SOIL TEST INTERPRETATION JIM FASCHING Technical Field Representative jfasching@midwestlabs.com 507 273-3339
TERMS ppm = parts per million 2 million pounds of soil represented by soil samples taken 6 inches deep. ppm x 2 = pounds per acre of the element measured.
RELATIONSHIP OF NUTRIENT ELEMENTS TO PLANT FUNCTIONS PLANT FUNCTION Photosynthesis Enzyme Regulation Protein Synthesis Carbohydrate Metabolism Nitrogen Metabolism Hormone Synthesis Osmotic Pressure Translocation Grain Production MINERAL ELEMENTS INVOLVED N,P,K,Mn,Mg,S,Fe,Cl N,P,K,Ca,Mg,S,Fe,Mn,Zn,Cu,Mo N,P,S,Mn,Mo,Zn,Cu P,Ca,Cu,Mg,Fe,Mn,B,Mo N,P,K,Mn,Zn,Mo Mn,Zn,Cu K,Cl,Ca,Na K,B,Cl All essential elements Huber and Tsai-Purdue University
SOIL ph Measurement of the percent hydrogen ion (H+) concentration in the soil profile. As the H+ concentration on a soil clay colloid increases, the soil becomes acidic. 7 is NEUTRAL AND FOLLOWS A LOGRITHMIC SCALE 6 is 10 X MORE ACID THAN 7 5 is 100 X MORE ACID THAN 7 Measured in the lab using a 1:1 solution of soil and distilled water and measured with a ph meter.
BUFFER INDEX BUFFER INDEX BUFFER INDEX VALUE USED TO DETERMINE AMOUNT OF LIME TO APPLY ON ACID SOILS THE LOWER THE BUFFER INDEX, THE HIGHER THE LIME REQUIREMENT MIDWEST LABS USES THE SIKORA BUFFER SOLUTION After ph is determined the buffer solution is added. The ph meter is used to measure the drop in the ph of the buffer solution. Lime recs are based on the Buffer index.
Buffer index & lime rec as influenced by ph & C.E.C. Soil Type C.E.C. H+ con M/10 0g Soil ph Buffer Index Lime Rate/ A Sand 8 1.8 5.6 6.8 1 Ton Silt 14 4.2 5.6 6.6 2 Ton Clay 24 7.5 5.6 6.2 4 Ton
CATION EXCHANGE CAPACITY (CEC) MEASURES THE SOILS ABILITY TO HOLD NUTRIENTS DEPENDS ON TYPE AND AMOUNT OF CLAY MINERALS AND ORGANIC MATTER VARIES FROM 5 TO 35 MEQ/100G A SILTY CLAY LOAM WILL BE HIGHER THAN A SANDY LOAM SOIL HIGH CEC SOILS HOLD MORE NUTRIENTS
CATION EXCHANGE CAPACITY (CEC) VL L M H VH 0-5 5.1-10 10.1-15 15.1-20 20.1+
PERCENT BASE SATURATION PROPORTION OF THE CEC OCCUPIED BY A GIVEN CATION IN THE SOIL SOLUTION POTASSIUM, MAGNESIUM, CALCIUM, HYDROGEN AND SODIUM TOTAL OF 100% OPTIMUM RANGES POTASSIUM 2-5 % MAGNESIUM 12-18% CALCIUM 65-75%
CEC AND % BASE SATURATION CEC=3.5 CEC=20.5 %K = 3.8 %Mg = 20 %Ca = 75 %K = 3.8 %Mg = 20 %Ca = 75
CEC AND BASE SATURATION CEC=3.5 CEC=20.5 K = 52 ppm Mg = 88 ppm Ca = 525 ppm K = 274 ppm Mg = 540 ppm Ca = 3194 ppm
ORGANIC MATTER AMOUNT OF PLANT AND ANIMAL RESIDUE IN SOILS RESERVE FOR ESSENTIAL NUTRIENTS, ESPECIALLY NITROGEN RESERVES ARE MADE AVAILABLE THROUGHOUT THE SEASON BY BACTERIA VISIBLE RESIDUE/HUMUS IS NOT ORGANIC MATTER SOIL COLOR RELATES TO ORGANIC MATTER CONTENT DARKER SOILS ARE HIGHER IN ORGANIC MATTER RATINGS: VL L M H VH 1.5 1.6-2.5 2.6-3.5 3.6-4.5 4.6+
PHOSHOROUS ONLY SMALL AMOUNT OF P EXISTS IN SOIL SOLUTION DURING RAPID CROP GROWTH, MAY BE REPLENISHED UP TO 9 TIMES PER DAY 25 90 % OF THE TOTAL P IN THE SOIL IS IN THE ORGANIC MATTER ON AVERAGE, IT TAKES 9-20 POUNDS OF P2O5 PER ACRE TO RAISE THE P1 ONE PPM
PHOSPHORUS TYPES REPORTED P1 WEAK BRAY P2 STRONG BRAY BICARBONATE (OLSEN) MEHLICH WATER SOLUBLE MORGAN EXTRACT H3A EXTRACT (HANEY)
MAGNESIUM AFFECTED MAINLY BY SOIL TYPE, DRAINAGE, LIMING AND CROPPING PRACTICES CLOSELY RELATED TO SOIL ph, AS ph INCREASES SO DOES MG AND CA MG DEFICIENCIES ARE MORE COMMON IN SANDY LOW ORGANIC MATTER SOILS REPORTED IN PPM AS EXCHANGEABLE MG MG LEVELS SHOULD BE 130-330 PPM MG BASE SATURATION SHOULD BE 12-18 %
CALCIUM ASSOCIATED WITH NUTRIENT MOVEMENT INTO PLANTS ASSOCIATED WITH PROTEIN DEVELOPMENT, CELL WALL FORMATION AND SEED PRODUCTION. ASSOCIATED WITH IMPROVED VEGETATIVE GROWTH. IMPROVED PHOTOSYNTHETIC ACTIVITY AND PLANT HEALTH. REPORTED IN PPM AS EXCHANGEABLE CALCIUM. MOST CALCIUM APPLIED TO FIELDS THROUGH LIME APPLICATIONS.
SODIUM ESSENTIAL FOR SOME CROPS HIGH EXCHANGABLE SODIUM CAN CAUSE ADVERSE PHYSICAL AND CHEMICAL CONDITIONS CAN PREVENT PLANT GROWTH RECLAMATION INVOLVES USING CALCIUM AND MAGNESIUM TO REPLACE SODIUM BY LEACHING CAN BE A PROBLEM IN MORE ARID WESTERN SOILS HIGH LEVELS OF MANURE IN ARID AREAS CAN DRAMATICALLY INCREASE SODIUM LEVELS
NITRATE NITROGEN MEASURES WATER SOLUBLE AND PLANT AVAILABLE N INDICATES WHERE AND HOW MUCH NITRATE N IS PRESENT DEPTH TESTS DETERMINING NITRATE WILL GIVE MORE INFORMATION FOR N RECS (0-6,6-12, 12-24, 24-36+) MOST ABUNDANT FORM BENEFICIAL FOR SIDEDRESS N PRACTICE WHERE THERE IS A HIGH POTENTIAL FOR NITRATE CARRYOVER CORN AFTER CORN CORN AFTER LEGUME WITH MANURE OR N ADDED PREVIOUS CROP YIELDS BELOW EXPECTED
SULFUR MEASURES ELEMENTAL SULFUR SULFUR IS VERY MOBILE IN THE SOIL HIGH LEVELS CAN BE CAUSED BY REDUCED INTERNAL DRAINAGE OR HIGH SOIL ph EFFECTIVENESS OF SULFUR FERTILIZERS IS BASED ON THE ABILITY OF THE SULFUR PRODUCT TO BREAK DOWN AND BECOME WATER SOLUBLE IN THE SOIL OPTIMIMUM LEVELS DEPEND LARGELY ON ORGANIC MATTER SOIL TEXTURE DRAINAGE YIELD GOAL
Lab Extraction Procedures MIDWEST USES DTPA AND DTPA-SORBITOL Diethylenetriaminepentaacetic acid. Most consistent test across Midwest and High Plains. Used on all micronutrients.(zn, Cu, B, Fe, Mn). Extraction solution read with an ICAP.
THANK YOU FOR YOUR TIME AND ATTENTION! JIM FASCHING jfasching@midwestlabs.com 507 273-3339 www.midwestlabs.com
TESTING FOR SOIL HEALTH Matt Stukenholtz Wet Chemistry Supervisor matts@midwestlabs.com (402) 829-9884
Take Away Message Look at things differently We don t need to reinvent the wheel Test your soil Balance the nutrients and ph Diversity is a key component with soil health
Soil Health provides an overall picture of the condition of MANY processes and properties. The terms Soil Health and Soil Quality can be used interchangeably. Soil health is the soils fitness to support crop growth without resulting in the degradation of the soil. A healthy soil system is a resilient soil system.
Soil Properties Chemical nutrients and minerals Biological Soil organisms Physical soil structure and texture
How and What How and what are we measuring If you are going to manage soil health you need to be able to measure it Haney Test and 1 day CO2 burst The Soil Health Tool
Soil Health Calculation (1 day CO2 Burst/10) + (Organic Carbon/100) + (Organic Nitrogen/10) (94.13/10) + (195/100) + (10.8/10) 9.41 + 1.95 +1.08 = 12.4 SHC
Cover Crop Rec s Rick Haney SHC 0-2.5 70% Legume 30% Grass SHC 2.5 5.0-60% Legume 40% Grass SHC 5-10 - 50% Legume 50% Grass SHC 10-15 40% Legume 60% Grass SHC 15-20 30% Legume 70% Grass SHC 20+ - 20% Legume 80% Grass
Additional Nitrogen Credit PctMac = 1 day CO2 / Organic Carbon = 94.13 / 195 PctMAC =.48 MAC WEON = Org N x PctMAC x 2 (ppm to lbs) x 4 (yearly rainfall events) = 10.8 x.48 x 2 x 4 = 41.5 If Then = MAC WEON > Org N x 2 then MAC WEON = Org N x 2
Org N x 2 = 21.6 MAC WEON = 21.6 Nitrogen Credit = MAC WEON + (Water Sol Ammonia x 2) =21.6 + (3.2 x 2) = 28lbs Haney will add Nitrate 26lbsfor credit of 54lbs