Soils were collected from 2-year (2-y) and 3-year(3-y) old red-pine seedling plots in two tree nurseries,Hayward in the north and Wilson in the southwestern part of Wisconsin State respectively,and equilibrated with 0.01 M Ca(NO3)2) for soil solution Zn and Mn (solu-Zn and Mn),and with 0.01 M Ca(NO3)2+0.005 M EDTA for soil absorbed Zn and Mn(ad-Zn and Mn).Buffering capacity of soil Zn and Mn (b-Zn and Mn) was obtained from the ratio of ad-Zn and Mn to the solu-Zn and Mn.The concerned traces in pine seedling needles(ndls),stems(sts) and roots (rts) were simultaneously measured.The results obtained show that: About 60% of solu-and ad- Zn ranged from 0.2 to 0.4 and from 1 to 2μg/ g soil respectively.About 70% of b-Zn was within 3-10.The highest content of solu-Zn compared with the lowest showed a discrepance of more than 10-fold.The two forms of soil Zn were commonly higher in Wilson than in Haywark Nursery. About 80% of solu-,ad- and b-Mn were within 3-10,5-5.8μg/ g soil and 1-2 respectively.Influence of low buffering capacity on solu-Zn and Mn was about 20 times stronger than that of the high.The E-value,a ratio of accumulated Zn and Mn in needles to those in the soil solution,is proved to be:E-Zn> E-Mn;E-sts> E-ndls or E-rts;and E-2y>E-3y.Curvilinear and/ or linear correlations between soil solu-,ad- and b-Zn and Mn and ndls-,sts-,rts-Zn and Mn were at very significant or significant levels.For predicting ndls-Zn and Mn,two realizable and simple models from two regression equations were established through the selection of related parameters and dependent variables.Binary regression analysis basically eliminated the influence of soil pH on the prediction of Zn and Mn in needles.Soil pH was thus thought to be excluded from the model.
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