TEMPORAL VARIATIONS OF MICROBIAL PHOSPHATASE ACTIVITY AND AVAILABLE PHOSPHORUS IN SOILS AMENDED WITH OLIVE MILL RESIDUES.

H. PAROLDI; E. MEDINA; A. VEGA AVILA; V. PESCE; F. BALAGUER; M. TORO; F. VAZQUEZ; P. MONETTA

Congreso; XI Congreso General de Microbiología General SAMIGE; 2015

Alperujo (oiled two-phase olive mill waste) can be used as soil amendment inolive groves. This practice has been widely evaluated in Mediterranean countries, however, there is still little consensus about the effects that it may produce on soils quality microbiological indicators. Soil degradation is closely related with the diminution of the available phosphorus and phosphataseactivity, therefore their quantitation is an important indicator of soil quality. Soil phosphatases are mostly microbial exoenzymes involved in the biochemical process of phosphorusmineralization. These enzymes are responsible for the inorganic phosphorus release from organic and inorganic compounds. In phosphorus cycle they have an essential role in the phosphate solubilizationprocess, increasing its availability for crops.The objective of this study was to evaluate temporal variations of phosphatase activity and available phosphorus in olive groves soils within two years of alperujo applications. The assays were performed in San Juan, Argentina, during 2013 and 2014 in an intensively managed olive orchard. Samples (0-15 cm depth) were taken twice a year (in winter and summer seasons). Treatments were: 1- superficial application of alperujo (50 kg pl-1 ), 2-superficial application of alperujo (50 kg pl-1 ) with subsequent incorporation to first 15 cm of soil. Controls were: a- Unremoved soil withoutamendment, b- Removed soil without amendment. The available phosphorus (P2O5) was measured by colorimetric assays. The enzymatic activity values were determined by p-nitrophenol colorimetric technique, using p- nitrophenylphosphateas substrate. Results of availablephosphorus and enzymatic activity were different among thedifferent treatments and controls. These differences were closely related with alperujo soil treatments. Analyzed data of the first year showed no significantdifferencesin the summer samples, while in the winter samples the alperujo incorporated treatment showed the highest values with significant differences for both variables, 127,67 +/- 26,73 ppm P2O5and 182,77 +/-27,8 gp-NF. In summer sample of the second year both treatments showed higher values than control treatments, while in the winter samplesalperujo incorporated treatment recorded the highest values. These results show that the addition of alperujo as amendment increase the available phosphorus and phosphatase activity.Both of them are important factors related to improving soil quality.