Estimating the Contribution of New Seed Cultivars to Increases in Crop Yields: A Case Study for Corn

Abstract

Sustainability in agricultural development relies on continuing seed (cultivar) development and adoption. Measuring the contribution made by new seed cultivars to yield increases nationwide is essential, but this process remains challenging for academics. This study develops a method to estimate the overall contribution of new seed cultivars to crop yield increases by dividing the study period into several diffusion periods in terms of the replacement in major seed cultivars, and by defining a yield response model incorporating a series of dummy variables to capture net increases due to new cultivars’ diffusion in each period. According to this method, corn cultivars tested in the period from 1980 to 2013 in China can be divided into five periods. Significant increases in corn yields due to cultivar replacement were captured, and the contributions over the base period were calculated as 61.7%, 47.6%, 46.0%, and 48.9% for periods 2, 3, 4, and 5, respectively. Their respective contributions over the previous periods were therefore 61.7%, 34.6%, 26.7% and 56.7%. Estimation results indicate that the introduction of new corn seed cultivars significantly contributed to corn yield increase. This method is likely to have practical applications for other crops or livestock.