现代农业经营广泛存在规模经济，小农的存活和现代化源于外部“支持”，使现代技术采用的规模经济由农户内部转向外部。中国土地均分形成了小农经营规模的高度同质性，客观上有利于聚合相似的技术需求，实现技术推广服务的规模经济，从而降低农业生产成本。在学理上，这种影响被称为“区域性外部经济”，其本质是一种区域内部、农户外部的规模经济，也是一种外部性。尽管“小而均”的土地经营格局有利于实现区域性外部经济，但小农户仍会因缺乏规模效益而导致学习和应用新技术激励不足，即无法实现内部规模经济效率。中国非农就业和土地流转的发展正在改变这一格局。在这一变化过程中，市场自发形成的土地经营规模分布倾向于分散而非集中，会导致区域内部技术需求异质而零散，不利于服务供应者提高服务效率。并且经营者特别是大农户采用新技术具有很强的正外部性和引领示范作用；但问题是经营者仅会根据自身的成本收益来决定对他们而言最优的土地经营规模，并不会考虑对区域内其他农户成本收益的影响。因此，促进经营规模扩大且“均等化”的政策干预可以提高效率。
已有文献注意到工业和农业生产的区域性外部经济，主要讨论了区域内同类产品生产者增多对各生产者成本的影响，未涉及同类规模生产者的分析。工业部门由于不存在公共技术推广且不同规模企业因面临相同或相似的要素价格体系、有类似的技术选择和需求，分析规模相似还是规模迥异本身意义不大。但在农业特别是以家庭劳动为主的小农生产中，经营规模异质性是重要问题。因此，本文将从同类产品且相似规模的视角分析现代农技推广中农户经营规模变动的区域性外部经济。与上述论证和猜测相关，有一系列研究疑问需要讨论：在中国这样一个现代技术推广严重依赖外部市场和支持的小农经济中，不同规模农户技术需求的异质性是否会降低农技推广服务效率？各类规模农户数量的增减是否会对区域内规模相似或迥异的农户产生外部影响？具体而言，从时变与相对规模变动的角度来看，对于以转入经营为主的大农户，区域内规模相似的大农户数量的增加是否有利于他们获取外部技术服务，从而降低了他们的生产成本或增加了他们的单产？同时，大农户数量的增加对仍以承包经营为主的小农户获取外部技术服务及其经营绩效的影响又是如何？从区域与绝对规模的对比来看，在人均土地少、小农户盛行的时空，是否内生出适宜小农户生存的外部环境，使大农户显得“独木不成林”、经营成本优势不显而单产劣势明显；相反，在人均土地多、大农户盛行的时空是否内生出适宜大农户生存的外部环境，小农户反而显得“独木不成林”、经营成本劣势明显而单产优势不显？
围绕上述研究疑问，本研究结合小农经济中现代技术推广的区域性服务规模经济特性以及不同规模农户技术需求的异质性，揭示农户经营规模变动的区域性外部经济特征，确定区域内土地经营规模分布变动对不同规模农户生产经营绩效的影响，并探究其机制，特别是对农技推广服务供应体系的重塑作用；进而揭示外部服务规模经济对农户内部规模经济特征（或者说不同规模农户的相对经营绩效）的影响。
本文主要研究内容和相关结论如下：
研究内容1：厘清不同土地经营规模农户技术采用差异以及获取农机、农资与农技知识的渠道差异。
基本逻辑是随着土地经营规模扩大，人少地多的禀赋特征会使农户倾向于采用节约劳动的农机、农艺与品种。并且由于农户层面规模经济的存在，不同土地经营规模农户获取农机、农资与农技知识的渠道存在明显差异。本文利用2018年全国3省农户调查数据分析不同规模农户的技术采用差异以及获取农机、农资与农技知识的渠道差异。研究结果表明，经营规模越大的农户会倾向于购置更大型的机械而非购买机械作业服务或采取人工作业，从更远距离的经销商处购买农资并获得送货上门的运销服务，以及从更高级别的推广渠道（例如上级公共推广部门）获得节劳的农技知识。
研究内容2：确定区域内土地经营规模分布变动（即大农户增多而小农户减少）对农技推广服务供应体系的塑造作用，以及揭示农技推广的区域性服务规模经济特性。
基本逻辑是区域内经营规模分布的不均等蕴含着技术需求的多样性和推广渠道选择的多样性；相比单一渠道推广同质技术，多种渠道推广异质性技术不利于实现农技推广的区域性服务规模经济。随着小农户减少而大农户增多，大农户自购机械、上移农资购买渠道和农技知识获取渠道的做法，可能让部分环节农机作业服务供应商、村农资经销店等因生意不足而退出市场，下沉到村庄、就近可得的公共推广服务也可能因为服务对象减少而弱化。不过，大农户增多也会诱致出适合他们的技术类型和服务供给商。
本文利用2018年全国3省农业生产性服务组织和农户调查数据分析区域内（村或镇或县）土地经营规模分布特征对本地农机服务供应商作业环节选择和服务定价、农资经销商选址以及上级公共推广部门农技培训的影响。研究结果表明，区域内经营规模分布集中于更大规模区间，会抑制农机服务供应商提供耕地服务但会促进提供播种和植保服务，促使农资经销商不再就近选址但会提供送货上门服务，以及增加上级农技推广部门农技培训次数。此外，对于相同类型机械技术，在需求量和服务提供量越大的区域，其单位服务价格越低，即存在区域性服务规模经济。
研究内容3：确定区域内土地经营规模分布变动对大农户和小农户的外部技术服务可获性和粮食生产经营绩效的影响，证明农业规模经营存在区域性外部经济特征和对小农户具有“引领”作用。
基本逻辑是大农户在利用诸多机械技术以及搜寻并学习生物技术知识上，仍需要依赖外部市场和公共农技推广体系。当周边经营规模类似的大农户不断出现时，可能会通过外部技术服务共享与外溢、采用新品种等节本增产新技术的外溢以及传播性病虫害防治的正外部性等途径来实现节本或增产。同时，随着大农户增多而小农户减少，大农户自购机械、上移农资购买渠道和农技知识获取渠道的做法，使部分环节农机作业服务供应商和村农资经销店退出，村农技推广职能弱化；其结果可能表现为恶化小农户的经营绩效。不过，大农户也可能通过外部技术服务共享和外溢、新技术的外溢以及病虫害防治的正外部性等途径对周边小农户产生正的外部影响。
本文利用2014年和2017年全国4省农户面板数据实证分析区域内大农户增多对大农户和小农户主要粮食作物（水稻和玉米）生产的影响，具体涉及生产成本、单产、机械使用来源和作业服务价格等。研究结果表明，就大农户的经营绩效而言，从成本方面看，区域内经营规模相似的大农户增多总体上表现出提高机械作业服务可获性进而降低水稻和玉米的单位产品生产成本的区域性外部经济特征。从单产方面看，对于水稻，规模相似的大农户增多总体上会增加50-200亩大农户单产，但会降低200亩以上大农户单产。而对于玉米，规模相似的大农户增多总体上不影响单产；而就小农户的经营绩效而言，对于水稻，区域内大农户增多对小农户总体上表现出提高机械作业服务可获性、降低服务价格进而降低单位产品生产成本的“引领”作用，但随着经营规模扩大，引领力度会逐渐降低。而对玉米则不然，大农户增多对小农户经营绩效的影响方向并不确定。
研究内容4：确定区域内土地经营规模分布变动对“大农户-小农户”相对经营绩效的影响；证明小农户盛行的时空，大农户“独木不成林”，其相对于小农户的经营绩效不显。而在大农户盛行的时空，其相对经营绩效更明显。
基本逻辑是区域内经营规模相似的农户增多主要表现为有利于他们获取外部服务规模经济的一面，从而提高其相对经营绩效。本文利用2014年和2017年全国4省农户面板数据实证分析区域内土地经营规模分布变动对经营粮食作物（水稻和玉米）的农户内部规模经济的塑造作用。研究结果表明，就水稻和玉米种植而言，区域内规模相似的大农户相对小农户越多，会明显提高其成本优势，但降低单产劣势的作用不明显。
综合以上四方面研究内容得出以下主要结论：不同土地经营规模农户在技术采用以及渠道上存在明显差异；区域内小农户减少而大农户增多，有利于诱致出适合大农户的外部技术服务，以及由此带来小农户生存环境改变；区域内经营规模相似的大农户增多有利于增加面向该类大农户和小农户的外部技术服务可获性并降低技术服务采用成本，从而提高其经营绩效；大农户和小农户的相对经营绩效取决于区域内土地经营规模分布：区域内经营规模相似的大农户相对小农户越多，会提高其相对绩效，反之则反是。概言之，上述结论揭示了现代农技推广中农户经营规模变动的区域性外部经济特征。因此，从外部性治理角度来看，本文的研究结论支持促进土地转入端的经营规模“均等化”的发展战略。

Modern agriculture has extensive economies of scale. As the survival and modernization of smallholder farmers come from the external "support,” the economies of scale generated by the adoption of modern technology are shifted from the inside of farmers to the outside. The average division of land in China has resulted in a high degree of homogeneity in the operation scale of small farmers, which is objectively conducive to the concentration of similar technical needs, the realization of economies of scale of technology extension services, and the reduction of agricultural production costs. In academic theory, this kind of influence is called "local external economies". Its essence is a scale economy that exists inside and outside the region, and it is also a type of externality. Although the "small and average" land management pattern is conducive to the realization of local external economies, small farmers still lack the incentive to learn and apply new technologies due to the lack of economies of scale, and thus cannot achieve internal economies of scale efficiency. The development of nonfarm employment and land transfer in China is changing. In this process of change, the scale of land management spontaneously formed in the market tends to be dispersed rather than concentrated, which will lead to heterogeneous and scattered technical demands within the region, which is not conducive to service providers' improvement of service efficiency. In addition, operators, especially large farmers, adopt new technologies with strong positive externalities and lead the demonstration. However, there is a problem that operators only decide the optimal land operation scale according to their own cost and income, and do not consider the impact on the cost and income of other farmers in the region. Therefore, promoting the expansion of peasant household operation scale and "equalizing" policy interventions can improve agricultural production efficiency.
Regional external economies with respect to industrial and agricultural production are mentioned in the literature. These studies mainly discuss the influence of the increase in producers of similar products on the cost of each producer in the region but do not analyze the influence of the increase in producers of the same scale on the cost of each producer in the region. Since there is no public technology promotion in industrial sectors, and there is no fact that enterprises of different sizes face the same factor price system and similar technology demand, it is not necessary to analyze the scale similarity or scale difference of the industrial sectors. However, in agricultural production, especially smallholder production based on family labor, the difference in the operation scale is an important problem. Therefore, based on the perspective of the same products and similar scales, this study analyzes the local external economies produced by the scale change in farmers' management in the promotion of modern agricultural technology. There are a number of research questions related to the above arguments and speculations that need to be discussed. In China, the extension of modern technology to small-scale peasant economies relies heavily on external markets and support. Under the development of a small-scale peasant economy, will the difference in the technology needs of farmers of different sizes reduce the service efficiency of agricultural technology extension? Will an increase or decrease in the number of farmers of various sizes have external effects on farmers of similar or different sizes in the region? More specifically, from the perspective of time change and relative size change, does the increase in the number of large farmers of similar size in the region help large farmers who are mainly transferred to management to obtain technical services, thereby reducing their production costs or increasing their unit output? At the same time, what will be the impact of the increase in the number of large farmers on the acquisition of technical services and the business performance of small farmers mainly engaged in contract management? From the comparison of intra-regional scale and absolute scale, in the time and space with less land per capita and the prevalence of small farmers, whether there is an external environment suitable for small farmers to survive will make large farmers appear to be "the lone wolf dies but the pack survives", the operating cost advantage is not obvious but the unit output disadvantage is obvious; on the contrary, in the time and space with more land per capita and the prevalence of large farmers, whether there is an external environment suitable for large farmers to survive will make small farmers appear to be "the lone wolf dies but the pack survives", the operating cost disadvantages is obvious but the unit output advantage is not obvious?
Around the above research questions, this study examines the regional service-scale economy of modern technology popularization and the difference in the technology demand of different scale farmers in the smallholder economy. Next, it reveals the regional external economic characteristics caused by the change in farmer operation scale, determines the impact of the distribution of land operation scale within the region on the production and operation performance of farmers, and explores its mechanism, especially its role in reestablishing the agricultural technology extension service supply system. It then reveals the influence of the external service-scale economy on the characteristics of farmers' internal economies (or the relative operational performance of farmers of different sizes). The main research contents and relevant conclusions are as follows.
Research Content 1: To clarify the differences in the technology adoption of farmers with different land operation scales and the differences in their access to agricultural machinery and equipment, agricultural means of production, and agricultural technical knowledge.
The basic logic of this research is that with the expansion of the land management scale, the characteristics of fewer people and more land will make farmers tend to use labor-saving agricultural machinery and equipment, agronomy, and varieties. In addition, due to economies of scale at the farmer level, there are obvious differences in the channels for farmers of different land operation scales to obtain agricultural machinery and equipment, agricultural production materials, and agricultural technical knowledge. This study uses data from farmers’ surveys in three provinces in 2018 to analyze the differences in the adoption of technology of farmers of different scales and the differences in their access to agricultural machinery and equipment, agricultural production materials, and agricultural technical knowledge. The results show that larger land management farmers will tend to buy larger machinery rather than machinery services or manual operations, from more distant dealers to buy agricultural production materials and obtain door-to-door delivery services, and from a higher level of promotion channels (such as the superior public promotion department) to obtain agricultural technical knowledge of labor conservation.
Research content 2: To determine the role of the distribution change of land operation scale (the number of large farmers increased and the number of small farmers decreased) in shaping the service supply system of agricultural technology extension services and reveal the scale economy brought by the regional services of agricultural technology extension. The basic logic of this research is that the unequal distribution of business scale within a region contains the diversity of technical needs and the diversity of promotion channel selection. Compared to the method of using a single channel to promote similar technologies, the method of using multiple channels to promote different technologies is not conducive to the economies of scale generated by obtaining regional services for agricultural technology promotion. As the number of small farmers decreases and the number of large farmers increases, large farmers buy machinery themselves, changing the purchase channels of agricultural production means and agricultural technical knowledge acquisition channels. It may cause suppliers of agricultural machinery and equipment services and distributors of rural agricultural production materials to exit the market due to poor business. In addition, close and easily accessible public promotion services to villages may also be weakened by the reduction of service objects. However, the rise of large farmers will also lead to suppliers of technology and services that suit their production needs.
This study used data from agricultural productive service organizations and farmers surveyed in three provinces in 2018. To analyze the impact of the characteristics of land operation scale distribution in the region (village, town, or county). This impact concerns the selection of production activities of local agricultural machinery and equipment services, service pricing, dealer location of agricultural production means, and agricultural technology training of superior public promotion departments. The results show that the distribution of land operation scale in the region is concentrated in a larger range, which inhibits agricultural machinery service providers from providing cultivated land services. However, the concentrated distribution of business scale in a larger range within the region will promote the provision of seeding and plant protection services, encourage agricultural material dealers to provide door-to-door delivery services instead of a location close to the consumer market, and increase the frequency of agricultural technology training in the superior agricultural technology extension department. Moreover, for the same type of mechanical technology, in areas where there is more demand for mechanical technology and more services are provided, the service price per unit is lower and there are regional economies of service scale.
Research content 3: Determine the impact of changes in the distribution of land operations within the region on the availability of technical services and food business performance of large and small farmers. Thus, this proves that agricultural scale operations have regional external economic characteristics and a leading role for small farmers.
The basic logic of this research is that large farmers not only need to use a variety of mechanical technologies and search for and learn biotechnology knowledge but also rely on the external market and the public agricultural technology extension system. When large farmers with similar business scales continue to appear, they may realize cost savings or increase output through the sharing and outflow of external technical services, the outflow of new technologies, such as adopting new varieties and increasing output, and the positive externalities of transmissible pest control. At the same time, as the number of large farmers increases and the number of small farmers decreases, large farmers buy machinery themselves and change the channels of purchasing agricultural materials and acquiring agricultural technology knowledge. This practice withdraws the suppliers of agricultural machinery production activities and services and the outlets of rural agricultural production means from the market and weakens the function of agricultural promotion in rural areas. The result of this practice may manifest in the deterioration of the business performance of small farmers. Large farmers may also have a positive external impact on the surrounding small farmers through the sharing and outflow of external technical services, outflow of new technologies, and positive externalities of pest control.
This study uses the Farmer panel data from four provinces in 2014 and 2017 were used in the empirical analysis. It reveals the influence of the increase in large farmers on the production of major food crops (rice and maize) of large farmers and small farmers in the region, specifically involving the production cost of food crops, output per unit area, source of machinery use, and price of production services. The results show that, in terms of the operation performance of large farmers, from the perspective of cost, the increase of large farmers with similar operation scale in the region shows the regional external economic characteristics of improving the availability of mechanical operation services and thereby reducing the production cost per unit product of rice and maize. From the aspect of yield per unit area, for rice, the increase of large farmers with similar scales will increase the yield per unit area of large farmers by 50-200 mu, but it will decrease the yield per unit area of large farmers by more than 200 mu. However, for corn, the increase in large farmers with similar scales will not affect the yield per unit area overall. In terms of the operation performance of small farmers, for rice, the increase of large farmers with a similar scale in the region generally shows the leading role of improving the availability of mechanical operation services, reducing the price of services, and thus reducing the production cost of unit products. However, with the expansion of the operation scale, the leading force gradually decreased. However, for corn, the influence of the increase in the number of large farmers on the management performance of small farmers is uncertain.
Research content 4: To determine the influence of changes in the distribution of land management scale on the relative management performance of large farmers and small farmers. It is proved that in the era and region where small farmers prevail, large farmers "the lone wolf dies but the pack survives" and the relative management performance of large farmers is not obvious compared with that of small farmers, while in the era and region where large farmers prevail, the relative management performance of large farmers is more obvious.
The basic logic of this research content is that the increase in the number of farmers with similar operation scale in the region is mainly beneficial to them to obtain economies of scale of external services, so as to improve their relative operation performance. This study uses the farmer panel data from four provinces in 2014 and 2017 were used for empirical analysis. It reveals the changes in the distribution of land management scale in the region shape the internal scale economies of farmers who manage food crops (rice and maize). The results show that for rice and maize, the more large farmers of similar size relative to small farmers in the region will significantly improve their cost advantage, but the effect of reducing the yield disadvantage per unit area is not obvious.
Based on the above four research contents, the following main conclusions are drawn. There are obvious differences in technology adoption and channels among farmers with different land management scales. With the decrease of the number of small farmers and the increase of the number of large farmers in the region, it is beneficial to induce the external technical services suitable for large farmers and thus bring about the change of the living environment of small farmers. The increase of large farmers with similar operation scale in the region is conducive to increasing the availability of external technical services for such large farmers and small farmers and reducing the cost of technology adoption, so as to improve their business performance. The relative management performance of large farmers and small farmers depends on the distribution of land management scale in the region. The more large farmers with similar operation scale relative to small farmers in a region, the better their relative performance will be; the less large farmers with similar operation scale relative to small farmers in a region, the worse their relative performance will be. In short, the above conclusions reveal the regional external economic characteristics of the changes in the scale of farmers' management in the extension of modern agricultural technology. Therefore, from the perspective of externality governance, the research conclusions of this study support the development strategy of promoting the equalization of operation scale at the land transfer end and leading small farmers by scale operation, as well as improving the efficiency of land transfer allocation.