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Peter Motavalli, Bunjirtluk Jintaridth, Johannes Lehmann, Keith Goyne, and Jere Gilles

ASSESSING AND MANAGING SOIL QUALITY FOR SUSTAINABLE AGRICULTURAL SYSTEMS SANREM-CRSP CROSS-CUTTING INITIATIVE. Peter Motavalli, Bunjirtluk Jintaridth, Johannes Lehmann, Keith Goyne, and Jere Gilles. INTRODUCTION.

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Peter Motavalli, Bunjirtluk Jintaridth, Johannes Lehmann, Keith Goyne, and Jere Gilles

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  1. ASSESSING AND MANAGING SOIL QUALITY FOR SUSTAINABLE AGRICULTURAL SYSTEMS SANREM-CRSP CROSS-CUTTING INITIATIVE Peter Motavalli, Bunjirtluk Jintaridth, Johannes Lehmann, Keith Goyne, and Jere Gilles

  2. INTRODUCTION • Soil degradation is a major global environmental problem, resulting in increased poverty and severe environmental problems (e.g., decreased biodiversity and water quality) (Eswaran et al., 1997). • For example, the loss of potential productivity due to soil erosion world wide is estimated to be equivalent to some 20 million tons of grain per year (UNEP, 1999).

  3. INTRODUCTION (CONT.) • Almost 75% of Central America’s, 45% of South America’s, and 11% of Asia’s agricultural land have been seriously degraded. (Scherr, 1999; Heerink, 2001). • Three-quarters of Africa’s farmland has severe soil degradation caused by wind and soil erosion and loss of mineral nutrients (Heano and Baanante, 2006).

  4. SOIL QUALITY Definition : “ the capacity of a soil …. to sustain biological productivity, maintain environmental quality, and promote plant and animal health” (Doran and Parkin,1994).

  5. SOIL QUALITY (CONT.) • Soil quality depends on the capacity of a soil to perform a desired ecosystem function • Soil functions – • sustaining biological activity, diversity, andproductivity • regulating and partitioning water and solute flow • filtering, degrading, immobilizing and detoxifyingorganic and inorganic species • storing and cycling of nutrients • providing structural support

  6. SOIL QUALITY (CONT.) • Biological indicators – (e.g., microbial community structure and activity) • Chemical indicators – (e.g., pH , CEC) • Physical indicators – (e.g., infiltration, bulk density, water-holding capacity) • Soil organic matter is an importantsoil quality index because ofits integral role in soil biological,physical and chemical processes(Carter, 2002) USDA Soil Quality Test Kit

  7. OBJECTIVES • Assess community perceptions and indicators of soil quality, including differences in perceptions of soil quality due to gender, environment and socio-economic factors. • Determine the effectiveness of spectroscopic-based (i.e., near-infrared, mid-infrared, and visible range) analytical methods to evaluate soil organic matter fractions and soil quality in degraded and non-degraded soils in a wide range of environments. • To collaborate in the evaluation of soil metagenomic methods as an indicator of soil degradation.

  8. METHODOLOGY • Will use participatory workshops of community members and professionals • What are the specific soil quality indicators that community members use to evaluate soil quality among the different soil types and crops? • How has soil quality changed over time and why? • The communities will be surveyed to determine the characteristics of a field soil quality testing procedure that would be appropriate for their conditions and for evaluating sustainable agricultural management practices.

  9. COMMUNITY PERCEPTIONS OF SOIL RESOURCES AND SOIL-RELATED PROBLEMS IN BOLIVIA • Soil-related problems are only one of several factors limiting crop production. • Soil management problems identified were: • Low soil quality and soil fertility(low soil nutrient content, high clay content and stoniness) • Excessive water and wind-induced soil erosion • Insufficient soil moisture due to lower rainfall • Inadequate soil management practices(Inappropriate tractor tillage practices, lack of a suitable crop rotation strategy, insufficient soil fertility inputs, and overgrazing by sheep)

  10. METHODOLOGY • Soils will be collected from depths of 0-10 to 10-20 cm from degraded and non-degraded agricultural fields (i.e., Sanborn Field, Bolivian, Ecuadorian, Zambian, and Asian studies) • The soil will be freeze-dried, ground and sieved to a size fraction <2 mm diameter. • Climatic information will be obtained. • All samples will be analyzed by using spectroscopic methods. • Soil texture, pH, CEC, total organic C, total N, water-soluble total organic C and total N, particulate organic matter C and N, soil test P (Bray 1 P), exch. K, Ca, and Mg will be determined.

  11. FIELD METHODS Labile C Determination Using KMnO4 (Weil, 2003)Evaluating two methods: • Portable field spectrometer – 550 nm • Field chart

  12. FIELD METHODS Portable Field Near Infrared (NIR) Spectrometer • Determination of soil organic C using a portable field NIR spectrometer, Fieldspec Pro FR (Stevens et al., 2006) • It may relate to use of remotely sensed infrared imagery to improve diagnostic capabilities to assess plant and soil health. • For this study, we will do theNIR analysis of soil samples in the laboratory and not inthe field.

  13. LABORATORY METHOD Diffuse Reflectance Fourier TransformInfraredAnalysis (DRIFT) – MidInfraredAnalysis • Can determine changes in ratios of reactive (O-containing) and recalcitrant (C, H and/or N) functional groups due to management practices. • Will test sample preparation method • Extraction of HA fraction of SOM • Removal of mineral constituents using hydrofluoric acid • Analysis of intact soil

  14. DRIFT INFRARED SPECTRA PEAK ASSIGNMENTS Peak assignmentWave number (cm-1) Mineral OH 3690 CH2 symmetric stretch 2962-2950 CO-OH H bonded 2500 C=O stretch 1850 C=O ketonic, COOH 1735-1713 C=O, C=O-H bonded, 1650 C=C aromatic 1630-1608 Aromatic ring, amide 1509 CO, COOH, COC, phenol OH 1260-1240 Aliphatic, alcoholic OH 1190-1127 CO aliphatic alcohol 1080-1050 Aliphatic COC, aromatic ether, Si-O 1030 CH aromatic bend 779 COO salt, Mg/Si-O aliphatic 560 (Adapted from Stevenson, 1982 and Baes and Bloom, 1989)

  15. EFFECT OF TILLAGE ON DRIFT SPECTRA Conventional Tillage Conservation Tillage cooH cooH aromatic 0 – 5 cm aromatic 0 – 5 cm 5 – 10 cm 5 – 10 cm 10 – 15 cm 10 – 15 cm (Ding et al., 2002)

  16. EFFECT OF TILLAGE ON DRIFT SPECTRA HADepth (cm) Total O/R ratio (1727+1650+1160+1127+1050) (2950+2924+2850+1530+1509+1457+1420+779 Conservation tillage CnT1 0-5 0.87 a CnT2 5-10 0.69 b CnT3 10-15 0.70 b Conventional tillage CT 1 0-5 0.74 ab CT 2 5-10 0.69 b CT 3 10-15 0.67 b * Means with different letters are significantly different P = 0.05 • The ratio of O/R (reactive/recalcitrant) was highest in conservation tillage (CnT) at 0-5 cm, suggesting relative enrichment of O-associated C over time in CnT plots as compared with conventional tillage(CT). (Ding et al., 2002)

  17. TASKS • Coordinate soil quality survey with collaborators in the SANREM Projects • Distribute and organize field tests with soil quality kits with collaborators • Obtain soil samples and site histories from degraded and non-degraded sites in coordination with SANREM and soil metagenomic projects • Develop laboratory methodologies and conduct analyses. • Two graduate students (one Thai and one Bolivian)are being trained.

  18. QUESTIONS? COMMENTS? SUGGESTIONS?

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