Biological N Fixation in Forage-Livestock Systems
ISBN: 9780891182948
Platform/Publisher: WOL / ACSESS
Digital rights: Users: Unlimited; Printing: Unlimited; Download: Unlimited
Subjects: Agriculture Aquaculture & Food Science; Agriculture;

Beginning in 1973, N prices escalated rapidly in the U. S. until the price per kilogram of N was approximately twice what it was during the stable period of the late 50's and early 60's and three times the prevailing prices of the late 60's. At the same time, cattle prices declined to levels that were prevalent 20 years before. This unfavorable price relationship caused a decline in the amount of commercial N used on grasslands and a consequent reduction in forage production. Current projections indicate that the cost of the natural gas used as a raw material in N fertilizer manufacturing will continue to increase because of scarcity as well as high recovery costs. Thus, we may not see another period when commercial N is so cheap and plentiful that N fixation by legumes can be ignored as a crop production resource. For this reason it seems important that we take a new look at biological N fixation in forage-livestock systems. While interest in biological N sources has been fairly low at the farm level for many years, researchers have continued to study in this area and have generated additional information on symbiotic fixation by grasses and legumes and on nonsymbiotic biological N fixation. At the same time, additional information has become available on the contribution of legumes to forage yields and animal performance and researchers have taken a new look at finishing slaughter cattle on high forage-low concentration rations.


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