Salt and Water Balance for Seawater Irrigation of Salicornia bigelovii: Geochemical Model and Soil Column Study

Abstract

The incorporation of biofuels into the aviation fleet has been widely considered as a way to ensure energy sustainability within the aviation industry. Given the issues of competition between biofuel crops and food crops for precious land and water, salt tolerant plants such as Salicornia bigelovii have been proposed as alternatives, as they can be cultivated on saline soils and complete their life cycle under seawater irrigation. However, irrigation of crops with saline water poses several challenges, one of which is soil sodicity due to excess sodium input. This calls for strategies to remove excess sodium from these soils, thus maintaining a healthy soil structure for the cultivation of salicornia. While amendment of sodic soil with gypsum has been widely practiced, its applicability in seawater agriculture settings has not been fully investigated. In this study, a reactive transport model was developed to predict the fate of gypsum and calcium ions in an engineered soil formulated with different mass fractions of gypsum. Bench experiments were subsequently carried out to validate the outcome of the model. Further determinations were made employing biochar as a source of organic carbon at the root zone. The impact of these strategies on the soil sodicity was quantified in all scenarios. The results show that the accuracy of the model prediction will depend on the concentration of gypsum added to the soil, and the accuracy of the model parameters such as the longitudinal dispersivity. Although conventional application rates of gypsum and biochar appeared to have only marginal impact on soil sodicity in seawater irrigation, there are indications that sodicity cross-over points can be estimated, serving as guideline for the timing of replacement treatments.

Date of Award	May 2014
Original language	American English
Supervisor	Farrukh Ahmad (Supervisor)