A study was conducted to distinguish between the effects of cations (Ca and Mg) and soil pH on the B uptake and yield of crops. In the absence of added B, decreased B uptake appeared to be related to increased soil pH, rather than to the availability of Ca or Mg. In the presence of added B, however, this effect was not evident. The yield increases with added B were much greater where Ca, Mg, or both were added as carbonates, rather than as sulfates. Boron-deficient rutabaga roots from the carbonate treatments had more severe brown-heart than roots from the sulfate treatments. The B-deficient plants had reddish-violet and yellow leaves in the carbonate treatments, compared to light yellow leaves in the sulfate treatments. After the harvest of crops, lower quantities of B were found in soil that had received Ca and/or Mg as sulfates than in soil that had received them as carbonates. Calcium and Mg concentrations in plant tissues were not affected by the application of B.
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