G77-340 Scheduling Irrigation by Electrical Resistance Blocks

Delay of irrigation for a few days during a critical part of the growing season can be expensive. A week\u27s delay in supplying irrigation water to corn or grain sorghum can reduce potential yield more than 30 bushels per acre. Several methods are available to help you schedule the right amount of water at the right time. One of these methods uses electrical resistance blocks discussed in this NebGuide

G84-690 Estimating Soil Moisture by Appearance and Feel

This NebGuide provides a guide to determining how much mositure is in different soil textures, and where it is located in the soil profile. Evaluating soil moisture is one of an irrigator\u27s most important management tools. Determining the status of the soil moisture reservoir guides the decision of not only how much to irrigate, but also when to irrigate. The appearance and feel method of monitoring soil moisture using a soil probe is still a valid procedure no matter how sophisticated the irrigation scheduling system. A measurement of soil moisture is essential to update knowledge of the need for and timing of irrigation, and the appearance and feel method can be used to obtain that information. In addition to indicating how much moisture is in the soil, this method also reveals where that moisture is located in the profile. This information is important to the irrigator as well as the dryland farmer. The depth of water penetration from irrigation or rainfall is useful in planning and making management decisions. For example, problem areas with compacted soil layers that restrict water penetration may be detected with the soil probe

EC58-704 Efficient Irrigation

Extension Circular 58-704: This is about how to efficiently irrigate your crops

EC81-713 It Pays to Test Your Irrigation Pumping Plant

Extension Circular 81-713 discusses how it pays to test your irrigation pumping plant

EC81-713 It Pays to Test Your Irrigation Pumping Plant

Extension Circular 81-713 discusses how it pays to test your irrigation pumping plant

It Pays to Test Your IRRIGATION PUMPING PLANT

A pumping plant performance test can determine the energy efficiency of an irrigation pumping plant and provIde information on adjustments needed to improve energy efficiency. The performance of an irrigation pumping plant should be evaluated by trained personnel using accurate testing equipment. This service can be performed by consulting engineers, by many well drilling companies, and some Natural Resources Districts and Public Power Districts. See your County Extension Agent for more information concerning these services. A pumping plant test should be performed regardless of the age of your system. Test all new systems so that you can be assured that your unit meets the contract specifications, which should be at least equal to the Nebraska Performance criteria for pumping plants (Table 1). The components must be carefully selected, installed, adjusted and operated to obtain these standard values. For an existing pumping plant a test can determine: 1. If energy and money can be saved by adjusting, rebuilding, or replacing the existing pump, drive systems, or power unit. 2. If the well is being operated at too great a discharge rate for existing pump and well conditions

Pumping liquid manure from swine lagoons and holding ponds

1 online resource (PDF, 6 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

High frequency oscillations of Newton's constant induced by inflation

We examine the possibility that an epoch of inflationary expansion induces high-frequency oscillations of Newton's constant, $G$. The effect occurs because inflation can shift the expectation value of a non-minimally coupled, Brans-Dicke-like field away from the minimum of its effective potential. At some time after inflation ends, the field begins to oscillate, resulting in periodic variations in $G$. We find conditions for which the oscillation energy would be sufficient to close the universe, consistent with all known constraints from cosmology and local tests of general relativity.Comment: 30 pages, Penn Preprint UPR-0628T, Wash. U. Preprint WUGRAV 94-10 Four figures available by ftp (read comment at head of file

The Behaviour Of Cosmological Models With Varying-G

We provide a detailed analysis of Friedmann-Robertson-Walker universes in a wide range of scalar-tensor theories of gravity. We apply solution-generating methods to three parametrised classes of scalar-tensor theory which lead naturally to general relativity in the weak-field limit. We restrict the parameters which specify these theories by the requirements imposed by the weak-field tests of gravitation theories in the solar system and by the requirement that viable cosmological solutions be obtained. We construct a range of exact solutions for open, closed, and flat isotropic universes containing matter with equation of state $p\leq \frac{1}{3}\rho$ and in vacuum. We study the range of early and late-time behaviours displayed, examine when there is a `bounce' at early times, and expansion maxima in closed models.Comment: 58 pages LaTeX, 6 postscript figures, uses eps

Linking species concepts to natural product discovery in the post-genomic era

A widely accepted species concept for bacteria has yet to be established. As a result, species designations are inconsistently applied and tied to what can be considered arbitrary metrics. Increasing access to DNA sequence data and clear evidence that bacterial genomes are dynamic entities that include large numbers of horizontally acquired genes have added a new level of insight to the ongoing species concept debate. Despite uncertainties over how to apply species concepts to bacteria, there is clear evidence that sequence-based approaches can be used to resolve cohesive groups that maintain the properties of species. This cohesion is clearly evidenced in the genus Salinispora, where three species have been discerned despite very close relationships based on 16S rRNA sequence analysis. The major phenotypic differences among the three species are associated with secondary metabolite production, which occurs in species-specific patterns. These patterns are maintained on a global basis and provide evidence that secondary metabolites have important ecological functions. These patterns also suggest that an effective strategy for natural product discovery is to target the cultivation of new Salinispora taxa. Alternatively, bioinformatic analyses of biosynthetic genes provide opportunities to predict secondary metabolite novelty and reduce the redundant isolation of well-known metabolites. Although much remains to be learned about the evolutionary relationships among bacteria and how fundamental units of diversity can be resolved, genus and species descriptions remain the most effective method of scientific communication