Determining the water footprint of tomato and butternut production towards enhanced water security at Nwanedi irrigation scheme

Abstract

Declining underground water, unpredictable rainfall patterns and high temperatures pose a threat to future food and water security. Water security is also threatened by the growing demand for water in the agriculture sector to meet food needs. Knowing the water footprint and total water consumed by major agricultural crops is critical in devising appropriate intervention strategies. This study assessed tomato and butternut water footprint at Nwanedi irrigation scheme in Musina local Municipality, Limpopo Province, South Africa; tomato and butternut are popular horticultural crops grown year round in the region. Data was collected, explored and quantified using a convergent parallel mixed method design. Purposively selected small scale farmers provided data for the study. Quantitative data was analysed descriptively using SPSS version 26 while qualitative data was analysed thematically aided by Atlas Ti version 8.1. The results revealed that tomatoes had less water footprint (134.62 m³/t) compared to butternuts (393 m³/t). On the other hand, seeding and maturity stages were observed as using less water, although, a substantial number of farmers believed that all the stages of crop production required the same amount of water. The results further revealed that there were distinct water-saving strategies commonly used in different growth stages for both tomato and butternut and those that were specific to each growth stage and crop. At the seeding stage, for example, nursery, seed soaking, and choice of crop variety were the main methods used. In early growth, flowering, fruit formation, fruit growth and fruit maturity strategies such as mulching, drip irrigation, irrigation monitoring and watering-time optimisation were used variedly and in combination. Given these results, it is recommended that water footprint be calculated for each stage of plant growth to devise appropriate interventions and that farmers with smaller production areas be prioritised in devising water footprint reduction strategies. It is also recommended that farmers practice deficit irrigation to calibrate watering needs for each plant at different growth stages, as part of the strategies to reduce water footprint in vegetable production. There is, therefore, a need for the intensification and adoption of more innovative water reduction strategies at different growth stages for both crops.