Evaluation enzymatic profiles as indicator of soil health in relation to the diversification and intensification of crops in agricultural rotations

COVELLI J; GABBARINI L; ROBLEDO B; FRENE JP; WALL LG

Rosario

Congreso; 7th World Congress on Conservation Agriculture; 2017

CAAPAS-AAPRESID

The project Chacra Pergamino started in 2011 aimed to develop knowledge about soil health in relation to the intensification and diversification of crop rotations (DIRC). Treatments were replicated at three independent productive fields: Las Matreras, La Matilde and San Nicolás, separated each other about 100 km in the Pampas, Buenos Aires, Argentina Each productive field belongs to a different soil series. The treatments included one pasture and four different rates of crop rotation intensification (IIR). The different sub-plots were part of a plot with a common history of use before this assay. After three years of treatments no significant differences were found in chemical and physical soil quality, so farmers asked for soil biology characterization after four years of crop rotation.. As a part a more comprehensive study that includes analyses from DNA to macrofauna, here we report our results regarding how the soil enzymes profiles are affected by the intensification and diversification of crop rotation. Soil samples were taken at each location in two consecutive years (2015/2016) in autumn and spring. For each treatment, five replicates were taken (0-5 and 5-10 cm) and six enzymes involved in carbon, nitrogen and phosphorus cycle were determined using a fluorescent assay. A clear dynamic was found in the data along sampling time in the enzymatic profile, together with a "site" effect that separated the data by location. Nevertheless, when the analysis was performed at each location, significant differences between treatments were observed. Finally, a good correlation was found between the enzymatic activities related to the C-cycle and the N-cycle and the IIR. Thus, DIRC would favour the increase of the enzymes of the soil, improving the quality of the soil and its biofertility. The changes in profiles enzymatic were detected in shorter time than the changes in chemical and physical indicators suggesting the advantage of biological indicators in the short term to monitor the agronomic process.