Growth of a low-cost tensiometer driven irrigation control unit and assessment of its aptness for irrigation of lychee trees in the uplands of Northern Thailand in a participatory approach

Abstract

In upland areas of Northern Thailand, lychee (Litchi chinensis, Sonn.) is one of the predominant fruit 
crops. Fruit development takes place during the dry season (January until June). Therefore, high lychee 
yields can only be obtained under irrigation. As water is an increasingly scarce resource in the hillsides, 
strategies for more efficient water use are fundamental for a sustainable increase in agricultural 
production. An Automatic Tensio Control (ATC) unit was developed to use soil matric potential to open 
and close the inlet valve of a micro-irrigation lateral. In order to test the functioning of the ATC in the 
field, four different irrigation regimes have been tested in cooperation with local farmers on 10 year old 
lychee trees on a commercial orchard in Mae Sa Mai, close to Chiang Mai, Thailand. Testing the ATC on 
station and under field conditions, it has proven its reliability in maintaining a favorable moisture regime 
in the soil. The irrigated lychee trees responded to ATC irrigation with a higher yield and higher fruit 
weight compared to the other treatments. ATC works without electric components, so that it can be 
operated in areas without electricity. Furthermore, it is assembled from cheap and simple materials. 
Thus, it can be easily copied and adapted to different agro-ecological and socio-economic 
environments.