Soil Testing and Nutrient Management. Craig Cogger Soil Scientist WSU Puyallup

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1 Soil Testing and Nutrient Management Craig Cogger Soil Scientist WSU Puyallup

2 Soil Testing Nutrients Soil Quality Contaminants Biological

3 Simple Soil Quality Tests Texture Structure Color

4 Texture: Proportions of Sand, Silt, and Clay Sand.05-2 mm Silt Clay mm <.002 mm Coarse Fragments >2 mm

5 Nutrient Management Meet crop nutrient needs Maintain soil quality Conserve resources Protect water quality - reduce leaching and runoff risk

6 Plant Nutrients Major Nutrients Nitrogen Phosphorus Potassium Calcium Magnesium Sulfur Micronutrients Boron Iron Manganese Zinc Copper Chloride Molybdenum

7 Soil is full of nutrients, but most are not available to plants Mineral K Ca Insoluble, unavailable Organic N S Ca ++, K + Soluble, available NH 4+, SO -- 4

8 Nitrogen Cycle Organic N Ammonium NH 4 + Nitrate NO 3 - Soil organic matter, Plant residues, Manure Biosolids Plants, Microbes N fixation Leaching Gases (N 2, N 2 O) Atmosphere

9 Soil ph Indicates relative acidity or alkalinity ph 7 = neutral; less than 7 = acid; more than 7 = alkaline or basic Logarithmic scale

10 Why is ph Important? Nutrient availability Availability of toxic metals Microbiological activity

11 What Affects ph? Climate Humid areas tend to have acid soils, and arid areas tend to have alkaline soils. Parent material Some parent materials contain lime and keep soil ph higher. Management Many fertilizers tend to produce acidity.

12 New publication on liming and ph management

13 Soil Nutrient Testing

14 What is a soil nutrient test? A chemical evaluation of the nutrient supply from the soil. Soil test results are calibrated with crop response research to develop fertilizer recommendations.

15 Soil test vs. crop response Calibration of Bray P1 soil test for winter wheat in western Oregon 30 field sites, Roberts et al., Fertilizer Experiments with Winter Wheat in Western Oregon. OSU Ag Expt Sta Tech Bull 121

16 Make a Sampling Plan 2 hillside Pasture A 4 Pasture B valley 3 1 Vegetables house

17 When to Take a Sample? Sample before applying manure or fertilizer Repeat every 1-3 years, or as required

18 Use sampling tools that collect uniform cores Hydraulic Probe Hand Probe

19 How to Take a Representative Sample? Take small samples! Mix them in a plastic bucket 0-12 inches deep

20 Mix the Sample and Spread It to Dry Dry it in fresh air

21 When the Sample is Dry: Mix it again Send it to an agricultural laboratory Put it in a plastic bag and close the bag

22 Choosing a lab Does the lab routinely do ag tests? Do they use UI or OSU test methods? Do they give fertilizer recommendations? What information do they need? How to send sample? Cost? Turn-around time? What does report look like?

23 Choosing a Lab Quality assurance: Does lab participate in proficiency testing program or sample exchange? Quality assurance: Submit a known sample for a check.

24 Soil Nutrient Test Basic test: P, K, Ca, Mg, B, ph, lime requirement Options: Micronutrients (Zn, Mn, Cu, Fe), N, S, CEC, base saturation, organic matter, salts What nutrient is missing?

25 Soil Nutrient Test Basic test: P, K, Ca, Mg, B, ph, EC ( salts), lime requirement Options: Micronutrients (Zn, Mn, Cu, Fe), N, S, CEC, base saturation, organic matter What nutrient is missing?

26 Interpreting soil tests Nutrient status Low: fertilizer response likely Medium: sometimes a fertilizer response High: fertilizer response unlikely Fertilizer recommendation Reference: Reference: EC Soil Test Interpretation Guide Oregon State University. Revised 2011

27 Soil tests indicate how much of a nutrient is likely to be available to plants

28 Soil tests indicate how much of a nutrient is likely to be available to plants

29 Electrical Conductivity Not traditionally done for soils west of the Cascades Now required by WSDA for nutrient management recordkeeping Measure of salts Salts leach quickly in humid environments, but can accumulate under some conditions in arid regions.

30 Use soil test results along with fertilizer guides to determine how much fertilizer to use.

31 Considerations for fields receiving repeated applications of manure Expect higher levels of organic matter Higher rate of soil N release (not measured by soil testing) High levels of P and K Photo by Joe Harrison

32 One-Minute Drill What are the three most common forms of nitrogen in soils and soil amendments? Which of these forms are available to plants? Leaching Gases Atmosphere

33 We evaluate soil N status using inseason and post-season nitrate tests Pre-sidedress nitrate test o Mid-season nitrate test to determine need for additional N. o Calibrated for corn. Sampling: o taken when corn is 6-12 inches tall o Sample 0-12 inch depth.

34 Post-harvest nitrate test Is excess leachable N in soil at end of season? Use to modify next year s N management. September 1 to October 15 Sample 0-12 inch depth. Sample preservation is important

35 The nation that destroys its soil destroys itself. Frankin Delano Roosevelt, 1937 Thank you!

36 Why the concern about phosphorus? Phosphate is main form in nature A plant nutrient Not toxic Not reactive So, why the fuss?

37 Excess P leads to eutrophication of lakes and some streams Too much of a good thing Eutrophication is an excess supply of nutrients. Excess of nutrients causes overabundance of algae and plants This leads to degradation of water quality Photo by Gene Williams, Snohomish County Surface Water Management

38 Agronomic and environmental interpretations of soil test P are not the same: In: Sharpley et al., 1999; ARS-149

39 The Phosphorus Index is an assessment tool to estimate risk of P loss to surface water. P index is based on source and transport factors: Source Soil Amendment Type Rate,method, and timing of P application Transport Runoff Surface and subsurface Erosion

40 Phosphorus Index High potential for transport to water High P source High P transport Based on Sharpley et al., 1999

41 Source factors Soil: Soil test P level Amendment: Application rate Application method

42 Transport factors Soil erosion Soil erosion from irrigation Runoff class Distance to perennial surface waters/buffer widths Subsurface drainage Flooding frequency

43 P index calculations Each source factor is weighted and scored Each transport factor is weighted and scored Source and transport sums combined + +

44 Soil Sampling and Interpretation Information Click on Soils and Soil Testing for information on soil sampling, soil testing labs, and soil test interpretation.

Fertilizing with Biosolids Dan M. Sullivan Craig G. Cogger

Fertilizing with Biosolids Dan M. Sullivan Craig G. Cogger BioFest, Chelan, WA, Sept. 2015 Pacific NW Extension publication 508-E Biosolids: Fertilizer replacement value of nutrients Publication under