Application of Bicarbonate to High-Phosphorus Soils to Increase Plant-Available Phosphorus

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Vegetable growers in the northeastern United States often have soils with P levels so high that fertilizer applications have environmentally detrimental effects. However, growers raise crops that require P fertilizer in cool soils regardless of soil P levels. A method to increase bioavailable P to vegetable seedlings in cool soils would have great value. Bicarbonate is a safe and inexpensive material that solubilizes some pools of adsorbed phosphate. Incubation of 50 mmol KHCO3 kg−1 soil increased water-extractable P three- to eightfold in soils characteristic of P-impacted vegetable soils in the northeastern United States. A banded treatment at this rate is equivalent to 28 kg ha−1. Multivariate analysis of soil characteristics revealed that the most responsive soils were those high in sand content. The response increased linearly with sand content >50%. A bicarbonate application technique would therefore have particular promise on sandy, high-P soils such as those found on the Atlantic seaboard.

Thomas Björkman
Stephen Reiners
Soil Science Society of America Journal