Relation between the irrigation rate and the yield of long-fruit cucumbers grown in the Sofia field

  • 1 Institute of Soil Science, Agro-Technology and Plant Protection “Nikola Pushkarov", Sofia, Bulgaria


In order to establish the parameters of the dependence of irrigation norm – yields of long – fruit cucumbers a field experiment was carried out in the period 2001-2004, on a chromic luvisols soil (chromic forest soil) . Different irrigation regimes have been tested – from full satisfaction of the culture’s daily needs of water, to irrigation with irrigation norms reduced with 20% and 40% .The soil moisture content in the layer 0-0.5 m is used as a criterion for determining the time for making a polish. Under optimal variant (variant 2), the same is maintained with over 85% of WHC.
It has been found that reducing the irrigation rate leads to a corresponding reduction in yield but it is disproportionate. In all cases, the reduction in yield is less than the decrease in the irrigation rate.Parameters of “water-yield” dependency are determined by the two-step formula of Davidov, which approximates the test points by S-curve at a correlation coefficient R = 0,999. The results show the variation of yields depending on the reduction of the irrigation rate. In the calculations obtained, the values of the gradation indicators n = 2,25 and m = 1,48 can be used to optimize the irrigation regimens of long-fruit cucumbers.



  1. Varlev I., P. Petkov, K. Karaivanov, 2012. Optimization of the duration of one irrigation. "Agricultural Machinery" magazine, No 3. S, р.7
  2. Varlev I. Et. al. 2013. Economic optimal irrigation rate for water users. "Agricultural Machinery" magazine No 1. S, р.9
  3. Varlev I. 1981. Study of the "yield-water" dependence and its use in irrigation. International Agricultural Magazine No 3. С, р.26
  4. Davidov D. 1982. The connection "yield-water". Sp. "Hydrotechnics and meliorations" №7. S, p.8
  5. Petkov P., I. Varlev, K. Karaivanov, 2013. Determination of economically optimal dimensioning norm and the economic effect of drip irrigation of vegetables.. "Waterworks" № 5/6. s, p 33
  6. Davidov,D., 1994. On the Grounds of the Relationship “Yield–Water”. 17th European Regional Conference on Irrigation and Drenage ICID–CIID, Varna, Bulgaria, vol. 1, 251-253 (Bg)
  7. Frecman, B., Carzoli, 1980, Localized Irrigation FAO, Irrigation and Drainage pp 36

Article full text

Download PDF