Soil Quality -- Why it Matters

1. Soil Quality --Why it Matters Rhonda Janke Assoc. Prof. and Ext. Specialist, KSU Sustainable Cropping Systems

2. Definition of Soil Quality Soil Fertility Physical Properties Biological Activity “The ability of soil to function; to supply plants with adequate nutrients, have good drainage and aeration, promote root growth and biological activity.”

3. A Definition of Soil Quality Context: soil type, slope, climate……. Problems -Salinity -Low in nutrients -Erosion -Drainage • Soil Quality • - High OM • - Tilth • - Infiltration • Nutrient buffering Soil is OK

4. Soil is not Dirt

5. Soil Tests for Quality: physical, chemical, & biological

6. Fill a jar 2/3 with soil. Fill the same jar about 7/8 full of water. Add detergent (optional) to break up aggregates. Shake well. Measure height of settling at 30 seconds, 30 minutes, and 24 hours – or -- look at particle size differences – sand, silt, and clay layers. Physical Tests -- Soil Texture

7. Simple calculations: • 30 seconds = sand. • 30 minutes = sand + silt. • 24 hours (total) = sand + silt + clay. • Subtract 30 minute from 24 hr to get clay. • Subtract 30 sec. from 30 min. to get silt. • Take each fraction (in mm) divided by the total to get % sand, % silt, and % clay. • Use a texture triangle to determine soil texture classification. More than 50% of any one texture determines primary qualities.

8. Texture largely determined by parent material of soil, past erosion, and new deposits(such as topsoil addition) • Sandy soil – good drainage, but doesn’t hold water or nutrients well. (particles 0.05 to 2 mm) • Silt – moderate drainage, moderate nutrient and water holding capacity. (0.002 – 0.05 mm) • Clay – poor drainage, can supply K mineral, shrink/swell with water (<0.002 mm) All of these characteristics are helped with the addition of organic matter, especially composts.

9. Any type of container with straight sides will work.

10. Can also examine “macro-organic matter flotation” with the same system. Grass sod Ag field with no residue Composts Various garden plots Macro-organic matter is important because it feeds the “active” organic matter pool, that promotes water stable aggregates, infiltration, and other positive soil attributes.

11. Organic Matter Pools Active OM Stable OM Soil Test for OM Macro-Organic Matter (mulch, residue, roots, large pieces of compost, etc.) Active Decomposing Organic Matter (particulate OM or POM) Humus test Stable Humus

12. Humus test results [using LaMotte humus index test.] Newer garden soil with mulch = 1.0 Improved garden soil = 3.0 Near-by ag field (with subsoil) = 0 Fresh worm compost = 5

13. Water Stable Aggregates • Formed by the aggregation of clay (smallest particles), followed by gluing together of macro-aggregates with bacterial secretions, fungal hyphae, and root hair bonding.

14. Use a stack of sieves under water. Demonstrate with a few aggregates in a shallow dish. To measure water stable aggregates: Field soil Prairie soil

15. To measure the effect of water stable aggregates:

16. Assemble filter paper, funnel, and jar. Add 1 scoop (dry) soil. Gently add 1 scoop water and start timer. Record first reading when water is not visible. Repeat with 2nd scoop of water. Procedure:

17. First scoop: Field = 38 seconds Prairie = 20 seconds. Second Scoop: Field = 2:06 minutes. Prairie= 1:15 minutes. Faster infiltration means that more rainfall will soak in to your soil. Results: Notice the lack of soil structure on the left (field soil) and the presence of water stable aggregates on the right (prairie soil)

18. A similar test can be run in the field. Use a section of irrigation pipe or coffee can to create an “infiltrometer.” Figure 14. Illustration of an infiltrometer In a 6 inch diameter ring, pour 1 7/8 cup water. Measure amount of time to soak in. Repeat measurement.

19. Four Ways to Improve Infiltration: • Adding organic matter • Adding organic matter • Adding organic matter • Don’t work the soil when wet!!!

20. Organic Matter NO3 (ppm) Total N (ppm) Soluble P (ppm) Total P (ppm) Ag 3.0 % 22.1 1363 58 412 Prairie 7.6 % 26.4 2828 34 652 Prairie Soil vs. “Ag” Soil N and P in the organic matter pools.

21. Organic Matter Level (%) Soluble Nitrate N (NO3 N in ppm) Total N (digested OM in ppm) 1.3 13.3 375 3.0 14.7 1742 3.6 14.8 2156 5.4 12.4 2219 8.4 12.9 2763 Organic Matter and Nitrogen

22. Organic Matter Level (%) Soluble P (Bray P1 in ppm) Total P (digested OM in ppm) 1.6 55 378 2.8 57 599 4.2 63 659 7.0 66 749 7.2 49 832 Organic Matter and Phosphorus

23. “Banking” on Soil Nutrient Levels Your Savings Account -- Organic matter content, total N, total P, clay release of K. -- These are slowly available, but can accumulate over time to be available later. -- This is sometimes called nutrient “buffering.” Your Checking Account -- Mineral N, available P and K -- This is an indication of what will be available that growing season -- Soil pH will influence the availability of these and micro-nutrients

24. How to build up your soil “savings” account. Local, on-farm sources: - cover crops, annuals and perennials. - hay mulch - compost - raw manure (use with caution, not on leafy crops) - wood chips, ash (also use with care) Purchased products: - alfalfa and soybean meal (N) - bone meal, rock phosphate (P) - lime (for pH) - sulfur (to lower pH) - blood meal (for N)

25. Practices that deplete your soil “savings” account. • Too much tillage. • Bare ground (no mulch on top). • No living crops (no roots in the soil). • Soluble fertilizers without concurrent addition of carbon rich mulches or composts.

26. Lab soil fertility tests available: Organic Matter Pool, or “Savings Account” Available Nutrient Pool, or “Checking Account” -- Organic matter -- Total N & P -- Total C & N Extractable N, P, K, pH and micro-nutrients

27. In addition to laboratory tests, quick tests are available for soil nutrients (N, P, K) and pH.

28. Most kits based on simple extraction methods, combined with color charts for interpretation. pH Nitrogen (NO3) Phosphorus Potassium

29. 1 scoop soil (1/8 c.) 1 scoop Dist. Water Put on lid and shake. Let settle a few minutes. Filter to get clear liquid. Can test with Hach test strips for pH, NO3, and NH4. E. coli (microbial test) may also be useful. Test strips and other methods can use a 1:1 soil water extraction:

30. Test strips: Petri-plates: Hach test strip measure pH from 4 to 9, and NO3 from 0 to 50 ppm NO3-N. Ammonia nitrogen (NH4) test also available. 3-M Petri plates develop pink colonies with coliform bacteria, and blue colonies with E. coli (intestinal) bacteria. Incubate for 48 hrs.

31. Example results from my garden: Drinking water GH with Parsley Composting Area Livestock Water

32. Comparison of test kits to KSU lab values: r2 or correlation value (higher is better)

33. Cost Comparison • LaMotte EL Combination kit costs $41.95 for pH (30) and N, P, & K (15), or $0.56 per test. • Hach pH strips are $13.50 per 50, or $0.27per test, and nitrate strips are $15.00 per 25, or $ 0.61 per test. • LaMotte Humus test is $74.25 for 50 tests, or $1.49 per test. • KSU combination test is $10.50 for pH, N, P, K, and OM. ($10.00 for total N&P) Total LaMotte $116.20 for above tests. Total KSU for same quantity is $490.

34. Soil biology: important, but difficult to measure.

35. Soil biological tests include earthworm counts (by hand), extraction of soil insects with light above and funnel below into a jar. No accurate tests yet for microbial species diversity. Soil respiration rate tests also available, but difficult to interpret. Soil Biology Cont…….

36. Wet filter paper. Place in bottom of flat covered dish. Fill dish with moist soil. Add a little more water if needed. Incubate and watch. Observe the amount of decomposition after certain length of time. Examples (see photos) incubated for 1 week at 95o F. The “will it rot?” soil test. Garden soil Worm compost Field soil

37. Physical Texture Macro-organic matter Water stable aggregates Infiltration rate (lab & field) Bulk density Water holding capacity Summary of tests for soil quality:

38. Chemical pH Nitrogen (NO3 and NH4) Phosphorus Potassium Organic Matter (lab) Humus (quick test) Total N & P in OM (lab) Summary of tests for soil quality:

39. Biologial Earthworms Soil insects and other arthropods Coliform bacteria & E. coli Respiration rate Simple “will it rot” test with filter paper or other materials. Summary of tests for soil quality:

40. Good Roots Need Good Soil • Many “sick” plants don’t have a disease, they just need better roots/soil. • Good soil conditions can also help plants fight off disease and insect pests (like a healthy immune system in a person). • Try to improve the subsoil and also the topsoil. Limit compaction, and keep adding organic matter over a period of years.

41. Close observation of your soil is probably one of the best results of doing your own soil tests.

42. For more information: • http://www.oznet.ksu.edu/ (to get to all KSU publications, soil test lab info, etc.) • http://www.oznet.ksu.edu/kswater (for “Citizens Guide to Soil and Water Testing”) • http://soils.usda.gov/sqi/index.html (fact sheets and other info on soil quality) • http://www.woodsend.org/ (copies of other soil quality publications, compost testing) • http://www.amazon.com or other book seller (for copies of “Soul of the Soil.”)

43. Product Related Web Sites: • http://www.woodsend.org/ (compost testing, respiration rate tests) • http://www.lamotte.com (for nutrient and humus test kits) • http://www.hach.com (for nitrate, pH, and ammonia test strips) • http://www.3m.com (for E. coli plates, order #6484 EC plates, $70 for 50, also need pipets)