Influencia de factores edafo/climáticos sobre poblaciones microbianas de suelos áridos con agricultura bajo riego

Abstract

El objetivo de este trabajo exploratorio fue evaluar el efecto de las prácticas agrícolas a largo plazo (30 años) sobre la actividad y los aspectos estructurales de la comunidad microbiana de los suelos áridos con agricultura bajo riego. Para ello, se evaluaron tres ambientes, recolectando muestras de un suelo árido Prístino (sin riego y sin disturbar) y dos suelos agrícolas bajo riego con diferente historial de manejo (Alfalfa y Maíz) a lo largo de la temporada 2014-2015. Se realizó un análisis fisicoquímico de los suelos, se registró la temperatura y humedad, así como la actividad biológica total (hidrólisis FDA) y la huella molecular (DGGE y T-RFLP) para cada tratamiento.

The agricultural frontier over the arid marginal zones is steadily expanding by means of irrigation technology. Considering the impact of bacterial population and its biological activity on soil homeostasis, information on soil biodiversity and its biological activity are a significant input to maximize the production with minimal impact on these susceptible environments. The aim of this exploratory work was to assess the effect of long term agricultural practices (30 years) on the activity and structural aspects of the microbial community from arid irrigated agricultural soils. For this, three environments were evaluated, collecting samples of a Pristine arid soil (without irrigation and undisturbed) and two different irrigated agricultural (Alfalfa and Corn) throughout the 2014-2015 season. For this, samples from Pristine (without irrigation) arid soil and (Alfalfa and Corn) were collected along the 2014-2015 season. Soil physicochemical analysis was performed, temperature and humidity were recorded, as well as total biological activity (FDA hydrolysis test) and molecular fingerprinting (DGGE and T-RFLP) for each treatment. Soil physicochemical analysis show that agricultural practice improved the edaphic properties like organic matter level, although the contribution of water in limited quantities (pressurized irrigation) an increase in electrical conductivity. Total biological activity along the seasons showed similar profiles for all scenarios, and the coldest/unirrigated and hottest/irrigated-rainy months showed the lowest and highest activities respectively. Overall, the Pristine condition presented significantly lower biological activity levels along the season. The DGGE fingerprint showed a discrete pattern with low number of bands and, against expected, showed no differences between the three scenarios. Subsequent T-RFLP analysis confirmed that soil bacterial biodiversity was not modified by decades of intensive irrigated agricultural activity.