emissions and phosphatase activity were measured as
indicators of general and specific soil microbial activity, respectively.
Microbial phosphatases play a central role in the mineralization
of P by catalyzing the hydrolysis of esterified phosphoric acid
and releasing phosphate that can be taken up by microbes and
plants [50]. Microbial activity was higher in the N300 and PS45
plots than the N0 plots in both years, but especially in 2011 when phosphatase activity. However, no such effects were observed in
N300 or PS45 plots even after 8 years of continuous applications,
and others have published similar results [55]. Indeed the treated
plots showed a higher phosphatase activity than control plots,
probably due to the presence of phosphatase in maize roots. High
levels of soluble inorganic phosphate are probably required to
inhibit phosphatase activity in the soil