Bachelor of Environmental Management tutor Dr Tapuwa Marapara undertook a number of research activities in 2019. One of these involved supervising student Rebecca Crack's project into riparian planting in the Waituna Catchment area.
Riparian planting is an activity where by various vegetation types such as grasses, shrubs and trees are planted on the margins/banks of waterways (rivers, streams, creeks). The vegetation is meant to absorb excess nutrients and process waste minerals before they enter waterways. ‘The increase in agricultural development and intensification of farming in the Waituna Catchment has contributed to the decline of water quality and environmental health of the Waituna lagoon,’ explains Tapuwa. ‘The Waituna Lagoon and surrounding wetlands are a designated area of International Significance, yet testing by Environment Southland shows that water quality is poor due to high levels of suspended sediment and nutrients as a result of increasing agriculture in the area.’
The purpose of this research was to carry out an investigation on the knowledge and application of riparian planting by dairy farmers in the Waituna Catchment. ‘The aim was to see if the science that researchers generate is adopted by practitioners on the ground,’ says Tapuwa. ‘Specifically we looked at the adoption of riparian planting by farmers in the Waituna Catchment.’
Data were collected via a questionnaire administered by phone, with a number of farmers who live in the area, and also vegetation surveys of six sites were carried out. The results of the questionnaire showed that participants were generally well informed about riparian planting. ‘The two functions of a riparian zone which were most commonly identified were reducing runoff and nutrient leaching,’ says Tapuwa. ‘But participants also showed awareness of a number of other functions such as take up of excess nutrients, acting as a filtering zone, and providing shade for the waterway.’ The majority of participants stated that they had planted out their riparian zones. They also noted a number of concerns with riparian planting, such as the costs involved in preparation and maintaining it, along with issues of blocking of tile drains. The vegetation survey identified the most common plantings to be toe toe, carex, red tussock, Manuka and Cabbage trees. ‘There were also pest plants such as bracken, blackberry, broom, gorse and buttercups identified in the vegetation survey,’ says Tapuwa.
Tapuwa notes that a number of organisations offer advice on riparian planting. ‘Environment Southland have Land Sustainability Officers who offer on-farm advice, organise field days, and work with groups in the community to raise awareness of these issues. Organisations such as DairyNZ and programmes such as the Living Water programme all provide support and education for riparian planting and good environmental management practices.’ The participants mentioned some of these in their comments in the questionnaire responses.
While this was a small study, it nevertheless provides encouraging data and suggests that some farmers in the Waituna Catchment are showing a positive approach to managing water quality deterioration. The results of the research were published in a staff-student edition of SITJAR in 2019.