Boron deficiencies as revealed by plant and soil tests
1940
Berger, K.C. | Truog, E.
The amount of boron present in the leaves of table beets gives an indication of the amount of available boron present in the soils on which the beets were grown. Thus, plant tissue analysis for boron may be used to determine the level of available boron in soils. The boron present in soils may be divided into three categories, namely, total boron, acid-soluble boron, and water-soluble boron. Results of analyses show that the total boron content of a soil is not a reliable indicator of the need for boron fertilization because, generally, less than 5% of the total boron is in available form. The unavailable, or better, difficultly available, form is often present largely as tourmaline. The acid-soluble boron content of a soil gives a somewhat better indication, but does not appear to correlate as well with the incidence of black spot in garden beets as does the amount of boron extracted with boiling water. Furthermore, acid extractions introduce difficulties in the case of calcareous soils, since these may neutralize all or a part of the acid. Extraction by treatment of the soil with boiling water for 5 minutes appears, at the present, to be the best method of extracting what may be called the available boron in soils.
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