AN ANALYTICAL MODEL OF FARMERS DEMAND FOR REPLACEMENT SEED

Seed replacement choices differ from decisions about other inputs, such as fertilizer, because the farmer can reproduce seed. Assumptions about rates of improvement in yield potential and depreciation of retained seed are combined with behavioral assumptions and price and technical information to develop a model predicting the number of years before a farmer will buy new seed. Parameter estimates for wheat in Pakistan are fed into the model and results compared with observed replacement times. Time horizon strongly conditions effects of model parameters. To speed varietal change, better information for farmers is likely to be preferred to seed subsidies.