style="font-size:15px;"> 116 Reganold, J. P., Palmer, A. S., Lockhart, J. C., and Macgregor, A. N. (1993). Soil quality and financial performance of biodynamic and conventional farms in New Zealand. Science 260, 344–349.117 Reganold, J. P. (1994). Response to statistical analyses of soil quality. Science 264, 282–283.
118 Rodale Institute. (1991). Conference report and abstracts. International conference on the Assessment and Monitoring of Soil Quality. Emmaus, PA, 11‐14 July 1991. Emmaus, PA: Rodale Press.
119 Rosenzweig, S. T., Carson, M. A., Baer, S. G., and Blair, J. M. (2016). Changes in soil properties, microbial biomass, and fluxes of C and N in soil following post‐agricultural grassland restoration. Applied Soil Ecology 100, 186–194. https://doi.org/10.1016/j.apsoil.2016.01.001
120 Schipper, L. A., and Sparling, G. P. (2000). Performance of soil condition indicators across taxonomic groups and land uses. Soil Science Society of America Journal 64, 300–311.
121 Shepherd, T. G. (2000). Visual soil assessment. Volume 1. Field guide for cropping and pastoral grazing on flat to rolling country. Palmerston North, New Zealand: Horizons.mw/Landcare Research.
122 Shepherd, T. G., Ross, C. W., Basher, L. R., and Saggar, S. (2000a). Visual soil assessment. Volume 2. Soil management guidelines for cropping and pastoral grazing on flat to rolling country. Palmerston North, New Zealand: Horizons.mw/Landcare Research.
123 Shepherd, T. G., and Janssen, H. J. (2000). Visual soil assessment. Volume 3. Field guide for hill country land uses. Palmerston North, New Zealand: Horizons.mw/Landcare Research.
124 Shepherd, T. G., Janssen, H. J., and Bird, L. J. (2000b). Visual soil assessment. Volume 4. Soil management guidelines for hill country land uses. Palmerston North, New Zealand: Horizons.mw/Landcare Research.
125 Singer, M. J., and Ewing, S. (2000). Soil quality. In M. E. Sumner (Ed.), Handbook of soil science (pp. G‐271–G‐298). Boca Raton, FL: CRC Press.
126 Skold, M. D. (1989). Cropland retirement policies and their effects on land use in the Great Plains. Journal of Production Agriculture 2, 197–201.
127 Smith, J. L., and Doran, J. W. (1996). Measurement and use of pH and electrical conductivity for soil quality analysis. In J. W. Doran and A. J. Jones (Eds.) Methods for assessing soil quality (pp. 169–185). Soil Science Society of America Special Publication No. 49. Madison, WI: SSSA.
128 Soil Quality Institute (SQI). (1996). The soil quality concept. Edited by Soil Quality Institute. USDA‐NRCS.
129 Soil Quality Institute (SQI). (2003). Interpreting the soil conditioning index: A tool for measuring soil organic matter trends. Soil Quality – Agronomy Technical Note No. 16. Auburn, AL: Soil Quality Institute. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_053273.pdf (verified 6‐12‐2020)
130 Sojka, R. E., and Upchurch, D. R. (1999). Reservations regarding the soil quality concept. Soil Science Society of America Journal 63, 1039–1054.
131 Sojka, R. E., Upchurch, D. R., and Borlaug, N. E. (2003). Quality soil management or soil quality management: Performance vs semantics. Advances in Agronomy 79, 1–68.
132 Sparling, G. P., Wheeler, D., Vesely, E.‐T., and Schipper, L. A. (2006). What is soil organic matter worth? Journal of Environmental Quality 35, 548–557.
133 Stott, D. E., Andrews, S. S., Liebig, M. A., Wienhold, B. J., and Karlen, D. L. (2010). Evaluation of β‐glucosidase activity as a soil quality indicator for the Soil Management Assessment Framework (SMAF). Soil Science Society America Journal 74, 107–119.
134 Stott, D. E., Cambardella, C. A., Wolf, R., Tomer, M. D., and Karlen, D. L. (2011). A soil quality assessment within the Iowa River south fork watershed. Soil Science Society America Journal 75, 2271–2282.
135 Van Bavel, C. H. M., and Schaller, F. W. (1950). Soil aggregation, organic matter and yields in a long‐time experiment as affected by crop management. Soil Science Society of America Proceedings 15, 399–408.
136 Van Doren, C. A., and Klingebiel, A. A. (1952). Effect of management on soil permeability. Soil Science Society of America Journal 16, 66–69.
137 Veum, K. S., Kremer, R. J., Sudduth, K. A., Kitchen, N. R., Lerch, R. N., Baffaut, C., Stott, D. E., Karlen, D. L., and Sadler, E. J. (2015). Conservation effects on soil quality indicators in the Missouri Salt River Basin. Journal of Soil and Water Conservation 70, 232–246.
138 Voorhees, W. B., Senst, C. G., and Nelson, W. W. (1978). Compaction and soil structure modification by wheel traffic in the northern Com Belt. Soil Science Society of America Journal 42, 344–349.
139 Voorhees, W. B. (1979). Soil tilth deterioration under row cropping in the northern Corn Belt: Influence of tillage and wheel traffic. Journal of Soil and Water Conservation 34, 184–186.
140 Voorhees, W. B. (1983). Relative effectiveness of tillage and natural forces in alleviating wheel‐induced soil compaction. Soil Science Society of America Journal 47, 129–133.
141 Voorhees, W. B., and Lindstrom, M. J. (1984). Long‐term effects of tillage method on soil tilth independent of wheel traffic compaction. Soil Science Society of America Journal 48, 152–156.
142 Waksman, S. A., and Starkey, R. L. (1924). Microbiological analysis of soil as an index of soil fertility: VII. Carbon dioxide evolution. Soil Science 17, 141–162.
143 Waksman, S. A., and Hutchings, I. J. (1935). The role of plant constituents in the preservation of nitrogen in the soil. Soil Science 40, 487–497
144 Wardle, D. A. (1994). Statistical analyses of soil quality. Science 264, 281–282.
145 Warkentin, B. P., and Fletcher, H. F. (1977). Soil quality for intensive agriculture. In Proceedings of the International Seminar on Soil Environment and Fertilizer Management in Intensive Agriculture (pp. 594–598). Japan: Society of Science of Soil and Manure.
146 Warkentin, B. P. (1992). Soil science for environmental quality – How do we know what we know? Journal of Environmental Quality 21, 163–166.
147 Warkentin, B. P. (1995). The changing concept of soil quality. Journal of Soil and Water Conservation 50 226–228.
148 Warkentin, B. P. (2008). Soil structure: A history from tilth to habitat. Advances in Agronomy 97, 239–272.
149 Whiteside, E. P., and Smith, R. S. (1941). Soil changes associated with tillage and cropping in humid areas of the United States. Agronomy Journal 33, 765–777.
150 Wienhold, B. J., Karlen, D. L., Andrews, S. S., and Stott, D. E. (2009). Protocol for indicator scoring in the Soil Management Assessment Framework (SMAF). Renewable Agriculture Food Systems 24, 260–266.
151 Wilson, H. A., and Browning, G. M. (1945). Soil aggregation, yields, runoff and erosion as affected by cropping systems. Soil Science Society of America Proceedings 10, 51–57.
152 Yoder, R. E. (1937). The significance of soil structure in relation to the tilth problem. Soil Science Society of America Proceedings 2, 21–33.
153 Young, C. E., and Osborn, C. T. (1990). Costs and benefits of the conservation reserve program. Journal
