Joint International Conference on Long-term Experiments ...

dosages significantly reduced the amount of cellulose-decomposing microbes. The high
dosage treatments with bentonite composted with manure had a weaker inhibiting
effect.
In treatments with the two high dosages of bentonite, CO2 production was lower
than that of the control. Medium and high dosages of bentonite + manure also
significantly reduced the formation of CO2 in the soil.
The soil biomass-C value reduced under that of the control already at applying medium
dosages of bentonite. The small dosages of composted treatments caused a significant
increment, while the two high dosages reduced its values and treatment 10 resulted in a
significant reduction.
Regarding saccharase enzyme activity, a higher value was measured in treatment
2 among the bentonite treatments. Further treatments reduced the enzyme activity,
though not significantly. Composted treatments resulted in a smaller, non-significant
increase in enzyme activity.
Sample
Table 2. The effect of treatments on the amount of microbe groups and their
microbial activity (average of 2003-2005)
Dosage
Total
bacteria
(*10 6 g -1 soil)
Total fungi
(*10 3 g -1 soil)
Cellulose
decomposing
bacteria
(*10 3 g -1 soil)
CO2production
(CO2 mg
100g -1 )
Biomass-C
(µg g -1 )
Saccharase
(glucose
mg 100g -1 )
1. - 3.20 82.01 11.59 8.47 99.14 7,96
2. 1.× 3.80 64.69 9.89 8.73 100.71 9,10
3. 2.× 5.35 82.92 12.79 8.45 85.35 8,75
4. 3.× 3.94 54.91 7.90 5.74 85.27 8,76
5. 4.× 4.14 55.18 4.01 7.98 83.27 7,55
6. - 5.33 82.73 9.03 8.23 117.72 8,01
7. 1.× 6.15 71.21 20.95 8.10 136.18 8,94
8. 2.× 6.07 95.47 9.49 6.89 127.27 8,24
9. 3.× 6.05 88.73 7.03 8.37 118.67 8,34
10. 4.× 6.60 91.37 8.10 7.16 83.05 8,07
(SD5%) 0.25 3.54 4.73 0.30 3.86 0.72
In correlation analysis, we searched for correlations between the physical, chemical and
microbial soil parameters for both treatment series (Table 3). In our analysis, we
emphasize only the strong correlations.
In bentonite treatments, a strong correlation was found between the nitrate-N
content and readily available phosphorus content of soil (r=0.71). A strong correlation
was observed between changes in soil nitrate-N content and biomass-C content
(r=0.91). Among the microbial parameters, a strong positive correlation was found
between the total number of bacteria and the number of cellulose-decomposing bacteria
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