Assessing the effect of different soil management strategies on soil moisture supply capacity, runoff, and crop performance in southern Uruguay

Supervisors

Walter Rossing (FSE Wageningen UR)
Santiago Dogliotti (Universidad de la Republica, Uruguay)
Florencia Alliaume (FSE Wageningen UR, Uruguay)

Introduction

The sustainability of family vegetable farms in South Uruguay is severely threatened. Continuous deterioration of physical soil quality is an important limitation to increasing production and productivity of the farming systems performance. Model-based explorations have shown that increasing the use of green manure and animal manure in crop rotations have promise to enhance soil quality and yields. However, these practices can be costly on small-scale horticultural farms, and results may be variable, which together may cause disappointing technology adoption. Better understanding of the interactions between crop rotations, inter-crop activities, and their effects on soil physical properties and soil moisture supply capacity (SMS) is required to improve farming systems re-design.

The goal of this project is to contribute to the exploration and quantification of the potential impact of alternative soil management strategies on the sustainability of these farm systems, specifically in relation to soil moisture supply capacity to a summer crop, erosion risk and crop yields.

Objectives (more than one thesis)

  1. To compare the effect of different inter-crop and soil intervention alternatives: cover crops incorporated or left as mulch (minimum tillage), the use of animal manure and a combination of those on the soil water capture, and water availability to crops.
  2. To assess the impact of the previous soil interventions on erosion risk
  3. To assess the impact of the previous soil interventions on yields of a summer crop.

Procedures

Processes related to runoff, water capture and moisture supply capacity to crops will be studied and quantified. Data for quantification and understanding the effects of soil interventions on these processes will be collected in Uruguay, from the second year of a field experiment (tomato crop) on a research station.

Field work can be done from September 2011 to March 2012, but you do not need to be there the whole period of field work. Soil chemical and soil physic properties will be analysed in the field as well as in the laboratory. We will monitor soil water content during tomato crop, take samples to estimate bulk density, take soil samples for chemical analysis (SOC, pH, nutrients) and texture. In the same field, a runoff parcels essay will be carried on, and infiltration will be deduced from rainfall and these measurements.  Depending on the interest more emphasis can be given to field experiments or to laboratory work. Data collected will be analysed.

Experiences gained

  • set up field experiments (experimental design, soil properties assessment, biomass and yield evaluation)
  • collect and analyse quantitative data on soil properties and processes (field and/or  laboratory)
  • statistical analysis and interpretation of result
  • practice your Spanish
  • write a MSc thesis and preferably a manuscript for a scientific journal in English (with Spanish summary optional).