Effects of Cutting Frequency and Nitrogen from Fertilizer and Cattle Manure on Growth and Yield of Leaf Amaranth (Amaranthus hybridus) in a South African Semi-Arid Environment

ABSTRACT

Leaf amaranth (Amaranthus hybridus) is an important indigenous plant especially for rural households in South Africa. Amaranth is one of the oldest food crops. It is now receiving attention and has generated demand for information on production and management practices under local smallholder conditions. This study investigated the effects of nitrogen fertilization and cutting frequency on growth and yield of the crop. Edible leaves of plants were harvested weekly, every 2 weeks, every 3 weeks and once only at the end of the growing period. Soil fertilization regimes were 40 kg N ha⁻¹ supplied by chemical fertilizer or cattle manure, and soil only as a control. Plants were grown in pots in a glasshouse during both summer and winter seasons of 2002. The addition of nitrogen either as chemical fertilizer or manure significantly (p < 0.05) improved the growth and yields of amaranth. Shorter cutting intervals enhanced regrowth, but very frequent (weekly) cutting reduced the total dry matter of edible leaves. The results suggest that amaranth has the potential for production as a green leaf vegetable and that nutrient input from both organic and inorganic fertilizers are essential for high productivity. The study concluded that there is a need to cut the leaves of amaranth frequently. Since bi-weekly cutting increased the number of leaves, fresh weight and leaf dry matter produced per plant, a cutting interval of 2 weeks is recommended.