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

Xiaodong Du (), David Hennessy and Cindy Yu

Staff General Research Papers Archive from Iowa State University, Department of Economics

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 (search for similar items in EconPapers)
Date: 2012-03-29
New Economics Papers: this item is included in nep-agr and nep-ias
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (10)

Published in American Journal of Agricultural Economics, January 2012, vol. 94 no. 1, pp. 225-237

Downloads: (external link)
http://www2.econ.iastate.edu/papers/p15022-2012-03-29.pdf (application/pdf)

Related works:
Journal Article: Testing Day's Conjecture that More Nitrogen Decreases Crop Yield Skewness (2012)
Working Paper: Testing Day's Conjecture that More Nitrogen Decreases Crop Yield Skewness (2010)
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:isu:genres:35022

Access Statistics for this paper

More papers in Staff General Research Papers Archive from Iowa State University, Department of Economics Iowa State University, Dept. of Economics, 260 Heady Hall, Ames, IA 50011-1070. Contact information at EDIRC.
Bibliographic data for series maintained by Curtis Balmer ().