关键词: 农业生态系统, 生产力, 能值, 最大潜能

Abstract: What is the connotation and the extension of the productivity concept and how to calculate it are the core problems in evaluating an agricultural production process. The attributes of agricultural production processes have changed greatly in the last 100 years, and the methods to describe and measure the productivity failed to keep up with, resulting in a totally vague, incomplete valuation of the production processes. Sometimes the serious pollution is missed behind shortdated money making, bringing along a blooming and flooding polluting; sometimes the great ecological benefits are ignored and the corresponding production processes are died from "economic deficit". With the old agricultural productivity indices, it can't be told what an agroecosytem is ultimately producing to mankind, pollution or welfare. A new concept, Agricultural Productivity on Ecosystem Scale(APES) and the related indices are defined here to solve these problems. Emergy and exergy are introduced to help the measurement of the indices. Emergy is the memory of energy, can be used to measure the total cost, including natural capital and social capital. APES of the agroecosystem is the aggregated contributions of all components to mankind and its habitat in uniformed dimensions, may be expressed in material, energy, information, organization or pollution, damage etc., positive or negative, are calculated based on exergy methods. And a related index Agroecological Coupling Degree(ACD)shows sustainability.

Key words: Agroecosystem, Productivity, Emergy, Exergy