I've read from various University Extension sites (e.g., here and here) that boron levels would be deficient in sandy soils with low organic matter.

  • This would suggest that boron levels would be higher in non-sandy soils with high organic matter (OM) levels.

However, in a series of upland forest patches in central NC with clayey (low sand) soils with substantial OM, I've found the opposite to be true: Soil boron-levels in these low sand/high OM plots were regionally amongst the lowest levels measured (<0.2 ppm; more than 4x lower than nearby sandy soils with low OM).

  • This seems to contradict the above stated trend from extension websites.

Question: What would cause this trend? What would cause boron levels to be so deficient in clayey (non sandy) high OM soil?

Other information about sites: relatively dry, high topographic position and exposure, acidic (pH < 6) soil, high {K, Al, S} in soil. Vegetation = mid-to-late successional mixed hardwood/oak-hickory forests with relatively open understory due to deer overbrowse.

Note: soil methods: Mehlich III extraction for plant nutrients; loss-on-ignition method for OM.

  • $\begingroup$ What type of bedrock are your sites on? Is it the same for all sites? $\endgroup$
    – Eonema
    Feb 5, 2023 at 0:27


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