The influence of garden treatments on the nutritional profile and agronomic performance of a dark green leafy vegetable grown in a peri-urban setting.

Abstract

Introduction Many nutrition interventions have been implemented to try and combat the high prevalence rate of micronutrient malnutrition and food insecurity in South Africa (SA). One of these interventions is home food gardening. Home food gardens growing Swiss chard, a commonly consumed dark-green leafy vegetable (DGLV) throughout SA, may contribute to food and micronutrient security. Aim The aim of this research was to identify, through a home food gardening study, the best affordable method of soil treatment for the production of nutrient dense Swiss chard in KwaZulu-Natal, SA. Objectives The objectives of the study were: 1. To determine the effect of fertiliser and mulch treatment combinations on the growth rate (number of days to reach maturity) of Swiss chard. 2. To determine the effect of fertiliser and mulch treatment combinations on the leaf number (yield) of Swiss chard. 3. To determine the effect of fertiliser and mulch treatment combinations on the nutrient profile of Swiss chard. Methods The study site was a home food garden in kwaMnyandu, KZN. A two factor Randomised Complete Block Design (RCBD) was used, where fixed factors (mulch and fertiliser garden treatments) were crossed with random factors (the treatment blocks containing Fordhook Giant Swiss chard (Beta vulgaris var. cicla) plants). Some of the garden treatments used in the study, organic kraal manure fertiliser and organic grass mulch, were being used at the study site. These garden treatments were available at the study site, free of charge. The other treatments used (inorganic chemical fertiliser and inorganic plastic mulch) may not be accessible by food gardeners in poorer areas due to their price. The nutrient content of Swiss chard was analysed and the garden treatment that produced the best quality of Swiss chard in terms of nutrients was identified Results When combined, fertiliser and mulch together did not significantly affect the maturity period of Swiss chard. However individually, organic and inorganic fertiliser and mulch had a significant effect on the maturity period (mean number of days taken to reach maturity) of Swiss chard compared to the control (no treatment). Fertiliser and mulch, applied to the soil in combination or individually, had no effect on the number of leaves present on Swiss chard plants at the study site. Both fertiliser and mulch treatments, independent of each other, significantly altered the nutrient profile of Swiss chard (p< 0.05), with fertiliser having a greater effect (p=0.002) than mulch (p=0.0389). However, experimental treatments containing a combination of fertiliser and mulch treatments, did not significantly affect the nutrient profile of Swiss chard (p>0.05). Conclusion Adding combinations of fertiliser and mulch to the soil, when growing Swiss chard, is not recommended to shorten the growth rate, improve the leaf number, or improve the nutrient profile of Swiss chard. To grow Swiss chard in the shortest time period (days) the most affordable garden treatment recommended is organic grass mulch. To produce Swiss chard with the best nutrient profile) the most affordable garden treatment recommended is organic kraal manure fertiliser. Considering the relevance of nutrient deficiencies in SA, the significance of the nutrient profile of the Swiss chard grown is more important than the number of days taken for the Swiss chard to reach maturity, and the number of leaves present on the plant. Therefore, the most affordable gardening method to use, to produce the best quality Swiss chard is organic kraal manure fertiliser.