An Approach to the Development of Inherent Soil Productivity Indices

ational November 2006 Issue 37 N ooperative oil C urvey SS Newsletter In This Issue— An Approach to the indices occur with only a minor difference in the numerical values Development of Inherent between the same data element. Figure An Approach to the Development Soil Productivity Indices 1 demonstrates the use of a continuous of Inherent Soil Productivity evaluation to assign numerical rating Indices ............................................ 1 By H. Raymond Sinclair, Jr., Robert R. Dobos, and Sharon W. Waltman, Soil Scientists, values for a soil property. The Wade G. Hurt Receives SSSA NRCS. continuous evaluation typically assigns Award ............................................. 6 values ranging from 0.01 to 1.0. In table 1, rating classes are assigned NRCS Receives ESRI Award ............. 7 Introduction numerical values. The rating classes are Retirement of Frederick M. Kaisaki ... 8 This article describes a prototype typically assigned values ranging from model of Soil Rating for Plant Growth, 5 to 100. The numerical values Retirement of Robert J. Engel ............ 8 version 4 (SRPG4), which generates assigned to the rating classes are more Nonretirement of Stanley P. inherent productivity indices for soils ambiguous than the values in a Anderson: A Reprise..................... 8 in the United States using soil survey continuous evaluation. In this example, data. The article demonstrates how this both the class and continuum indicate a Web-Based Soil Extent Mapping system assigns productivity indices to condition that is more favorable for Tool ................................................ 9 soils growing commodity crops. The plant growth as the assigned numerical Phil Derr Passes Away ...................... 10 soil data elements in NASIS and soil values become larger. interpretations model (Soil Survey Rooftops to Rivers Publication Staff, 2006a and 2006b) in the NASIS Table 1.—Values assigned to crisp Available ...................................... 11 interpretation module will be used to classes Job Aids ............................................ 11 generate the productivity indices. The Class definition Assigned value article will outline how the model is being developed. It is the first in a Most favorable 100, or else series of publications that will explain 95, or else, the development and use of this model. Future publications will discuss all 85, or else aspects of the SRPG4 model in detail. 75, or else This article will not discuss some aspects that are still in developmental 60, or else Editor’s Note stages. These planned aspects are Least favorable 5. Issues of this newsletter are available in the NASIS interpretation available on the World Wide Web module. (http://soils.usda.gov/). Under Quick The Soil Survey Staff (2000) K.W. Flach (1985) indicated the Access, click on NCSS, then on explained the use of rating classes or need for modeling in soil science, that Newsletters, and then on the desired traditional “crisp” limits (table 1) to is, the need for “a model of the issue number. assign soil productivity indices for relationship between kinds of soils and You are invited to submit stories for commodity crops. Users suggested that landscape.” The mapper “maps ahead this newsletter to Stanley Anderson, a continuous evaluation of soil using this model.” Verbalizing the National Soil Survey Center, Lincoln, properties (SRPG4) could possibly model usually is difficult, as is “putting Nebraska. Phone—402-437-5357; assign soil productivity indices that it into quantitative terms,” but the FAX—402-437-5336; email— avoid boundary conditions where mapper “could not function effectively [email protected]. drastically different productivity without it.” 1 NCSS Newsletter module of the soil survey database indicates the degree of membership of system (Soil Survey Staff, 2006b) to that attribute in the set of soils that are assess the impact of numerous soil productive. In this example, a soil constraints or qualities on plant growth component having a pH of 6.5 would and thus compute a soil productivity or receive a score of 1, whereas a soil inherent soil quality index for component having a pH of 5.0 would components of soil map units (Soil receive a score of less than 1. The Figure 1.—Values assigned for a continuous Survey Staff, 2006a). The SRPG4 shape of the curve depends on the soil evaluation. calculations followed the “Storie Index attribute being modeled (see figures 2 Rating” (Storie and Weir, 1958; Storie, through 5). 1978), which was based on soil The rating from the evaluation is fed Many crop indices with their characteristics that govern the land’s into a base rule indicating the impact of published methodology have been potential utilization and productive the soil attribute in question on the land developed for many geographical areas capacity. The Storie index was use. The base rule is a logical diagram over the past years. Each model originally adapted to semiarid and arid depicting the relationship between the developed criteria and used data regions and included profile soil attributes and the land use being elements that enable it to work for a characteristics that influenced the modeled. Base rules can be put selected area. Everyone should study effective rooting depth and the quality together to make various levels of the methodology that results in the of the root zone; subsurface properties subrules, depending on the complexity generation of indices that satisfy the (permeability, available water capacity, of the land use situation being customers using these models. After the drainage class, and soluble salts); and considered (Soil Survey Staff, 2001). models were examined, none seemed to landscape properties, such as slope, Table 2 lists the four subrules generate indices that would array the microrelief, and the degree of erosion. (chemical and physical properties and soils of the United States for growing SRPG4 also considers climate as an climate and landscape factors) used to commodity crops. Huddleston (1984) additional factor in calculating the calculate SRPG4. As is indicated in details the development and use of soil index. Climate is a particularly table 2, base rule level 2 has 22 productivity ratings in the U.S. The significant parameter, given the range elements, which mathematically Storie Index is a method of soil rating of climate across regions. SRPG4 calculate the values for the four that is based on soil characteristics that provides a reasonable semi-quantitative elements in subrule level 1. govern the land’s potential utilization index (from 0.01 to 1) of soil Soil attribute data can be and productive capacity. It is productivity applicable to map unit manipulated in a variety of ways to independent of other physical and components of the soil survey database. arrive at a value that is meaningful in economic factors that might determine A table near the end of this article terms of soil productivity. For example, the desirability of growing certain (table 4) shows a productivity index roots are sensitive to the bulk density of plants in a given location. The generated by an early version of a soil layer, since penetration resistance publications by Huddleston and Storie SRPG4. is partially a function of bulk density. are only two of the more than 90 The conceptual model of the soil At some point, a soil layer becomes too citations available on the subject of interpretations module, or prototype as dense for root ramification. The values crop indices. outlined in this article, consists of four for nonlimiting, critical, and root- basic parts. These are “main rules” limiting bulk densities for each family Methodology and Development (also called “interpretations”), particle-size class are shown in table 3 of SRPG4 “subrules” (composed of “base rules”), (Pierce et al., 1983). “evaluations,” and “properties.” A The information in table 3 is Soil productivity is strongly “property” is a Structured Query manipulated in a property script to influenced by the capacity of a soil to Language (SQL) script that retrieves arrive at a way of comparing the supply the nutrients and soil-stored the desired soil attribute data, such as populated bulk density to a bulk water that a crop growing in a given the pH of the surface horizon. This density that is conducive to root growth climate needs (Olson and Lang, 2002). piece of data is placed into an for any particular combination of sand, SRPG4 uses the soil interpretations evaluation, which is a graph that silt, and clay. The resulting number is 2 NCSS Newsletter Figure 2.—Precipitation. Figure 3.—pH, 0-20 cm, weighted average. Figure 4.—Available water capacity (AWC), 0-150 cm. Figure 5.—Frost-free days. then scored on the basis of its zone. Table 4 illustrates the numerical productivity index for commodity estimated impact on soil productivity values generated by the rule, subrules, crops. using the appropriate evaluation. and base rules in the SRPG4 model. The SRPG4 model should be The soil interpretations module The table also indicates the taxonomic tested in many different geographical allows the logical relationships, such as classification of the soil. areas. Constructive suggestions interactions and weighting, among soil, The ratings for the subrule level 1 would be appreciated. Ideas and landscape, and site features to be factors are weighted and used in the suggestions are continually being modeled. In SRPG4, the weight of a calculation of the final SRPG tested and incorporated into the particular variable can be assigned in the subrule diagram. Figure 6 is an example of how physical soil factors might be related in a subrule. The “divide” boxes are used to adjust the weight of the individual factors or groups of factors. The results are multiplied together, as in the Storie index. Some products that can be generated using the SRPG4 model are indicated in figure 7 and table 4. Figure 7 shows the available water capacity of the root zone for the soils in Tazewell County, Illinois (Soil Survey Staff, 2005). There is a very good relationship between crop yields and the available water capacity of the root Figure 6.—A subrule diagram of physical soil properties.

Load more