1. Integrated approach for Rehabilitation of Severely Eroded Soils for Agricultural Sustainability and Natural Resources Preservation of the Micronesian island of Guam Mohammad H. Golabi, Ph.D., Soil Scientist Margaret J. Denney, past graduate student Clancy Iyekar, Soil Lab Tech College of Natural and Applied Sciences University of Guam

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4. Soils of Guam Nineteen different soil series have been mapped on Guam
Soils of Guam can be grouped into three primary categories:
Soils over limestone
Soils on volcanic uplands
Soils on bottomlands and coastal margins

5. Soils of Guam (cont’d)
Predominant location of Limestone-derived soils is in Northern Guam
Predominant location of Volcanic soils is in Southern Guam
Shallow - limestone-derived Guam soil series covers approximately 24% of total land area (55,445 hectares or 214 square miles)

7. Conditions Threatening Guam’s Soils
Approximately 1,644 hectares of land (30% of total) are at risk of erosion
Severe erosion of the varied soil series on Guam exposes infertile subsoil restricting regrowth of vegetation and having negative effect on crop productivity
A major problem of agricultural soils in Guam is the low organic matter content

8. A typical Badland area in Southern Guam

9. Farmers and hunters burn natural vegetation for clearing purposes

10. Challenges facing Guam’s agricultural and the soil scientists
Soil and agricultural scientists must develop strategies to control erosion on the farms, rangelands as well as the watershed areas
New techniques must be introduced for soil conservation and natural resources protection both in the farm fields as well as on the watershed areas in the southern mountains.

11. Facing the challenges - Research Objectives
Evaluate the use of composted organic wastes as soil amendment for the enhancement of the overall quality of soils for crop productivity and agricultural sustainability as well as for erosion control purposes
Evaluate the effect of Vetiver Grass Systems (VGS) to prevent sediment loss and control soil erosion at the watershed level
Evaluate the effect of conservation techniques on soil erosion and crop productivity

12. Case study No. 1
Effect of Compost Application Rates on Crop Growth

13. Manual spreading of Compost

14. Completed Compost Application

15. Some of the Results

16. Corn performance after compost application↑
0 tons/acre ↑
120 tons/acre

17. Inarajan Corn Plots ↑
30 tons/acre ↑
0 tons/acre

18. Corn cups produced under different treatment (compost application rate)

19. Soil Quality parameters affected by different application rate
Treatment
O.M %
Bulk Density (gr/cm3)
Moisture
0 t/acre
2.78
1.06
25.86
30 t/acre
5.52
0.99
26.01
60 t/ace
6.40
1.02
28.07
120 t/acre
10.34
0.95
32.16

20. Average yield per treatment following different application rates

21. Effect of Application Rate on Some Chemical
Properties of the Soil under study

22. Effect of Compost Application Rate on Some of the Soil Nutrients

23. Conclusion
These findings clearly showed that productivity can be improved by proper use of organic materials and the environment also benefits through the re-use of organic wastes that otherwise would be buried in the land fill.

24. The effect of conservation tillage on soil erosion
Case Study No. 2
The effect of conservation tillage on soil erosion
and its impact on crop productivity on the following soil:
Oxide rich, highly weathered acid soils (very fine, kaolinitic, isohypothermic oxic Haplustalf) derived from the volcanic deposit.

25. No-Till and Reduced Till

26. Conventional Till (CT) and No-Till

27. Using rainfall simulator for measuring infiltration

28. Rainfall simulator (cont’d)

29. Effect of conservation tillage practices on infiltration

30. Effect of conservation tillage practices on crop yield

31. 2006 yield results Treatment Yield (t/ha) Reduced Till 1.44 No Till
2006 yield results
Treatment
Yield (t/ha)
Reduced Till
1.44
No Till
0.51
Conv. Till
1.25
Conv. Till/SH
1.45

32. Case Study No. 3
Use of Vetiver Technology to control erosion as a watershed management technique for water quality improvement and natural resource preservation

33. Project Importance Watershed Degradation Water Quality Problems
Limited Water Sources
Coral Reef Degradation
Economic Impacts

34. What Causes Erosion?
Occurs Naturally
- Wind
- Rain

35. Water Erosion in the Fields

36. Human Activities
Construction
Burning
Farming
ATV’s, Off-Road

37. Mud in Pauliluc Bay
Courtesy of Dr. Minton, NPS

38. Healthy Coral Reef

39. Coral reef degradation as the result of Severe Soil Erosion

40. What can be done? Erosion Mitigation - Surface Cover - Education
- Stop Burning
- Farming BMP’s
- Use of Vetiver Technology to reduce
Sedimentation

41. About Vetiver

42. What Is Vetiver Grass Scientific Name; Vetiveria Zizanioides Seedlings
Vetiver in Nature

43. Mainly found in Thailand
Vetiver Origin
Mainly found in Thailand
Also found and Used In:
* China * Indonesia
* Australia * South Africa
* Madagascar * Guam
* Persia

44. Special Characteristics
Adoptable to Various Soil Conditions:
* Low pH: < 4 * High pH: > 12
Able to take up heavy metals
* Zn, As, Mn, Cu, Al, & Pb
Water Purifier (Sediment & Nutrients)
* Nitrates & Phosphates

45. Vetiver Root System
Scientific Name; Vetiveria Zizanioides

46. Comparing root systems of common Savanna Sword grass with Vetiver
Local Sword Grass
Vetiver Grass

47. Main Uses of Vetiver
Badland
Six Months after Planting

48. End Goal
Stop Erosion From Source
Stop Major Sediment Outfalls

49. Vetiver Technology experimentation in the island of Guam using flume enclosures

51. Evaluating sedimentation under 4 different watershed conditions
Burned
Vetiver & Sunn Hemp
Tilled (simulating badland)
Natural condition

52. Runoff & sediment sampling techniques
Flume Drain
Sampling Design
Sampling Protocol
Tank Drainage

53. Results

55. Table 1.: Soil characterization prior and following the treatments.
Management
Practices
3.9
54.4
24.9
20.7
Initial soil characteristics
Soil characteristics as affected by study treatments
Soil Texture
(%)
O.M.
Clay
Sand
Silt
Avg. % O.M.
Burn
57.2
20.5
22.3
5.1
Vetiver
51.8
28.2
20.0
5.4
Till
54.8
26.1
19.1
3.0
Natural
56.8
25.7
17.5
3.8
Table 1.: Soil characterization prior and following the treatments.

56. (Soil surface conditions)
Size and slope of the study plots
Management practices
(Soil surface conditions)
Soil loss
(tons/ha/yr)
Area ha
Length m
Slope %
0.0037
21.95 12
Burn
14.13
Vetiver
1.47
Till
104.75
Natural
5.22
Table 2: Annual Soil loss from each plot with different treatments.

59. Concluding Remarks
Vetiver Technology is a viable system to mitigate sedimentation at the watershed level for water quality improvement and natural resources preservation and the environmental protection

60. Overall Conclusion Preserving natural resources and
protecting the environment requires:
Highly coordinated holistic approach towards natural resource management that include:
Soil
Water
Rangelands
Forests
And watershed protection

61. Overall conclusion (cont’d)
Holistic approach towards natural resource
management also include:
Inspirational leadership and intelligent national efforts from:
government leaders, educators, business and public sectors
Good Scientific information and monitoring
Broad educational efforts for conservation of natural resources

62. Thank You