good nutrient management begins with routine soil testing

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 61356815-872-7790815-872-1928gcampbell@agrienergy.netAdditional member:Ann Berry - aberry@agrienergy.net

AgSource Cooperative ServicesSteve Peterson106 N. Cecil St., PO Box 7Bonduel, WI 54107Tel: 715-758-21Fax: 78715-758-2620speterson@agsource.comAdditional member: Dave Sievert

Alvey LaboratoryRandy AlveyPO Box 175Belleville, IL 62222Tel: 618-233-0445Fax: 618-233-7292alveylab@aol.comAdditional member: Dan Jackson

ASM Inc.Don Van EngelenburgPO Box 3655Champaign, IL 61826Tel: 217-356-5756Fax: 217-356-8609asm@volomail.netBBlacklog Ag ServicesVicky WagnerRR1, Box 23Lakewood, IL 62438Tel: 217-774-4838blacklogtesting@yahoo.comBrookside Lab, Inc.Mark Flock308 E. Main St.New Knoxville, OH 45871Tel: 419-753-2448Fax: 419-753-2949mflock@blinc.comCCentral Illinois Soil TestingLarry Camp29689 Bowman Station RoadJerseyvilleIL62052Tel: 618-535-5052Fax: 618-498-1918lccist@sincsurf.netConserv FSJulie Barr20048 Webster RoadDeKalb, IL 60115Tel: 815-756-2739Fax: 815-756-2795webster@conservfs.comCropsmith 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: 419-547-8538geophyta@nwonline.netGMS LaboratoriesGeorgia SteffenPO Box 61, 23877 E. 00 North RoadCropsey, IL 61731Tel: 309-377-2857Fax: 309-377-2017office@gmslab.comAdditional member: Herb Steffen

Greene County Farm BureauStephanie Knittel319 6th St.Carrollton, IL 62016Tel: 217-942-6958Fax: 217-942-9054greenefb@gcctv.comIIllini FSJohn Irle1509 East University Ave.Urbana, IL 61802Tel: 217-384-8300Fax: 217-384-6317jirle@illinifs.comIngram’s Soil Testing CenterDale Ingram7 Oaks Farm, 13343 Fitschen RoadAthens, IL 62613Tel: 217-636-7500Fax: 217-636-7548istc1@sbcglobal.net

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: 217-774-2866ksilabdbrummer@consolidated.net    MM & R Ag ServicesMick Capouch16747 W 200NMedaryville, IN 47597Tel: 219-843-4491Fax: 219-843-4491mick@capouch.netMississippi Valley Soil Testing LabPatricia Reed1074 Broadway St.Hamilton, IL 62341Tel: 217-847-3539Fax: 217-847-3539mvsoil@mchsi.comMowers Soil Testing Plus, Inc.April HolmesPO Box 540, 117 E. MainToulon, IL 61483Tel: 309-286-2761aholmes@mowersplus.comAdditional members: Steve Wiedman, Kim Witt

PPike County Farm BureauBlake RoderickPO Box 6Pittsfield, IL 62363Tel: 217-285-2233Fax: 217-285-2421pikecfb@pikecfb.orgPro-Ag ConsultingDonald HackersonPO Box 41Windsor, IL 61957Tel: 217-459-2029proagllc@consolidated.netSSoiltech Inc.Ernest Bartoli22256 3375 E. St.Arlington, IL 61312Tel: 815-638-2522Fax: 815-638-2522ebart@mtco.comSouthern Illinois Soil LaboratoryRandy Klenke375 N. Old Route 66, PO Box 448Hamel, IL 62046Tel: 618-633-1811Fax: 618-633-1810sisl@madisontelco.comSparks Soil Testing LabGreg Phillips1200 N. Kickapoo StreetP.O. Box 841Lincoln, IL 62656-0841Tel: 217-735-4233Fax: 217-732-4626sstlinfo@aol.comSpectrum Analytic Inc.Vernon Pabst1087 Jamison RoadWashington Court House, OH 43160Tel: 740-335-1562Fax: 740-335-1104vernon@spectrumanalytic.comUUnited Soils Inc.David Allen108 S. Crystal Lane, PO Box 226Fairbury, IL 61739Tel: 815-692-2626Fax: 815-692-4483agronomist@unitedsoilsinc.comAdditional members: Bob Charter, Corina Ardelean, Sally Goembel, Greg Ikins

Universal Analytical LaboratoryScott Diekemper15006 State Route 127Carlyle, IL 62231Tel: 618-594-2627Fax: 618-594-2637ualab@ualab.comAdditional member: Adam Dulle

WWaters Agricultural Laboratories Inc.Rhonda Werner2101 Calhoun RoadOwensboro, KY 42301Tel: 270-685-4039Fax: 270-821-3989rhonda.c@watersag.com

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.