PRI reduced the total dry mass of pot-grown maize plants
slightly but the water consumption substantially, thus leading to
increased canopy water-use efficiency (WUE). Within the same
irrigation method (CI, APRI or FPRI), added organic N also increased
the total dry mass and canopy WUE. The highest activities of
catalase, urease and acid-phosphatase in the soil occurred in the
higher soil water content (CI and PRI wet side), but the highest
activity of invertase in the soil occurred in the lower soil water
content (PRI dry side). Therefore, soil water content affects soil
enzyme activities, but its effect varies with soil enzyme type.
Compared to the CI and FPRI treatment, APRI can maintain higher
soil enzymatic activities and had no significant difference of soil
enzymatic activities between the dry and wet root-zones at the
three growth stages under the three ratios of inorganic to organic N
fertilizer. Soil catalase, urease and invertase activities increased
with more organic N, but the maximal soil acid-phosphatase
activity occurred at the treatment with 70% inorganic N + 30%
organic N.