Soil property indices for assessing short-term changes in soil quality

• Published in: Renewable agriculture and food systems 2008-03, Vol.23 (1), p.70-79
• Main Authors: Bell, M.C., Raczkowski, C.W.
• Format: Article
• Language: English
• Subjects: Acid soils; Acidic soils; Agrology; Agronomy; best management practices; conventional tillage; Environmental quality; Farming systems; Infiltration; large-scale systems research; multidisciplinary research; Nematoda; Nematodes; no tillage; organic; Organic matter; Organic soils; Other Research Papers; Pseudomonas; Soil biology; Soil degradation; Soil density; Soil fertility; soil function; Soil management; Soil organic matter; Soil pH; Soil properties; Soil quality; Soil respiration; Soil sciences; Sustainable agriculture; Tillage
• ISSN: 1742-1705; 1742-1713
• DOI: 10.1017/S1742170507001883

Soil quality has been proposed as a prime indicator for characterizing and defining management factors contributing to soil degradation. In this study, biological (soil respiration, fluorescent Pseudomonas bacteria and entomopathogenic nematode populations), chemical (pH, inorganic N, and total C & N), and physical (bulk density and infiltration) indicators were used to determine soil quality. The specific research objective was to determine the capacity of this specific set of indicators to assess soil quality and determine its ability to detect short-term changes in soil conditions and processes. The assessment was comparative because of the lack of specific criteria or guidelines available in the literature for interpretation of most soil property indices measured. The following treatments were chosen from an ongoing farming systems study to achieve a preplanned set of comparisons that would make this type of assessment possible: (1) best management practices/conventional tillage (BMP/CT), (2) BMP/no-tillage (BMP/NT), (3) an organic system, and (4) a successional fallow system. Assessments were made multiple times between 1999 and 2000. Statistical differences between systems were found for all soil quality indicators except for entomopathogenic nematodes. Differences between systems varied across dates, a result that supports other research stating the need to consider the temporal variability of these indices for an unbiased overall soil quality assessment. Differences in total carbon and total nitrogen between systems were most evident in the 2000 sampling dates with BMP/NT showing greater contents on the last sampling date. The soil pH and inorganic N results did not suggest a possible difference in soil function status between any of the three agricultural systems studied. All three agricultural systems, BMP/NT, BMP/CT and organic, had similar pH values and overall low soil inorganic N levels. The non-agricultural successional system had a slightly more acidic soil condition than the three agricultural systems. Soil bulk density increased with time in the untilled BMP/NT and successional systems but the resulting values were not considered detrimental to either productivity or environmental quality. Infiltration was lower in the BMP/NT and successional systems than in the BMP/CT and organic systems. In conclusion, all soil quality indicators except for entomopathogenic nematodes proved to be sensitive to the detection of rapid changes in soil condi