Sp. Deng et Ma. Tabatabai, EFFECT OF TILLAGE AND RESIDUE MANAGEMENT ON ENZYME-ACTIVITIES IN SOILS .3. PHOSPHATASES AND ARYLSULFATASE, Biology and fertility of soils, 24(2), 1997, pp. 141-146
This study was carried out to investigate the effect of tillage and re
sidue management on activities of phosphatases (acid phosphatase, alka
line phosphatase, phosphodiesterase, and inorganic pyrophosphatase) an
d arylsulfatase. The land treatments included three tillage systems (n
o-till, chisel plow, and moldboard plow) in combination with corn resi
due placements in four replications. The activities of these enzymes i
n no-till/double mulch were significantly greater than those in the ot
her treatments studied, including no-till/bare, no-till/normal, chisel
/normal, chisel/mulch, moldboard/normal, and moldboard/mulch. The effe
ct of mulching on activities of phosphatases was not as significant as
on activities of arylsulfatase. The lowest enzyme activities were fou
nd in soil samples form no-till/bare and moldboard/normal treatments,
with the exception of inorganic pyrophosphatase, which showed the lowe
st activity in no-till/bare only. Among the same residue placements, n
o-till and chisel plow showed comparable arylsulfatase activity, where
as the use of moldboard plow resulted in much lower arylsulfatase acti
vity. The activities of phosphatases and arylsulfatase were significan
tly correlated with organic C in the 40 soil samples studies, with r v
alues ranging from 0.71** to 0.92***. The activities of alkaline phos
phatase, phosphodiesterase, and arylsulfatase were significantly corre
lated with soil pH, with r values of 0.85**, 0.78***, and 0.77***, re
spectively, in the 28 surface soil samples studied, but acid phosphata
se and inorganic pyrophosphatase activities were not significantly cor
related with soil pH. The activities of phosphatases and arylsulfatase
decreased markedly with increasing soil depth and this decrease was a
ssociated with a decrease in organic C content. The activities of thes
e enzymes were also significantly intercorrelated, with r values rangi
ng from 0.50** to 0.92***.