20 Heller, M.C. and Keoleian, G.A. (2003). Assessing the sustainability of the US food system: A life cycle perspective. Agricultural Systems 76(3), 1007–1041. doi:10.1016/S0308‐521X(02)00027‐6521X(02)00027‐6
21 Helms, D. (1991). Two centuries of soil conservation. OAH Magazine of History 5(3), 24–28. doi:10.1093/maghis/5.3.24
22 Hillel, D. (1991). Out of the earth: Civilization and the life of the soil. Oakland, CA: University of California Press
23 Hobbs, P.R. (2007). Conservation agriculture: What is it and why is it important for future sustainable food production? J. Agric. Sci. 145, 127–137. doi:10.1017/S0021859607006892
24 Hurisso, T.T., Culman, S.W., and Zhao, K. (2018). Repeatability and spatiotemporal variability of emerging soil health indicators relative to routine soil nutrient tests. Soil Sci. Soc. Am. J. 82, 939–948. doi:10.2136/sssaj2018.03.0098
25 Janzen, H.H. (2001). Soil science on the Canadian prairies– Peering into the future from a century ago. Can. J. Soil Sci. 81, 489–503. doi:10.4141/S00‐054
26 Janvier, C., Villeneuve, F., Alabouvette, C., Edel‐Hermann, V., Mateille, T., and Steinberg, C. (2007). Soil health through soil disease suppression: Which strategy from descriptors to indicators? Soil Biol . Biochem. 39(1), 1–23. doi:10.1016/j.soilbio.2006.07.001
27 Karlen, D.L., Mausbach, M.J., Doran, J.W., Cline, R.G., Harris, R.F., and Schuman, G.E. (1997). Soil quality: A concept, definition, and framework for evaluation. Soil Sci. Soc. Am. J. 61(1), 4–10. doi:10.2136/sssaj1997.03615995006100010001x
28 Karlen, D.L., Veum, K.S., Sudduth, K.A., Obrycki, J.F., and Nunes, M.R. (2019). Soil health assessment: Past accomplishments, current activities, and future opportunities. Soil Tillage Res. 195, 104365. doi:10.1016/j.still.2019.104365
29 Kaspar, T.C., and Parkin, T.B. (2011). Soil carbon dioxide flux in response to wheel traffic in a no‐till system. Soil Sci. Soc. Am. J. 75(6), 2296–2304. doi:10.2136/sssaj2011.0129
30 Keen, B.A. (1931). The physical properties of the soil. Rothamsted monograph on Agricultural Science. Ser. London: Longmans, Green and Co.
31 King, F.H. 1911. Farmers of forty centuries. Madison, Wisconsin: F.H. King.
32 Ladoni, M., Basir, A., and Kravchenko, A. (2015). Which soil carbon fraction is the best for assessing management differences? A statistical power perspective. Soil Sci. Soc. Am. J. 79(3), 848–857. doi:10.2136/sssaj2014.10.0426
33 Ladoni, M., Basir, A., Robertson, P.G., and Kravchenko, A.N. (2016). Scaling‐up: Cover crops differentially influence soil carbon in agricultural fields with diverse topography. Agric. Ecosyst. Environ. 225, 93–103. doi:10.1016/j.agee.2016.03.021
34 Li, C., Fultz, L.M., Moore‐Kucera, J., Acosta‐Martínez, V., Horita, J., Strauss, R., Zak, J., Calderon, F., and Weindorf, D. 2017. Soil carbon sequestration potential in semi‐arid grasslands in the Conservation Reserve Program. Geoderma 294, 80–90. doi:10.1016/j.geoderma.2017.01.032
35 Li, C., Fultz, L.M., Moore‐Kucera, J., Acosta‐Martínez, V., Kakarla, M., and Weindorf, D.C. (2018). Soil microbial community restoration in Conservation Reserve Program semi‐arid grasslands. Soil Biol. Biochem. 118, 166–177. doi:10.1016/j.soilbio.2017.12.001
36 Lowdermilk, W.C. (1953). Conquest of the land through 7000 years. Washington, D.C.: USDA Soil Conservation Service, U.S. Department of Agriculture.
37 Magdoff, F., and van Es, H . (2009). Building soils for better crops: Sustainable soil management , 3rd ed. Sustainable Agriculture Research and Education, Handbook Series Book 10. College Park, MD: Sustainable Agriculture Research and Education.
38 McBratney, A., Field, D.J., and Koch, A. (2014). The dimensions of soil security. Geoderma 213, 203–213. doi:10.1016/j.geoderma.2013.08.013
39 Mena Mesa, N., Ruiz‐Vega, J., Funes‐Monzote, F.R., Carrillo‐Rodriguez, J.C., and Velasco‐Velasco, V. (2014). Indicators of agroecological sustainability of three tillage systems for maize (Zea mays L.) production. Agroecology and Sustainable Food Systems 38(4), 410–426. doi:10.1080/21683565.2013.870626
40 Moebius‐Clune, B.N., Moebius‐Clune, D.J., Gugino, B.K., Idowu, O.J., Schindelbeck, R.R., Ristow, A.J., van Es, H.M., Thies, J.E., Shayler, H.A., McBride, M.B., Kurtz, K.S.M., Wolfe, D.W., and Abawi, G.S. (2016). Comprehensive assessment of soil health–The Cornell framework , edition 3.2, Geneva, NY: Cornell University.
41 Montgomery, D.R. (2007). Dirt: The erosion of civilizations , 2nd ed. Berkeley, CA: University of California Press.
42 Morrow, J.G., Huggins, D.R., Carpenter‐Boggs, L.A., and Reganold, J.P. (2016). Evaluating measures to assess soil health in long‐term agroecosystem trials. Soil Sci. Soc. Am. J. 80, 450–462. doi:10.2136/sssaj2015.08.0308
43 Mulder, V.L., de Bruin, S., Schaepman, M. (2011). The Use of Remote Sensing in Soil and Terranin Mapping‐ A Review. Geoderma 162 (1–2): 1–19, https://doi.org/10.1016/j.geoderma.2010.12.018
44 Necpálová, M., Anex Jr., R.P., Kravchenko, A.N., Abendroth, L.J., Del Grosso, S.J., Dick, W.A., Helmers, M.J., Herzmann, D., Lauer, J.G., Nafziger, E.D., Sawyer, J.E., Scharf, P.C., Strock, J.S., and Villamil, M.B. (2014). What does it take to detect a change in soil carbon stock? A regional comparison of minimum detectable difference and experiment duration in the north central United States. J. Soil Water Conserv. 69(6), 517–531. doi:10.2489/jswc.69.6.517
45 Ontl, T.A., Cambardella, C.A., Schulte, L.A., and Kolka, R.K. (2015). Factors influencing soil aggregation and particulate organic matter responses to bioenergy crops across a topographic gradient. Geoderma 255–256, 1–11. doi:10.1016/j.geoderma.2015.04.016
46 Rasul, G., and Thapa, G.B. (2004). Sustainability of ecological and conventional agricultural systems in Bangladesh: An assessment based on environmental, economic and social perspectives. Agric. Syst. 79(3), 327–351. doi:10.1016/S0308‐521X(03)00090‐8
47 Reicosky, D.C. (2015). Conservation tillage is not conservation agriculture. J. Soil Water Conserv. 70(5), 103–108. doi:10.2489/jswc.70.5.103A
48 Roper, W.R., Osmond, D.L., Heitman, J.L., Wagger, M.G., and Reberg‐Horton, S.C. (2017). Soil health indicators do not differentiate among agronomic management systems in North Carolina soils. Soil Sci. Soc. Am. J. 81(4), 828–843. doi:10.2136/sssaj2016.12.0400
49 Rule, G.K. (1937). Conserving corn belt soils. Farmers’ Bulletin No. 1795. Washington, D.C.: U.S. Gov. Print. Office.
50 Schindelbeck, R.R., van Es, H.M., Abawi, G.S., Wolfe, D.W., Whitlow, T.L., Gugino, B.K., Idowu, O.J., and Moebius‐Clune, B.N. (2008). Comprehensive assessment of soil quality for landscape and urban management. Landsc. Urban Plan. 88(2‐4), 73–80. doi:10.1016/j.landurbplan.2008.08.006
51 Schnepf, M., and Cox, C. (2006). Environmental benefits of conservation on cropland: The status of our knowledge. Ankeny, IA: Soil and Water Conservation Society.
52 Shoshany, M., Goldshleger, N., Argaman, E., Chudnovsky, A. (2013). Monitoring of Agricultural Soil Degradation by Remote‐Sensing Methods: A Review. International Journal of Remote Sensing 34 (17): 6152–6181, https://doi.org/10.1080/01431161.2013.793872
53 Skaggs, R.W., Breve, M.A., and Gilliam, J.W. (1994). Hydrologic and water‐quality impacts of agricultural drainage. Crit. Rev. Environ. Sci. Technol. 24(1), 1–32. doi:10.1080/10643389409388459
54 Sparks, D.L., A.L. Page, P.A. Helmke, and R.H. Loeppert, editors. 1996. Methods of soil analysis part 3—chemical methods. SSSA Book Ser. 5.3. Madison, WI: SSSA, ASA. doi:10.2136/sssabookser5.3.
55 Steffan, J.J., Brevik, E.C., Burgess, L.C., and Cerdà, A. (2017). The effect of soil on human health: A review. Eur. J. Soil Sci. 69(1), 159–171. doi:10.1111/ejss.12451
56 Stoll,