Testing Day's Conjecture that More Nitrogen Decreases Crop Yield Skewness

13 Pages Posted: 8 Apr 2020

See all articles by Xiaodong Du

Xiaodong Du

University of Wisconsin-Madison

David Hennessy

Iowa State University

Cindy Yu

Iowa State University

Date Written: January 2012

Abstract

While controversy surrounds skewness attributes of typical yield distributions, a better understanding is important for agricultural policy assessment and for crop‐insurance rate setting. Day (1965) conjectured that crop yield skewness declines with an increase in nitrogen use at low levels but not at higher levels. Employing four corn yield experimental plot datasets, we investigate the conjecture by introducing (a) a flexible Bayesian extension of the Just–Pope technology to incorporate skewness and (b) a quantile‐based measure of skewness shift. Bayesian estimation provides strong evidence in favor of negative skewness at commercial nitrogen rates and for Day's conjecture. There was weaker evidence in favor of positively skewed cotton yield and little evidence in favor of the conjecture. The results are confirmed by the quantile‐based measure. We also find evidence that skewness becomes more negative upon moving from corn‐after‐corn to corn‐after‐soybean.

Keywords: crop insurance, Gibbs sampler, Just and Pope technology, negative skewness, quantile regression, rotation effect

Suggested Citation

Du, Xiaodong and Hennessy, David and Yu, Cindy, Testing Day's Conjecture that More Nitrogen Decreases Crop Yield Skewness (January 2012). American Journal of Agricultural Economics, Vol. 94, Issue 1, pp. 225-237, 2012, Available at SSRN: https://ssrn.com/abstract=3571643 or http://dx.doi.org/10.1093/ajae/aar091

Xiaodong Du (Contact Author)

University of Wisconsin-Madison ( email )

716 Langdon Street
Madison, WI 53706-1481
United States
6082620699 (Phone)

David Hennessy

Iowa State University

Cindy Yu

Iowa State University ( email )

613 Wallace Road
Ames, IA 50011
United States

Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Downloads
1
Abstract Views
61
PlumX Metrics