Factors Affecting the Mobility and Plant Availability of Boron in Some Western Oregon Soils
1982
Parker, D. R. | Gardner, E. H.
Surface soil from five diverse soil series was used to investigate the influence of soil properties and constituents on the mobility of boron (B) in a greenhouse study. Using pots 16.5 by 18.5 cm in diameter, from 13 to 61% of a 2.0 mg/kg liquid application of B was recovered in 25 cm of leachate. Recovery of B decreased with increased soil organic matter, clay, and free Fe and Al oxide content, but statistical separation of the effects of individual components was complicated by intercorrelations among these soil properties. No effect of soil pH on B mobility over a range of 5.4 to 7.5 was observed. Following leaching, the soils were cropped with New Zealand white clover (Trifolium repens L.). Yield differences were not correlated with hot water-extractable B levels ranging from 0.47 to 2.34 µg/g or with B applied at planting. Plant B concentrations were high, ranging from 60 to 150 µg/g. As the range in hot water-soluble B values encompassed current concepts of deficiency levels in western Oregon soils, the merits of investigating soil-B critical levels under greenhouse conditions are questioned. A balance sheet approach indicated that soils have reserves of leachable and plant-available B not detected in the conventional hot water extraction. The boron-supplying power of these soils varied both within and among soil series and depended on soil properties and the amount of B in the soil system.
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