In my first lecture on the economics of fertilization, I examined the concept of diminishing marginal returns and how th在肥料经济学的第一讲中，我阐述了边际报酬递减的概念及其与生产函数形状之间的关系。
More specifically, I showed that diminishing marginal returns is equivalent to a marginal physical product (MPP) that de具体地说，我说明了边际报酬递减就是边际产量随着肥料用量的增加而递减。