1. Ag Expo 2004 Greg Schwab and Lloyd Murdock Extension Soil Specialists UK Department of Agronomy Soil Management for Higher Yields

2. Nitrogen Deficiency

3. Low Soil pH

4. Idealized Kentucky Soil Air 25% Soil Minerals (Silt loam) 47% Water 25% Organic Matter 3%

5. Compacted KY Soil Air 5% Soil Minerals (Silt loam) 72% Water 20% Organic Matter 3% Macropores are compressed soil oxygen decreased dramatically Effects Poor Drainage Slow Root Growth Growth

6. (Tire pressure remained at 12 psi for all tire sizes) (Tire size 11 x 28, load 1,650 lbs, pressure 12 psi) Depth of compaction as (6) axle load and (7) soil moisture increases

7. 8 10 12 14 16 18 20 22 Potential Compaction Soil Moisture Content (%) Optimum M.C.=14.3% for a silt loam Proctor Compaction Curve

8. More tires will spread weight … BUT allows operations in wetter conditions and compacts a greater soil volume.

9. Sometimes we need to admit … There really are days we shouldn’t be in the field ! (Even if equipment lets you)

10. Compaction Survey Compaction Survey Murdock and County Agents 1992-1993 Categories –Little or None – Less than 30% of penetrometer readings in field were 300 psi or greater –Slight – 30 to 50% of the penetrometer readings were 300 psi or greater –Moderate – 50-75% of the penetrometer readings were 300 psi or greater –Severe – 75 to 100% of the penetrometer readings were 300 or higher

11. Stunting, uneven stands are often the first symptoms

12. Compaction Survey Compaction Survey Murdock and County Agents 1992-1993 Results –Little or None – 46% –Slight – 18% –Moderate – 18% –Severe – 18% By Drainage Class –77% of poorly drained fields had moderate to severe compaction –20 % of well drained fields had moderate to severe compaction 169 Fields

13. Compaction Survey Compaction Survey Murdock and County Agents 1992-1993 Tillage Amount of Compaction HistoryFieldLittleSlightModSevere No.% --------------- % --------------- No-till321950221513 Disc37222732446 Conventional945645251713 Subsoiled646701617 Total169100

14. Higher Yield Potential?

15. Effects of Compaction on Crop Yield Corn and Tobacco –Extreme 30-50% Yield Reduction –Severe 10-20% Yield Reduction –Moderate 5-10% Yield Reduction Soybean and Wheat –Extreme 15-25% Yield Reduction –Severe 5-10% Yield Reduction –Moderate <5% Reduction

17. Soil Compaction Questions How much will it decrease yields? Will deep tillage restore all of yield potential? How long will compaction last? Are penetrometers a good measure?

18. Methods Zanesville silt loam Tilled and no-tilled areas Treatments Compacted Compacted & Subsoiled Uncompacted Multiple passes of 10 ton equipment 12 inches in depth Tilled 6 in. each year Soil Compaction Effects on Corn and Soybeans Lloyd Murdock and John James, Princeton, KY

19. TillageYield (Bu/Ac) TillComp.‘97‘98‘99‘00‘01’02 CornSoybCorn SoybCorn TillYes763114811476103 TillYes8231138123*74*98* TillNo984017413584135 NTYes23615810982116 NTYes233163130*81*134* NTNo1044218011789130 Effect of Soil Compaction on Corn and Soybean Yields With and Without Compaction and Subsoiling *Treatment subsoiled only in fall of 1999

20. TillageYield (Bu/Ac) TillComp.‘97‘98‘99‘00‘01’02 CornSoybCorn SoybCorn TillYes763114811476103 TillYes8231138123*74*98* TillNo984017413584135 NTYes23615810982116 NTYes233163130*81*134* NTNo1044218011789130 Effect of Soil Compaction on Corn and Soybean Yields With and Without Compaction and Subsoiling *Treatment subsoiled only in fall of 1999

21. TillageYield (Bu/Ac) TillComp.‘97‘98‘99‘00‘01’02 CornSoybCorn SoybCorn TillYes763114811476103 TillYes8231138123*74*98* TillNo984017413584135 NTYes23615810982116 NTYes233163130*81*134* NTNo1044218011789130 Effect of Soil Compaction on Corn and Soybean Yields With and Without Compaction and Subsoiling *Treatment subsoiled only in fall of 1999

22. Results Tilled compacted yields were 75% of check and improved to almost 90%. No-tilled compacted yields were 2% of check and improved to 90% rapidly Recovery beyond 90% will probably be very slow Rapid no-till recovery is probably due to high rate of biological activity

23. Soil Compaction?

24. QUANTIFYING COMPACTION Crop and Soil Symptoms Penetration Resistance –Moisture Dependent –No Absolute Value –Note Depth and Relative Force –Compare Good and Bad Areas Bulk Density –Mass per Volume –Calculate Porosity –Texture Dependent

25. Effect of Time on the Percentage of Soil Penetrometer Readings Over 300 psi in Compacted Tilled and No-Tilled Treatments. Treatment No-Till Tilled 1997 100 94 1998 100 94 1999 88 94 2000 75 100 2001 88 100 2002 88 100 Percent Readings

26. COMPACTION AFFECTS NUTRIENT UPTAKE Potassium Affected Most Compaction Reduces Porosity Lowers Soil Oxygen O 2 Needed for Root Respiration and Active Uptake

27. Organic Matter and Soil Compaction

28. Conclusion DETERMINE THE NEED FOR SUBSOILING Evaluate Depth and Severity of Compaction Check with Penetrometer, Probe, Shovel Dig Plants to Examine Roots Leave Untreated Strips for Comparison