Aerated subsurface irrigation water gives growth and yield benefits to zucchini, vegetable soybean and cotton in heavy clay soils

Abstract

Inadequate oxygen concentration in the root zone is a constraint to plant performance particularly in heavy, compacted and/or saline soils. Sub-surface drip irrigation (SDI) offers a means of increasing oxygen to plant roots in such soils, provided irrigation water can be hyper-aerated or oxygenated. Hydrogen peroxide (HP) at the rate of 5 litre ha -1 at the end of each irrigation cycle was injected through SDI tape to a field-grown zucchini (courgette) crop (Cucurbita pepo) on a saturated heavy clay soil in Queensland, Australia. Fruit yield, number and shoot weight increased by 25%, 29% and 24% respectively due to HP treatment compared to the control. Two pot experiments with vegetable soybean (Glycine max) and cotton (Gossypium hirsutum) compared the effectiveness of HP and air injection using a Mazzei TM air injector (a venturi), throughout the irrigation cycle in raising crop yield in a heavy clay soil kept at saturation or just under field capacity. Fresh pod yield of vegetable soybean increased by 82-96% in aeration treatments compared with the control. The yield increase was associated with more pods per plant and greater mean pod weight. Significantly higher above ground biomass and light interception were evident with aeration, irrespective of soil water treatment. Similarly cotton lint yield increased by 14-28% in aeration treatments compared with the control. The higher lint yield was associated with more squares and bolls per plant which accompanied greater above ground biomass and an increase in root mass, root length and soil respiration. Air injection and HP effected greater water use, but also brought about an enhancement of water use efficiency (WUE) for pod and lint yield, and increased leaf photosynthetic rate in both species but had no effect on transpiration rate and stomatal conductance per unit leaf area. Aeration-induced enhanced root function was arguably responsible for greater fruit set and yield in all three crops, while in vegetable soybean greater canopy cover, radiation interception and total vegetative biomass were responsible for additional yield benefit. Increased aeration of the root zone in heavy clay soils employing either air injection or HP proved beneficial to SDI irrigated crops, irrespective of the soil water conditions, and can add value to grower investments in SDI.

Oxygation Improves Yield and Quality and Minimizes Internal Fruit Crack of Cucurbits on a Heavy Clay Soil in the Semi-arid Tropics

“…Ookawa et al (2001) established that the greater functionality of the root system, greater root length density and greener leaf surface (as noted by higher SPAD reading) reflected a slowed down senescence. The higher SPAD values in the current study recorded for oxygation are consistent with our earlier findings on tomato (Bhattarai et al, 2008), soybean, zucchini and cotton (Bhattarai et al, 2004), and associated increase (13-14%) in canopy cover, measure by grid, during the flowering period with oxygation are consistent with our earlier work on other species.…”

“…However, in a previous experiment oxygation hastened flowering in tomato (Bhattarai et al, 2008), and there was an indirect indication of earlier maturity of pumpkin in another field trial (Bhattarai et al, 2008). Earlier flowering in soybean and cotton in pot trials has been noted with oxygation (Bhattarai et al, 2004). Of interest, with oxygation the crop duration was extended by 21 days for watermelon and 15 for pumpkin.…”

“…Options to aerate irrigation water have been developed, and trialled for delivering water to the root zone to alleviate hypoxia, and such system using aerated water for DI and SDI has been referred to as oxygation (Bhattarai et al, 2008). We have measured the occurrence of hypoxia in the root zone of drip-irrigated crops in a range of soil types as it affects the performance in controlled environment experiments (Bhattarai et al, 2004). Previous research on drip irrigated zucchini in a loamy soil aerated with hydrogen peroxide at the rate of 5 L/ha at the end of each irrigation cycle increased yield and root biomass (Bhattarai et al, 2004).…”

“…We have measured the occurrence of hypoxia in the root zone of drip-irrigated crops in a range of soil types as it affects the performance in controlled environment experiments (Bhattarai et al, 2004). Previous research on drip irrigated zucchini in a loamy soil aerated with hydrogen peroxide at the rate of 5 L/ha at the end of each irrigation cycle increased yield and root biomass (Bhattarai et al, 2004). Benefits with oxygation have been recorded in different soil types, with variable response, in a number of crops largely grown under controlled environments in pots and in cotton in field conditions where planting density, therefore the root mass is comparatively higher (Bhattarai et al, 2008).…”

Eco-innovations in the German fertilizer supply chain: Impact on the carbon footprint of fertilizers

“…FG has two benefits: (1) reduction of fertilizer and water needed for crop production and (2) nutrient application can be scheduled at the precise times they are needed (Bhattarai et al 2004, Kafkafi 2008. With the combination of these two mechanisms a reduction of N 2 O emissions is feasible.…”