Evaluation of the reduction of non-beneficial evaporation losses with an inorganic mulch structure (Tree Hog) in a commercial citrus orchard in the Western Cape of South Africa

E. Lötze, G.F.A. Lötze, C. Jarmain
The Western Cape, South Africa, has been identified as a region to be seriously affected by climate change (Midgley et al., 2014). Being a winter rainfall region, the commercial production of fruit crops necessitates irrigation. In 2018, the worst drought experienced in 100 years placed a renewed focus on water savings. The introduction of various commercial devices, e.g. T-Pee®, Tree Grow and Tree Hogs (TH), with water saving claims, came as no surprize. This paper evaluated the contribution of TH as abiotic mulch in reduction of non-beneficial water use (related to soil evaporation) in a commercial Eureka lemon orchard in Robertson, South Africa. The orchard was divided into two irrigation blocks of 0.5 ha each. TH were installed on each tree in one of these block (January 2016), after planting in October 2015. Each tree was irrigated with a micro-sprinkler. Various physiological parameters were monitored from January 2016 to December 2018, using 10 single tree replicates per block. Irrigation volume applied was monitored with a flow meter in each block. Plant-based physiological parameters indicated no stress despite severe reduction of irrigation volumes in the TH treatment. Stomatal conductance and stem water potential was significantly higher for the control than TH treatment in 2017 and 2018 (data not shown). Increases in tree height, stem diameter and canopy diameter were recorded in the TH treatment in the 2018 season. Differences in the block average actual evapotranspiration (ET) and evapotranspiration deficit (ETdeficit) (and indication of plant stress) were evaluated using satellite derived data (FruitLook.co.za). ET from the control and TH treatments were similar in the 2016/17 and 2017/18 seasons, with increased differences from October 2018 (Control ET exceeding TH ET). Differences in ETdeficit between treatments were negligible, indicating no increased stress in the TH compared to the control. For certain instances the ETdeficit of the TH exceeded that of the control.
Lötze, E., Lötze, G.F.A. and Jarmain, C. (2022). Evaluation of the reduction of non-beneficial evaporation losses with an inorganic mulch structure (Tree Hog) in a commercial citrus orchard in the Western Cape of South Africa. Acta Hortic. 1335, 145-152
DOI: 10.17660/ActaHortic.2022.1335.17
https://doi.org/10.17660/ActaHortic.2022.1335.17
Et deficit, stomatal conductance, yield
English

Acta Horticulturae