Introduction to the LESA-CALES System

Background

The Computer-Assisted Land Evaluation System (CALES) is an outgrowth of the NRCS Agricultural Land Evaluation and Site Assessment (LESA) program.  The LESA program is designed to determine the relative quality of land for agricultural uses, including their economic viability.  The CALES system is designed to be an aide in obtaining the necessary soils information and doing the calculations for the land evaluation part of LESA.  The CALES system does not include the site assessment part.

A user should be familiar with the Land Evaluation part of the LESA handbook and the Soil Potential section of the NRCS National Soil Survey Handbook before running the CALES system.

In agricultural land evaluation, soils are rated from the best to the worst for a specific agricultural use based on an indicator crop.  A relative value is determined for each group based on the cost of overcoming soil production limitations. The group with the highest relative value, the best for agricultural use, is assigned a value of 100 and all other groups are assigned lower values.  The land evaluation is based on soils data from the National Cooperative Soil Survey, local conservation practice and economic information.

Before this program can be run on a county, the soil mapunit data must be available. The soils must be mapped and a certified mapunit legend must be available in the NRCS NASIS database.

NASIS Soil Survey Database

The soil survey data used in this implementation of CALES is accessed from the NRCS NASIS database. This NASIS database is used by soil scientists to manage the data for soil surveys from all parts of the country, but was not originally intended to be directly used for access by national programs, such as CALES. The variations among the various regions in managing their soil survey data sometimes makes consistent retrieval of the proper data for a national purpose very difficult.

The CALES program has the following NASIS data requirements. The soil survey data retrieved must be stored as "Non-MLRA Soil Survey Area" legends under the "NSSC Pangaea" database name. Legends retrieved must be marked with a "legend suitability for use" of 2, meaning that the legend is ready for use. For the retrieval of county data, the legend area overlap table and the mapunit area overlap table must be properly and completely populated for the county selected. Otherwise no map units can be retrieved for the county. The overlap acres must also be entered in the mapunit area overlap tabl, or CALES acres will be missing.

If the county or survey area you want to process with CALES is not available from the NASIS database or if the data retrieved appears to be incomplete or incorrect, contact the NRCS state soils staff to discuss your CALES needs and the status of the data. The above description may not mean much to many CALES users, but will be useful in discussions with the NRCS soils staff.

In the future, the CALES system will likely access soils data from the NRCS soils distribution warehouse, which should simplify data access and consistency. But that system is not yet developed.

Overview of the CALES Web System

The current version of CALES has been developed with a web user interface, which can be accessed at the following URL "http://www.nrcs.usda.gov/fpcp/cales/". It is designed for use by those within NRCS having land evaluation responsibilities, as well as others interested in the land evaluation process.

Certain information must be known and entered into the CALES system to perform the land evaluation portion of LESA and to determine soil potential.  Prior to beginning a CALES web session, you should have the following information available:

1. County or area to be evaluated.

2. List of important farmland soils of local and state significance.

3. Identified soil limitations.

4. Conservation measures needed to overcome identified soil limitations and their related annual costs.

5. Strategy for defining agricultural groups of soils based on characteristics of land capability class, important farmland and productivity index.

When using the CALES web system, you should follow the CALES steps in order to properly complete the land evaluation process. Some steps may be skipped if they are not useful for the particular evaluation. At any time in the CALES process, you may save your work and then, if desired, come back to it at a later time.

At the beginning of a CALES session, you will be asked to enter a userid and password. You can select whatever userid and password you would like, as long as they are unique to CALES. This same userid and password should be used each time you come into CALES. These are used in saving files and in later retrieving saved files. Do not forget the userid and password you have chosen. Saved files will be kept for 6 months, after which time they will automatically be deleted. Userids and passwords will be removed if no saved files remain.

The CALES program creates and utilizes two different worksheets. Worksheet #1 is a list of the soil mapunits for the selected area. This list is edited in various ways as part of the CALES process. Worksheet #2 is the final result of the CALES process, showing acreage totals and relative value for the various agricultural groups. Final CALES results for a county will provide the information needed to fill out the soils portion of FPPA Form 1006.

Getting Help

Help in understanding and using the CALES system is available both in the user's manual and in the online help screens in the program. Comments and questions can be sent using the "E-mail comments" option on the CALES home page. CALES questions can also be directed to Cheryl Simmons, NRCS Office of Farmland Protection and Community Planning (202-720-8890 or cheryl.simmons@usda.gov), Ray Sinclair, NRCS National Soil Survey Center (402-437-5699 or ray.sinclair@lin.usda.gov), or Harvey Terpstra, Iowa State University Statistical Laboratory (515-294-8177 or hpterp@iastate.edu).

Important NRCS Sources of Information

The detailed land evaluation procedure is in the "National Agricultural Land Evaluation and Site Assessment Handbook, 310-IV. Issue 1" issued by NRCS (formerly SCS) February 3, 1983, and in "Soil Potential Ratings", National Soil Survey Handbook, Section 621, issued by NRCS July 2001.

Please read the land evaluation part of the national LESA handbook and the soil potential part of NSSH before you run this program. This CALES computer assisted procedure follows the same steps that appear in the national LESA handbook, once logging in procedures are completed. Details about particular steps are given in the user's manual and the online help screens.