Developing environmental principles, criteria, indicators and norms for potato production in South Africa through field surveys and modelling

• Published in: Agricultural systems 2011-04, Vol.104 (4), p.297-306
• Main Authors: Franke, A.C., Steyn, J.M., Ranger, K.S., Haverkort, A.J.
• Format: Article
• Language: English
• Subjects: Biocide; Biocide Biodiversity Cape floral kingdom Fertilizer Irrigation Resource use efficiency; Biocides; Biodiversity; Cape floral kingdom; carbon dioxide; certification; crop yield; embodied energy; emissions; environmental impact; Fertilizer; growers; interviews; Irrigation; land use; monitoring; phosphorus fertilizers; potatoes; Resource use efficiency; Solanum tuberosum; surveys; sustainable agriculture; use efficiency; water use efficiency; winter
• ISSN: 0308-521X; 1873-2267
• DOI: 10.1016/j.agsy.2010.12.001

► A method to assess sustainability of crop production is applied to South African potato. ► A farmer survey and crop model outcomes are used to quantify sustainability indicators. ► Results indicated scope among potato farmers to improve resource use efficiencies. ► Different ways to derive sustainability threshold norms are proposed. The sustainability of agricultural production is linked to the environment from which it draws its resources. Potato production in the Sandveld in the South African Western Cape occurs in the Cape Floral Kingdom: a vulnerable and globally significant biodiversity hotspot. A scientific approach defining and monitoring sustainability criteria and indicators is required to improve the sustainability of potato production in such a sensitive area. In this paper we propose principles related to the ecological impact of potato production (nature preservation, water preservation and the minimization of chemical and carbon-dioxide emissions) and their derived criteria related to land clearing, irrigation, emissions, and others. Next we defined calculable and measurable indicators of the efficiency with which resources are used, such as proportion of land cleared, water use by the crop, amount of biocides used, the embodied energy of biocides, and the energy needed for farming operations versus the potato yields obtained. In-depth interviews were held with 14 farmers representing 20% of the total potato production area to obtain the current values of these indicators. These were compared to model outcomes of two main sustainability indicators: land and water use efficiency. The land use efficiency varied least between growers, from (36 to 58 Mg (tonnes) ha −1), water use efficiency returned values between 3 and 9 g potato l −1 water, while chemical fertilizer phosphorus use efficiency varied most at 98 and 995 g potato g −1 P applied. Model outcomes confirmed some of the trends revealed by the survey, e.g. growing potatoes in winter and growing them with less than optimal water offers possibilities to double water use efficiency. Ways to derive indicator threshold norms are proposed based on the knowledge of physical and biological processes determining resource availability, the observed variation among farmers and the model outcomes. Knowing indicator values, their range and the means to improve resource use efficiency will aid in establishing sustainability norms by providing a quantitative approach to any environmental certificati