Improving Rabbiteye Blueberry Performance in a Calcareous Soil by Growing Plants in Pits Filled with Low-CaCO3 Growth Media

Abstract

Calcareous soils are not suitable for blueberry cultivation. Our aim was to improve the performance of blueberry plants in calcareous soils by using pits filled with growth media in combination with high levels of RNH4+ (proportion of N-NH4+ among the total applied N). Rabbiteye blueberry (Vaccinium virgatum Ait. cv. Ochlockonee) plants were grown in pits filled with a tuff/peat mixture (TP), a sandy soil (S) or a calcareous (CC), in full factorial combination with three levels of RNH4+: 33%, 66% or 100%. The two higher RNH4+ treatments decreased the pH of the low-CaCO3 (S) and no-CaCO3 (TP) media to ≤6.0 over 250 days of fertilization, but did not affect the pH of the CC soil over 650 days. Plant performance was superior in the TP and S media, as compared to the CC soil. The type of growth medium was the dominant factor accounting for the improved plant performance. The plants were sensitive to Mn deficiency in leaves during the spring period. The current results suggest that growing blueberry in pits filled with good aeration and low pH buffering capacity medium in combination with a high level of RNH4+ is a positive approach for its cultivation in calcareous soils.

Combined effects of alkaline pH and high Ca concentration on root morphology, cell-wall polysaccharide concentrations and blueberry plant performance

“…It has been suggested that plant growth may be retarded due to deficiencies of microelements, mainly iron (Brown, 1978;Haynes and Swift, 1985;Poonnachit and Darnell, 2004;Darnell et al, 2015;Nunez et al, 2015). Recently, we demonstrated that Mn is the main element that is lacking in blueberry plants under alkaline pH conditions (Tamir et al, 2021a;Tamir et al, 2021b;Tamir et al, 2022). Other studies have suggested that blueberry plants favor an ammonium form of nitrogen (Cain, 1952;Merhaut and Darnell, 1995;Merhaut and Darnell, 1996;Claussen and Lenz, 1999;Poonnachit and Darnell, 2004;Darnell et al, 2015).…”

“…Blueberry plants are defined as calcifuge (Korcak, 1988) and retarded growth of blueberry plants in calcareous soils has been reported in many publications (Claussen and Lenz, 1999;Tamir et al, 2018;Tamir et al, 2021b;Tamir et al, 2022). In contrast to the above described literature, other publications (Haynes and Swift, 1985;Schreiber and Nunez, 2021), reported that the addition of low dose of CaCO 3 to an acidic substrate with very low buffer capacity growing medium improved the performance of blueberry plants.…”

“…The treatments included two levels of pH (4.5 or 7.5) combined with two concentrations of Ca (10 or 100 mg L -1 ). We chose these two levels of pH based on our previous works (Tamir et al, 2021a;Tamir et al, 2021b;Tamir et al, 2022) which showed optimal biomass production of blueberries at pH 5.5 or maximum damage to plant biomass production at pH 7.0 and higher. The treatments of Ca concentration were chosen based on the Ca concentrations that characterize alkaline or neutral pH in different soils (>100 mg L -1 , Bar-Tal et al, 1991;Tyler and Olsson, 2001;Erner et al, 2017) or a minimal concentration (10 mg L -1 ) which will prevent inhibition to the biomass production as a results of deficiency of this element.…”