Diagnosing problems in horticultural soils

1. Diagnosing problems in horticultural soils

5. Soil color should be your first clue

6. Water movement in soils Not always down hill!!

7. Causes of Drainage Problems • Compaction • Excessive Tillage – No organic matter • Lack of topsoil – Exposed parent material • Pore size discontinuity

8. Idealized Kentucky Soil Pore Space 50% Soil Minerals (Silt loam) 47% Organic Matter 3%

9. Macropores • Include earthworm channels • Old root channels • Surface Cracks Controls soil permeability and aeration Beach sand is almost entirely macropores – infiltration is very high, but water holding capacity is very low

10. Micropores • Very fine pores • Similar to pores in a sponge or towel • Hold water against the force of gravity Much of the water held in micropores is available to plants, but some is held so tightly that plant roots cannot use it.

11. Idealized Kentucky Soil Macropores 25% Soil Minerals (Silt loam) 47% Miropores 25% Organic Matter 3%

12. Disturbed/Compacted KY Soil Air 5% Water 20% Soil Minerals (Silt loam) 72% Organic Matter 3%

13. Characteristics of soil with poor internal structure • Slow permeability • Very wet natured • Crust easily • Poor plant productivity Once lost, soil structure is very hard to rebuild – prevention is the key

14. Optimum M.C.=14.3% for a silt loam Potential Compaction 8 10 12 14 16 18 20 22 Soil Moisture Content (%) Maintaining Soil Structure • Prevent soil compaction

15. Higher Yield Potential?

16. Maintaining Soil Structure • Use roto tiller sparingly

17. Compaction caused by tillage 4 – 8” 0.5 – 2” Inaccessible water and nutrients Slide by: R. Pearce

19. Pore Size Discontinuity Fine Textured Soils Coarse Texture Soil

20. Pore Size Discontinuity Coarse Textured Soil Fine Texture Soil

21. Use mulch to control weeds and conserve moisture and reduce tillage

22. Use Cover Crops • Turnips and mustard greens • Grow very good in the fall • Provide ground cover to prevent erosion • Have strong tap roots to break compaction and provide future root channels for better infiltration • Wheat • Roots provide organic matter • Improves soil structure • Reduces winter annual weed pressure

23. Incorporate Compost or Organic Material when Tilling • Don’t exceed 10% per year • ½ inch mixed into the surface 5 inches • Stabilized compost is much better • Fresh manure use very sparingly • Uncomposted leaves or straw tie up soil nitrogen • Wood ash is a good sources of nutrients, but doesn’t contain organic matter

24. Soil Minerals Macropores 25% Soil Minerals (Silt loam) 47% Miropores 25% Organic Matter 3%

25. Soil Mineral Phase • Sand • Large soil particles – feel gritty and can be seen with the naked eye • Silt • Much smaller than sand – feel smooth about the size of flour particles • Clay • So small particles can only be seen under a microscope • Chemically active part of the soil Soil Texture

26. Changing Soil Texture • To change soil sand content by 10% would require more than 200,000 lbs/a if mixed only in the top 6 inches • Its probably better to learn to deal with what Mother Nature gave us. Contractor left us.

27. Ca++ Plant Root NH4+ H+ K+ - - - H+ - - - - - - Ca++ H+ - - Ca++ - - - - - K+ NH4+ K+ Mg++ Ca++ Ca++ Mg++ Ca++ K+ NH4+ H+ H+ Mg++ H+ H+ K+ Mg++ Mg++ Ca++ NH4+ Ca++ Cation Exchange Capacity Clay Clay K+ Clay Clay H+ Ca++ H+ K+ Soil Solution

28. azaleas Vegetables Soil pH is the most important soil test conducted

29. A handheld pH meter is a good investment Forestry Suppliers Inc ~$76.00 Also needed buffers for calibration and distilled water

30. Estill County Soil Test Results Elemental Sulfur Reduces pH Lime Increases pH Gypsum Has No Effect

31. Gypsum Has No Effect??

32. Dunn, 2002, Cotton Study Southeast Missouri

33. What About Gypsum’s Effects on Bulk Density and Compaction?? • Mark Schonbeck. 2000. Soil Nutrient Balancing in Sustainable Vegetable Production, In Organic Farming Research Foundation Project Report No 99-05. • Five locations in Virginia and eastern Tennessee for three years with three replications.

34. Vegetable Study (Cont) • Low and high Ca treatment • Low Ca:Mg = 2.64 • High Ca:Mg = 4.00 Created using Calcitic and Dolomitic limestone Measured effects of ratio on soil physical properties and soil biological properties.

35. Soil Physical Properties

36. What About Gypsum’s Effects on Biological Properties??

37. Positive Effects of Gypsum • Used to replace sodium on soil exchange sites • Does increase infiltration if soil is saturated with sodium. • Only used to reclaim soil in arid regions or salt spills.

38. Soil Testing - Nitrogen • Nitrogen is the fertilizer needed most in KY soils • Very little soil nitrogen is in the plant available form so soil testing is not generally recommended • Soil testing can be used to diagnose excessive fertilizer applications • Plants take up inorganic (NO3 and NH4) nitrogen – Organic sources must be mineralized before they are plant available

39. Fertilizer Recommendations Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. If soil test phosphorus is above 100 lbs/a PLEASE DON’T apply any more phosphorus

40. Fertilizer Recommendations Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. Potassium has no negative environment effects

41. Fertilizer Analysis Analysis Nutrient Concentration 34-0-0 34% N – 0% P2O5 – 0% K2O 5-5-5 5% N – 5% P2O5 – 5% K2O Fertilizer recommendation is for 1 lb N per 1000 sq ft how much 34-0-0 or 5-5-5 is needed? 1 lb N/1000 sq ft 0.34 lb N/lb material 3 lbs 34-0-0 per 1000 sq ft

42. Nutrient Content of Manure

43. Other Essential Elements Sulfur, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, Boron, Molybdenum, and Chlorine Are almost always adequate if soil pH is adjusted for the crop

44. Questions ???