面对全球性环境问题——气候变化，各国均在探寻绿色低碳发展之路。农业低碳转型是我国实施“碳达峰·碳中和”战略目标的应有之义，面对资源和环境的双重约束，厘清提高农业碳生产率的内在机理和关键路径，化解资源环境和农业经济发展之间的矛盾是发展绿色低碳农业的内在要求。农业绿色创新作为农业低碳转型的关键推动力得到大力发展，政府也十分注重使用环境规制干预来实现环境与经济的协调发展，但环境规制对绿色创新产生的作用仍存在争议。研究异质性环境规制对农业绿色创新的影响以及对农业碳生产率的作用路径，检验农业领域“波特假说”是否成立，探究如何按照国情合理优化农业环境规制从而有效进行宏观调控，对实现农业绿色、高质量发展，从而实现“双碳”目标具有重要的理论与现实意义。

文章使用中国2000—2021年省级面板数据，首先测算了农业碳生产率并对其进行描述性特征分析；其次，构建了联立方程模型进行实证分析，将农业环境规制分为命令型、市场型与自愿型三类，农业绿色创新主体细分为涉农企业与涉农科研院校两类，探讨了农业环境规制对农业绿色创新、农业碳生产率的影响机制、异质性作用以及农业绿色创新的溢出效应。结果表明：（1）命令型、市场型与自愿型三类农业环境规制均对涉农企业的农业绿色创新具有正向效果，且进而提升了农业碳生产率，验证了农业领域的强“波特假说”。其中，市场型环境规制对农业碳生产率的直接影响更为重要。命令型与自愿型环境规制还对涉农科研院校的农业绿色创新产生显著促进作用，但该主体的农业绿色创新对农业碳生产率的影响未通过检验，进而验证了农业领域的弱“波特假说”；（2）分区域看，东、中部地区的命令型规制可以直接和间接提升农业碳生产率，市场型规制仅在东部地区发挥了直接正向作用，而在西部地区引致了“绿色悖论效应”，西部的命令型规制与东、中部的自愿型规制仅能通过农业绿色创新间接提升农业碳生产率。（3）将农业绿色创新的溢出效应纳入模型后，结果仍与基准回归的结论一致，但环境规制作用与农业绿色创新的本地效应有所减小。结果还表明邻近地区或生态相似地区的农业绿色创新溢出可以直接提升本地区的农业碳生产率，还可以显著促进本地区两类主体农业绿色创新水平的提升，且通过涉农企业的农业绿色创新可以间接提升本地区农业碳生产率。基于研究结论，论文提出的政策建议如下：第一，建立均衡多样的环境规制体系，注重规制工具的协调配合，并因地制宜科学实施；第二，增强对涉农企业绿色创新活动的政策扶持力度，激励农业绿色研发供给，改善“市场失灵”；第三，提高公共科研投资效率，破解公共部门农业绿色技术供需不相符问题，改善“政府失灵”。

In the face of global environmental issues - climate change, countries are exploring the path of green and low-carbon development. Low-carbon transformation of agriculture is the proper meaning of China's implementation of the strategic goal of "carbon peaking and carbon neutrality", and in the face of the dual constraints of resources and environment, clarifying the internal mechanism and key path of improving agricultural carbon productivity, and resolving the contradiction between resource environment and agricultural economic development are the inherent requirements for the development of green and low-carbon agriculture. As a key driving force for low-carbon agricultural transformation, green innovation in agriculture has been vigorously developed, and the government has also paid great attention to the use of environmental regulation intervention to achieve coordinated development of environment and economy, but the role of environmental regulation on green innovation is still controversial. It is of great theoretical and practical significance to study the impact of heterogeneous environmental regulation on agricultural green innovation and the effect path of agricultural carbon productivity, test whether the "Porter hypothesis" in the agricultural field is valid, and explore how to reasonably optimize agricultural environmental regulation according to national conditions to effectively carry out macro-control, which has important theoretical and practical significance for achieving green and high-quality development of agriculture and thus achieving the goal of "dual carbon".

Based on China's provincial panel data from 2000 to 2021, this paper first calculates and analyzes agricultural carbon productivity. Secondly, an simultaneous equation model is constructed for empirical analysis, and agricultural environmental regulation is divided into three categories: command-type, market-oriented and voluntary, and the main body of agricultural green innovation is subdivided into two categories: agriculture-related enterprises and agriculture-related scientific research institutions, and the impact mechanism and heterogeneity of agricultural environmental regulation on agricultural green innovation and agricultural carbon productivity are discussed. The results show that: (1) The three types of agricultural environmental regulation of command, market and voluntary have positive effects on agricultural green innovation of agricultural-related enterprises, and then improve agricultural carbon productivity, which verifies the strong "Porter hypothesis" in the agricultural field. Among them, the direct impact of market-based environmental regulation on agricultural carbon productivity is more important. Imperative and voluntary environmental regulation also played a significant role in promoting agricultural green innovation in agriculture-related research institutions, but the impact of agricultural green innovation on agricultural carbon productivity failed to pass the test, which verified the weak "Porter hypothesis" in the agricultural field. (2) From a sub-regional perspective, command-type regulation in the eastern and central regions can directly and indirectly increase agricultural carbon productivity, market-type regulation only plays a direct positive role in the eastern region, while it leads to the "green paradox effect" in the western region, and the command-type regulation in the western region and voluntary regulation in the eastern and central regions can only indirectly improve agricultural carbon productivity through agricultural green innovation. (3) After incorporating the spillover effects of agricultural green innovation into the model, the local effects of environmental regulation and agricultural green innovation are reduced. The results also show that the spillover of agricultural green innovation in neighboring areas can directly improve the agricultural carbon productivity of the region, and can also significantly promote the improvement of the level of agricultural green innovation of the two types of subjects in the region, and the agricultural green innovation of agricultural-related enterprises can indirectly improve the agricultural carbon productivity of the region. The policy recommendations put forward are as follows: first, establish a balanced and diverse environmental regulation system, pay attention to the coordination and cooperation of regulatory tools, and implement measures according to local conditions; Second, strengthen policy support for green innovation of agricultural-related enterprises, stimulate the supply of green R&D in agriculture, and improve "market failure"; Third, improve the efficiency of public scientific research investment, solve the problem of mismatch between supply and demand of agricultural green technologies in the public sector, and improve "government failure".