MEASURING SUSTAINABLE COTTON PRODUCTION USING TOTAL FACTOR PRODUCTIVITY

Continuous cotton (Gossypium hirsutum L.) production was examined usin g data from Alabama's long-term Old Rotation experiment (c. 1896). Ind ex values were used to examine trends in productivity and sustainabili ty for 95 yr. Treatments studied were those receiving (i) no N fertili zers and no winter legumes for 95 yr, (ii) only winter legumes as a so urce of N, and (iii) chemical fertilizer N. Three sets of index number s were calculated from all inputs and outputs involved in the producti on systems: (i) total factor productivity (TFP), which accounts for al l direct production inputs, but which does not consider production ext ernalities; (ii) productivity relative to a base plot; and (iii) total serial factor productivity (TSFP), which accounts for all direct prod uction inputs as well as externalities of soil erosion and pesticide u se. Viewed from the 95-yr perspective of the Old Rotation experiment, all three treatments fulfill at least one criterion required for a sys tem to be considered sustainable. Output per unit of input is higher i n 1991 than in 1896, even when externalities are valued. None of the s ystems showed a linear trend in output or TFP over the life of the exp eriment; productivity cycles are present in all three systems, despite a positive overall t;end. An average annual rate of TSFP growth of 1. 8%/yr was attained. Accounting for erosion and pesticide externalities reduced the annual productivity growth rate by 0.2%/yr. The system th at has neither an organic nor a chemical source of added N was less pr oductive and less sustainable than the two other systems, with a 0.3%/ yr TSFP growth rate. The plots using organic and chemical sources of N had similar productivity impacts. Valuing soil erosion and pesticide externalities had only a modest effect on measured productivity. The m ost dramatic single event to affect the productivity of cotton farming was the introduction of the mechanical cotton picker. The impact of t his technology was powerful enough to offset the effect of many other changes in the system.