CHAPTER ONE

INTRODUCTION

1.1. BACKGROUND

Geometric increase in world population, coupled with effects of global warming/climate change, have had deteriorative effects on agricultural productivity. With an estimated 815 million people undernourished in the world today (FAO, 2017), it is necessary to take fervent steps to improve agricultural productivity. Such steps could include improving seed quality, germination conditions, farming practices and soil quality.

Soil quality can be improved by the use of fertilizer, which can either be of chemical or biological sources. Chemical fertilizers have been in popular use since the 20th century, especially since their contribution to the Third Agricultural (Green) Revolution.

However, excessive and extensive use of chemical fertilizers have resulted in a large number of environmental problems (Savci, 2012); which include water, soil and air pollution. Nitrate content from chemical fertilizers can get into water bodies by drainage, leaching, and flow. This cause eutrophication, leading to algal bloom and suffocation of aquatic life. Also, chemical fertilizers contain heavy metals, such as cadmium and chromium. As such, long-term use may result to accumulation of inorganic compounds in the soil, degrading its quality. Continuous use of chemical fertilizers effects soil degradation and deterioration of soil fertility. This is as it affects soil pH, usually with negative effects on soil organisms, such as worms, soil mite.

Chemical fertilizers also contribute to air pollutions during evaporation of ammonia (NH3) from ammonia fertilizer; which may be oxidized to nitric acid, and cause acid rain. Also, emissions of nitrogen oxides (NO, N2O, NO2) contribute to global warming and climate change.

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These detriments of chemicals propagated concerns on the best approach to increase agricultural productivity, while protecting the environment.

The advent of biofertilizer has served to counter the deleterious effects of chemical fertilizers, while being more advantageous. Biofertilizer is commonly referred to as the fertilizer that contains living micro-organisms and it is expected that their activities will influence the soil ecosystem and produce supplementary substance for the plants (Parr et. al., 2002). They contain live and efficient formulates of bacteria, algae and fungi either separately or in combination that are capable of fixing atmospheric nitrogen, solubilising phosphorus, decomposing organic materials or oxidising sulphur and; on application will enhance the availability of nutrients for the benefits of the plants (Hanapi et. al., 2012). They also accelerate certain microbial processes in the soil which augment the extent of availability of nutrients in a form easily assimilated by plants.

The first generation of commercial biofertilizer – ‘Nitragin’ – was developed in 1895 by Nobbe and Hiltner, from nitrogen-fixing rhizobacteria isolated from legumes; followed by the discovery of Azotobacter, then the blue green algae and a host of other microorganisms (Ghosh, 2003; Gavrilescu & Chisti, 2005).

Based  on  formulation,  biofertilizers  can  be  either  solid  or  liquid  (Chandra  et.  al.,  2005).

1.2. STATEMENT OF PROBLEM

Among the crop nutrients, nitrogen as well as phosphorus and potassium play important roles in increasing the crop productivity (Pindi & Satyanarayana, 2012). Biofertilizers provide an effective alternative to chemical fertilizers. However, with the short shelf-life and high risk of contamination encountered with solid biofertilizers, liquid biofertilizers serve as a better option.

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