This dataset is dynamically loaded from our live database. Once a survey is selected a table appears. University of Illinois Base Yield Indices By Component" is a method of arraying the soils in Illinois for non-irrigated commodity crop production based on their inherent soil properties. Ratings are for soils in their present condition. (Absence of an entry indicates that a crop productivity index is not assigned). Please allow 60 seconds to load. For more information about the table,

Productivity and Yield Indices that have been Adjusted for Slope, Erosion, and Flooding

Summary

In Illinois, USDA Natural Resources Conservation Service (NRCS) uses the base productivity index (PI) and base yield indices for corn, soybeans, winter wheat, oats, grain sorghum, and grass-legume hay from University of Illinois (UI) Bulletin 811 “Optimum Crop Productivity Ratings for Illinois Soils (Olson and Lang, 2000) with revised data from “Table S2, Revised—Productivity of Illinois Soils Under Optimum Management, Slightly Eroded, 0 to 2 Percent Slopes (Olson and Lang, 2012). NRCS uses base indices for grass-legume pasture from UI Bulletin 810 “Average Crop, Pasture, and Forestry Productivity Ratings for Illinois Soils (Olson, et al. 2000) with revised data from “Table 2 revised—Productivity of Illinois Soils Under Average Management, Slightly Eroded, 0 to 2 Percent Slopes (Olson et al., 2012). The base indices are used for conservation planning and policy after adjusting for major-component percentage of the soil mapping units and for phase, including slope, erosion, and flooding.

NRCS developed calculations for the Web Soil Survey based on the indices from the University of Illinois. Previously, yields and indices were populated manually in the National Soil Information System (NASIS). They were then delivered through the Web Soil Survey, the digital soil survey geographic database (SSURGO), and published soil survey reports for individual counties. Manually editing the NASIS database to account for updates to the productivity and base index from UI generated a significant workload. Edits were needed for the 7 indexed crops in more than 10,000 soil map units in Illinois.

Soil Database Composition

A soil series represents the central, characteristic concepts of a soil. Soil map units are identified as phases of soil series based on variations in slope, erosion, flooding, surface texture, substratum (layers below the developed soil profile), drainage, or other specifically identified properties. Consociations are map units containing one major-component soil series that makes up at least 85 percent of that map unit. Complexes and undifferentiated groups are map units that contain more than one major-component soil series. Additional map units are composed of miscellaneous soil areas or materials that are not represented by standard soil series concepts. Examples of miscellaneous areas include urban land, dams, beaches, dumps, oil-waste land, pits, riverwash, rock outcrop, water, and miscellaneous water. Certain types of soil materials that are identified on a soil map do not typically have interpretations because of high variability (Soil Survey Division Staff, 1993). Examples include Orthents of several kinds, Alfic Udarents, and Aquents.

Indices for consociations are calculated by representing the major component as 100 percent of the whole map unit. Complexes and undifferentiated groups are developed by ignoring minor component percentages and re-calculating the major components to equal 100 percent of the map unit. These methods allow the major components in complexes and undifferentiated groups to proportionately dominate productivity and yield indices. If a miscellaneous area is included in a map unit as a component, it carries a value of zero in subsequent calculations, significantly impacting the map unit index.

Yield indices and productivity indices for row crops are not calculated for agricultural purposes where land capability classification (LCC) of the map unit is 6s, 6e, 7e, 8, or 8s or where the map unit component is identified as “Taxon above family or Miscellaneous area. Grass-legume hay indices are not calculated where LCC is 7s, 7e, or 8. Grass-legume pasture indices are not calculated where LCC is 8 or 8s.

These indices are not used for real estate land assessment or for valuation of real estate tax base in Illinois.

Yield indices in Illinois have been adjusted by NRCS for several years on the basis of slope, erosion, and flooding. Additional factors may be needed to address differences among specific sites or series phases. Yields and productivity indices given in the table are generally accurate, but local variability and slight differences in soil characteristics still exist across the landscape. Some soils are more variable than others, and some soils respond differently to management. Variations in landform and in landform position also affect soil moisture and nutrient availability and consequently affect yield.

Yield indices are determined for nonirrigated land under normal management, including drainage for agricultural purposes where appropriate. Soils that are typically drained under normal management but have not been drained will have lower yield indices than given in the table. Soils under irrigation management will have higher yield indices than given in the table.

The calculated yield indices are relative to one another and the base yields of UI bulletins 810 and 811. The indices are intended for ranking, comparing, and estimating yields and productivity of crops typically grown on the named soil series.

University of Illinois Bulletin 811 (Olsen and Lang, 2012) provides index factors for determining RV optimum productivity index and optimum yield indices for row crops and hay. The calculated indices reflect soil productivity for crops and hay under dominantly optimum management.

University of Illinois Bulletin 810 (Olsen et al., 2012) provides base yield index factors for calculating representative values (RV) for soil map units. The resulting values for average productivity index and average pasture yield index reflect the overall productivity and productivity for pasture under average management for each soil map unit.

Hay and pasture yields are delivered as grass-legume mixed hay and grass-legume mixed pasture. Well drained soils typically use alfalfa yields. Vegetation is more mixed on wetter soils where alfalfa is not grown. Dominantly, both hayland and pasture support mixed grasses and legumes.

Factors used for slope and erosion are applied as defined by bulletin 810 and 811. In Illinois, NRCS uses relative value (Rv) slope, assigned erosion class, and a simple table to determine which value (from table S3 in bulletin 811) to use for row crops and hay. Table 7 in bulletin 810 is used with the Rv slope and assigned erosion to determine the number of animal unit days, which is then divided by 30 to get animal unit months.

Productivity indices derived with this method have been incorporated with the statewide Land Evaluation and Site Assessment (LESA) system for the protection of farmland relative to The Illinois Farmland Preservation Act, 1982 (505 ILCS 75/1 et seq.), in which the Illinois Department of Agriculture (IDA) was legislatively directed to review all State agency projects and activities that may have a direct or indirect effect upon the potential conversion of farmland in Illinois (IDA, 2001; CCRPC, 2011).

Productivity indices derived with this method have been incorporated with the Federal Farmland Protection Policy Act (FPPA), 1981, which directs all Federal agencies to evaluate their programs and projects and to modify their actions so as to produce the least impact on farmland. The FPPA also seeks to ensure that Federal programs are administered in a manner that, to the extent practicable, will be compatible with State and local government programs, private programs, and policies to protect farmland. Additional information on the FPPA is online at http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/landuse/fppa/.

Further documentation regarding the indices, including information on how they were derived, is available from the University of Illinois soil productivity website athttp://soilproductivity.nres.uiuc.edu/ (Olson and Lang, 2000, 2012; Olson, et al. 2000, 2012). Other information regarding the Illinois productivity and yield indices can be found on the Illinois Field Office Technical Guide (FOTG). Select Illinois from the map at http://efotg.sc.egov.usda.gov/; select a county of interest from the next map; select Section II from the drop-down menu on the left; select “Soil and Site Information; select Productivity and Yield Indices; and select a document of interest.

References:

Champaign County Regional Planning Commission. 2011. Brief history of LESA development with focus on Illinois.http://www.ccrpc.org/planning/pdfs/Brief%20History%20of%20LESA%20Development.pdf (accessed 10 March 2015).

Illinois Department of Agriculture. 2001. Illinois LESA system. Land evaluation and site assessment. http://www.agr.state.il.us/Environment/LandWater/LESA.pdf (accessed 10 March 2015).

Olson, K.R., and J.M. Lang. 2000. Optimum crop productivity ratings for Illinois Soils. Bulletin 811. Office of Research, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. http://soilproductivity.nres.uiuc.edu/ (accessed 26 March 2013).

Olson, K.R., and J.M. Lang. 2012. Table S2 revised. Productivity of Illinois soils under optimum management, slightly eroded, 0 to 2 percent slopes. Bulletin 811. Office of Research, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. http://soilproductivity.nres.uiuc.edu/ (accessed 26 March 2013).

Olson, K.R., J.M. Lang, J.D. Garcia-Paredes, R.N. Majchrzak, C.I. Hadley, M.E. Woolery, and R.M. Rejesus. 2000. Average crop, pasture, and forestry productivity ratings for Illinois soils. Bulletin 810. Office of Research, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. http://soilproductivity.nres.uiuc.edu/(accessed 26 March 2013).

Olson, K.R., J.M. Lang, J.D. Garcia-Paredes, R.N. Majchrzak, C.I. Hadley, M.E. Woolery, and R.M. Rejesus. 2012. Table 2 revised. Productivity of Illinois soils under average management, slightly eroded, 0 to 2 percent slopes. Bulletin 810. Office of Research, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. http://soilproductivity.nres.uiuc.edu/ (accessed 26 March 2013).

Soil Survey Division Staff. 1993. Soil survey manual (revised). U.S. Department of Agriculture, Soil Conservation Service . http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054262 (accessed 11 November 2014).

U.S. Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. Sections 618.6, Available water capacity; 618.30, Flooding frequency class, duration class, and month; and 618.49 Ponding depth, duration class, frequency class, and month. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054242 (accessed 11 November 2014).