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United States Department of Agriculture

Agricultural Research Service

Research Project: REMOTE SENSING FOR CROP AND WATER MANAGEMENT IN IRRIGATED AGRICULTURE

Location: Water Management and Conservation Research

Title: Soil Profile Sulfate in Irrigated Southern High Plains Cotton Fields and Ogallala Groundwater

Authors
item Bronson, Kevin
item Malapati, A -
item Booker, J -
item Schubert, A -
item Hudnall, W -

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2010
Publication Date: N/A

Interpretive Summary: Soil Profile Sulfate in Irrigated Southern High Plains Cotton Fields and Ogallala Groundwater Interpretive Summary: Sulfate (SO4) is one of the most important anions in soils and groundwater in semiarid regions, including West Texas. Crops’ sulfur (S) requirement is about 10 to 20 % of the nitrogen (N) requirements. However, there is far less information on soil test SO4-S (S in the SO4 form) for the western US, compared to the humid eastern US. The deposition of S from the atmosphere has declined nationwide, as coal-fired power plants have been scrubbing their emissions of S. This, combined with greater cotton yields and the lack of S fertilization on the Texas Southern High Plains (SHP) point to the need for a soil profile SO4-S assessment. The first objective of this study was to assess residual soil profile SO4-S content in irrigated cotton (Gossypium hirsutum) fields across a range of soil types and counties of the Texas SHP. The second objective was to compile regional SO4-S concentration data from the Texas Water Development Board irrigation well water quality data base and analyze Ogallala groundwater SO4-S levels by county, soil map unit, and by well depth. Soil profile (0 - 0.9 m) (0 – 36 in.) SO4-S content ranged from 120 to 475 kg ha-1 (107 to 424 lb ac-1) among seven center-pivot fields sampled. About half of this S was in the 0.6 - 0.9 m (24 – 36 in.) soil layer, which typically was sandy clay loam or clay loam in texture. Well water SO4-S concentration ranged from 9 to 220 mg L-1 (ppm) in clayey soils with deep groundwater to sandy soils with shallow groundwater, respectively. Groundwater SO4–S concentration was greater than the EPA drinking water standard of 83 mg L-1 (ppm) in 32 % of the wells, especially in the southeastern corner of the study area. There was no consistent relationship between soil map unit and SO4–S content in soil profile (0 – 0.9 m). A significant negative relationship between well depth and well water SO4-S concentration was observed in all the eleven-county study area of the SHP of West Texas. In conclusion, soil profile SO4 content to 0.9 m (36 in.) is high in SHP irrigated cotton fields, and in most cases should be adequate for crop S nutritional requirements.

Technical Abstract: Soil Profile Sulfate in Irrigated Southern High Plains Cotton Fields and Ogallala Groundwater Abstract: Sulfate (SO4) is one of the most important anions in soils and groundwater in semiarid regions, including West Texas. Crops’ sulfur (S) requirement is about 10 to 20 % of the nitrogen (N) requirements. However, there is far less information on soil test SO4-S (S in the SO4 form) for the western US, compared to the humid eastern US. The deposition of S from the atmosphere has declined nationwide, as coal-fired power plants have been scrubbing their emissions of S. This, combined with greater cotton yields and the lack of S fertilization on the Texas Southern High Plains (SHP) point to the need for a soil profile SO4-S assessment. The first objective of this study was to assess residual soil profile SO4-S content in irrigated cotton (Gossypium hirsutum) fields across a range of soil types and counties of the Texas SHP. The second objective was to compile regional SO4-S concentration data from the Texas Water Development Board irrigation well water quality data base and analyze Ogallala groundwater SO4-S levels by county, soil map unit, and by well depth. Soil profile (0 - 0.9 m) (0 – 36 in.) SO4-S content ranged from 120 to 475 kg ha-1 (107 to 424 lb ac-1) among seven center-pivot fields sampled. About half of this S was in the 0.6 - 0.9 m (24 – 36 in.) soil layer, which typically was sandy clay loam or clay loam in texture. Well water SO4-S concentration ranged from 9 to 220 mg L-1 (ppm) in clayey soils with deep groundwater to sandy soils with shallow groundwater, respectively. Groundwater SO4–S concentration was greater than the EPA drinking water standard of 83 mg L-1 (ppm) in 32 % of the wells, especially in the southeastern corner of the study area. There was no consistent relationship between soil map unit and SO4–S content in soil profile (0 – 0.9 m). A significant negative relationship between well depth and well water SO4-S concentration was observed in all the eleven-county study area of the SHP of West Texas. In conclusion, soil profile SO4 content to 0.9 m (36 in.) is high in SHP irrigated cotton fields, and in most cases should be adequate for crop S nutritional requirements.

Last Modified: 10/1/2014
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