Nitrogen as a Capital Input and Stock Pollutant: A Dynamic Analysis of Corn Production and Nitrogen Leaching under Non-Uniform Irrigation

A spatially dynamic programming model of nonuniform irrigation is developed to investigate the nitrogen leaching problem associated with irrigated agriculture. We evaluate the importance of temporal and spatial elements in (i) appropriately modeling the interseasonal corn production problem with nitrogen carry-over and leaching under non-uniform irrigation, and (ii) in adequately evaluating alternative policy instruments for pollution control. Comparisons of the time profiles under spatially variable nitrogen levels arising from nonuniform irrigation are provided along with an evaluation of three different price-based policy instruments for reducing nitrogen leaching.Environmental Economics and Policy,

AJAE Appendix: Spatial Dynamics of Water and Nitrogen Management in Irrigated Agriculture

The material contained herein is supplementary to the Article named in the title and published in the American Journal of Agricultural Economics, forthcoming.Crop Production/Industries, Farm Management,

INTEGRATED DRAINWATER MANAGEMENT IN IRRIGATED AGRICULTURE

Drainwater management strategies include source control, reuse, treatment, and evaporation ponds; questions of interest are efficient management, policy instruments, and sustainability. A high level of source control is indicated absent reuse due to the relatively high cost of evaporation ponds; this is accomplished largely through high uniformity/high cost irrigation systems. With reuse, the primary form of source control is reduction in land area devoted to freshwater production; the released land goes to reuse production. Reuse appears as an economically promising solution to the drainage problem. A high level of net returns is achieved while maintaining overall hydrologic balance in the system. Economic efficiency and hydrologic balance may be attained through pricing or market schemes. With pricing, growers are charged for deep percolations flows, while reuse and evaporation pond operators are paid for extractions. With markets, permit supply is generated by extractions from the water table, while permit demand is generated by deep percolation. Competitive equilibrium exists, is efficient, and implies hydrologic balance. The analysis suggests that a high level of agricultural production may be possible for some period of time while still maintaining environmental quality.Resource /Energy Economics and Policy,

MICROECONOMICS OF IRRIGATION WITH SALINE WATER

Water management and reuse at the field level are analyzed under saline, limited drainage conditions. A function relating crop yield and deep percolation flows to applied water and salinity concentration is developed. This function fits simulated data well and is tractable for theoretical and empirical analysis of irrigation economics. With a single irrigation source, irrigation water for cotton and tomatoes at first increases and the decreases with salt concentration. Drain-water reuse is found to be an efficient strategy in events of high surface-water prices and costly solutions to drainage-related environmental problems. However, blending freshwater and drainage appears plausible only under surface water scarcityResource /Energy Economics and Policy,

Competition between Kondo screening and indirect magnetic exchange in a quantum box

Nanoscale systems of metal atoms antiferromagnetically exchange coupled to several magnetic impurities are shown to exhibit an unconventional re-entrant competition between Kondo screening and indirect magnetic exchange interaction. Depending on the atomic positions of the magnetic moments, the total ground-state spin deviates from predictions of standard Ruderman-Kittel-Kasuya-Yosida perturbation theory. The effect shows up on an energy scale larger than the level width induced by the coupling to the environment and is experimentally verifiable by studying magnetic field dependencies.Comment: 5 pages, 2 figures, v3 with minor change

Targeting Liver Cancer: First Steps toward a miRacle?

In a recent issue of Cell, Iliopoulos and colleagues demonstrate a novel and targetable epigenetic amplification loop in hepatocellular carcinoma involving HNF4α, miR-124, IL6-R, Stat3, miR-24, and miR-629. These results establish microRNAs as novel players in early stages of hepatocarcinogenesis and as potential targets for the treatment of hepatocellular carcinoma