Toxic Salt Reduction 610

USDA NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD ARIZONA

SALINITY AND SODIC SOIL MANAGEMENT (acre) CODE 610

DEFINITION CONDITIONS WHERE PRACTICE Management of land, water and plants to APPLIES control and minimize accumulations of salts Applies to all land uses where the and/or sodium on the soil surface and in the concentration or toxicity of salt limits the crop rooting zone. growth of desirable plants or where excess sodium causes crusting and permeability PURPOSE problems. This practice also applies to non-  To reduce and control harmful salt irrigated land where a combination of factors concentrations in the root zone such as topography, soils, geology, precipitation, vegetation, land use, and  To reduce problems of crusting, cultural/structural practices can increase the permeability, or soil structure on extent and concentration of salts in saline seep sodium affected soils areas.  To promote desired plant growth and to utilize excess water in the root zone in non-irrigated saline seep areas and their recharge areas.

NRCS Field Office Technical Guide, Section IV NRCS-AZ Conservation practice standards are reviewed periodically, and updated if needed. To obtain Jan, 2005 the current version of this standard, contact the Natural Resources Conservation Service or download it from the electronic Field Office Technical Guide. 610 - Toxic Salt Reduction Standard

CRITERIA under section 106 of the National Historical Preservation Act of 1966, as amended, before General Criteria Applicable to All soil disturbance occurs. See the NRCS Purposes Arizona Handbook of Cultural Resources Procedures - Applicability and Exceptions All work, including associated practices for Section - for identification of practices that are management of drainage and runoff, shall exempt from, or that require cultural resources comply with Federal, State, and local laws and surveys. regulations. Endangered Species Type and rate of application of soil amendments shall be based on the chemistry Determine if installation of this practice with of both the soil water and irrigation water any others proposed practice will affect any (where applicable) regarding concentrations federal, tribal, or state listed Threatened or and types of salts and/or sodium, sodium Endangered species or their habitat. NRCS's adsorption ratio (SAR or RNa), exchangeable objective is to benefit these species or at least sodium percentage (ESP), concentration and not have any adverse effect on a listed types of salts, and pH. species. If the Environmental Evaluation indicates the action may adversely affect a listed species or result in adverse modification Improve surface and subsurface drainage as of habitat of listed species which has been needed to reduce localized ponding and or determined to be critical habitat, NRCS will high water tables. advise the land user of the requirements of the Endangered Species Act and recommend Additional Criteria to Reduce Salt alternative conservation treatments that avoid Concentrations in the Root Zone the adverse effects. Further assistance will be provided only if the On irrigated lands, leaching requirements shall landowner selects one of the alternative be determined as presented in National conservation treatments for installation; or at Engineering Handbook Part 623, Chapter 2. the request of the landowners, NRCS may initiate consultation with the U.S. Fish and On non-irrigated land, reclamation shall utilize Wildlife Service. If the Environmental vegetative methods, soil amendments, and/or Evaluation indicates the action will not affect a enhanced drainage to effect a reduction in soil listed species or result in adverse modification salinity. of critical habitat, consultation generally will not apply and usually would not be initiated. Additional Criteria to Reduce Problems of Document any special considerations for Crusting, Permeability or Soil Structure on endangered species in the Practice Sodium-affected Soils. Requirements Worksheet.

Apply soil amendments containing soluble CONSIDERATIONS calcium, or that cause calcium in the soil to become available. Water Quantity Effects on the water budget, especially on Additional Criteria Specific to Saline Seeps infiltration, deep percolation, and ground water and Their Recharge Areas recharge. Consider the variability (volume and timing) of the leaching fraction, the need for Plant and/or maintain adapted high water use additional irrigation water, and the impact of vegetation in recharge areas to utilize soil drainage if installed as an associated practice. water. Water Quality Cultural Resources Effects on irrigation induced erosion, If this practice involves soil disturbance, the sedimentation, and soluble and sediment- area of potential effect for each undertaking attached substances in irrigation tailwater. must be investigated for cultural resources

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Effects of leaching on the volume of toxic salts Water of slight to moderate salinity not and soluble nutrients and pesticides removed dominated by sodium can enhance leaching of from the root zone. Identify the ultimate salts. residence of the chemicals and the surface and ground water impact of drainage if Residue management can improve the organic installed as an associated practice. matter content of the soil, improve infiltration Additional Considerations and minimize surface evaporation and capillary rise of salts to the soil surface. Soil salinity levels can be monitored to minimize the effects of salinity on crops and to Consider selecting crops with tolerance to evaluate management practices. salinity/ sodium levels in the soil.

Tools such as electromagnetic induction (EMI) Consider using bedding and planting methods and salinity probes are appropriate for designed to reduce salinity near plant root evaluating and for monitoring soil salinity zone, especially for germinating seeds. levels. PLANS AND SPECIFICATIONS The drainage water from this practice may have high levels of salts. Select an outlet or Specifications for establishment and operation disposal area that will minimize the effects of of this practice shall be prepared for each field this saline water. or treatment unit according to the Criteria, Considerations, and Operation and Removal of salts from the root zone by Maintenance described in this standard. leaching operations may increase Specifications shall be recorded using contamination of water tables. Avoid approved specification sheets, job sheets, excessive leaching and schedule leaching narrative statements in the conservation plan, operations during seasons when potential or other acceptable documentation. contaminants in the soil profile, such as OPERATION AND MAINTENANCE nitrogen, are low. No operation and maintenance requirements, For irrigated conditions, an irrigation water national in scope, have been identified for this management plan should minimize non-point practice. pollution of surface and groundwater resources. REFERENCES Chiseling and subsoiling can improve Ayers, R.S., and D.W. Westcot, 1994. FAO permeability, root penetration and aeration Irrigation and Drainage Paper 29 Rev. 1, Water where water movement is restricted by layered Quality For Agriculture. soils. Avoid inversion tillage that can bring salinity to the surface and interrupt the ASCE, 1990. Agricultural Salinity Assessment leaching process. and Management, ASCE Manuals and Reports on Engineering Practice No. 71, New York, Green manure crops or applications of organic NY. matter can improve soil structure and permeability. California Fertilizer Association. 1998. Water and plant growth. p. 21-66. In Western Polyacrylamides may improve effectiveness of Fertilizer Handbook. Interstate Publishers, leaching and reclamation of some soils. Inc., Danville, Illinois. Applications of gypsum, sulfur or calcium will Rhoades, J.D., and J. Loveday. 1990. Salinity help in displacing sodium from the root zone. in Irrigated Agriculture. p. 1089-1142. In B.A. Stewart and D.R. Nielsen (ed.) Irrigation of

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Agricultural Crops. Agron. Monogr. 30. ASA, 623, Chapter 2- Irrigation Water Requirements. CSSA and SSSA, Madison, WI. Washington, D.C. USDA. 1954. Diagnosis and Improvement of USDA, Soil Conservation Service. 1993. Saline and Alkali Soils. Agriculture Handbook National Engineering Handbook (NEH), Part No. 60. Washington, DC.

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