HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Levin, I. Articles by van Rooyen, F. C. Search for Related Content PubMed Articles by Levin, I. Articles by van Rooyen, F. C. Agricola Articles by Levin, I. Articles by van Rooyen, F. C.

The Effect of Discharge Rate and Intermittent Water Application by Point-source Irrigation on the Soil Moisture Distribution Pattern¹

ABSTRACT

A comparison was made between the results of laboratory and field experiments regarding predictions of soil moisture distribution from a point source on the one hand, and those theoretically calculated by a computer simulation model (Bresler, 1975) on the other hand. A good agreement was found between computed and experimental data. When the verified model was used for predictions regarding soil water distribution under point-source irrigation, it was found that when the same total amount of water (12 liters) was added to the soil with a 2, 4, or 8 liters/hour continuously applied trickle source, a loss of 26% of the total amount applied was affected below the 60 cm depth after 12 hours. The initial water content of the soil was adjusted to the field capacity value. Under identical conditions I liter/hour continuously applied and 2 liters/hour pulsed (intermittent) irrigation resulted in only a 12% loss. The lateral distribution of the water showed that in the first group of treatments 80% of the water in the wetted soil volume was distributed 45 and 43 cm horizontally from the point source after 12 and 24 hours respectively. In the second group of treatments the distribution was to 29 and 40 cm. Thus the second group of treatments showed a clear advantage in reducing water loss under the root zone while still not significantly affecting the horizontal distribution. The pulse treatment can therefore replace the advantageous low (1 liter/hour) discharge rate while to a large extent avoiding the difficulties of blocking of outlets by maintaining a higher (2 liter/hour) discharge rate.

¹ Contribution from the Fruit and Fruit Technology Research Institute, Stellenbosch, South Africa. Project No. (S)WP 179/10.

² Soil Scientist, Institute of Soil and Water, ARO, Volcani Center, Bet-Dagan, Israel, on sabbatical leave in South Africa.

³ Soil Scientist, Winter Rainfall Region, Department of Agricultural Technical Services, Private Bag X5023, Stellenbosch 7600, Republic of South Africa.

⁴ Soil Scientist, Fruit and Fruit Technology Research Institute, Private Bag X5013, Stellenbosch 7600, Republic of South Africa.

Received for publication January 24, 1977. Accepted for publication October 3, 1978.