Boron Concentration Adjacent to Fertilizer Granules in Soil, and Its Effect on Root Growth1
- J. J. Mortvedt and
- G. Osborn2
Rates of dissolution of B from granules of rasorite and three boronated fertilizers in limed Hartsells fine sandy loam decreased in the order: Nitric phosphate (2.2% B) > rasorite (20.2% B) ≫ calcium silicate slag (7.5% B) > calcium metaphosphate (2.1% B). Movement of B from the granules increased with B concentration gradient and soil moisture content.
Concentration of hot water-soluble B in soil near the granules at a given time depended on: (i) B content of the granule, and (ii) the relative rates of B dissolution from the granule and movement of B from the granule site. Concentrations of B near rasorite granules—as high as 80 parts per million (ppm) in a large volume (4 kg of soil in gallon cans) and 385 ppm in thin soil layers (80 g of soil in Petri dishes)—were inversely proportional to the amount of soil affected.
Root growth of oats and alfalfa was slightly depressed at soil B concentrations of 2 to 5 ppm, and markedly so at concentrations above 10 ppm B. Thus, high concentrations in soil near some B sources may inhibit root growth. Root injury may be prevented by decreasing the B content per fertilizer granule and by applying less soluble sources or lower amounts of B.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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