Managing Soil to Keep It Productive

1. Managing Soil to Keep It Productive Developed by: Hudson Minshew Oregon State University Extension Service Susan Donaldson University of Nevada Cooperative Extension NRCS, Bozeman, Mont.

2. Part One: Fertilizing • What do my soil test results mean? • What nutrients do plants need? • How can I supply those nutrients?

3. pH • Indicates relative acidity or alkalinity • = pH 7 => neutral; • < pH 7 => acid; • > pH 7 => alkaline or basic Adapted from library.thinkquest.org by A. Miller CO Soils generally 7.0-7.8 Western CO Valley Soils generally 7.5-8.5

4. Soil pH and nutrient availability Adapted from www.soil.ncsu.edu by A. Miller Widest part of the bar indicates maximum availability

5. What makes soils acid? • Acid soils: pH is below 7 • Soils become acid due to heavy rainfall that weathers soils quickly • Basic cations such as calcium, magnesium, and potassium are leached from the soil profile • This natural weathering process makes soils acid

6. Raising the pH of acid soils • Add lime to raise the pH (making soil less acid) • Lime most often consists of calcium carbonate • Plant response will be relatively slow, taking weeks or months

7. What makes soils alkaline? • Alkaline soils: pH is above 7 • Soils that have not been greatly weathered or leached • Soils high in calcium • Reduces solubility of all micronutrients Adapted from library.thinkquest.org by A. Miller

8. Example of crop grown in alkaline soil http://ag.arizona.edu

9. Adapted from ag.arizona.edu by A. Miller

10. Soluble salts • A measure of inorganic chemicals that are more soluble than gypsum, such as: • sodium, • calcium, • magnesium, • chloride, • sulfate, • bicarbonate. • Salty soils are a problem in arid regions or in poorly drained soils USDA NRCS

11. Classifying salt-affected soils • Electrical conductivity measurements (EC) • Exchangeable sodium percentage (ESP) • Salt-affected soils are commonly classified for management purposes into three groups based on EC and ESP: • saline, • sodic, and • saline-sodic Grand Valley, CO

12. Managing salt-affected soils • Select plants that can tolerate salinity • Avoid excess or salty forms of fertilizers • Incorporate organic matter • If appropriate, add sulfur to lower the pH

13. Managing salt-affected soils • In soils with good drainage, periodically leach the salts below root zone with high quality irrigation water (avoid if high water table present)

14. Plant nutrients • Substances necessary for plant growth • Some, such as hydrogen, oxygen and carbon, come from the air and water • Others, such as nitrogen and phosphorus, may need to be added • Excess or improper use of fertilizers may result in water pollution

15. Macronutrients N = nitrogen P = phosphorus K = potassium BIG 3

16. H = hydrogen O = oxygen C = carbon Ca = calcium Mg = magnesium S = sulfur More macronutrients Micronutrients Fe = iron Mn = manganese Zn = zinc B = boron Mb = molybdenum Ni = nickel Cu = copper Co = cobalt Cl = chlorine

17. Six questions to ask yourself before you add fertilizer • Which elements do I need? (N, P, K, S, Ca) • How much do I apply? • What type of material do I use? • Which application method is best? • When is the best time to apply it? • Will I get a return on my investment?

18. Types of fertilizers • Chemical fertilizers • Organic fertilizers (bone meal, compost, manure, etc.) www.farmphoto.com

19. WAY TO GROW FERTILIZER 28 – 14 - 5 Product name GUARANTEED ANALYSIS NPK formula Total nitrogen 28% 6% Ammonium nitrogen Nitrogen content 14% Urea nitrogen 14% Phosphorus content Available phosphoric acid Soluble potash 5% Potassium content Specific sources Derived from sulfur-coated urea, etc. What’s in the bag?

20. How much fertilizer do I need to apply? • Estimate the amount of fertilizer needed based on soil test results, crop needs and area to receive fertilizer • Most fertilizer recommendations are in pounds per 1,000 square feet, or pounds per acre

21. X 100 Pounds of nutrient recommended Percentage of nutrient in fertilizer material Calculating fertilizer rates To convert a recommendation to pounds/acre of an actual fertilizer material, use the following formula:

22. 200 ft 150 ft 150 ft 100 ft Calculating land area • Length x Width = Area • If the area is oddly shaped or oval, calculate using a regular shape that closely fits the shape of the land to be fertilized

23. Fertilizing with manures • Good source of nutrients and organic matter • Protects soil from raindrop impact and erosion • Local supply often available at no cost OSU Extension Service

24. Different sources of manure have different amounts of nutrients • Poultry manure is high in nitrogen • Beef and horse manure tends to be lower in nitrogen • Sheep manure is high in potassium UNCE, Reno, Nev.

25. Cautions for fertilizing with manures • Watch out for weeds and pathogens • Know the manure nutrient content • Consider the salt content Univ. of Oregon

26. Cautions for fertilizing with manures • Incorporate or apply evenly to avoid smothering plants • Don’t apply on frozen slopes • Avoid leaching nutrients into waterways UNCE, Reno, Nev.

27. Nutrient deficiencies • Nitrogen • Phosphorus • Potassium • Calcium • Zinc • Manganese USDA NRCS

28. What we’ve learned • Use soil test results to guide you in amending your soil • Test results are only as good as the sample you collect • Fertilize to meet plant needs, and avoid costly overuse that may pollute water

29. Web Soil Survey • How to use a soil survey • How to find a map unit • Map unit descriptions • Soil ratings and capabilities

30. http://websoilsurvey.nrcs.usda.gov

31. Soil map units • A map unit describes a soil “type” in the soil survey • “Map-unit descriptions” are found at the beginning of the survey

32. Soil map unit example 630 Fleischmann gravelly clay loam Name given by soil scientists conducting survey Number designation Soil textural class is part of map unit name

33. Soil limitations NRCS, Bozeman, Mont.

34. Suitability ratings Freeze dates and growing season Productivity (tons/acre) Building site development Suitability for irrigation Physical and chemical properties (percent OM, pH, available water capacity) Soil surveys can differ in the information they provide. Other information

35. Restrictive features • Cemented pan • Droughty • Erodes easily • Flooding • Low strength • Restrictive layer • Shrink-swell potential UNCE, Reno, Nev.

36. Capability classes Classes • I and II - good farmland with few to moderate limitations • III and IV - severe to very severe limitations for growing crops • V and VI - limitations that are impractical to remove. • VII and VIII - very severe, unsuited for cultivation.

37. Capability classes USDA NRCS

38. To wrap it up... • Soil surveys are generated by NRCS scientists • Available in printed form or on the Web • Soil surveys are useful for determining capabilities and limitations of your soils at the large scale.