Overview

Cotton is predominantly grown throughout the southern U.S., with the most acreage historically in Texas. The summary chart for cotton indicates steady improvement over time in energy use, GHG emissions and irrigation water use, with recent trends since 2010 stalling in soil erosion and land use (Figure 1.4.1). Table 1.4.1 presents a summary of all indicators for cotton for reference years. Figure 1.4.1. Summary chart of indicators for cotton during 1980-2020 Data are presented in index form, where all indicators have been scaled by indicators averages for the period 1998 to 2002. A 0.1 point change is equal to a 10% difference. Index values allow for comparison of change across indicators with different units of measure. A smaller area represents improvement over time. Additional illustrations of cotton sustainability on a per acre basis and for total resource use are available in Appendix B, accessible from the Download Report link.

Land Use

The acreage planted to cotton has varied from 8 million to more than 16 million acres over the study period (Figure 1.4.2), and total production has seen variability in the 2000 to 2020 period (Figure 1.4.3). The land use indicator for cotton shows increased efficiency (yield) in the 1980s and 2000s with reduced yield through the 1990s and a leveling of yield in the 2010s, with significant interannual variability throughout the study period (Figure 1.4.4).

Energy Use Efficiency

Energy use efficiency for cotton production has improved through the study period (Figure 1.4.5). Energy use per acre shows variability and higher values in the 1990s and 2000s compared to the 2010s; however, the 2010s show a moderate rate of increase in energy use per acre (Figure B.13). Energy used for management energy and fertilizer and crop protectant manufacturing are the greatest contributors to energy use per pound of harvested lint and show an upward trend for the last four years of this study (Figure B.14).

Greenhouse Gas Emissions

Trends for GHG emissions from cotton production are similar to energy use efficiency, with some reductions followed by a leveling off in the past decade (Figure 1.4.6). The top four contributors for energy use and GHG emissions for cotton during 2010 to 2020 are listed in Table 1.4.2.

Irrigation Water Use

Irrigation water use efficiency for cotton showed consistent improvement from 1980 through 2010, but has been largely unchanged since around 2008 (Figure 1.4.7). Water use per acre by cotton has decreased likely in part due to the shift of production away from California, Arizona and New Mexico. In 1980, approximately 16% of planted acreage for cotton was in those three arid states, dropping to less than 2.7% in 2020. Water application rates for cotton have decreased approximately 38% during the period of this study, from 25.2 acre-inches/acre to 15.6 acre-inches/acre. The average irrigated harvested acreage across the 2008, 2013 and 2018 Irrigation and Water Management Survey for cotton was approximately 39% of the total harvested acres.

Soil Erosion

Soil erosion trends for cotton are very similar to that for corn, showing clear improvement for the period 1980 to 2000 but, since then, holding steady with a consistent erosion rate of nearly 11 tons of soil loss per acre (Figure 1.4.8). While there was rapid adoption of no-till technologies in the period from 1990 to 2010, the share of no-till cotton has remained steady near 18% over the past decade, with a further 20% grown using reduced tillage and the remaining 60% still using conventional tillage. Download Cotton Data