A laboratory experiment was performedto evaluate the suitability of moist olive pomace(MOP) as soil amendment. Moist olive pomace wasobtained from a new olive-oil industrial processcalled the `two-phases method'. Soil samples weremixed with MOP to approximate a field application of40 t ha-1 and incubated under aerobic conditionsat 20 °C and 60% of soil water holdingcapacity. To estimate the effect of different loadingrates and N supply on mineralization, 40, 80, 120 and160 t ha-1 of MOP and 200 ppm of N as(NH4)2SO4 were used. CumulativeCO2-C evolution, total microbial activity andbiomass-C were monitored during a 60-day period.Results indicate that the CO2-C evolution fromMOP depends on soil type and is temporarily inhibitedin acidic soils. Evolution of CO2-C increaseswith incremental addition of MOP, but the percentagesof the added C that were mineralized decreased withincreasing application rates. Mineral N supplementsresult in more efficiency of the mineralizationprocess. Among the kinetic models tested to describethe mineralization dynamics, a first-order exponentialmodel including a constant term provides the best fitto the experimental data. Both amount and activity ofsoil microbial biomass are enhanced by MOP added atthe 40 t ha-1 rate, at least in the first periodof incubation. At higher rates of MOP addition, aconstant increase of biomass C during incubation isobserved, while the biological activity decreases atthe end of incubation. Following application ofmineral N, both amount and activity of microbialbiomass is enhanced.
[1]
B. Ellert,et al.
Comparison of Kinetic Models for Describing Net Sulfur and Nitrogen Mineralization
,
1988
.
[2]
F. Broadbent.
EMPIRICAL MODELING OF SOIL NITROGEN MINERALIZATION1
,
1986
.
[3]
T. Rosswall,et al.
Fluorescein Diacetate Hydrolysis as a Measure of Total Microbial Activity in Soil and Litter
,
1982,
Applied and environmental microbiology.
[4]
P. Brookes,et al.
AN EXTRACTION METHOD FOR MEASURING SOIL MICROBIAL BIOMASS C
,
1987
.
[5]
T. Rosswall,et al.
Seasonal Variation of Potentially Mineralizable Nitrogen in Four Cropping Systems
,
1987
.
[6]
C. Jones.
Estimation of an active fraction of soil nitrogen
,
1984
.
[7]
C. Clapp,et al.
Potentially Mineralizable Nitrogen in Soil: The Simple Exponential Model Does Not Apply for the First 12 Weeks of Incubation1
,
1980
.
[8]
M. Amato,et al.
Differential effects of rotation, plant residue and nitrogen fertilizer on microbial biomass and organic matter in an Australian alfisol
,
1994
.
[9]
A. Saviozzi,et al.
Decomposition of vegetation-water sludge in soil
,
1993
.