Artificial soil profile for vegetable production: a potential case of urban agriculture.

Abstract

A significantly large population of South Africa migrates from rural to urban areas, leaving opportunities for small-scale subsistence agriculture for a perceived better livelihood. Food insecurity and poverty seem to increase in the peri-urban areas because of poor opportunities for food production and the inescapable need for money to survive. The advantages of urban farming have been published in the literature for many years, but there are still opportunities to introduce innovative methods that are confirmed by scientific findings. This study aimed to determine the efficiency of portable bags and artificial soil profiles on year-round production of common vegetables in South Africa, namely, Swiss chard, lettuce, onion, beetroot, and green pepper. Artificial soil profiles were created in the bags using commonly found urban homestead common organic garden refuse (grass and wood) garden soil and collected rock, respectively. One vegetable, lettuce was used to represent fertilizer requirements and three recommendations (0, 50, and 100%) were applied. Measured crop growth parameters included plant height, leaf number, stomatal conductance, chlorophyll content index, leaf area index, and photosynthetically active radiation. Soil moisture content, soil water potential, and soil temperature were also determined. Crop biomass yield and mineral content at harvest were also determined. The artificial environment was compared with soil plot environment (sandy loam soil with 110 mm depth) under rainfed conditions, with limited supplemental irrigation during dry periods. Results showed that vegetable production is possible all year round in both artificial and real profile conditions. The vegetable yield was reduced in non-soil artificial profiles, but the fertilizer application supported it all year round. Vegetable nutritional value, in terms of selected minerals, differed significantly between seasons and less between normal and artificial profiles, where even no fertilizer application produced yield all year round. The study concludes that disposable bags have a potential role for vegetable production in urban areas, where land area is limited. Potential food security benefits are linked more to nutrient access than quantity access. There is a need to test the findings of the study a different environmental and socio-economic conditions, to influence government policy. Keywords: artificial soil profile, fertilizer, season, temperature, vegetable nutrient content.