Hydrologic scenarios applied to the agricultural management of the northwest of the Buenos Aires Province,Argentina

The study area is located in the Pampean region of Argentina, in the northwest of Buenos Aires Province, covering about 50,000 km², within an area of great plain with particular hydrologic characteristics, where vertical water movements predominate over horizontal. The objective of this work is the analysis of the relations between different hydrologic scenarios (characterized by the soil water balance and the water table levels) and the yields of soybeans that have been increasing in recent years. It is concluded that water table fluctuations are strongly related to the elements of the local hydrologic balance. On the other hand, the geographic distribution of soybean yields corresponds directly with the values of the soil water reserve during the critical stages of the growth. After dry periods, the lowering of the water table makes access to water from the root zone difficult, and the crop is susceptible to the effects of drought. However, after wetter periods the extra contribution from the water table situated near the surface is favorable for growth, often preventing its deterioration in conditions of drought. Nevertheless, an excessive rise of the water table can produce disadvantages at seedtime and during harvest. The importance of an evaluation of the different scenarios that may have significant implications for agricultural activity is discussed.