Effects Of Different Combinations Of NPK And Organic Manure On The Growth And Yield Of An Okra Variety (Abelmoschus Esculentus)


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Justification of Study

The application of inorganic fertilizers results in yield increase of this crop. Unfortunately, inorganic fertilizers reduce the quality of arable lands. The Economic Commission for Africa (2001) reported that tropical soils are adversely affected by suboptimal soil fertility and erosion, causing a deterioration of the nutrient status and changes in soil organism populations. Animal and farmyard manure have been used to improve and supplement soil nutrients from time immemorial. However, the advent of inorganic fertilizer has almost eliminated the use of these manures by farmers as sources of plant nutrients and soil amendment because of its relative ease of application and quick results. A lot of organic manures lie waste in rural areas in Nigeria and even in developing urban centres and mega-cities like Lagos and Ibadan. They are usually dumped around farmsteads. Some of these organic wastes are burnt periodically while others are just dumped on the ground surface, increasing the problem of environmental pollution and constituting health hazards. Hence, there is a need to look for ways of combining the advantages of both organic and inorganic fertilizers1.3 Objectives of the study The objectives of this study is to determine the effect of different combination of NPK fertilizer and organic manure on the growth and yield on okraSelect the best combination that give the best yield

Background of Study

Okra [Abelmoschus esculentus (L.) Moench] is a vegetable crop grown both in tropical and subtropical regions of the world (Ahmed et al., 2006). Okra is known by many local names in different parts of the world. It is called lady’s finger in England, gumbo in the United States of America, guino-gombo in Spanish, guibeiro in Portuguese and bhindi in India, Ila by the Yoruba’s of Nigeria, in the Middle East it is known as bamia, bamya or bamieh. It is an erect herbaceous annual crop species that belongs to the family Malvaceae and is principally used in the preparation of soup in Nigeria (Tindall, 1986). According to Awodoyin and Olubode (2009), the immature fruits and leaves of Abelmoschus esculentus are used in soup as a thickener because it is a rich source of vitamins and minerals. Okra is recommended for consumption by World Health Organization due to its ability to fight diseases. Okra has been found to be a rich source of vitamins A and C, calcium, thiamine and riboflavin. It is also rich in iron and is used as a medicine in the treatment of the peptic ulcer (Uka et al., 2013).

Soil productivity maintenance is a major constraint of tropical agriculture. Crop cultivation is usually moved between fields to utilize only fertile soils for some years without use of fertilizers. However, this cannot be sustained to meet increased demand of an increasing population. The Economic Commission for Africa (2001) reported that tropical soils are adversely affected by suboptimal soil fertility and erosion, causing a deterioration of the nutrient status and changes in soil organism populations. Akanbi et al. (2010) asserted that inorganic fertilizers can improve crop yields and soil pH, total nutrient content, and nutrient availability, but their use is limited due to scarcity, high cost, nutrient imbalance and soil acidity. Hence the need to look for alternative ways of improving this crop plant. Use of organic manures as a means of maintaining and increasing soil fertility has been advocated (Rodale, 1984; Alasiri and Ogunkeye, 1999; Smil, 2000). Animal manures, when efficiently and effectively used, ensure sustainable crop productivity by immobilizing nutrients that are susceptible to leaching. Nutrients contained in manures are released more slowly and are stored for a longer time in the soil ensuring longer residual effects, improved root development and higher crop yields (Sharma and Mittra, 1991; Abou El Magd et al., 2005). Manures are usually applied at higher rates, relative to inorganic fertilizers. When applied at high rates, they give residual effects on the growth and yield of succeeding crops (Makinde and Ayoola, 2008) Improvements of environmental conditions as well as the need to reduce cost of fertilizing crops are reasons for advocating use of organic materials (Bayu et al.,2006). Organic manures improve soil fertility by activating soil microbial biomass (Ayuso et al., 1996). Application of manures sustains cropping system through better nutrient recycling (ElShakweer et al., 1998). Manures provide a source of all necessary macro- and micro-nutrients in available forms, thereby improving the physical and biological properties of the soil (Abou El-Magd et al., 2006). Mixing organic and inorganic fertilizers may be a sound soil fertility management strategy in many countries. Apart from enhancing crop yields, the practice has a greater beneficial residual effect that can be derived from use of either organic or inorganic fertilizers applied alone. Makinde et al. (2001) reported that maize (Zea mays L.) yields obtained from application of a combination of synthetic fertilizer and 0manure improved yield over that from manure alone. Akande et al. (2003) reported that combined use of ground rock phosphate applied together with poultry manure significantly improved growth and yield of Okra (Abelmoschus esculentus L. Moench) compared to application of each material separately. Akanbi et al. (2005) reported that the combined application of 4 Mt·ha-1of maize straw compost and N mineral fertilizer at 30 kg·ha-1 improved plant growth and gave higher tomato (Lycopersicum esculentum L.) yields than other combinations. Okwuagwu et al. (2003) combined NPK and cattle manure at 125 kgha-1 and 1.5tha-1 respectively in soil amendment for the growth of okra and reported of increases in the growth and yield parameters of the crop.

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