EFFECTS OF DIFFERENT TYPES OF ORGANIC FERTILIZERS ON GROWTH PERFORMANCE, NUTRIENTS AND TOXICOLOGICAL COMPOSITION OF AMARANTHUS CAUDATUS AND AMARANTHUS CRUENTUS
Increasing population of the world has doubled the food demands and inundated the available land resources. Alongside other food alternatives, vegetables are considered cheap source of energy (Hussain et al., 2009). Vegetables are rich sources of essential biochemicals and nutrients such as carbohydrates, carotene, protein, vitamins, calcium, iron, ascorbic acid and palpable concentration of trace minerals (Salunkhe and Kadam, 1998). Plants also contain compounds which can potentially compromise health. These are termed ‗anti-nutritive‘ compounds such as oxalates, tannins, nitrates which are present in spinach. Amaranth is one of important vegetables of Amaranthaceae family. Amaranth has been naturalized in central parts of Asia and possibly Iran (Kawazu et al., 2003) and has cultivation history of more than 2000 years (Daneshvar, 2000), but it is also widely grown in Nigeria and many part of the North including Kaduna state. Amaranth is eaten as a vegetable across various states in Nigeria.
Organic and inorganic fertilizers are essential for plant growth. Both fertilizers supply plants with the nutrients needed for optimum performance (Erisman et al., 2008). Organic fertilizers have been used for many centuries whereas chemically synthesized inorganic fertilizers were only widely developed during the industrial revolution. Inorganic fertilizer has significantly supported global population growth, it has been estimated that almost half the people on the earth are currently fed as a result of artificial nitrogen fertilizer use (Erisman et al., 2008). Commercial and subsistence farming has been and is still relying on the use of inorganic fertilizers for growing crops (Masarirambi et al., 2010). This is because they are easy to use, quickly absorbed and utilized by crops. The continued dependence of developing countries on inorganic fertilizers has made prices of man agricultural commodities to skyrock (Makinde et al., 2010). Most vegetable farmers in tropical Africa are small holders who cannot afford cost of inorganic fertilizers, although soil fertility limits yield of vegetables especially in urban centres (Makinde et al., 2010). In Nigeria, fertilizer being costly and sometimes scare can make farmers not apply enough for good growth (Alonge et al., 2007). Fertilizer application rates in intensive agricultural systems have increased drastically during recent years in Nigeria. Farmers depend largely on locally sourced organic fertilizers (Makinde et al., 2010). In Nigeria, huge amount of organic wastes such as poultry waste, animal excreta, sewage sludge, refuse soil and palm oil mill effluent are generated and heaped on damp sites, posing potential environmental hazard (Agboola and Omueti, 1982). Incorporating these wastes materials into the soil for crop production is expected to be beneficial to the buildup of organic matter layer that is needed for a steady supply of nutrients by tropical soils (Agboola and Omueti, 1982). However, due to high quantity needed, adequate quantity of an organic and inorganic waste may be obtained, hence the farmers often apply organic and inorganic fertilizer combined. Also, getting the appropriate application protocol or rates is important in obtaining good yield (Agboola and Omueti, 1982).
Oyedeji et al. (2014) reported that NPK and poultry manure improve the growth and yield of three different species of amaranth (Amaranthus hybridus, Amaranthus deflexus and Amaranthus cruentus) but influenced proximate composition differently where NPK had the highest crude fibre, protein and fat while poultry manure showed the highest fat content. Emede et al. (2012) reported that poultry manure influenced the plant growth and yield of Amaranthus cruentus L. positively. Makinde et al. (2010) reported that organic material alone or in combination with NPK significantly increased protein and ash while fibre was reduced;
DIFFERENT TYPES ,ORGANIC FERTILIZERS ,GROWTH PERFORMANCE, NUTRIENTS ,TOXICOLOGICAL COMPOSITION ,AMARANTHUS CAUDATUS ,AMARANTHUS CRUENTUS