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This article in AJ

  1. Vol. 81 No. 5, p. 752-757
    Received: May 19, 1988

    * Corresponding author(s):
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Cotton Canopy and Drying Effects on Runoff During Irrigation with Moving Sprinkler Systems

  1. M. Ben-Hur ,
  2. Z. Plaut,
  3. I. Shainberg,
  4. A. Meiri and
  5. M. Agassi
  1. Soil Erosion Res. Stn., Ruppin Inst., Emeg-Haffer, Israel



Self-propelled moving sprinkler irrigation systems (MSIS) have become increasingly popular in recent years. However, high amounts of runoff were measured from fields during irrigation with MSIS. Surface runoff from a silt loam loess soil (Calcic Haploxeralf) and a clay vertisol soil (Typic Chromoxerert) under different irrigation management was studied in field plots (3 m2, with a slope of about 2%). The experimental fields were irrigated with a lateral MSIS (spray nozzle) with a discharge of 650 L m−1 h−1 and an average water application rate of about 100 mm h−1. The percent surface runoff in loess and vertisol soils was 22 and 0%, respectively, under straw mulch conditions vs. 53 and 39% under unmulched conditions. The greater runoff was due mainly to crust formation at the soil surface. The impact energy of the irrigation water drops caused the soil surface structure to break down and form a surface crust with a resultant decrease in the infiltration rate (IR). Coverage of the loess-crusted soil surface by the cotton (Gossypium hirsutum L., cv. Acala SJ-2) canopy did not reduce the percent runoff from weekly irrigations of 50 mm. A drying period of 7 d between water applications did not break the crust, which was formed at the beginning of the irrigation season, and the large amount of runoff (50%) remained constant until the end of the season. Conversely, 14 to 18 d of drying caused a breakage of the crust, resulting in increased IR. Under these conditions, the cotton canopy prevented the reformation of the crust during consecutive irrigations and the runoff decreased to 15% at the end of the season. When the amount of water per irrigation was 15 to 30 mm and the drying period was 2 to 3 d, the runoff value was about 20%. This low percentage apparently resulted from insufficient amounts of water necessary to form a fully developed crust.

Contribution from the Agric. Res. Org., The Volcani Ctr, Bet Dagan, Israel. No. 2362-E, 1988 series. Research was supported by the U.S.-Israel Binational Agric. Res. and Develop. Fund.

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