POTENTIAL AND PROSPECTS OF BIOFERTILIZER

POTENTIAL AND PROSPECTS OF BIOFERTILIZER USAGE AS
ALTERNATIVE TO CHEMICAL FERTILIZER IN NIGERIA.

*Salihu Shina
S.Shina@ncribadeggi.org.ng
*National Cereals Research Institute, Moor Plantation, Ibadan, Nigeria.

ABSTRACTS
Farmers in Nigeria use more chemical fertilizers than the recommended levels for
many crops. Excessive use of chemical nitrogen fertilizer not only accelerates soil
acidification but also risks contaminating groundwater and the atmosphere and to achieve
food security through sustainable agriculture, the requirement for fixed nitrogen must be
increasingly met by BNF rather than by industrial nitrogen fixation. Biofertilizer are cost
effective, eco-friendly and renewable source of land nutrient. They play a vital role in
maintaining a long term soil fertility and sustainability. Biofertilisers enhance the nutrient
availability to crop plants (by processes like fixing atmosphere N or dissolving P present in
the soil); and also impart better health to plants and soil thereby enhancing crop yields in a
moderate way. It is a natural method without any problems like salinity and alkalinity; soil
erosion etc. this paper tries to review the potentials and prospects of biofertilizer usage in
the country, the challenges that are encountering in the process and the overall gains for
both farmers and the government.

Keywords: Nigeria, biofertilizer, chemical fertilizer, soil fertility and BNF.

INTRODUCTION

With the introduction of green revolution technologies, modern agriculture is
getting more and more dependent upon the steady supply of synthetics inputs (mainly
fertilizers).However adverse effects are been noticed due to the excessive and imbalanced
use of these synthetics inputs. The ill-effects being displayed gradually include leaching out,
polluting water basin which results in high fish mortality rates and severely reducing the
water quality, destroying microorganism and friendly insects, making crop more susceptible
to the attack of diseases.The aforementioned effects of chemical fertilizers have brought
about the need for alternatives such as biofertilizers; Biofertilizers is defined as a large
population of specific or group of beneficial microorganisms for enhancing the productivity
of the soil either by fixing atmospheric nitrogen or by solubilizing soil phosphorus or by
stimulating plant growth through the synthesis of growth promoting substances Rajan
(2002).Biofertilizers help to correct the ill-effects of chemical fertilizers since they do not
contain traces of hazardous and poisonous materials. Also they are cost effective, ecofriendly (as it will not pollute the environment) and convenient to use safely. The advantage
of biofertilizers over chemical fertilizers is enormous; they provides certain growth antifungal promoting substances like hormones, vitamins, amino acid e.t.c while crops have to
be provided with chemical fertilizers repeatedly to replenish the loss of nutrient utilized for
crop growth, biofertilizers supply the nutrients continuously throughout the entire period of

crop growth in the field under favourable conditions. The continuous use of chemical
fertilizer adversely affects the soil structure whereas biofertilizers when applied to soil
improve the soil structure and quality of crop products, increase in crop yield by 20 - 30%,
replacement of chemical nitrogen and phosphorus by 25%, also chemical fertilizers are
toxic at higher dose while biofertilizers have no toxic effects (Gyaneshwar et al., 2002).The
soil microorganisms used in production of biofertilizers are phosphate solubilizing bacteria
like B. magaterium, Pseudomonas striata, the nitrogen fixers like Azospirillum,
Azotobacter, BGA, and Rhizobium, and phosphate mobilizing Mycorrhiza have been widely
accepted as bio-fertilizers. (Rodriguenz et al., 1999).
Need For Biofertilizers.
Indiscriminate use of synthetic fertilizers has led to the pollution and
contamination of the soil, polluting water basins, destroying micro-organisms and friendly
insects, making the crop more prone to diseases and reduced soil fertility. And the high cost
of chemical fertilizers which is becoming unaffordable by small and marginal farmers, and
the huge amount of foreign exchange invested in the importation of synthetic fertilizers can
be drastically reduced by using the biofertilizers instead. Besides above facts, the long term
use of bio-fertilizers is economical, eco-friendly, more efficient, productive and accessible

to marginal and small farmers over chemical fertilizers (FEPSAN, 2011) .Also an earlier
work carried out by Chima et al (2013) on organic waste and biogas production, they

conclude that Nigeria will be able to generate about 88.19 million tons of dry biofertilizer
from biogas technology per annum. This is about 13 times the tonnage of synthetic fertilizer
consumed in Nigeria between 2001 and 2010, for which the Federal Government of Nigeria
spent N 64.5 billion ($ 410, 828, 025.48) on fertilizer subsidy. This potential amount of dry
biofertilizer obtainable is valued at N 3.53 trillion ($ 22.77 billion) per annum.
The Roles of Biofertilizers in Crop Production
Soil microorganisms play significant roles in regulating the dynamics of organic
matter decomposition and the availability of plant nutrients such as N, P and S (Silva et al.,
2001). It is well recognized that microbial Inoculants constitute an important component of
integrated nutrient management that leads to sustainable agriculture. In addition, microbial
inoculants can be used as an economic input to increase crop productivity. A healthy plant
usually has a healthy rhizosphere which would be dominated by beneficial microbes.
Conversely, in unhealthy soil, dominated by pathogenic microbes, optimum plant growth
would not be possible (Young et al., 2003). The following are microorganisms used as
biofertilizers and their functions.
a.

Rhizobia:

Rhizobia are symbiotic bacteria that fix atmospheric N2 gas in

plant root nodules and have a mutually helpful relationship with their host plants. The plant
roots supply essential minerals and newly synthesized substances to the bacteria. It is
reported that Rhizobium can fix 50 – 300kg N/ha. (Ratti et al., 2002).
b. Azotobacters and Azospirillum: These are free living bacteria that fix
atmospheric nitrogen in cereal crops without any symbiosis and they do not need a specific
host plant. Azotobacters are abundant in well drained, neutral soil, produce anti-fungal
compounds, increase germination and vigor in young plants. They can fix 15 – 20kg/ha N
per year (Kundu et al., 2002).
c. Phosphate Solubilizing Bacteria(PSB): Under acidic or calcareous soil
conditions, large amount of phosphorus are fixed in the soil but are unavailable to the
plants. Phosphobacterins, mainly bacteria and fungi, can make insoluble phosphorus
available to the plant. The solubilization effects of phosphobacterins is generally due to the
production of organic acids that lower the soil PH and bring about dissolution bound of
forms of phosphate. It is reported that PSB culture increased yield of cereals up to 200 –
500 kg/ha and thus 30 –50kg of superphosphates can be saved (Kunda et al., 2005).
d. Vesicular Arbuscular Mycorrhiza (VAM)
Mycorrhizae are mutually beneficial (symbiotic) relationships between fungi and
plant roots; VAM fungi infect and spread inside the root. Fungi aid in transmitting nutrients

and water to the plant roots. They increase seedling tolerance to drought and high
temperatures.
e. Plant Growth Promoting Rhizobacteria (PGPR)
PGPR represent a wide variety of soil bacteria which when grown in association
with a host plant, result in stimulation of host growth. PGPR help in fixing N 2 and
increasing the availability of nutrients in the rhizosphere. They influence root growth and
morphology and promote other beneficial plant – microbe symbioses (Ratti et al., 2001).
f.

Blue Green Algae (Cyanobacteria) and Azolla: These belongs to eight

different families, phototrophic in nature and produce Auxin, Indole acetic acid and
Gibberllic acid, fix 20-30 kg N/ha in submerged rice fields as they are abundant in paddy, so
also referred as ”paddy organisms”. N is the key input required in large quantities for low
land rice production. Soil N and BNF by associated organisms are major sources of N for
low land rice. (Wani et al., 1995)

Inoculation of Biofertilizers
Application of the microbial biofertilizer is an important step in the Biofertilizer
technology. If the microbial inoculants are not applied properly, the benefits from the

biofertilizer may not be obtained. During application one should always remember that the
most of the microbial biofertilizers are heterotropic, i.e. they cannot prepare their won food
and depend upon the organic Carbon of soil for their energy requirement and growth. So,
they either colonize in rhizosphere zone or live symbiotically within the root of higher
plants. The bacteria which colonized the rhizosphere zone obtain their organic carbon
compounds from the root exudes of the higher plants. The symbiotic ones obtain organic
carbon directly from the root. So, microbial inoculants must be applied in such a way that
the bacteria will be adhered with the root surface.

Biofertilizers are generally applied to

soil, seeds or seedling, with or without some carrier for the microorganisms, for example
peat, compost or stickers. Regardless of methods, the number of cells reaching the soil from
commercial products is similar to the existing numbers of soil or rhizosphere
microorganisms (Sujatha et al., 2004). These added cells are unlikely to have a beneficial
impact on the plant unless multiplication occurs. In addition, the population of introduced
microorganisms will decline and be eliminated in a very short time, often days or weeks.
The formulation of inocula, method of application and storage of the products are all critical
to the success of a biological product. Short shelf life, lack of suitable carrier materials,
susceptibility to high temperature, problems in transportation and storage are biofertilizer

bottlenecks that still need to be solved in order to obtain effective inoculation. (Abdul
Halim., 2009). On the basis of the above principal, the following inoculation methods have
been developed:
Seed Inoculation
Seed inoculation uses a specific strain of microbe that can grow in association
with plant roots. Soil conditions have to be favorable for the inoculants to perform well.
Selected strains of N-fixing Rhizobium bacteria have proven to be effective as seed
inoculants for legumes (Gyaneshwar et al., 2002).Seed treatment can be done with any of
two or more bacteria without antagonistic effect. In the case of seed treatment with
Rhizobium, Azotobacter, Azospirillum along with PSB, first the seeds must be coated with
Rhizobium or Azotobacter or Azospirillum. When each seed has a layer of the
aforementioned bacteria then the PSB inoculants has to be treated on the outer layer of the
seeds. This method will provide maximum numbers of population of each bacterium to
generate better results (Antoun et al., 2001).
Soil Inoculation
In soil inoculation, microbes are added directly to the soil where they have to
compete with microbes already living in the soil that are already adapted to local conditions
and greatly outnumber the inocula. Inoculants of mixed cultures of beneficial
microorganisms have considerable potential for controlling the soil microbiological

equilibrium and providing a more favorable environment for plant growth and protection.
(Ratti et al., 2001).
CROP RESPONSES TO BIOFERTILIZER INOCULATION
Tambekar et al., (2009) studied the promoting of plant growth by inoculation
with aggregated and single cell suspensions of A. brasilense. They reported that inoculation
of single cell suspensions of Azospirillum (prepared with fructose) significantly increased
the root surface area, root and foliage dry weight of the maize seedling as compared to
plants inoculated with malate grown Azospirillum or the controls. Crops inoculated with
Azotobacter and Azospirilla reviewed by Wani (1990) indicated that Pearl millet and
Sorghum, which are grown as dry land crops showed 11-12% increased yields due to
inoculations. Beans with R. leguminosarum and P. putida increased the number of nodules
and acetylene reduction activity (ARA) significantly (de Freitas et al., 1993). Also the
findings of Shina et al., (2014) shows that many strains of bacteria native to the soil of
(university of Ilorin) have the ability to solubilize phosphorus. However, the degree of
solubilization varies from strain to strain. The use of these bacteria as seed inoculants may

result in significant improved seed germination, seedling growth and generally increased
productivity. A significant positive effect on grain yield and ARA in roots of barley was
obtained due to combined inoculation of nitrogen fixer’s

A. lipoferum, Arthrobacter

mysorens and the phosphate solubilizing strain Agrobacterium radiobacter by Belimov et
al. (1995). Radhakrishnan (1996) reported that inoculation of Azospirillum and phosphobacteria resulted in higher root biomass and more bolls in cotton. Findings of Mohammadi
(2010) showed that inoculation of biofertilizers (PSB+ Trichoderma fungi) + application of
FYM had a great influence on canola growth, height and grain yield in compared to control
treatment. Findings of Mohammadi et al. (2011) showed that application of biofertilizers
had a significant effects on nutrient uptake of chickpea combined application of Phosphate
solubilizing bacteria and Trichoderma harzianum produced the highest leaf P content and
grain P content. These findings also showed that chickpea inoculated with biofertilizers
have significantly higher grain protein content.
FUTURE PERSPECTIVE OF BIO-FERTILIZERS IN NIGERIA.
Excess nutrients are accumulated in soils, particularly P as a result of over
application of chemical fertilizers by farmers during intensive agricultural practices. Hence,
major research focus should be on the production of efficient and sustainable bio-fertilizers
for crop plants, wherein inorganic fertilizer application can be reduced significantly to avoid
further pollution problems. In view of overcoming this bottleneck, it will be necessary to
undertake short-term, medium, and long-term research, in which soil microbiologists,
agronomists, plant breeders, plant pathologists, and even nutritionists and economists must
work together. The most important and specific research needs should highlight on

following points:
1. Selection of effective and competitive multi-functional bio-fertilizers for a
variety of crops.
2. Quality control system for the production of inoculants and their application in
the field.
3. Study of microbial persistence of biofertilizers in soil under stressful
environments conditions.
5. Transferring technological know-how on biofertilizer production to the
industrial level for optimum formulation.
6. Establishment of "Bio-fertilizer Act" and strict regulation for quality control in
markets and application.

CONCLUSION
Bio-fertilizers being essential components of organic farming play vital role in
maintaining long term soil fertility and sustainability by fixing atmospheric nitrogen,
mobilizing fixed macro and micro nutrients or convert insoluble P in the soil into forms
available to plants, there by increases their efficiency and availability. Currently in the
country, there is a gap of ten million tones of plant nutrients between removal of crops and
supply through chemical fertilizers. In context of both the cost and environmental impact of
chemical fertilizers, excessive reliance on the chemical fertilizers is not viable strategy in

long run because of the cost, both in domestic resources and foreign exchange, involved in
setting up of fertilizer plants and sustaining the production. In this context, organic manures
(bio-fertilizers) would be the viable option for farmers to increase productivity per unit area;
thus creating an employment opportunity for the teeming youth population. The
environmental and health benefits cannot be

overemphasizes as biofertilizers are known

to be non toxic at any dose. Also the use of biofertilizer will help to conserve the soil and
animal life (both flora and fauna) since they stabilize and feed soil and providing nutrients
for a very long time thereby preventing soil erosion and conserving ground water.
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