Zinc availabilities can change with different cropping management prac
tices. The objective of this study was to identify some of the causati
ve factors associated with previous crops contributing to Zn uptake di
fferences in a subsequent crop. Field studies over 3 yr evaluated the
Zn availability after four precropping treatments: bean (Phaseolus vul
garis L.), corn (Zea mays L.), wheat (Triticum aestivum L.), and fallo
w, across two Zn fertilization rates (with and without 11 kg Zn ha(-l)
as ZnSO4), using the 'Viva' bean as a test crop. Soil samples taken b
efore and after the test crop were analyzed for extractable P, Zn, Cu,
Mn, and Fe, and organic matter. Soil respiration during the test crop
was periodically estimated the last cropping year. Whole plant sample
s estimated nutrient concentration and uptake. Soil Zn extracted by di
ethylenetriaminepentaacetic acid (DTPA) was increased by Zn fertilizat
ion but not affected by precropping treatments. Zinc uptake by bean wa
s significantly higher after precropping with corn and lower after fal
low regardless of Zn fertilization. Uptake differences were most prono
unced during early plant growth. Phosphorus and Cu uptake varied with
treatment in a similar pattern as Zn uptake, and were positively corre
lated with each other. Zinc up. take was also positively correlated wi
th soil organic matter and negatively correlated with soil P. Soil res
piration rate was significantly lower after the fallow treatment compa
red with other precropping treatments. Vesicular-arbuscular mycorrhiza
(VAM) colonization in the test crop roots was higher after corn and l
ower after fallow regardless of soil Zn concentrations. Colonization w
as positively cor-related with Zn, P, and Cu uptake during early plant
growth. The VAM colonization, soil respiration, and DTPA-extractable
Zn were selected by a stepwise regression procedure as the important v
ariables affecting Zn uptake during early plant growth. These results
emphasize the importance of the soil's biological activities on Zn ava
ilability and may help explain some field observations where chemical
soil tests appear to fail.