Now showing items 11919-11938 of 20709

    • N and P fertilization on rangeland production in Midwest Argentina

      Guevara, J. C.; Stasi, C. R.; Estevez, O. R.; Le Houérou, H. N. (Society for Range Management, 2000-07-01)
      Low soil nutrient status may be the major limiting factor to forage production in rangelands of the Mendoza plains 4 years out of 10. We studied vegetation responses to annual applications of N and P on such rangelands. Fertilizer application rates were 0 or 25 N and 0 or 11 P (kg ha-1) in a factorial arrangement. Dry matter production of grasses and palatable shrubs and crude protein (CP) content of grasses were determined annually from 1996 to 1998. Experimental plots received rains of 189, 278, and 346 mm during the 3 study years compared to mean growing season rainfall of 258 mm. Forage production was increased by N+P fertilization only in 1998 (1,390 vs 980 kg ha-1, P 0.05), producing 16.5 kg forage kg-1 N applied. Crude protein concentration was increased by N fertilization in 1997 (6.3 vs 5.3%, P < 0.05) and N+P application increased in 1998 (6.8 vs 5.7%, P < 0.05). Nitrogen and P application increased seasonal rain-use efficiency when the rainfall exceeded 300 mm. In 1998, the increase of grass production per kg N applied with and without P was 18.4 and 12.4 kg, respectively. The break-even point between rain and nutrients as the main primary production determinant on sandy soils in the central Mendoza plains is around 400 mm year-1 instead of 300 mm in other arid lands of the world. The value of meat increment derived from the N fertilization, with and without P application (US 0.07 ha-1 year-1 kg-1 N) was lower than the fertilizer cost (US 0.87 kg-1 N). A 5-fold increase in forage yields would be required to offset the cost of fertilizer. Fertilizer application did not increase forage production enough to be profitable for cattle production at present fertilizer and meat prices.
    • N, P, And K Fertilization of Tall Fescue (Festuca arundinacea Schreb.) Overseeded Range in Eastern Oklahoma

      Mitchell, R. L.; Ewing, A. L.; McMurphy, W. E. (Society for Range Management, 1985-09-01)
      A native hay meadow in northeastern Oklahoma was overseeded with tall fescue (Festuca arundinacea Schreb.) and fertilized for 6 years with N in August and February to encourage tall fescue growth in late fall and early spring, thus extending the green forage season. The effect of P and K fertilizer on forage yield and plant nutrient concentration was determined. Cool-season N fertilization (112 kg/ha) nearly doubled tall fescue yield and increased forage nitrogen concentration without altering warm-season grass production. Additions of P (15, 29 kg/ha) and K (28, 112 kg/ha) increased cool-season forage yield marginally and increased fertilizer N recovery but had no desirable effect on forage N, P, and K content. Tall grass decreaser species were dominant at the end of the study. Available soil P increased with P fertilization and available soil K increased with K fertilization.
    • N-alkane as an internal marker for predicting digestibility of forages

      Sandberg, R. E.; Adams, D. C.; Klopfenstein, T. J.; Grant, R. J. (Society for Range Management, 2000-03-01)
      Independent digestion trials with 5 forages were conducted to compare n-alkane with indigestible acid-detergent fiber (IADF) as internal markers to predict in vivo dry matter digestibility (digestibility). Forages were mixed grasses from subirrigated meadow (meadow), meadow regrowth (regrowth), native range (range), mature mixed grass hay from meadow, and alfalfa (Medicago sativa L.) hay. Meadow, regrowth, and range diets were immature grasses harvested 0.5 hours before feeding. Feces from the meadow hay and alfalfa hay trials were divided to compare freeze drying and oven drying (60 degrees C). All diets were subjected to in vitro fermentation for 0, 48, or 96 hours. N-alkane was separated from samples by 4.5-hour saponification with alcoholic KOH followed by extraction with n-hexane. Indigestible ADF was measured by 96-hour in vitro fermentation followed by ADF extraction. Digestibility estimated by markers was compared with in vivo digestibilities. N-alkane based digestibilities were lower (P < 0.01) than in vivo digestibility for all diets. N-alkanes provided higher estimates of digestibilities than IADF for meadow (P < 0.01), regrowth (P = 0.06), and alfalfa hay (P = 0.06), and lower digestibility for meadow hay (P = 0.02). Digestibilities calculated using n-alkanes for range tended to be higher (P = 0.14) than IADF values. Freeze drying increased (P < 0.01) the amount of n-alkane extracted from alfalfa hay, but did not affect (P = 0.1) the amount extracted from meadow hay. N-alkane disappeared (P < 0.001) from residue collected after 48 hours of in vitro fermentation, but no additional disappearance (P = 0.78) was evident at 96 hours. Neither marker was completely recoverable, although recovery of n-alkane was higher than indigestible ADF for 4 of the 5 forages tested.
    • N-P-K or N-P2-05-K20?

      Fuller, Wallace H.; Department of Agricultural Chemistry and Soils (College of Agriculture, University of Arizona (Tucson, AZ), 1964)
    • NAFTA and the Environment--Making the Side Agreement Work [Article]

      Baron, David S. (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1995)
    • NAFTA and the Harmonization of Domestic Legal Systems: The Side Effects of Free Trade [Article]

      Zamora, Stephen (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1995)
    • NAFTA Chapter 11, Regulatory Expropriation, and Domestic Counter-Advertising Law [Article]

      Salazar, Alberto R. V (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 2010)
    • NAFTA Chapter Twenty--Reflections on Party-to-Party Dispute Resolution [Article]

      Picker, Sidney Jr. (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1997)
    • NAFTA in the Grand and Small Scheme of Things [Article]

      Kozolchyk, Boris (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1996)
    • NAFTA: Reflections on Environmental Issues during the First Year [Article]

      Bustani, Alberto A.; Mackay, Patrick W. (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1995)
    • NAFTA: Reflections on the First Year and Visions for the Future [Note]

      The University of Arizona James E. Rogers College of Law (Tucson, AZ), 1995
    • Nail-Board Method of Root Sampling

      Schuster, J. L.; Wasser, C. (Society for Range Management, 1964-03-01)
    • Name Changes for Legumes Used in Southwest Landscapes: Acacia, Caesalpinia, Lotus, and Sophora

      Johnson, Matthew B.; Univ Arizona (University of Arizona (Tucson, AZ), 2017-10)
    • Name Changes of Legumes Used in Southwest Landscapes

      Johnson, Matthew B.; Desert Legume Program, The University of Arizona (University of Arizona (Tucson, AZ), 2015-05-20)
    • Name: Dr. Wayne Coates, Occupation: Equipment Designer

      College of Agriculture, University of Arizona (Tucson, AZ), 1986
    • Names, Objects, Histories: Intercultural Learning in Action

      Varga-Dobai, Kinga; Moua, Ze; Kelley Campbell, Sarah; Georgia Gwinnett College (Worlds of Words: Center for Global Literacies and Literatures (University of Arizona), 2015-09)
    • Nancy Natural Radiocarbon Measurements I

      Coppens, R.; Durand, G. L. A.; Guillet, B. (American Journal of Science, 1968-01-01)
    • Nancy Natural Radiocarbon Measurements II

      Hassko, B.; Guillet, B.; Coppens, R. (American Journal of Science, 1969-01-01)
    • Nancy Natural Radiocarbon Measurements III

      Hassko, B.; Guillet, B.; Jaegy, R.; Coppens, R. (American Journal of Science, 1974-01-01)
    • Nancy Natural Radiocarbon Measurements IV

      Richard, P.; Guillet, B.; Jaegy, R.; Coppens, R. (American Journal of Science, 1978-01-01)