In this paper, we use agent-based modeling (ABM) to study different obstacles to the expansion of contract rice farming in the context of Mekong Delta (MKD)'s rice supply chain. ABM is a bottom-up approach for modeling the dynamics of interactions among individuals and complex combinations of various factors (e.g., economic, social or environmental). Our agent-based contract farming model focuses on two critical components of contractual relationship, namely financial incentives and trust. We incorporate the actual recurrent fluctuations of spot market prices, which induce both contractor and farmer agents to renege on the agreement. The agent-based model is then used to predict emergent system-wide behaviors and compare counterfactual scenarios of different policies and initiatives on maintaining the contract rice farming scheme. Simulation results firstly show that a fully-equipped contractor who opportunistically exploits a relatively small proportion (less than 10%) of the contracted farmers in most instances can outperform spot market-based contractors in terms of average profit achieved for each crop. Secondly, a committed contractor who offers lower purchasing prices than the most typical rate can obtain better earnings per ton of rice as well as higher profit per crop. However, those contractors in both cases could not enlarge their contract farming scheme, since either farmers' trust toward them decreases gradually or their offers are unable to compete with the benefits from a competitor or the spot market. Thirdly, the results are also in agreement with the existing literature that the contract farming scheme is not a cost-effective method for buyers with limited rice processing capacity, which is a common situation among the contractors in the MKD region. These results yield significant insights into the difficulty in expanding the agricultural contracting program in the MKD's rice supply chain.

中文翻译：

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湄公河三角洲稻米供应链中的合同农业：基于代理的建模研究的启示

在本文中，我们使用基于代理的模型（ABM）研究了在湄公河三角洲（MKD）的稻米供应链背景下扩大承包稻米种植的各种障碍。ABM是一种自下而上的方法，用于对个人之间以及各种因素（例如，经济，社会或环境）的复杂组合之间的互动动态进行建模。我们基于代理的合同耕种模型关注合同关系的两个关键组成部分，即财务激励和信任。我们将现货市场价格的实际经常性波动纳入考虑范围，这会导致承包商和农民代理人违反协议。然后，将基于代理的模型用于预测系统范围内的紧急行为，并比较维护合同稻谷种植计划的不同政策和举措的反事实情况。模拟结果首先表明，在大多数情况下，机会充分利用合同农户中相对较小的比例（不到10％）的设备齐全的承包商在每种作物获得的平均利润方面要优于现货市场承包商。其次，一个承诺的承包商提供的采购价格低于最典型的采购价格，则可以获得每吨大米更好的收益以及更高的单季利润。但是，在这两种情况下，这些承包商都无法扩大他们的合同农业计划，因为要么农民对他们的信任逐渐下降，要么他们的报价无法与竞争对手或现货市场的收益竞争。第三，结果也与现有文献一致，即对于大米加工能力有限的买家，合同农业计划不是一种经济有效的方法，这在MKD地区的承包商中很常见。这些结果对扩展MKD稻米供应链中的农业承包计划的难度产生了深刻的见解。