Abstract
Agriculture in the southwestern USA is limited by water supply due to high evaporation and limited seasonal precipitation. Where water is available, irrigation allows for production of a variety of agricultural and horticultural crops. This review assesses the impacts of agriculture on greenhouse gas emission and sequestration of atmospheric C in soils of the hot, dry region of the southwestern USA. In Texas, conservation tillage increased soil organic C by 0.28 Mg C ha-1 year-1 compared with more intensive tillage. Conversion of tilled row crops to the conservation reserve program or permanent pastures increased soil organic C by 0.32 ± 0.50 Mg C ha -1 year-1. Soil organic C sequestration was dependent on rotation, previous cropping, and type of conservation tillage employed. Relatively few studies have interfaced management and C cycling to investigate the impacts of grazing management on soil organic C, and therefore, no estimate of C balance was available. Irrigated crop and pasture land in Idaho had soil organic C content 10-40 Mg C ha-1 greater than in dryland, native grassland. Soil salinity must be controlled in cropland as soil organic C content was lower with increasing salinity. Despite 75% of the region's soils being classified as calcic, the potential for sequestration of C as soil carbonate has been only scantly investigated. The region may be a significant sink for atmospheric methane, although in general, trace gas flux from semiarid soils lacks adequate characterization. Agricultural impacts on C cycling will have to be better understood in order for effective C sequestration strategies to emerge.
Original language | English (US) |
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Pages (from-to) | 95-119 |
Number of pages | 25 |
Journal | Soil and Tillage Research |
Volume | 83 |
Issue number | 1 SPEC. ISS. |
DOIs | |
State | Published - Aug 2005 |
Externally published | Yes |
Keywords
- Conservation tillage
- Irrigation
- Livestock production
- No-tillage
- Soil inorganic carbon
- Soil organic carbon
ASJC Scopus subject areas
- Agronomy and Crop Science
- Soil Science
- Earth-Surface Processes