An Overview of Soil Health-Presented at Westerin IOWA No-Till Field Day-Shelby Iowa
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This presentation gives an overview of soil health and the role of cover crops. Presented at the WIN field day in Shelby Iowa, June 2014
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An Overview of Soil Health-Presented at Westerin IOWA No-Till Field Day-Shelby Iowa
- 1. Tim Reinbott and Kerry Clark
- 2. Soil health has three main components • Sustained biological productivity • Environmental quality • Plant and animal health
- 3. 3 Kristen Veum and Robert Kremer
- 4. SOM is derived from Plant residue (both litter and roots) Animal remains and excreta Living soil microbes (microbial biomass) Over time fresh organic material is transformed into soil organic matter Crop Residues Bacteria Fungi Actinobacteria SOM 4
- 5. Loss of Organic Matter Soil structure Soil microbial biomass Release of CO2 Soil Erosion Why Till? Weed Control
- 9. 20 – 40% of SOM is lost on cultivation Management effects on SOM Tillage (disturbance) Chemical Fertilization Manure Residue Retention Crop Crop Rotation Cover Crop 9 Decline in SOC from Sanborn Field Plots showing increase following the return of residues beginning in 1950
- 10. 10
- 11. 58% Carbon P, S, and other nutrients 95% of Soil Nitrogen in SOM
- 13. Soil Life (macro) Help create soil structure and break down larger plant residues • Earthworms • Nematodes • Beetles • Ants • Termites • Springtails
- 14. One tablespoon of soil has approximately 1 billion soil microbes: • Bacteria: 3,000,000 to 500,000,000 • Actinobacteria: 1,000,000 to 20,000,000 • Fungi: 5,000 to 1,000,000 • Yeast: 1,000 to 1,000,000 • Protozoa: 1,000 to 500,000 • Algae: 1,000 to 500,000 • Nematodes: 10 to 5,000
- 15. This is the mass equivalent of two cows per acre that need to be fed Soil organisms are much like cows, they need inputs of plant residues for food and energy Specifically, they need the carbon that is contained in plant residue and soil organic
- 18. • Natural ‘tillage’ by earthworms • Burrows enhance water infiltration and soil aeration. This reduces runoff, and increases soil water storage for dry spells. • Worms redistribute organic matter and nutrients throughout the topsoil layer. • The soluble nutrient content of worm casts is considerably higher than that of the original soil.
- 19. • General saprophytic fungi (i.e., decomposers) • Produce glomalin – glue in aggregation • Nutrient cycling! Especially hard to decompose SOM
- 21. Bacteria bridge short distances, but fungi can work over long distances to explore and to transport nutrients thanks to their fine hyphal system. Thus, mycorrhizas (symbioses between roots and fungi) have been very successful Photo: David Read
- 22. • Some cause disease • Can keep bacterial and fungal pathogens in check- keep balance in microbe world • Bacterial feeders may dominate in tilled plots, and herbivorous nematodes may dominate in no- till (Lenz & Eisenbeis, 2000) • Bacterial feeders may be stimulated by tillage (Wardle, 1995) • Tillage may promote a bacterial-dominated decomposition pathway (vs. fungal), which in turn supports bacterial feeders.
- 23. • Have cells like bacteria and filaments like fungi – (were misclassified as fungi) • Decompose cellulose and chitin & important in organic matter and nutrient cycling • Tend to be drought/temp resistant • Responsible for the “earthy” smell of soil due to geosmin • May produce special chemicals when stressed (e.g., under low P, N, or O2) or secondary metabolites (e.g., antibiotics), & some are pathogenic Photo: Wikipedia
- 24. Increased aggregate stability Increased water infiltration Reduced runoff Increased water holding capacity Decreased erosion Improves aeration and macroporosity Avoid this! Photo: iastate.edu
- 25. LONG TERM PASTURE TILLED IN A CORN/SOYBEAN/WHEAT ROTATION
- 26. 0 500 1000 1500 2000 2500 3000 Biomass(mg/g) Cropping Type PLFA Analysis at Bradford Research Center Bacteria Actinomycetes Fungi Protozoa No Protozoa in Corn/Soybean Rotations. Micro Organism biomass highest in perennial cover Bradford Research Center, 2012
- 27. 0 50 100 150 200 250 300 350 400 450 500 Biomass(mg/g) Cropping System PLFA Sub-categories at Bradford Rhizobia Arbuscular Mycorrhizal Saprophytes Soybean-Conventional-had no Mycorrihizae or Rhizobia
- 28. Scientists describe 3 pools of soil organic matter **really is a continuum of decomposition Passive SOM 500 – 5000 yrs C/N ratio 7 – 10 Active SOM 1 – 2 yrs C/N ratio 15 – 30 Slow SOM 15 – 100 yrs C/N ratio 10 – 25 • Recently deposited organic material • Rapid decomposition • 10 – 20% of SOM • Intermediate age organic material • Slow decomposition • 10 – 20% of SOM • Very stable organic material • Extremely slow decomposition • 60 – 80% of SOM 28
- 29. Results are read in a spectrometer in lab or field or from a color card Potassium Permanganate Test KMnO4 oxidizes active carbon. The purple color of the chemical changes to pink the more active carbon there is in a soil sample.
- 33. Table 3. PLFA concentrations Treatment Total Gram+ Gram− Actino Fungi AM Fungi Protozoa Bare 15.07 DE 4.45 CD 3.94 DE 2.17 BC 0.42 BC 0.58 DE 0.07 B Black Poly 13.27 E 4.10 D 3.28 E 1.87 C 0.36 C 0.48 E 0.04 B White Poly 15.49 CDE 4.61 BCD 4.04 DE 2.20 BC 0.45 BC 0.59 CDE 0.08 AB Rye 19.33 AB 5.48 AB 5.58 AB 2.69 A 0.61 AB 0.85 A 0.18 AB Rye Roots 18.39 ABC 5.26 ABC 5.16 ABC 2.53 AB 0.60 AB 0.73 ABC 0.14 AB Rye Shoots 16.72 BCD 4.90 BCD 4.51 CD 2.41 AB 0.44 BC 0.66 BCD 0.11 AB Vetch 20.38 A 5.82 A 5.76 A 2.71 A 0.73 A 0.81 AB 0.20 AB Vetch Roots 19.04 AB 5.47 AB 5.36 ABC 2.59 AB 0.54 BC 0.72 ABCD 0.27 A Vetch Shoots 17.39 BCD 5.05 BC 4.77 BCD 2.46 AB 0.55 ABC 0.71 ABCD 0.13 AB Plastic Has Much Less Than Cover Crops!! Buyer, et al, 2010
- 35. Doug Peterson
- 36. 140° F 130° F 100° F 70° F Soil bacteria die 100% moisture lost through evaporation & transpiration 15% moisture is used for growth 85% moisture lost through evaporation & transpiration 100% moisture is used for growth J.J. McEntre, USDA SCS, Kerrville, TX, 1956
- 38. Surface crust impedes infiltration. Open, granular surface structure enhances infiltration. Biopores (earthworm channel) enhance infiltration. Conventionally tilled field No-till field 38
- 39. Aggregate Stability-Better Water Infiltration Fungal-produced glomalin helps bind aggregates http://ed.fnal.gov/trc_new/pandp/soil_research/soil _aggregates.html Wright, et al., 1999
- 40. From Steve Groff Cover Crop No Cover Crop
- 41. No-Till With Cover Crop Took Several Hours For Water To Run-Off