studia universitatis babeş-bolyai biologia 2

A. SAMUEL, S. KISS, M. ŞANDOR
Table 4
Enzymatic (phosphatase) indicators of soil quality in plots of the 6-crop rotation
Position Plot Enzymatic (phosphatase) indicator
of soil quality
1 Farmyard-manured maize 293.0
2 Minerally fertilised (M.f.) soybean 257.8
3 M.f. clover 252.3
4 M.f. maize (plot 4) 250.3
5 M.f. wheat 247.4
6 M.f. maize (plot 1) 240.1
Another hierarchy of the six plots was registered by us [10] in October 1997
when we determined soil actual and potential dehydrogenase and catalase activities.
Thus, position 1 was occupied by the minerally fertilised wheat plot, whereas the
farmyard-manured maize plot and the minerally fertilised soybean and clover plots
were placed on positions 3, 4 and 5, respectively. The minerally fertilised maize
plot occupied the last position as did the minerally fertilised maize plot 1 in 1999.
The different hierarchies of the six plots as registered in 1997 and 1999 may
be related to the different nature of the enzymes studied in these two years.
Dehydrogenase and catalase activities, determined in 1997, are considered as indicators
of the global and respiratory activity of soil, whereas phosphatase activities are
related to the P cycling in soil.
Farmyard-manuring and using of legumes in crop rotations are well-known
fertility-increasing measures. As the phosphatase indicators of soil quality in the
studied 6-crop rotation were highest in the farmyard-manured maize plot and in the
minerally fertilised soybean and clover plots, we consider that by determination of
phosphatase activities valuable information can be obtained regarding fertility
status of soils.
Conclusions. 1. The soil phosphatase activities decreased in the order: phosphatase
activity measured in unbuffered reaction mixtures > acid phosphatase activity > alkaline
phosphatase activity.
2. Each phosphatase activity decreased with increasing soil depth.
3. No-till – in comparison with conventional tillage – resulted in higher
phosphatase activities in the 0–20-cm soil layer and in lower activities in the 20–40-
and 40–60-cm soil layers.
4. The 6-crop rotation – as compared to the 2-crop rotation – led to higher
phosphatase activities in the soil layers under maize or wheat.
5. In the 2-crop rotation, the soil layers under wheat were more phosphataseactive
than those under maize.
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