Emergy analysis of farmer producing system in the transitional zone of Qinghai-Tibet Plateau on Loess Plateau: Tongwei-Weiyuan-Xiahe Transect as an Example

The Tongwei-Weiyuan-Xiahe transect is located in the ecological zone where the Loess Plateau transitions to the Qinghai-Tibet Plateau. It is a typical agricultural-pastoral transition zone in my country. For a long time, the unreasonable agricultural production structure has brought about a series of ecological and economic problems, which has restricted the sustainable development of grassland agriculture in the region. To this end, analyzing the regional agricultural production structure from the perspective of energy value can provide a theoretical basis for farmers' (pastoral) decision-making and a scientific basis for optimizing the regional agricultural production structure. The input-output data of crop and livestock production of farmers in the study area were collected, and the structural characteristics of farmers' production system, farmers' production decision-making behavior and production system coupling were analyzed using the energy value method. The flow of energy between components of farmers' production system was analyzed using the structural equation model (SEM). The study found that with increasing altitude, farmers' crop production activities decreased and the total crop output energy value decreased; although the main input and output factors of crop production were the same, there were significant differences in the same factor input, output energy value and energy value rate of return of the same crop in different locations ( P < 0.05); the same factor input, output energy value and energy value rate of return of different crops in the same location were significantly different ( P < 0.05); among the crop production input factors, the energy value of organic fertilizer had a high contribution in Tongwei and Weiyuan; the farmers' production decision thresholds of crop input and output energy value decreased from east to west, and when the energy value input initially increased, the scale of crop production of farmers in Xiahe expanded most rapidly. The scale of livestock breeding, energy input and output increase from east to west; in Tongwei and Weiyuan, wheat straw and alfalfa are used as intermediate inputs, and the energy contribution rate reaches 80%; among the input factors of livestock production in Xiahe, the energy contribution rate of supplementary feeding grain is as high as 90%; the threshold point of farmers' production decision of livestock input and output energy increases from east to west; the energy yield rate increases exponentially with the increase of coupling degree, and the increase rate of energy yield in Tongwei and Weiyuan tends to slow down with the increase of coupling degree, while the growth rate of energy yield in Xiahe increases with the increase of coupling degree. Adjust the proportion structure of grain, cash and feed products in crop production, strengthen the coupling effect of crop production and livestock production, optimize the use of natural grassland, and maximize ecological benefits; the threshold point regulates the production decision behavior of farmers to optimize the agricultural production structure in the region.