Sustainable agriculture has been proposed by the United Nations as a key indicator of the Sustainable Development Goals (SDGs). It presents diverse features and rich connotations in the transformation towards modernization. However, for a long time in China, transformations of agricultural modernization have not been the concern of spatial planning, nor the emerging land use requirements of agricultural modernization under the trends of urban–rural integration, such as the application of modern technologies for the mechanization of agricultural production, the coexistence of multiple forms of business entities with agricultural enterprises as the main body, the extension of the industrial chain from the primary to the secondary and the tertiary, and the concentration of industrial spaces, as well as specific land use due to those transformations. This paper constructs an analytical framework of “business entity, business model, production technology, and production space” based on the literature studies and selects eight representative agricultural cases from Beijing, Zhejiang, and Yunnan to conduct field investigations and case studies to reveal the transformative aspects of agricultural modernization in China and its land use requirements, enriching the understanding of modern agriculture from the perspective of spatial planning. This study finds that the transformation of agricultural modernization has generated new requirements for the construction of necessary production facilities, but these requirements cannot be met in terms of land use due to the constraints imposed by China’s current land use regulations. The paper advocates for the development of agricultural parks, the optimization of land use regulations, and the allocation of agricultural land use in spatial planning in line with the trends of agricultural modernization, thus supporting the sustainable development of agriculture.

Soils in alpine mining areas suffer from severe heavy metal contamination and infertility, yet little is known about the effects of different materials on soil improvement in such regions. In this study, a field experiment was conducted in farmlands contaminated by the Lanping lead–zinc mine in Yunnan, China, to compare the effects of four materials (biochar, organic fertilizer, lime, and sepiolite) on soil properties, heavy metal (lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) fractions and their availability, and the growth of Phaseolus coccineus L. Results showed that biochar and organic fertilizer significantly enhanced soil nutrient content and enzyme activities. Lime, biochar, and sepiolite effectively reduced heavy metal bioavailability by promoting their transition to residual fractions. Notably, biochar outperformed other materials by substantially increasing grain yield (by 82%), improving nutritional quality (sugars, protein, and starch contents raised by 20–88%), and reducing heavy metal accumulation in grains (by 36–50%). A comprehensive evaluation based on subordinate function values confirmed biochar as the most effective amendment. Structural equation modeling further revealed that biochar promoted plant growth and grain quality primarily by enhancing soil available nutrients and immobilizing heavy metals. These findings demonstrate the strong potential of biochar for remediating heavy metal-contaminated farmlands in alpine lead–zinc mining regions.