Comparison of passive and active methods of soil solution sampling for fertigation control in a Mediterranean greenhouse

M.D. Fernández, S. Bonachela, M. Robles, M.R. Granados, F.J. Cabrera, D.E. Meca, J.C. López
In intensive and heavily fertigated agricultural systems, such as that of the Almería greenhouse area, the development of methods and protocols for a better fertigation control is highly recommendable in order to optimise vegetable production and irrigation water use, while also minimising nutrient leaching losses. In this area, several methods of soil solution sampling have been introduced to monitor irrigation and fertigation of greenhouse fruit vegetable crops. Passive (drainage lysimeter, pan or plate lysimeter and wetting front detector or funnel lysimeter) and active (suction cup) methods of soil water sampling were evaluated in a drip-irrigated greenhouse tomato crop in an artificially layered soil that included an imported silty-clay-loam layer. Matric water potential in the soil wetted by the dripper was higher with than without the presence of passive sampling devices throughout the whole tomato cycle. This disturbance can be attributable to alterations caused by these devices in the soil water movement. Electrical conductivity of leachates collected from the funnel lysimeter installed inside the imported soil layer was lower than that measured in the soil solution extracted with the suction cup (the most widespread method of monitoring soil nutrient availability in Almería), but the seasonal electrical conductivity dynamics was rather similar for both sampling devices. On the other hand, the drainage and pan lysimeters, and the funnel lysimeter installed below the imported soil layer, presented much lower solute concentrations than those measured in the suction cup, and their values were not related. Moreover, drainage and pan lysimeters required near soil saturation conditions to collect solution samples. Therefore, these passive sampling devices do not appear to be appropriate for controlling soil nutrient availability or salt accumulation.
Fernández, M.D., Bonachela, S., Robles, M., Granados, M.R., Cabrera, F.J., Meca, D.E. and López, J.C. 2017. Comparison of passive and active methods of soil solution sampling for fertigation control in a Mediterranean greenhouse. Acta Hort. (ISHS) 1170:643-650
electrical conductivity, soil matric potential, suction cup, zero-tension lysimeter

Acta Horticulturae