Nemati, Mehdi

September, 2026

Impact of Drought on Adoption of Irrigation Technologies and Crop Mix in California

By: Prakash, Divya; Nemati, Mehdi; Dinar, Ariel; MacKenzie, Scott; Struthers, Cory; Slaughter, Matthew S.
Drought-driven water scarcity challenges in agricultural sector are projected to intensify with climate change. This paper examines the extent to which drought influenced California farmers’ adoption of alternative irrigation technologies and their crop mix decisions. Using county-level data from California (2000Ð2020), we find that extreme and exceptional drought relative to no drought or abnormally dry conditions significantly increase the likelihood of adopting more efficient irrigation technologies across all crop categories. We also find that moderate and severe droughts are associated with a reduction in harvested forage crop acreage, with no statistically significant effects observed for other crop categories.
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May, 2019

The ISO 14001 Standard and Firms’ Environmental Performance: Evidence from the U.S. Transportation Equipment Manufacturers

By: Nemati, Mehdi; Zheng, Yuqing; Hu, Wuyang
Manufacturers have relied on environmental management systems to meet government environmental regulations, enhance their environmental performance, and reduce their impact on the environment. We investigate the impact of ISO 14001 certification on manufacturers’ toxic release levels. We applied the censored quantile instrumental variable estimator (CQIV) to data on U.S. transportation equipment manufacturing subsector facilities. Results show that for large firms, encouraging voluntary adoption of ISO 14001 might be an effective government strategy to reduce on-site pollution. However, for small firms and for the purpose of reducing off-site pollution, other economic incentives or regulations might be warranted.
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January, 2018

Asymmetric Price Volatility Transmission between U.S. Biofuel, Corn, and Oil Markets

By: Saghaian, Sayed; Nemati, Mehdi; Walters, Cory; Chen, Bo
Linkages between agricultural commodity and energy prices have become more complex with increased ethanol production. The concern is whether the new corn–ethanol links lead to volatilityspillover transmission between food and energy prices. We investigate asymmetric volatility spillovers between oil, corn, and ethanol prices using a BEKK-multivariate-GARCH approach. Additionally, we use daily, weekly, and monthly futures prices to examine whether the use of different-frequency data leads to inconsistent results. The results support the existence of asymmetric volatility transmission between corn and ethanol prices. Furthermore, the volatilityspillover effects are different for the different-frequency prices, and positive and negative price changes generate inconsistent results.
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