Yield, water-use efficiencies and root distribution of soybean, chickpea and pumpkin under different subsurface drip irrigation depths and oxygation treatments in vertisols |
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Authors: | S P Bhattarai D J Midmore L Pendergast |
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Institution: | (1) Centre for Plant and Water Science, Faculty of Science, Engineering and Health, Central Queensland University, Rockhampton, QLD, 4702, Australia |
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Abstract: | Most trickle irrigation in the world is surface drip yet subsurface drip irrigation (SDI) can substantially improve irrigation
water use efficiency (IWUE) by minimizing evaporative loss and maximizing capture of in-season rainfall by the soil profile.
However, SDI emitters are placed at depths, and in many soil types sustained wetting fronts are created that lead to hypoxia
of the rhizosphere, which is detrimental to effective plant functioning. Oxygation (aerated irrigation water) can ameliorate
hypoxia of SDI crops and realize the full benefit of SDI systems. Oxygation effects on yield, WUE and rooting patterns of
soybean, chickpeas, and pumpkin in glasshouse and field trials with SDI at different emitter depths (5, 15, 25, and 35 cm)
were evaluated. The effect of oxygation was prominent with increasing emitter depths due to the alleviation of hypoxia. The
effect of oxygation on yield in the shallow-rooted crop vegetable soybean was greatest (+43%), and moderate on medium (chickpea
+11%) and deep-rooted crops (pumpkin +15%). Oxygation invariably increased season-long WUE (WUEsl) for fruit and biomass yield and instantaneous leaf transpiration rate. In general, the beneficial effects of oxygation at
greater SDI depth on a heavy clay soil were mediated through greater root activity, as observed by general increase in root
weight, root length density, and soil respiration in the trialed species. Our data show increased moisture content at depth
with a lower soil oxygen concentration causing hypoxia. Oxygation offsets to a degree the negative effect of deep emitter
placement on yield and WUE of SDI crops. |
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Keywords: | |
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