Irrigation Guide

Soil Interpretation for Irrigation

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Alamogordo(244KB) Albuquerque(297KB) Artesia & Carlsbad(302KB) Aztec(316KB) Capitan(224KB) Chama(654KB) Chama & Espanola(2573KB) Clayton(186KB) Clovis(181KB) Cuba(437KB) Deming(448KB) Espanola(215KB) Fort Sumner(98KB) Gallup(181KB) Grants(162KB) Las Cruces(339KB) Las Vegas (345KB)

Lordsburg(436KB) Los Lunas(527KB) Lovington(230KB) Magdalena(253KB) Mountainair & Estancia(180KB) Portales(351KB) Reserve & Quemado(793KB) Roswell(131KB) Santa Fe(173KB) Santa Rosa(326KB) Silver City(125KB) Socorro(226KB) Taos(113KB) T or C(724KB) Tucumcari(253KB) Tucumcari SW Quay(192KB)

This narrative explains the development of the attached "Soil Interpretations for Irrigation" and defines some of the terms used in this material.  For the field office or geographic area for which it was prepared, "Soil Interpretations for Irrigation" contains the irrigation characteristics, recommendations for maximum irrigation grades, and the adapted conservation irrigation systems.

The irrigation characteristics of the soils, as shown in the attached tables, are the best data presently available.  Every effort should be made to verify the data shown in columns 3 through 10, by using farm irrigation evaluations and irrigation trails.  As the data is verified, the irrigation systems developed from this data will be greatly improved.  Irrigation water management will also improve as landowners and technicians use this data of greater reliability.

The criteria contained in "Soil Interpretations for Irrigation" is to be used in obtaining irrigation water management and in the planning of farm irrigation systems for the field office.  If, through evaluations and irrigation trails, the data in these interpretations is found to be inadequate, a recommendation should be submitted for revising the material to include the new data.  These recommendations should be submitted in accordance with instructions for revising the Field Office Technical Guide.

Soils in the attached material are grouped according to similar irrigation characteristics and are listed by increasing intake families.  All soils in a group have similar irrigation characteristics which include:

1. Available moisture holding capacity in inches per foot of soil depth.

2. Moisture replacement depth from which plants remove moisture that must be replaced by irrigation water.

3. Net moisture to be replaced for each of the crop groups.

4. Family intake curve designation assigned to the soil for irrigation purposes

DEFINITIONS

Crop Groups - A group of crops having similar irrigated rooting depths and soil moisture extraction patterns when there are no soil limitations.  Generally, these crops are grouped as shown below:

Additional crops can be added to those shown above as needed by the Field Office.

MOISTURE REPLACEMENT DEPTH (feet)

The depth of soil to be refilled at each irrigation during the maximum consumptive use period of the crop growing season.  This varies with crops and soils.  The moisture replacement depths shown are for the period of peak or maximum consumptive use and are shown in columns 4, 6, and 8 of "Soil Interpretations for Irrigation."

NET MOISTURE TO BE REPLACED (inches)

The moisture required to fill the soil to field capacity to the moisture replacement depth when approximately one-half of the available moisture has been depleted.  These values are shown in columns 5, 7, and 9 of "Soil Interpretations for Irrigation."  The net moisture to be replaced is calculated by taking 50% (to the nearest, lowest, half-inch) of the total available moisture holding capacity per foot of soil depth (column 3) within the moisture replacement depth (columns 4, 6, or 8).

AVAILABLE MOISTURE HOLDING CAPACITY PER FOOT OF SOIL DEPTH (inches)

The inches of water which a plant can remove from a one-foot depth of soil profile.  For each group of soils, beginning with the soil surface, and in the same order as found in the soil profile, figures are given for the amount of available moisture from the surface to the end of the irrigated root zone.

FAMILY INTAKE CURVE DESIGNATION (curve number)

The figure entered in column 10 shows the approximate curve number for determining the design intake rate for irrigation systems.  These curve numbers are shown in the attached graph and table.

MAXIMUM IRRIGATION GRADE

The figure in column 11 indicates the maximum recommended irrigation grade in feet per hundred feet for the soil group.

ADAPTED CONSERVATION IRRIGATION SYSTEMS

The "X" shown in columns 12 through 17 indicates the type of farm irrigation systems adapted to the soil group concerned.