Impacts on Soil and Cowpea Plants Fertigated with Sanitary Sewage through Subsurface Drip Irrigation

Abstract

The application of sanitary sewage using subsurface drip irrigation can mitigate current challenges related to water availability and food production. However, before implementing these techniques, it is crucial to conduct studies to assess their impacts on soil and plants. The objective of this study was to evaluate chemical changes in the soil and the development of cowpeas subjected to sanitary sewage applied by drippers with different flow rates and installation depths. Drippers were positioned at various depths (0 to 30 cm) and operated with flow rates of 1.6 and 3.8 L h−1. Cowpeas were cultivated in pots with clayey soil, using synthetic sanitary sewage based on the maximum limit of nitrogen fertilization. Irrigation management was controlled in terms of soil moisture, which was monitored using TDR probes. The results indicated that reducing the depth of the drippers positively affected grain production and the development of cowpeas. Fertigation with sanitary sewage at greater depths increased soil phosphorus concentrations and base saturation. Dripper depth also influenced soil concentrations of phosphorus, potassium, calcium, and magnesium, while sodium concentrations decreased with greater depth. It is concluded that dripper flow rates did not impact soil chemical parameters or the agronomic characteristics of cowpeas. However, despite nutrient supply at greater depths, the subsurface drip irrigation system proved unsuitable for cowpea production in clayey soil.