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12 results

Trade in the Ancient Sahara and Beyond
  • Edited by D. J. Mattingly, V. Leitch, C. N. Duckworth, A. Cuénod, M. Sterry, F. Cole
  • Published online:
    17 November 2017
    Print publication:
    30 November 2017
  • Saharan trade has been much debated in modern times, but the main focus of interest remains the medieval and early modern periods, for which more abundant written sources survive. The pre-Islamic origins of Trans-Saharan trade have been hotly contested over the years, mainly due to a lack of evidence. Many of the key commodities of trade are largely invisible archaeologically, being either of high value like gold and ivory, or organic like slaves and textiles or consumable commodities like salt. However, new research on the Libyan people known as the Garamantes and on their trading partners in the Sudan and Mediterranean Africa requires us to revise our views substantially. In this volume experts re-assess the evidence for a range of goods, including beads, textiles, metalwork and glass, and use it to paint a much more dynamic picture, demonstrating that the pre-Islamic Sahara was a more connected region than previously thought.

  • N use by winter wheat established in cultivated and direct-drilled soils

  • M. H. Leitch, L. V. Vaidyanathan
  • Journal:
    The Journal of Agricultural Science / Volume 100 / Issue 2 / April 1983
    Published online by Cambridge University Press:
    27 March 2009, pp. 461-471

  • Labelled fertilizer N (15N depleted ammonium sulphate) was used to investigate both soil and fertilizer N use by winter wheat established in contrasting seed beds, these being soil cultivated to 20 cm depth or left undisturbed. The crop's response to, and recovery of, a range of N levels from 0 to 280 kg/ha given as a divided application in spring, were measured over two seasons. It was found that during the first season the direct-drilled wheat took up, on average, more fertilizer N but less soil N than wheat in cultivated soil, probably through differences in organic-matter mineralization. The different cultivation systems produced similar grain yields at all rates of applied N; however, when no fertilizer N was given, dry-matter production and soil-N uptake by the crop in the undisturbed soil were substantially less than by the crop in the cultivated soil. Crop recovery of the fertilizer N at harvest was between 29 and 40% of that given. After harvest, an average of one third of the applied fertilizer N was found in the top 60 cm of the soil profile. In the following season on the same plots a second winter wheat crop, receiving no fertilizer N, was drilled. At harvest there was shown to be an increase in grain yield and soil- and fertilizer-N uptake at the higher srates of N given in the previous season. In spite of this the recovery of the labelled residues was small, no more than 6% of the original application, or 15% of the residues remaining in the soil, irrespective of cultivation system.