Emergy-Based Evaluation of Changes in Agrochemical Residues on the Qinghai

Emergy-Based Evaluation of Changes in Agrochemical Residues on the Qinghai–Tibet Plateau, China

Xiuhong Wang / Yili Zhang

Study of changes in agrochemical residues on the Qinghai−Tibet Plateau is necessary for the agricultural green development of the fragile plateau and its downstream regions. The total agrochemical residue (TR) caused by main agrochemical inputs was estimated in the study area of Qinghai province and the Tibet Autonomous Region over 1995−2017 by using the emergy synthesis method. The total agrochemical residue was decomposed into the intensity factor, the structure factor, the productivity factor, and the labour factor by using the Logarithmic Mean Divisia Index (LMDI) decomposition method. The change in TR could be divided into four time periods, i.e., a rapidly increasing period during 1995−1998, a stable period during 1999−2004, a slowly increasing period during 2005−2011, and a fluctuant period during 2012−2017. The study area had a mean TR intensity in area (TRA) of 3.31 × 10¹⁴ sej/ha, which was only 38.21% of that in China; however, the annual growth rate of TRA in the study area was 2.93%, higher than the rate of 1.91% in China over 1995−2017. The study area had a mean TR intensity in production (TRP) of 4.06 × 10¹⁰ sej/CNY (Chinese Yuan), which was 71.05% of that in China; however, the annual decreasing rate of TRP in the study area was 0.95%, lower than the rate of 1.98% in China over 1995−2017. All the LMDI decomposed factors contributed to the TR increase during 1995−1998; the intensity factor, the structure factor, and the labour factor contributed to the TR decrease during 1999−2004; the structure factor and the productivity factor contributed to the TR increase during 2005−2011; and only the productivity factor contributed to the TR increase during 2012−2017. Compared with the whole country, the study area has more potential to reduce TR by improving agrochemical use efficiency, strengthening the recovery of plastic film residue, increasing organic agricultural materials, raising the efficiency of agricultural production, and accelerating the transfer of rural labours to secondary and tertiary industries.