When Less Is More
The global challenge of addressing sustainable use of nitrogen fertilizers is well characterized in “Fixing the Global Nitrogen Problem,” by Alan R. Townsend and Robert W. Howarth.
Where the authors fall short, however, is in considering some of the solutions that agricultural research and innovation offer to address these problems. Conventional breeding and biotechnology are being applied to improve crop utilization of available nitrogen, thus reducing fertilizer demand without sacrificing increased yields. And best practices today, through the use of urease and nitrification inhibitors, minimize off-target movement of nitrogen by reducing evaporation and by maintaining fertilizer nitrogen in the ammonium form, which is less mobile and more efficiently utilized by many crops.
Technology and innovation, combined with intelligent public policy to promote more timely development and adoption, will be the foundation for sustainable solutions allowing the world to continue reaping the benefits of the Haber–Bosch process.
Michael Shaw and Cliff Gerwick
Dow AgroSciences
Indianapolis
Fill In the Colors
In “Seeing Forbidden Colors,” Vincent A. Billock and Brian H. Tsou review work by Hewitt D. Crane and myself extensively and propose that our results and their replication of the forbidden-colors studies require a new winner-take-all alternative to well-established opponent-color theory. Neither Crane nor I ever posited that our findings of forbidden colors violated or even undermined color-opponent theory. In fact, we felt that our results told us nothing about color opponency in the retino-cortical pathways but much about how the visual mechanisms of the brain processed information once received. Our forbidden colors were neither “parlor tricks” nor hallucinations but the result of a series of experiments that explored the parameters of the “filling-in” mechanism.
Filling in, which functions across both naturally occurring stabilized images and artificially stabilized images, seems to “paint” colors and patterns across areas of the visual scene for which there are apparently no signals emanating from the retina. Our research showed that the color of the filled-in area appears to be determined by chromatic contrast at the perceptual boundary of the stabilized region. When we provided conflicting information at that boundary—for example, red on one side and green on the other—the filling-in mechanism “painted” both colors across the perceptual field. These results and others from our laboratory suggest that the filling-in mechanism functions according to its own rules, independent of color-opponent retino-cortical pathways.
Thus, there seems to be no need to propose a new color-opponent mechanism, because even such a mechanism cannot explain how we see colors where the retina sends no neural signals to higher centers, for example, at the optic nerve head and in the shadow of the many retinal blood vessels.
Thomas P. Piantanida
Greenleaf Medical
Palo Alto, Calif.
Cold and Dark
It seems odd that in the recent article “Cloudy with a Chance of Stars,” in which Erick T. Young discusses formation of massive stars, no mention is made of the potential role of cold dark matter or the alternative theories of modified Newtonian dynamics (MOND). The inadequacy of Newtonian gravity based purely on baryonic mass in describing the physics of galaxies has been well covered in Scientific American. One would think that the additional gravitation provided either by dark matter or by MOND would be significant in the formation of massive stars. Can Young explain why these important effects are ignored in the models he has described?
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5 Comments
Add CommentThe Eprida foundation have developped a cheap method of combining charcoal with atmospheric Nitrogen to produce a high quality fertiliser cheaply, as part of a pyrolysis cycle.
Reply | Report Abuse | Link to thisSee www.eprida.com for details. Farmers used to allow nitrogen fixing plants such as clover in cornfields. Today, fields are so over-sprayed with herbicides that plants such as clover are eliminated from farmlands, thereby worsening the natural regeneration cycle....
Re. Cold and Dark: Dark Matter is merely an unfounded proxy for unexplained gravitational effects.
Reply | Report Abuse | Link to thisAttributing unknown observational effects to Dark Matter does a disservice to astrophysics, as unexplained conditions are quickly dismissed as additional support for the now well established Dark Matter.
In fact, of course, no form of known matter meets the requirements specified for Dark Matter. Its hypothesis became well established based on the expectation that the dense distributed mass of spiral galaxies would rotate like the sparse, centralized mass of the Solar system. That expectation was simply unfounded.
The boogey man did it. Don't look under the bed - you don't know what you might find there!
@jtdwyer, all you have to do is prove your hypothesis. Shouldn't be so hard to do as you seem to regularly post how your conclusion is the obvious one. If it is so obvious and clearly superior to the dark matter hypthesis, then it should be quite simple to prove. I eagerly await your up and coming article here in sciam.
Reply | Report Abuse | Link to thisGenetically splice leguminous nodules to the roots of wheat to create a new self N fixing food plant, or use aquaponics on a massive scale, thus saving humanity along with the environment. Easy.
Reply | Report Abuse | Link to thisThe Big Bang wasnt so big after all, instead of 95% matter yet to be found, perhaps it mostly sucked.
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