Effects of NPK and plant tea manure (Tithonia diversifolia) on growth rate of amaranth (Amaranthus cruentus L.) in soilless growing media

Abstract

Many countries are running short of agricultural land. Even where land appears to be available, soil fertility, water availability as well as nutrient mining still remains a challenge yet at the same time the world’s demand for food is rapidly increasing. Millions of square meters of soil are mined each year for use in vegetable nurseries and in backyard gardens in addition to excessive use of inorganic fertilizers. There are however a number of soilless growth media and organic sources of plant nutrients that could be used to address this problem. This study investigated the effects of application of NPK (Nitrogen, Phosphorus and Potassium) and plant tea (Tithonia diversifolia) manure on selected soilless growing media on growth rate of Amaranthus cruentus L. This was to determine their suitability as an alternative growing media. A split plot design was used and the experiments carried out for two seasons. The soilless growing media investigated were: charcoal dust, saw dust, dry coffee husks, and mixture of charcoal and saw dust (1:1), saw dust and coffee husks (1:1), charcoal dust and coffee husks (4:1) and a compound mixture of charcoal dust, sawdust and coffee husks (2:2:1). The growing media were randomized in the three split blocks with eight pots each. Growth rates in terms of shoot height, number of leaves, leaf length, leaf width, stem girth and root length were measured for two seasons. Results indicated that all the growth media could support amaranth growth. However, a mixture of charcoal dust and dry coffee husk (4:1 respectively) with application of plant tea manure significantly affected the growth rate of A. cruentus (p<0.05). Mixture of charcoal dust and dry coffee husk (4:1 respectively) with application of either NPK or plant tea manure could be used as the best alternative growth media. Soilless growth media that constituted of charcoal dust and coffee husks could be explored for amaranth production in home kitchen gardens in rural areas and backyard gardens in urban areas. Key words: Soil, soilless growing media, plant nutrients, amaranth.