Leaching losses from blueberries grown in sandy soils amended with pine bark

Abstract

Leaching of irrigation water from blueberry (Vaccinium spp.) plants intensifies when sandy soils are amended with pine (Pinus spp.) bark. In a greenhouse study, leaching fractions of water (LFW) and nutrients (LFN) were determined from two blueberry (V. corymbosum L.) cultivars, 'Emerald' and 'Jewel', grown in biochar-treated and nontreated sandy subsoil and irrigated with drip emitters using one of three pulse frequencies in a factorial design. The LFW was >50% under Emerald and <20% under Jewel, which has a more extensive root system. When the frequency of same volume of irrigation was increased from 2 (F2) to 10 (F10) pulses per day, the average LFW decreased from 46 to 30%. The LFN from a single fertigation was much lower than the total LFN after 6 d of irrigations applied between two fertigation events. The LFN increased linearly with LFW. Amending subsoil with 2% biochar increased soil pH, limited root growth, and did not reduce nutrient leaching. Eighteen months after plant establishment, 1.9% of applied NO 3 −-N and 2.5% of applied PO 4 3−-P from Emerald and 0.8 and 1.0%, respectively, from Jewel leached below the root zone during a fertigation event. During irrigations following a fertigation event, 10.5% of both NO 3 −-N and PO 4 3−-P from Emerald and 3.0 and 2.5% from Jewel leached below the root zone. All growth parameters including root/shoot ratio were higher in Jewel than Emerald. This study indicated that leaching rates could be reduced by selecting blueberry cultivars with a dense root system and using a drip irrigation system with >5 pulses d −1 to supply the daily water requirements in pine bark-amended sandy soil. Abbreviations: EC, electrical conductivity; ET, evapotranspiration; ET o , reference evapotranspiration; LFN, leaching fraction of nutrients; LFN f , leaching fraction of nutrients during fertigation; LFN i , fraction of nutrients during irrigations between two fertigation events; LFW, leaching fraction of water; MAE, months after establishment; SHB, southern highbush blueberry. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Preplant Fertilization Increases Substrate Microbial Respiration But Does Not Affect Southern Highbush Blueberry Establishment in a Coconut Coir-based Substrate

“…Although it is likely that some P was taken up by the plants, it is safe to assume that most P leached out of the rhizoboxes thanks to the high leaching fraction used in this experiment and the negative charges in phosphates. Considerable P leaching has been observed in previous experiments with blueberry (Bandaranayake et al, 2020) and crape myrtle (Shreckhise et al, 2020) grown in pine bark-based substrates, suggesting that large P discharges might be a common characteristic of substrate-based production systems.…”