ABSTRACT
Evaluation
of the effect or organo-mineral on soil microbial population, carbon to
Nitrogen (C:N) ratio, growth and yield of cocoyam (Colocasia esculenta) (L.)
Schott, was conducted at the Research and Teaching Farm of Federal College of
Agriculture, Ishiagu Ebonyi State in 2017, cropping season. Ten treatments which include poultry dropping
10t/ha (T1), swine dung 10t/ha (T2), Neem leaves
10t/ha (T3), Rice husk dust 10t/ha (T4), poultry dropping 5t/ha swine dung
5t/ha (T5), Neem leaf 5t/ha Rice husk dust 5t/ha (T6), Swine dung 5t/ha + neem
leaf 5t/ha (T7), Rice husk dust 5t/ha + poultry dropping 5t/ha (T8), Swine dung
3.33 t/ha + neem leaf 3.33t/ha + poultry dropping 3.33t/ha (T9) and control,
untreated 0t/ha (T10) were fitted into a randomized design (RCBD) with three
replications. Soil samples were
collected before planting and at post harvest and were used for soil microbial
population and carbon to Nitrogen (C:N) ratio.
Data were collected for plant growth and yield parameters. These include height (cm) per plant, number
of leaves per plant, stem girth (cm) per plant, leaf area (cm2) per
plant, leaf area index per plant, number of corms and cormels per plot, weight
(t/ha) of corms and cormels. Data
collected were subjected to statistical analysis. The results indicated a significant
difference (P<0.05) among the treatments on microbial population, plant
height, number of leaves, stem girth, leaf area, leaf area index, number of
corms and cormels, weight (t/ha) of corms and cormels. Results showed that swine dung 10t/ha significantly
(P<0.05) had the highest bacteria population (8.8 x 104 cfu/g
soil). Results revealed that Rice husk
dust 5t/ha + poultry dropping 5t/ha significantly (P<0.05) produced the
highest number of leaves of cocoyam per plant.
Results indicated that swine dung 10t/ha and swine dung 5t/ha + Neem
leaf 5t/ha significantly (P<0.05) produced the highest leaf area and leaf
index per plant followed by neem least 10t/ha and neem leaf 5t/ha + Rice husk
dust 5t/ha. Results showed that Rice
husk dust 10t/ha significantly (P<0.05) produced the highest weight of corms
(9.0t/ha), cormels (19.2t/ha) and corms + cormels (28.2t/ha), followed by SD
3.33t/ha + NL 3.33t/ha + PD 3.33t/ha (23.4t/ha).
CHAPTER
ONE
1.0
INTRODUCTION
1.1 Background Of The Study
Cocoyam (Colocasia esculenta (1) schott) a member of the Areaceae farming is
subsistence and emergency food in many parts of the word, but major staple food
crop in Nigeria. South pacific Island and some parts of Asia (IFA 1992). The
corms and cormels are eaten in the same way as yam (Discorea spp) and sweet potato
(Ipomoeabatatas). Boiled,
fried, baked and roasted (Uwah et al
2011). Cocoyams are the cheapest and most handy carbohydrate source of meals
for diabeties, convalescents and most gastro – intestinal disorder patients and
a good carbohydrate base for infant foods on account of their small sized
starin grains which are easily digested compared to those of yam, cassava (Manihot spp) or sweet potato (SOM,
2007). The young leaves and petioles which contains more protein than corms in
addition to vitamin A and C and minerals are used as human food, while the
corms, cormels and leaves after curing can also be used as animal feed (Onwueme
and sinha 1991).
Manure sources are associated with
problem relating to unavailability, low quality depending on the type of
cocoyam, transportation and handling problems, high C.N ratio heavy metal
pollution and low nutrient release (Ayenils et
al 2010). The single use of either organic or inorganic fertilizer in
recent years has not really met the expected impact in boasting crop yield with
the geometric demand. This was the reason why integrated nutrient supply has
been advocated by the food and Agricultural organization of the united nation
(Olowokerefa et al., 2004).
In view of this, the combined use of
chemical fertilizers and organic manures (Organo-mineral fertilizer) has been
suggested (Egbuchua and Enujeke, 2013). Organo-mineral fertilizer combine the
good attributes of inorganic and organic nutrients to enhance crop yield. Current
studies on organo-mineral fertilizer have shown better yield performances than
the single use of them and have proved to be a sound soil fertility management
strategy in many countries of the world (Olatunji and Ayuba, 2011; and Ojeniyi et al., 2009).
Complementary use of organic manure and
mineral fertilizers which has proved to be a sound soil fertility management
strategy in many countries of the world is advocated.(Diaconom et al., 2010). Apart from enhancing
crop yield, the practice has a greater beneficial residual effect than can be
derived from the use of either inorganic fertilizer or organic manure when
applied alone (Ishiwater et al., 1987).
Nutrient use efficiency has also been reported to increase through the
combination of poultry manure and mineral fertilizer (Murwira and Kiramom 1993,
Ayoola and Adveniyan 2000). Cocoyam being a root crop has a high requirement
for potassium as yam and cassava (Dineshr et
al., 2010). The potassium content of poultry manure is usually very high
depending on the animal type, feed ration, storage and handling practice which
makes it very suitable for root crops. Surveys in Nigeria and elsewhere
revealed in consistencies in the amount of potassium for optimum performance of
cocoyam due mainly to differences in soil types and soil potassium status.
Soil microbial and biochemical
parameters can react rapidly to changes in soil management (Gil-sotres et al, 2005). Organic fertilizers
typically increase soil micro-biomas through the supply of carbon rich organic
compounds to the generally carbon limited microbial communities in arable soil
(Diacono and Monttemurro 2010 and Knap 2010). Incorporation of organic
fertilizers can also increase microbial activity in soils between 16% and 20%
as compared to inorganic fertilizers (Dinesh 2010 and Gonzalez et all.,).
Consequently, organic fertilizers can stimulate soil microbial processes and
increase crop yield as organic matter and soil fertility after long-term
repeated application of organic
fertilizers (Herenciaet al., 2008:
diacono and Montemurro, 2010). Soil microorganisms are critical factors that
determine soil organic matter decomposition, nutrient cycling, soil degradation
and bioremediation of soil pollution (Larkin, 2003 and Li, 2012). Repeated
fertilizer applications change the soil microbial community directly or
indirectly since they change the soil physical, chemical and biological
properties (Beauregard et al., 2010).
Some studies have documented that
fertilization has brought significant impacts on the population, composition
and function of soil microorganisms and that organic and inorganic fertilizer
amendments have increased the soil microorganism’s activity (Ge, 2008 and
Mandal, 2007). However, other studies have demonstrated that inorganic and
organic fertilizers have had reduced input of readily available plant nutrients
and the absence of rapid and short-term beneficial effects on microbial and
biochemical properties (Parthasarathi, 2006).
In addition to their role in cementing
soil aggregates, soil microbes are of paramount importance in cycling nutrients
such as carbon, nitrogen, phosphorus, and sulfur. They control the forms of
these elements and can regulate the quantities of nitrogen (W) available to
plants. It is only through the actions of soil microbes that the nutrients in
organic fertilizers are liberated for plants and used by other microbes
(mineralization). It is through the process of mineralization that crop
residues, grass clippings, leaves, organic wastes among others are decomposed
and converted to forms useable for plant growth as well as converted to stable
soil organic matter celled humus (Arancon, 2005).
Another benefit of soil microbes is
their ability to degrade pest control chemicals and other hazardous materials
reaching the soil. (Abbas, et al., 2014).
Research has shown that C:N ratios and
soil cover management choices must strike a balance between crop residues
covering the soil and nutrient cycling. According to Howell, (2005) material
added to the soil with a C:N material added to soil with a temporary nitrogen
deficit (immobilization) while a C:N ratio less than 24:1 will result in a
temporary nitrogen surplus (mineralization).it is important to pay attention to
crop reside C:N ratios in order to maintain soil cover when desired, yet allow
the cover to ultimately brake down and recycled. By adding a relatively high
C:N ratio to the crop through crop rotation, nitrogen are not available to soil
microorganisms while a low C:N ratio will be available to the soil organism,
thus allowing them brake down more quickly especially in some crops like wheat
straw (Wortman et al., 2006).Managing residues so they cover the soil when a
growing crop is not providing soil protection requires some planning and
experimentation to achieve a proper balance (Wortman et al., 2006). If crops with high C:N ratios are grown too
frequently in the rotation, residues will accumulate on the soil surface, and
nitrogen for crop growth may be scarce unless supplemented with other sources
of nitrogen (Muller, 2000).
A carbon-to-nitrogen ratio (C/N ratio)
is a ration of the carbon to the nitrogen in a substance. It can, amongst other
things, be used in analyzing sediments and compost. Carbon-to-nitrogen ratios
are an indicator for nitrogen limitation of plants and other organisms and can
identify whether molecules found in the sediment under study come from
land-based or algal plants. Further, they can distinguish between different
land-based plants, depending on the type of photosynthesis they undergo.
Therefore, the C/N ratio serves as a tool for understanding the source of
sedimentary organic matter which can lead to information about the ecology,
climate, and ocean circulation at different times in Earth’s history. C/N
ratios in the range 4-10:1 are usually from marine source, whereas higher
ratios are likely to come from a terrestrial source. Vascular plants from
terrestrial sources tend to have C/N ratios greater than 20. When composting, microbial
activity utilizes a C/N ratio of 30-35:1 and a higher ratio will result in
lower composting rates. However, this assumes that carbon is completely
consumed, which is often not the case. Thus, for practical agricultural
purposes, a compost should have an initial C/N ratio of 20-30:1. ( Gray and
Biddlestone 1973, Steward 2006).
1.2 Objective Of The Study
1.2.1 Broad/General Objective`
The general objective of the study is to
investigate the effect of organo- minerals on soil microbial populations, carbon
to nitrogen ratio, growth and yield of cocoyam (Colocasia esculenta).
1.2.2 Specific Objectives
The specific objectives include:
1.
To evaluate the effect of
organo-minerals on soil microbial populations.
2.
To determine the effect of organo–minerals
on carbon to nitrogen (C:N) ratio
3.
To evaluate the effect of
organo-minerals on growth and yield of cocoyam.
1.3
Statement Of Problem
Organic matter in tropical zone has been
discovered to be rapidly. The constant loss of organic matters in the tropical
zone has been attributed to high rainfall, high rate of mineralization (because
of high microbial activity, bush burning and high carbon losses accompanying
tillage operation.
The rapid depletion of plant nutrients,
low organic matter content and poor physical condition to the soil constitute
strong limitation to crop production in the area regarded as major food belt of
the Southeastern region. However attempt to restore the lost nutrient with the
use of organic fertilizer by rural farmers due to the above factors in some
soil of the area have lead to population and acidification of the soil. Organic
matter have been form to improve the physical properties of the soil to
maintain better tilth and increase water holding (Ogwu Sche et al, 2000).currently the currently the
combination of different organic matter constituent has been found to improve
the productivity of tropical soil more than ordinary use of farm manure (Agbola
and Obigbesan, 1999).
Ogwusche et al, (2000), stated that an insitu incorporation of green manure
along with organic mineral has been recommended and has also increase up to 86%
of top yield. They also indicated that farm yard manure has positive response
on yield parameter of cocoyam which might be due higher retention and availability
of all the essential nutrient as well as improvement in the soil physical
properties (Ogwusche et al, 2000).
1.4
Justification Of The Study
cocoyam (Colocasia esculenta (L)
Schott) is one of the subsistence and emergency food crop in the world, it
is a major staple food crop in Nigeria and considering the high level of
poverty and food scarcity, low level of agricultural productivity,
technological farming. It becomes necessary to source for an alternative and
food supply for an immediate wield population, therefore organic farming as a
form of agriculture that is
environmental friendly which minimized the use of inorganic fertilizer and
therefore sustainable. There is need to boost its production true the use of
organo minerals. This research will serve as a guide to a rural farmers in
Ishaigu, and Southeastern Nigeria to make a proper use of organo minerals to
boost cocoyam production for maximum food security.