1. ASSESSING AND MANAGING SOIL QUALITY FOR SUSTAINABLE
AGRICULTURAL SYSTEM
P.P. Motavalli1, B. Jintaridth1, J. Lehmann1, K.W. Goyne1, and J. Gilles1
1College of Agriculture, Food and Natural Resources, University of Missouri, Columbia, MO USA
SANREM-CRSP CROSS-CUTTING INITIATIVE
Objective 2 :
Soils will be collected from depths of to cm from degraded and on-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.
Introduction
Soil quality assessment is a process by which soil resources are evaluated on the basis of soil function. Soil organic matter (SOM) is one of the most widely knowledge indicators of soil quality (Gregorich et al., 1994). In general, SOC varies across landscapes, soil types and climatic zones. It is characterized by high levels of C in recalcitrant or humified forms and small changes in SOC resulting from changes in soil management are difficult to measure.
An approach to evaluate the impact of agricultural management of SOM dynamics is to separate SOM into pools which will depend on differences in decomposition rates (Wander et al., 1994). In two-pool exponential decomposition models, the pool with the smallest size and most rapid turnover is termed labile and the larger pool with slow turnover is termed recalcitrant. The lability of SOM is defined as the ease and speed with which it is decomposed by microbes and depends on both chemical recalcitrance and physical protection from microbes. Changes in labile fractions of SOC provide an early indication of soil degradation or improvement in response to management practices (Islam and Weil,2000).
In this research, soil samples will be collected from representative degraded and non- degraded soils at ongoing SANREM field sites, establish in-field and laboratory capacity to test soil quality, and develop analytical methodologies for the spectroscopic-based procedures. Collaboration with CGIAR system (i.e., ICRAF), USDA-ARS and USDA-NRCS are also important goals of this project due to the ongoing efforts and resources being invested at these institutions in developing low-cost methods for soil quality evaluation.
Objectives
1. To assess community perceptions and indicators of soil quality, including differences in perceptions of soil quality due to gender, environment ad socio-economic factors.
2. To 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.
3. To collaborate in the evaluation of soil metagenomic methods as an indicator of soil degradation.
LABORATORY METHODS
► Mid Infrared (MIR) RANGE
Diffuse Reflectance Fourier Transform Infrared Analysis (DRIFT)
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 soil organic matter
- Removal of mineral constituents
using hydrofluoric acid
- Analysis of intact core
FIELD METHODS
The effectiveness of spectroscopic-based (i.e., near Infrared, mid-infrared, and visible range) analytical methods
► VISIBLE RANGE
Labile C Determination Using KMnO4 (Weil, 2003)
Evaluating two methods
Portable field spectrometer (550 nm)
Field chart
► Near Infrared (NIR) RANGE
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 the NIR analysis of soil samples in the laboratory and not in the field.
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.
Materials and Methods
Objective 1:
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 soils 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.