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Fluid Journal : Fluid Journal 1996-1998
3 Fluid Journal Winter 1996 An excellent example of the marriage of sustainable systems research and long-term agronomic ramifications is the dryland agroecosystem project of Colorado State University. In this study, no-till practices allow for up to 35 percent greater retention of moisture, such that 16 inches of rain can sustain a greater cropping intensity over the traditional wheat/fallow rotation. Fertilizer is an important tool in this system. Greater residue production and subsequent management through tillage improve the economics of the rotation, yet reduce potential for N loss (Figure 2). Data from this study will tell us a great deal about the long-term effects of intensive cropping in the arid western Great Plains region. Veseth further notes that instead of trying to make one tillage and planting system work in all crops in annual rotations, most growers are typically rotating tillage systems along with the crop rotation. They are direct-seeding where they have the greatest chance of success, typically after low residue results of the four-year study averaged over all application rates. Compared to the other placement options, nitrogen centered between the rows and placed below the seed had a 3-to 4-bu/A advantage. Sulfur placed with the seed reduced yields by 5 to 7 bu/A when compared to other placements, probably because of dry conditions at two locations in the 1984-85 crop. Some general conclusions made were: I) fertilizer placed on the surface tended to stimulate weed production, 2) fertilizer with the seed tended to be associated with lower overall yield, 3) sulfur placed with the seed decreased emergence at two locations when soil water content was relatively low, 4) the first 20-lb/A increment of phosphorus produced virtually all the yield increase observed, 5) a split fall-spring nitrogen application generally resulted in highest yields. Dr. Smith is director of agronomy for J.R. Simplot in Pocatello, Idaho. crops such as peas, lentils, canola, winter rape, and other spring crops. After high-residue crops, particularly winter wheat, growers are gradually beginning to switch from the traditional fall moldboard plow to fall chiseling and using other combination tillage implements in minimum or reduced tillage systems. Environment. A Solutions to Environmental & Economic Problems (STEEP) study on no-till winter wheat seeded after spring peas or lentils in northern Idaho helps emphasize the fact that fertilizer placement can be overshadowed by soil, environmental or other factors. Five forms of application evaluated were: 1) surface, 2) with seed, 3) two inches below seed, 4) centered between 12-inch rows at seed depth, and 5) centered between 12- inch rows two inches below seed depth. The researchers found no advantage of applying fertilizer in one position over the other. The results were often site specific, varying between locations and years. Figure 3 summarizes the yield
Fluid Journal 1993-1995
Fluid Journal 1999-2001