The economics of soil nutrient stocks and cattle ranching in the tropics: optimal pasture degradation in humid Costa Rica
构建模型分析热带牧场土壤氮养分的经济最优存量，以哥斯达黎加湿润地区为例，发现当前价格和贴现率下私人最优策略是“开采”土壤养分，导致牧场退化，可持续管理仅在极低贴现率或极高肉价时才经济有效。
We present a model that can be used to analyse economically optimal nutrient (nitrogen) stocks in agricultural lands. The model is applied to study cattle ranching in humid Costa Rica. The numerical results indicate that, for current meat prices and discount rate, it is privately optimal to 'mine' soil nitrogen. In the long run, efficiency is consistent with degraded and abandoned pastures, as observed in the study region. Sustainable pasture management is economically efficient only for a discount rate close to zero or for meat prices at about twice the highest recorded value in 1985-1997. The results highlight the potential conflict between sustainability and economic efficiency. Caveats and externalities that are not included in our model are discussed.