Causes and Management of Root-zone Salinity and Sodicity in the Arid West Texas: Field-scale Experience

Abstract

Salinity and sodicity of the root-zone in the Rio Grande Project area (RGPA) are serious threats to the long-term viability of the irrigated agriculture. This chapter focuses on causes and management of root-zone salinity and sodicity at the field scale. Available data suggest that salinity and sodicity in many agricultural fields in the region exceed the threshold levels for dominant crops (pima cotton, pecan, and alfalfa) with maximum values reaching as high as 17 dS m⁻¹ and 33 mmol^1/2 L^−1/2, respectively. Efficacy of different tillage methods to modify seed environment and improve soil permeability to maintain salinity levels below the threshold is discussed. This chapter also evaluates various chemical approaches to correct root-zone sodicity management using irrigation water treatments and soil amendments. The review of results from various field studies suggests that adoption management practices to a large extent depend on profitability of the crop. While low-cost options such as seed environment modification are popular in pima cotton fields, more expensive methods such as tillage practices for profile modification and chemical treatments are used in remunerative crops such as pecans.