
may consist of on-the-fly “sensing” of soil hundreds to thousands of times
per acre like a yield monitor
Soil management zones
Soil 1
Soil 2
Soil 3
Soil 4
A management zone approach is possible if knowledge of soil
variation is preexisting.
Knowledge of soil variation:
County soil survey mapsOld field boundaries
Past management records
How well do soil survey mapping units relate to crop productivity ?
"We've been moving in circles for years," says Gyles Randall, soil scientist, University of Minnesota. "Grid
sampling was the hottest thing going, but it was expensive. The question was if growers were getting their money's worth. If land is owned or under a long-term rental agreement, I like grid-based sampling, but under a short-term rental basis, you can hardly justify
it."
Matt Duncan, Key Agricultural Services, Macomb, Ill., is a strong believer in grid sampling. However, it is only one part of the equation. "We found that after multiple soil test cycles using grid sampling based variable rate
applications, in many cases highs were getting higher and lows were getting lower," says Duncan. "When we looked at the GPS yield data
history, we noticed the crop yields were consistently higher in the field areas with decreasing soil test values and lower in the areas of increasing
soil test levels."
Monitoring change over time will be much easier if soil samples are collected from the same locations each time the field is sampled.
Sampling locations can be identified using GPS equipment or by more traditional methods such as a
measuring wheel.
The U of I recommends compositing 5 soil cores from within a 10-foot radius to represent each
sampling location.
Important soil sampling considerations
Avoid areas that are clearly not representative (old manure piles, eroded knolls…)
Use clean sampling tools
Collect samples from a depth that is appropriate for your soil management system:
conventional tillage = 6-8”
no-till or lawn = 4”
Sample at ~ the same time every year !
Late summer and fall are often recommended as the best times for collecting soil samples
- the soil samples used for soil test correlation are normally collected in the late summer/fall
- potassium test results are most reliable during the late summer/fall
- nutrient uptake by summer crops has occurred
- soil is more likely to be dry
Soil testing labs are normally the busiest in the late summer and fall
Choose a lab and stick with it !
Different labs often use different
analytical and interpretation
methods
2006 ISTA Members (alphabetical)
AA&L Great Lakes Laboratories, Inc.Lois K. Parker3505 Conestoga Dr.Ft. Wayne, IN 46808Tel: 260-483-4759Fax: 260-483-5274Additional member: Julie Bruggner
AgriEnergy ResourcesGary Cambpell21417-1950 E. St.Princeton, IL [email protected] member:Ann Berry - [email protected]
AgSource Cooperative ServicesSteve Peterson106 N. Cecil St., PO Box 7Bonduel, WI 54107Tel: 715-758-21Fax: [email protected] member: Dave Sievert
Alvey LaboratoryRandy AlveyPO Box 175Belleville, IL 62222Tel: 618-233-0445Fax: [email protected] member: Dan Jackson
ASM Inc.Don Van EngelenburgPO Box 3655Champaign, IL 61826Tel: 217-356-5756Fax: [email protected] Ag ServicesVicky WagnerRR1, Box 23Lakewood, IL 62438Tel: [email protected] Lab, Inc.Mark Flock308 E. Main St.New Knoxville, OH 45871Tel: 419-753-2448Fax: [email protected] Illinois Soil TestingLarry Camp29689 Bowman Station RoadJerseyvilleIL62052Tel: 618-535-5052Fax: [email protected] FSJulie Barr20048 Webster RoadDeKalb, IL 60115Tel: 815-756-2739Fax: [email protected] Inc.Tim Smith107 S. State Street, Suite 300Monticello, IL 61856Tel: 217-621-6117Fax: 217-621-7628
GGeophyta, Inc.Nathan Wright2685 CR 254Vickery, OH 43464Tel: 419-547-8538Fax: [email protected] LaboratoriesGeorgia SteffenPO Box 61, 23877 E. 00 North RoadCropsey, IL 61731Tel: 309-377-2857Fax: [email protected] member: Herb Steffen
Greene County Farm BureauStephanie Knittel319 6th St.Carrollton, IL 62016Tel: 217-942-6958Fax: [email protected] FSJohn Irle1509 East University Ave.Urbana, IL 61802Tel: 217-384-8300Fax: [email protected]’s Soil Testing CenterDale Ingram7 Oaks Farm, 13343 Fitschen RoadAthens, IL 62613Tel: 217-636-7500Fax: [email protected]
KKey Agricultural ServicesDean Wesley114 Shady LaneMacomb, IL 61455Tel: 309-833-1313Fax: 309-833-3993Additional members: Tad Wesley
KSI LaboratoryDavid Brummer202 S. Dacey Dr.Shelbyville, IL 62565Tel: 217-774-2421Fax: [email protected] MM & R Ag ServicesMick Capouch16747 W 200NMedaryville, IN 47597Tel: 219-843-4491Fax: [email protected] Valley Soil Testing LabPatricia Reed1074 Broadway St.Hamilton, IL 62341Tel: 217-847-3539Fax: [email protected] Soil Testing Plus, Inc.April HolmesPO Box 540, 117 E. MainToulon, IL 61483Tel: [email protected] members: Steve Wiedman, Kim Witt
PPike County Farm BureauBlake RoderickPO Box 6Pittsfield, IL 62363Tel: 217-285-2233Fax: [email protected] ConsultingDonald HackersonPO Box 41Windsor, IL 61957Tel: [email protected] Inc.Ernest Bartoli22256 3375 E. St.Arlington, IL 61312Tel: 815-638-2522Fax: [email protected] Illinois Soil LaboratoryRandy Klenke375 N. Old Route 66, PO Box 448Hamel, IL 62046Tel: 618-633-1811Fax: [email protected] Soil Testing LabGreg Phillips1200 N. Kickapoo StreetP.O. Box 841Lincoln, IL 62656-0841Tel: 217-735-4233Fax: [email protected] Analytic Inc.Vernon Pabst1087 Jamison RoadWashington Court House, OH 43160Tel: 740-335-1562Fax: [email protected] Soils Inc.David Allen108 S. Crystal Lane, PO Box 226Fairbury, IL 61739Tel: 815-692-2626Fax: [email protected] members: Bob Charter, Corina Ardelean, Sally Goembel, Greg Ikins
Universal Analytical LaboratoryScott Diekemper15006 State Route 127Carlyle, IL 62231Tel: 618-594-2627Fax: [email protected] member: Adam Dulle
WWaters Agricultural Laboratories Inc.Rhonda Werner2101 Calhoun RoadOwensboro, KY 42301Tel: 270-685-4039Fax: [email protected]
29 member labs in 2006
Members of ISTA are required to participate in a quality control program referred to as the Split Sample Soil Test Comparison Program. In this process, six samples are sent quarterly to all member labs. The labs test the soil and return the raw data to an independent accounting firm.
This information is then gathered yearly and used in a Reliability/Repeatability report. A level of proficiency is required to receive a Certificate of Good Standing from ISTA. This certificate is the member's accreditation and is their clients' assurance that the information they receive is reliable, consistent and accurate.
Some ISTA member labs also participate in an additional National Proficiency Testing Program (NAPT).
Quality Control
A variety of soil extractants have been used (and continue to be used) by soil testing labs in the
Midwest region.
Examples of extractants: Bray 1, Olsen, Ammonium acetate, Hot water, DTPA
of nutrient analysis
The Mehlich 3 extractant was developed by Dr. Adolph Mehlich to estimate plant availability of macronutrients and micronutrients in soils with a wide range of physical and chemical properties. Adopted by the NCDA soil testing lab in 1981, the Mehlich 3 extractant has reduced analytical costs by replacing multiple extraction methods.
Reference: Mehlich A. 1984. Mehlich-3 soil test extractant: a modification of Mehlich-2 extractant. Commun Soil Sci Plant Anal 15(12):1409–16.
Composition: (0.2N CH3COOH + 0.25N NH4NO3 + 0.013N HNO3 + 0.015N NH4F + 0.001M EDTA)
Mehlich 3 extractant
Plant root simulator probes
Ion exchange resins
Most labs use an Inductively Coupled Plasma Atomic Emission spectrometer to analyze extracts for multiple elements
Meaningful interpretation of soil test results requires field calibration
100 % yield
50 %yield
http://www.ipm.iastate.edu/ipm/icm/2003/11-17-2003/mehlich3.gif
Soil test P concentration (ppm)
Relationship between crop yield and soil test K
Response curves are derived from calibration data – response curves do
not describe all the variation in calibration data !
http://www.lamotte.com/
Results may be accurate but have little meaning without field calibration
Recommendations
Analytical results
So what do the numbers mean ???
Sufficiency approach
Critical levels of extractable nutrients can be identified using field experiments
Different soils have different critical levels of extractable nutrients
Build and maintenance approach
Maintenance applications of fertilizer (i.e., replacing nutrients removed in
harvested crops)make sense conceptually
**but** do not necessarily make sense
economically !
Soil is a black box !!!!
Regional variation in soil test K
http://soilfertility.unl.edu/Materials%20to%20include/2001%20NCR%20potassium_files/image008.gif
WHY??
Changes in soil test results between 2001 and 2005
Some of these trends are hard to explain !
Subsoil nutrient levels are probably getting depleted
Nutrient balancing concepts
Nutrients interact in plant and soil systems. Some important nutrient interactions include ammonium-calcium, phosphorus-iron, phosphorus-copper, phosphorus-zinc, and potassium-magnesium-calcium.
Some consultants and private labs place great emphasis on “base cation ratios”.
Typical target ratios: 65-75% Ca : 10-15% Mg : 2-5% K
Nutrient interactions and proper nutrient balance should be considered in relation to
nutrient supply – i.e. the availability of nutrients in the soil.
Nutrient supply is important because “recommended nutrient ratios" in soil or
plant tissue are possible when nutrients are deficient or excessively high.
Claims associated w/ “balanced” Ca:Mg ratios
• Improves soil structure• Reduces weed populations
• Stimulates populations of earthworms and beneficial microorganisms• Improves forage quality
• Excess soil Mg “ties up” and promotes leaching of other plant nutrients
• Better “balance” of soil nutrients• Improved plant and animal health
• “Cows milk easier”
Very little research indicates that specific cation ratios are critical for crops in the mid-west or any
other region of the US.
Ca is the cheapest non-acid cation, excessive levels of Mg and K
interfere with crop uptake of Ca, and adequate Ca is important for crop
quality.
U of WI Research• Alfalfa yield related to exchangeable K and soil pH,
not Ca:Mg ratio
• Neither Ca or Mg additions affected weeds
• Earthworms related to organic matter, not Ca:Mg ratio
• Alfalfa quality related to pH and stand, not Ca:Mg ratio
• No justification for using calcitic over dolomitic lime or adding extra Ca
Why no response to “Ca:Mg ratio” ?
• Ca and Mg levels are relatively high in soil solution compared to plant uptake
• Plant K uptake is 2-4 times that of Ca and Mg• Ca and Mg are supplied to roots by mass flow
According to the U of I, Ca deficiency does not occur in Illinois when soil pH is
greater than 5.5.
“Calcium deficiency associated with acidic soils should be corrected by using limestone. The laboratory procedure used for Ca is easy and
reliable—probably more accurate than the K test— but since the deficiency does not exist, there is
no reason to recommend the test”.
Gary Zimmer, WI farmer and author of
The Biological Farmer
Keith Schlapkohl, IA Farmer and owner of a gypsum spreading company
Cation balancing and annual applications of gypsum - unorthodox practices used by some
innovative farmers in the mid-west region.
Many crop consultants advocate greater use of calcium.
http://www.turfformula.com/images/images-new/super-cal.jpg
A wide range of calcium products
are available on the market.
IOWA Farmer Today – 3/25/2005 Schlapkohl believes gypsum increases production by improving water infiltration.
He says gypsum helps loosen heavier soils, such as a clay soil. The soil becomes more sponge-like and less compact, Schlapkohl notes.
The current compaction levels on his fields are 175 pounds per square inch (psi) at eight inches deep and 155 psi deeper than eight inches.
For comparison, soil compaction is considered a problem when it is greater than 300 psi, which prevents root penetration.
He also has noticed more worm holes in the soil.
"Its chemical tillage," Schlapkohl he says of using gypsum.
Comments » Ed Winkle wrote on Sep 18, 2006 6:17 AM:" I had the opportunity to visit Keith in August, take pictures, talk to him and look at his
crop. His soil health is amazing. Thanks for publishing his story. Ed Winkle HyMark Consulting LLC Martinsville, Ohio "
http://iowafarmertoday.com/articles/2005/03/25/crops/01nitrogenuse.txt
Is gypsum good for the soil ??
Gypsum (CaSO4 * 2H2O) is much more soluble than calcium carbonate (CaCO3)
Gypsum is a neutral salt
Can be used to reduce aluminum toxicity in subsoils
Can be used to replace Na in high Na soils – soil structure will improve when
Na is replaced by Ca
Can be used to increase infiltration/reduce crusting in humid regions but needs to be reapplied
regularly
Good source of S
Fertile waste 19 June 1999 From New Scientist Print Edition. SPREADING waste from power stations over fields can boost the yield of food crops. The waste helps water infiltrate the soil, reducing runoff and soil loss.The scrubbers that clean the emissions of coal-burning power stations produce gypsum, which is also found naturally. Sulfur dioxide gas reacts with ground-up limestone in the scrubbers to form the calcium sulfate mineral.
Darrell Norton of the US Department of Agriculture's National Soil Erosion Research Laboratory in West Lafayette, IN, found that using the waste product cut soil loss by a quarter in the lab. "New technologies to improve air quality have produced more and more gypsum by-products with potential for beneficial use in agriculture," says Norton, who presented his findings to the 10th International Soil Conservation Conference in West Lafayette last month.
Ken Curtis, a farmer from Prairie City, Illinois, who is taking part in Norton's field trials, found that spreading 5 tons of gypsum per acre raised the harvest of soybeans by almost 7 per cent. "I didn't expect that much response," he says. News of the technique has spread and farmers are now asking power stations to supply them with gypsum. Power plants in the US produce about 100 million ton each year, enough to provide over 1 ton per acre for a quarter of US farmland.
http://www.newscientist.com/article/mg16221911.700-fertile-waste.html
Is S a limiting nutrient ?
Sulfur deficiencies are increasingly common
- Enforcement of clean air standards has reduced SOx emissions from power plants and industry by > 50% in
the last 2 decades
- The S contents of current fertilizers are far lower than those used historically.
- Higher crop yields are removing higher amounts of S from soils as well as increasing the need for S.
Historically, experiments conducted across Illinois have only identified a response to sulfur at five of 85 locations.
Correlation between yield increases and measured S levels is low, indicating that soil test S does not reliably predict sulfur
need.
Sulfur Deficiency in Corn
Overall light green color, worse on new leaves during rapid
growth.
Overall light green color, worse on new leaves during rapid
growth.
Sulfur Deficiency in Wheat
Overall light green color, worse on new leaves during rapid growth.
Alfalfa is the crop most likely to respond to sulfur (S) application in Illinois. Corn has only been shown to respond
in a few experiments, primarily in northwestern Illinois.
Organic matter is the primary source of sulfur in soils, so soils low in organic matter are more likely to be deficient
than soils high in organic matter.
S deficiency is most likely on sandy soils.
Sulfur emissions in Wisconsin over the last 2 decades
a
The Soil Doctor System
Soil pH and lime requirement can
vary widely within fields
pH measurements on the fly
MISS has incorporated EC, NDVI readers and soil testing so that the client can rest assured that low application amounts prior to planting will not hurt the crop yield. By
going a step further and taking stalk nitrate tests at those same locations of soil testing, the client is able to further define the management map and customize the
following nitrogen applications to occur.
