Analyzing vulnerability and adaptation to soil and water loss is an important part of the study on the human–environment relationship in the Loess Plateau. It has also provided a new perspective for studying the farmers’ adoption behavior of soil and water conservation technology in the soil erosion area of the Loess Plateau. Based on the Turner vulnerability framework, this paper constructs a household-scale index system of soil and water loss vulnerability in the Loess Plateau and evaluates the soil and water loss vulnerability in the Loess Plateau using the field survey data of the Loess Plateau applied entropy method. Finally, we use the binary logistic model to estimate the impact mechanism of farmers’ soil erosion vulnerability on farmers’ adoption behavior of soil and water conservation technology. The main conclusions are as follows: (1) In the total sample, susceptibility > exposure > adaptability, whereas in the Shaanxi and Gansu subsample, susceptibility > adaptability > exposure. The Ningxia subsample was similar to the total sample. For each index, Ningxia > Gansu > Shaanxi; (2) The exposure and susceptibility of soil and water loss have a positive impact on farmers’ adoption behavior of soil and water conservation technology, and natural capital has a positive impact on farmers’ adoption behavior of soil and water conservation technology. Physical capital has a positive impact on farmers’ adoption behavior of biological measures. Financial capital has a negative impact on farmers’ adoption behavior of biological measures and farming measures. Social capital has a positive impact on farmers’ adoption behavior of engineering measures and biological measures; (3) Overall, the marginal effect of the adoption behavior of farmers’ soil and water conservation techniques, adaptability > susceptibility > exposure. Therefore, it is necessary to strengthen the monitoring of soil and water loss, encourage the government and farmers to respond in time, and reduce the losses caused by soil erosion. Enriching the capital endowment of farmers, breaking through the endowment restriction of farmers’ adoption of soil and water conservation technology.

The National Key Ecological Functional Areas (NKEFAs) of China rely on the main functional area planning, with the core goal of enhancing the supply of ecological products. Carbon sink is an important ecological product, and it is necessary to understand whether the establishment of NKEFAs has enhanced vegetation carbon sink (CS). Considering the establishment of NKEFAs as a quasi-natural experiment, based on the panel data of prefecture-level cities in China from 2001 to 2019, a time-varying difference-in-differences (DID) model is used to systematically examine the impact of NKEFAs on CS. The study found that the establishment of NKEFAs has significantly enhanced the CS, and compared to the non-NKEFAs, NKEFAs has increased CS in the covered areas by an average treatment effect (ATE) of 2.1625. The establishment of NKEFAs can enhance CS through the optimization of territory spatial structure, the upgrading of industrial structure and the inter-industrial mobility of labor. The enhancement roles of NKEFAs on CS are heterogeneous across different functional area types, geospatial locations, and quantile levels, with higher enhancement of CS at windbreak–sand fixation type, northwestern region and high quantiles, respectively. In addition, NKEFAs not only have a significant positive ecological spillover effect, but also balanced with local economic growth, they achieve the goals of “lucid waters and lush mountains are invaluable assets”.