Efecto de la profundidad y la capacidad de almacenaje de agua del suelo en el rendimiento de soja

In our country, most of the agricultural area is rainfed. Given the significant interannual variability in precipitation, it is crucial to understand how different environmental conditions influence yield generation. This knowledge helps identify ways to mitigate the risks associated with a potential water deficit, particularly in summer crops, when evapotranspiration is higher and the risk of drought is greater.

This study presents the following hypotheses: i) The soil’s available water storage capacity (CAAD) is relevant for mitigating the effects of precipitation deficits, especially during the critical period when the most important numerical component of yield is defined.
ii) The possibility of mitigating this effect depends on soil depth.

Data collection was carried out on agricultural fields located in the country's most important agricultural basin. The potential yield achieved—without the influence of diseases or pests—was measured, along with environmental water supply, radiation, and temperature throughout the crop cycle and at different growth stages. Additionally, soil depth was measured, and different horizons were characterized and analyzed to estimate the available water storage capacity at each site.

A quantitative analysis of the data was performed using the statistical software Infostat/E, applying multiple linear regressions to quantify the effects of CAAD and soil depth on soybean (Glycine max) yield.

The data were analyzed comprehensively and also segmented based on different water supply conditions during the critical yield-defining period (R4-R6) and throughout the crop cycle. An analysis was also conducted on fields with supplemental irrigation and under rainfed conditions.

The results showed a yield response to CAAD of 21 kg per mm. A response to soil depth was also observed, with a greater effect under rainfed conditions, where the increase was 10 kg per cm of additional soil depth.

When the dataset was segmented based on total water supply during the crop cycle, a yield response was found under medium water availability conditions (421–450 mm), with an effect of 10 kg per cm of increased soil depth.

During the critical period, a response was observed only when water supply was ≤ 90 mm, with an effect of 8 kg per cm of increased soil depth.

It was demonstrated that soil depth influences yield, with variations depending on environmental water availability. However, under unfavorable—though not extreme—conditions, soil depth provides an additional level of security for decision-making, serving as a way to mitigate the risks associated with water availability.