THE
USE OF ASH AS FERTILIZER
The use of ash as a fertilizer for
the agricultural production could return a considerable amount of nutrients
removed in wood. Harvest back to the natural cycle. Furthermore, oxides of
alkaline and earth alkaline cations formed in the burning process exert a
liming effect and counteract soil acidification. However, heavy metals acumulated in the ash especially cadmium (Cd),
have caused concern for environmental risks. Cadmium concentrations in ash
typically vary between 1 and 20 ug g-1 ash (Korpilaht, et al., 1998) and often exceed the level
allowed for fertilizers used in agriculture (Evald) 1998.
The environmental
risks caused by the ash do not only depend on the total concentration of
cadmium but also on its dissolution rate. When dissolved to soil solution
cadmium is easily taken up by plants and enriched especially in protein
compounds where it replace, Zinc. At high concentrations it also may disturb
micro-biological processe and thus, affect the nutrients cycling. Many of the
cadmium compounds are relatively mobile in the soil and readily taken up by
plant (Kabata-Pendias and Pendias, 1984;, Lund Borg, 1998; Stevenson and Cole,
1999). The most important soil factors governing the uptake are pH and the
amount of organic matter (Christensen; 1989; Odenius and Autio 1989). Also
microbial processes should be considered if cadmium containing ash is used as a
forest fertilizer (Fritze et al.,
2000).
Metal concentrations in ash
depending on the burning and granulation processes as well as on the particles
size fraction (Obernberger et al.,1997;
Dahl and Obernberger, 1998). The solubility of cadmium in the ash is dependent
on its chemical form, but the dominating form in the different kinds of ashes
have not been completely identified (Nordin and Ackman, 1998). Therefore, the
risk assessment cannot be based merely on the total cadmium concentration, but
more detailed information on reaction patterns cadmium denved from various ash
types in various soil types is needed.
Physical Characteristics of Soil Amended With Ash
According to Mbah et
al., (2009) reported that effect of ash on soil physical properties which
greatly improved soil structure by making finer particle and improve soil
colour, soil porosity and bulk density.
CHEMICAL
CHARACTERISTICS OF SOIL AMENDED WITH ASH
The chemical properties of the soil
amended with ash significantly increased soil organic matter, N,P,K, Ca, Mg, Fe
and Zn. Also ash had high content of alkaline properties with pH of 12.7 and
15.6Cmol kg-1 of Ca.
Exchangeable potassium (K) increased
significantly (P<0.05) in the ash amended plots relative to the control
plot. Since ashes are known to be of high potash content, the above
observations are under-stable. This is in line with some previously reported
observations that crop residue ash contained N,P,K Ca and Mg Odedina et al (2003), reported that ash
contained as high as 12.36% K in its nutrient composition with Ca and Mg values
of 3.40% and 0.76% respectively and this also agrees with Ogbodo (2009) that
plot treated with crop residue. Ash contains significantly higher levels of
exchangeable K, Ca, Mg, than other crop residue Ash specifically had liming
effect on the soil owing to its higher Ca and Mg content. Moreover, the result
underline the importance of ash in coping with high level of K leaching in this
sub-humid tropical environment. The rise was essentially due to the production
of K oxides hydroxides and carbonates, which did not persist through the next
season.
The ash-amendments significantly
increased Mg2+ over the control in spite of Mg2+ (3.5
cmol kg-1) in the soil. It agrees also with Sobulo and Osiname(1989), who
reported that low N. mighty be as a result of early mineralization of
Nutrients especially N for maize uptake.
This also agrees with Sarmalm et al.
(2001) and Arvidsson and Lundkrist (2003) who observed an increase in
ash-amended soils of almost all the soil nutrients except Nitrogen.
Effect
of the soil amended with Ash on maize grain yield
The effect of the different ash sources on the shelled
maize yield the result shows higher in grain in ash amended plot compared to
the control plot irrespective of the sources of ash. The amended plot yielded
higher than the non-amended plots. The result is in line the findings of Odiete
et al., (2008). That the application
of ash to maize. Significantly increased
the grain yield.
Lime is a common amendment agent
that is routinely applied to agricultural soils. The importance of lime or its
effects exceeds improving fertility and increased plants nutrients but also boasters of
good soil physical properties Pearzon (1975) discovered that on highly
weathered acid soils of the tropics, lime rate are often based on
neutralization of exchangeable of cations and this result in rise in soil pH
values. in the range of 5-3-5-6. (Haynes 1984) disclosed that crop yield
depression induced by lime usually involves the deficiencies of Mg, Sl, Cu, Zn,
P.k. The flocculation phenomena are important condition that determine the
effect of lime on soil physical proprieties (Summer, 1992) apart from ash which
we have proven to be an effective liming agent there are others such as Gypsum
which is a good option to raise calcium levels and greatly improve soil
structure Vizcaayno (2001) told how gypsum has a liming influence on acid soil
including its ability to improve drainage and aeration.
Dolomite is an important and effective liming
agent in agricultural production.
EFFECT OF ASH APPLICATION ON SOIL
When ash is applied to the soil and
a resultant pH increase occur there is an evident shift in the microbial
population from fungi to actinomycetes and to bacteria. Badagnicco et al., (1992) explained that liming
increases microbial biomass content, soil respiration rate the microbial
metabic respiration per unit biomass) soil enzyme activity dehydrogenate,
sulphastes and protease activity and net mineralization of soil organic N and
S.
Burns and Davies (1986) discussed
how liming could well have indirect effects on soil physical properties via its
ability to increase crop growth, soil organic matter content and thus soil
biological activities and such effects are usually seen as a major cause of
improvement in soil tith. The main reason for liming acid soils is to improve
crop growth and yield. The positive effect usually occur via amelioration of Al
and sometimes Mn toxicity and or alleviation of Ca deficiency. Cheshire (1990)
said that as a result of deposition of Ca large active microbial biomass
develops in rhizosphere. As we earlier noted. The microbial biomass produces
polysaccharides bindings agents and in addition root hairs and vesicular
arbuscular microrhizae (VAM) has a enmeshing effect forming a three dimensional
network which helps hold soil particles together to form stable aggregates.
Hayce and Swift 1990 discussed how
these complex poly-metric molecules are central to the formation of stable soil
aggregate, and are synthesized by the decomposer microform during the
decomposing process. Thus, the long term effect of liming may well be to
increase soil organic matter content by increasing root and crop growth and
thus, input or organic residue to soil and as a result soil physical condition
particularly soil aggregation and aggregate stability are likely to improve.
ENHANCED SOIL MICROBIAL ACTIVITY
In as much as ash influences
microbial activity. Liming can also increase the size and activity of earthworm
population. Springtt and Syers. (1984)
found out that most earthworms in temperate agricultural soils prefer a pH of
around 7 although the sensitivity of individual species vary (eg Apporectodea
caliginosa). This pH (Stockdill and Cossens, 1966) showed that liming
increases earthworm number and this is primarily a response to increase in pH
rather than added Ca. Dockson and Van Wingerden (1964) reported that at a low
or reduced pH value, earthworm would not only be reduced number but can go into
dispenses more rapidly upon the onset of dry condition. An increased earthworm
highest large amount of soil and organic debris mix them together and their
cast may form the base for several stable aggregates particularly in pasture
soils. The borrowing action of earthworm helps to increase the soil macro
porosity.
SOURCES
OF ASH
Wood ash is the residue powder left
after the combustion of wood material and it has been found to be effective liming
material due to the high cost of lime. It also has the potentials of supplying plant nutrient like N, P, K Ca, and Mg,
Wood ash contains calcium carbonate as its major
component, representing 25 or even 45 percent less than 10 percent as potash,
and less than 1 percent phosphate. There are trace elements of iron, manganese,
zinc, copper and some heavy metals. However these numbers vary as combustion
temperature is an important variable in determining wood ash composition.
For a long time wood ash has been used in agricultural
soil application as it recycle. Nutrients back to the soil. Wood ash has some
value as a fertilizer. But does not contain nitrogen because of presence of
calcium carbonate. It acts as a liming agent and will deacidity the soil
increasing pH Potassium hydroxide can be made from wood ash.
Rice Husk ash is the powder that remain after rice husk
has burial. This burnt rice husk contain valvable organic and in organic
nutrients which have the potentials to improve the soil physical properties. Burnt
rice husk ash contains about 0.45% N, 0.2% P and 0.4%K which is similar to
0.50, 0.25 and 0.50% N. P. K (Yarikar and Yayock 1987)
EFFECT
OF RICE HUSK ASH ON CHEMICAL PROPERTIES
Prior
to the wood ash and burnt rice husk as cereals provide the basic for management
of soil fertility. Burnt rice husk on the other side, have been regarded as a
primary source of nutrient since the earliest of civilization. With the
continuous application of this burnt rice husk, some properties of the soil are
constantly affected.