Oil and Gas Leases in Ohio Legal, Tax and Environmental Considerations

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The Albedo Distribution of Near Earth Asteroids

The cryogenic WISE mission in 2010 was extremely sensitive to asteroids and not biased against detecting dark objects. The albedos of 428 Near Earth Asteroids (NEAs) observed by WISE during its fully cryogenic mission can be fit quite well by a 3 parameter function that is the sum of two Rayleigh distributions. The Rayleigh distribution is zero for negative values, and follows $f(x) = x \exp[-x^2/(2\sigma^2)]/\sigma^2$ for positive x. The peak value is at x=\sigma, so the position and width are tied together. The three parameters are the fraction of the objects in the dark population, the position of the dark peak, and the position of the brighter peak. We find that 25.3% of the NEAs observed by WISE are in a very dark population peaking at $p_V = 0.03$, while the other 74.7% of the NEAs seen by WISE are in a moderately dark population peaking at $p_V = 0.168$. A consequence of this bimodal distribution is that the Congressional mandate to find 90% of all NEAs larger than 140 m diameter cannot be satisfied by surveying to H=22 mag, since a 140 m diameter asteroid at the very dark peak has H=23.7 mag, and more than 10% of NEAs are darker than p_V = 0.03.Comment: 7 pages LaTex, 4 figures, accepted for publication in the Astronomical Journa

Lithium and carbon isotopic fractionations between the alteration assemblages of Nakhla and Lafayette

Nakhla and Lafayette delta 7Li values for samples and extracts (4.1-14.2�) are consistent with brine evaporation. Relatively 13C-poor siderite in Lafayette suggests more than one carbon source was sampled

Crop Coefficient for Estimates of Daily Crop Evapotranspiration

Crop coefficients are used with values of reference evapotranspiration (ET) to estimate water use of a crop. Since the direct measurement of reference ET is expensive, time consuming, and laborious, it is usually preferable to calculate it tram more easily obtainable climatic data. Extensive research on reference ET methods and Improved crop coefficients has been conducted because of their application in irrigation scheduling and other aspects of water resources allocation. management and planning. Various procedures have been used to obtain the necessary experimental crop and reference ET data, and several types of crop coefficient curves have been published during the past ten years (Jensen 1974, Doorenbos and Pruitt 1977, Burmas et al. 1980, Wright 1979, 1981). Crop coefficients must be matched with the appropriate reference ET. The climatic adequacy of the methods, the necessary input data, and the time scale all need to be understood and carefully applied if accurate estimates of crop water requirements are to he obtained for either irrigation scheduling or water resources planning. The available methods for estimating reference ET and improved crop curves, when properly applied, permit estimates of crop ET which are within the accuracy of most field irrigation systems to deliver water (Jensen et al. 1971, Jensen and Wright 1978, Wright and Jensen 1978). This discussion briefly reviews the nature and origin of commonly used coefficients and outlines the conditions under which they can be appropriately applied. The application of recent "basal" crop coefficients (Wright 1981) is discussed and "mean" crop coefficients recently developed from ET data obtained with weighing lysimeters in Southern Idaho are also presented

Daily and seasonal evapotranspiration and yield of irrigated alfalfa in southern Idaho

Daily water-use data are needed for the development of modern irrigation scheduling techniques, the optimum allocation of water and energy resources, and improved irrigation management practices. This field study was conducted to measure evapotranspiration (ET) of well-irrigated alfalfa (Medicago satin L.) in the arid region of southern Idaho. The relationship of ET to forage yield was also investigated. The soil was Portneuf silt loam (coarse-silty, mixed, meek Durixerollic Calciorthids) common to much of the region. Daily and seasonal ET data were calculated for seven growing seasons from measurements obtained with mechanical weighing lysimeters equipped with electronic load cells. Daily alfalfa ET was highly variable. It occasionally exceeded 10 mm d-1 and averaged 8 mm d 1 during peak ET periods. From April through October, measured ET averaged 1022 mm for three harvests per season for 5 yr when soil water was nonlimiting. Corresponding average forage yield was 17.6 Mg ha1 (120 g kg-1 water content) giving an overall water requirement of 58.1 mm (depth equivalent) to produce 1 Mg ha 1 of forage (581 m3 Mg 1) for a water-use efficiency of 17.2 kg ha mm 1. Harvest period and seasonal ET appear linearly related to pan evaporation and forage yield. The actual ET of well-irrigated, high-yielding alfalfa may be as much as 50% greater than previous estimates indicated for southern Idaho

Nongrowing season ET from irrigated fields

The evaporative loss of water from agricultural fields during the nongrowing season is an important component of the annual water balance of irrigated lands. This study was conducted to measure daily ET from clipped grass and fallow fields from October through March and to compare the ET with precipitation received during the same period. Two weighing lysimeters near Kimberly, Idaho, were used to measure daily ET for six nongrowing seasons, from 1985 through 1991. ET averaged about 1 mm/day during the 6-month season, and total El' exceeded precipitation except for the 1985-86 period. ET from the grass lysimeter exceeded that from the mostly fallow lysimeter in early fall while the reverse was true during late winter. The results indicate that there is little, if any, potential for a net increase in stored soil water during the nongrowing season when fields receive an early or mid-fall irrigation in southern Idaho

Estimating crop evapotranspiration

Dominant crop and environmental conditions need to be considered to obtain accurate estimates of Et for a specific crop. Meteorological conditions determine the evaporative demand while the crop canopy and soil moisture conditions determine the extent to which that demand will be met. Evapotranspiration for a particular crop can be estimated if measurements or estimates of a potential or reference E, are available. These measurements or estimates represent the meteorological demand. Crop coefficients represent the crop and soil ability to meet the demand. Extensive research has been conducted on reference E, methods and crop coefficients because of their use in irrigation scheduling and water resources allocation, management, and planning. The available methods for estimating reference E, when properly used with reliable crop curves permit estimating crop E, within the accuracy of most field-irrigation systems to deliver water (Jensen et al., 1971; Jensen and Wright, 1978; Wright and Jensen, 1978). Various procedures have been used during the past three decades to obtain the experimental crop and reference Et data needed to develop Et crop coefficients. Several sets of curves derived from these data have been published (Burman et al., 1980; Doorenbos and Pruitt, 1977; Jensen, 1974; Pruitt et al., 1972, l987a; Wright, 1979, 1981, 1982). It is important that empirically derived-crop coefficients be used with the appropriate reference Et. The climatic adequacy of the methods, the necessary data, and the time scale all need to be understood and carefully applied if accurate estimates of crop water requirements are to be obtained