Effect of Compost Application and Mulch on Soil Physical and Hydraulic Properties

1. Effect of Compost Application and Mulch on Soil Physical and Hydraulic Properties Laosheng Wu, Ph.D. Department of Environmental Sciences UCCE-Riverside

2. Organic Soil Amendments • Waste-based products • Barks, shavings and chips, and saw dusts • Peat moss • Animal manure • Sewage sludge • Municipal solid waste composts - yard wastes

3. Benefits • Fertility • Disease & weed suppression • Water management

4. Fertility • Increase soil reserves of K, Zn, and Fe under serial applications • Increase soil organic matter with maintenance applications of at least 5 ton/year • Long term nutrient availability in potting soil applications

5. Yard Wastes • Need outlets for these products • Land application - a logical solution • Heavy promotion: eco-correctness • Readily assimilated into the soil • Produced in close proximity

7. Yard Wastes

8. Soil Conditioner • Incorporated to alter soil properties for a specific use • Bulk density • Water holding capacity • Permeability • Modulus of rupture (cohesion) • Nutrients

9. Reduce Bulk Density(Chang Et Al., 1983)

10. Improve With Rate(Chang Et Al., 1983)

11. Improved Water Infiltration(Reitemeier and Christiansen, 1946)

12. Improve Soil Permeability(Chang et al., 1983)

13. Improve with Rate(Chang et al, 1983)

14. Soil Structure(Pagliai et al., 1993) • Increased soil porosity • Formation of micro-aggregates: increased elongated micro-pores • Expanded the 50 - 500 mm fraction • Effects increased with application rates

15. Increased Aggregate Stability (Martens & Frankenberger, 1992)

16. Mulch • Surface cover for soil around plants • Organic: barks, wood chips, leaves, pine needles, grass clippings, sawdust, rice hulls, compost (sewage sludge, animal manure, etc.) • Inorganic: rocks, plastics, synthetic fabrics

17. Benefits of Mulch • Aesthetics • Preserve soil moisture • Moderate soil temperature • Reduce weed • Improve plant performance • Prevent erosion and soil compaction

18. Mulched Un-mulched Average 63oF 69oF Maximum 68oF > 90oF Fluctuation < 5oF 25 – 30oF Modulate Soil Temperature(Bushnell and Welton, 1931)

19. Preserve Soil Moisture(Bushnell and Welton, 1931)

20. Better Plant Performance(Bushnell and Welton, 1931)

24. Soil Mix • Formulated plant growth media • Mixture of organic and inorganic ingredients • Selected for physical properties or special nutritional needs • Used for potted plants, landscape plantings, golf greens

25. Property of Soil Mix(Richards et al., 1964)

26. Property of Soil Mix(Richards et al., 1964)

27. Property of Soil Mix(Richards et al., 1964)

28. Sewage Sludge(Chang et al., 1983)

29. Water Holding Capacity(Chang et al, 1983)

30. Sewage Sludge(Chang et al., 1983)

32. Summary • Advantages: • Improve soil structure (incorporated) • Increase water holding capacity (incorporated) • Increase infiltration (incorporated) • Reduce runoff (mulch) • Suppress weeds and diseases (mulch)

33. Summary (Continued) • Disadvantages: • Salinity problem if animal manure and sewage sludge application rate is too high • Heavy metals accumulation (sewage sludge) • Continuous application may required to maintain improved infiltration and water retention • Cost depends on processing, packaging, transportation