The Principal Role of Organic Fertilizer on Soil Properties and Agricultural Productivity -A Review
Sisay Assefa1* and Sisay Tadesse2
1Debre Berhan University ,College of Agriculture and Natural Resource Sciences, Ethiopia
2Aris University College of Agriculture and Environmental Sciences, Ethiopia
Submission:July 01, 2019; Published: August 09, 2019
*Corresponding author: Sisay Assefa, Debre Berhan University, College of Agriculture and Natural Resource Sciences, Ethiopia
How to cite this article: Sisay Assefa . The Principal Role of Organic Fertilizer on Soil Properties and Agricultural Productivity -A Review. Agri Res& Tech:
Open Access J. 2019; 22(2): 556192. DOI: 10.19080/ARTOAJ.2019.22.556192
As a key component of agricultural sustainability, organic fertilizer contributes greatly to improving soil fertility. Therefore, the objective of this review is to revise the role of organic fertilizer on agricultural product and productivity. The newly sourced artificial fertilizer had a short-term benefit, but it had severe long-term side effect such as soil toxicity and decline soil fertility. Afterward, the idea of organic farming was acceptable to developed organic agriculture system. The use of organic fertilizers has advantage of being cheap, improving soil structure, texture and aeration increasing the soils water retention abilities and stimulating healthy root development. Organic fertilizer has many sources such as minerals, animal source, sewage sludge and plant. Vegetables, animals and residue materials had a contribution to improve soil organic matter content in soil. Therefor it is recommended that, using integrated nutrient management is a continuous improvement of soil productivity on longer term basis through appropriate use of organic fertilizers (i.e. animal manure, plants residue and sewage sludge) and their scientific management for increments of optimum growth, yield and quality of different crops.
Among the problems inherent to tropical soils, soil acidity, characterized by low pH, excessive aluminium, deficient calcium, and low organic matter is the most serious. Tropical soils are often unproductive because some of these soils are prone to strong phosphate fixation that renders phosphorus unavailable to plant. Soils that are prone to strong phosphate fixation (adsorption to oxides and clay minerals) often require extremely high phosphate fertilization application in order to alleviate the effect of phosphate fixation. Soil acidity and mineral deficiencies can be corrected by lime and fertilizers. Unfortunately, lime and fertilizers are not always easy options available to small and resource-poor farmers. Agriculture was practiced for thousands of years without the use of artificial chemicals in the world. Artificial fertilizers were first formed during the mid-19th century. These organic fertilizers were cheap, powerful, and easy to transport in bulk. The new artificial fertilizer technology had a beneficial in the short term, had serious longer-term side effects such as soil compaction, erosion, and declines in overall soil fertility, along with health concerns about toxic chemicals entering the food supply. In the late 1800s and early 1900s, soil biologist began to seek ways to reme
dy these side effects while still maintaining higher production . Similarly, inorganic fertilizers were known for their high cost and their negative environmental effect if managed poorly . The agricultural sector in Ethiopia was the major part for sustaining the growth and reducing poverty. However, lack of adequate nutrient, the depletion of soil organic matter and soil erosion are the major obstacles to sustained agricultural production. Since 1998, Ethiopia has included conservational tillage and compost as part of its extension package to reverse land degradation . There exists ample evidence to show that compost and conservation tillage can result in higher and comparable yields, compared to chemical fertilizers . The use of organic fertilizers which emphasizes maximum reliance on renewable local or farm resource. The advantage this fertilizer was cheap, improving soil arrangement, texture and airing, increasing the soils water preservation abilities and stimulating healthy root development . In the developing world, many producers farm according to traditional methods that are comparable to organic farming, but not certified, and that may not include the latest scientific advancements in organic agriculture. In other cases, farmers in the developing world have converted to modern organic methods for economic reasons. Therefore, the
main objective of this paper is to overview the principal role of
organic fertilizer on agricultural productivity.
Organic fertilizers were defined as materials having definite
chemical composition with a high analytical value that supply
plant nutrient in available form . Organic fertilizers are fertilizers
derived from animal matter, human execrate or vegetable matter
(e.g. compost, manure). Organic fertilizers are made with natural
raw material; it usually pertains to our biodegradable wet suit.
Usually compost is made by decomposing biodegradable wastes.
These wastes include paper, leaves, fruit peelings left over foods
and even fruit juices. Organic fertilizers make a good addition to
the soil. It makes the soil reach and ideal to planting.
The main organic fertilizers were sourced from peat, animal
wastes (often from slaughterhouse), and plant wastes from agriculture
and sewage sludge. Naturally occurring organic fertilizers
include animal wastes from meat processing, peat, and slurry.
Organic fertilizers were carbon-based compounds that increase
the productivity and growth quality of plants. Organic fertilizers,
far from being purified and simplified chemicals, were complex
compounds that add numerous secondary and micro-nutrients.
Organics such as manures, powdered rocks (such as lime, rock
phosphate, and greensand), blood meal, bone meal, wood ash and
compost all contain important micronutrients, and their texture
would improve soil quality rather than degrading it. Organic farmer’s
emphasis using only organic fertilizers for fertility maintains.
In many aspects, organic farming was the way of life as it is a method
of farming. Soil nutrient depletion and likely degradation have
been considered serious threats to agricultural productivity and
have been identified as major causes of decreased crop yields and
per capita food production . The positive effects organic farming
has on the environment and quality of food, it also greatly helps
a farmer to become self-sufficient in his requirements for agro-inputs
and reduce his costs. Organic farming aspires to a combine
mixture of organic, environmental, social and ethic objectives.
Mined powdered limestone, rock phosphate and Chilean salt
peter were in organic (not of biological organs) compounds which
can be energetically intensive to harvest. mineral fertilizers containing
N, P, K and S not only increase crop yield but also improve
nutritional quality of crop yields, such as protein, oil, starch, essential
amino acids and vitamins in pulses, oil seeds, tubers, and
vegetables respectively. Animal source materials include the product
of slaughter of animal, blood meal, bone meal, hides, hoofs, and
horns were typically precursors. Chicken litters, which consists
of chicken manure mixed with sawdust, was an organic fertilizer
that has been shown to better condition soil for harvest than
synthesized fertilizers. Common form of animal manure includes
farmyard manure or farm slurry. Farmyard manure also contains
plant materials (often straw), which has been used as bedding for animal and has absorbed the faces and urine. Agricultural manure
in liquid form known as slurry is produced by more intensive livestock
rearing systems where concrete or salt are used, instead of
straw bedding. Manure from different animals had different qualities
and requires different application rates when used as fertilizer.
Sewage sludge is materials that contain human excreta, as
it is generated after mixing excreta with water and treatment of
wastewater in sewage treatment plant. Green manure are crops
grown for the express purpose of plowing them in those increasing
fertility through incorporation of nutrients and organic matter
into the soil Leguminous plant such as clover is often used for this,
as they fix nitrogen using rhizobia bacteria in specialized nodes in
the root structure. Green manure, wherever feasible, is the principal
supplementary meals of adding organic matter to the soil. It
consists in the growing of quick growing crop and ploughing it in
order to incorporate it into the soil . Decomposing crop residue
(green manure) from prior years is another source of fertility. Nitrogen
is required for the growth of vegetative parts such as the
stems and the leaves, while your plants will have healthy roots if
they get a sufficient amount of phosphorus. Phosphorus was also
required for good flowers and fruits. Potassium makes the plant
healthy by facilitating the circulation of nutrients within the plant.
Moreover, plants also require other nutrients, such as calcium and
magnesium. Since these were required, you need not add them
separately unless in exceptional cases, if the soil was totally devoid
of these minerals or the crop you wish to grow transforms organic
substrates into a stable, humus-like material . In addition to the
carbon storage benefits of adding compost to agricultural soils,
composting can lead to improved soil quality, improved productivity,
and cost savings. For example, nutrients in compost tend to
foster soil fertility .
Organic fertilizers were different from chemical fertilizers
in that the materials were a by- product of vegetables, animals
or minerals. The decomposing matter from these sources, break
down naturally and would provide nutrient and minerals to the
soil. When considering lawn maintenance, it was necessary to
make sure that the lawn or garden gets the all of nutrients that
it needed for health growth. Although nutrients were available in
regular soil, fertilizers can provide and ensure that the plant had a
balance and suitable access of nutrients, proper lawn care include
providing for the health of the lawn and garden. One of the benefits
of organic fertilizer was that the nutrients were related more
slowly than chemical fertilizers. This slower process allows the
plant to process the fertilizer in a more natural way and will not
result in over fertilizing which could damage the plant . The
soil drainage and air circulation of the soil can also be improved.
Having a compost pile was also a great way to get rid of food waste
and still contribute to your lawn care and environment. It was an
important valuable option that would help the soil and environmental
be health and produce the best plants. Synthetic fertilizers usually contain chemicals which were not easily biodegradable.
These chemicals leach into the soil and eventually find their way
into the water system where they were consumed by birds and
other wildlife. In contrast, organic fertilizer had no such harmful
compounds and therefore didn’t pose this danger, even with increased
use. In addition, when synthetic fertilizers were sprayed
on plants and lawns, they pose an immediate danger to kids and
pets that play in the garden and on the grass. Caution must be exercised
when using these toxins, and exposure must be limited.
Unlike chemical fertilizers, organic fertilizers reduce acidity in
the soil and do not cause leaching. They do not kill beneficial microorganisms
in the soil. Organic fertilizers also help improve the
structure of the soil including the circulation of air, which sustains
beneficial microorganisms that help release nutrients to the soil.
In many agriculture areas, pollution of groundwater causes
with synthetic fertilizers and pesticides. Organic fertilizers
through the use of greater biodiversity, enhancing soil structure
and water infiltration. Well managed organic systems with better
nutrient retentive abilities, greatly reduce the risk of groundwater
pollution. Organic agriculture contributes to mitigating the greenhouse
effect and global warming through its ability to sequester
carbon in the soil. Many management practices used by organic
agriculture increase the return of carbon to the soil, raising productivity
and favouring carbon storage. Combinations of plants
and animals optimize nutrient and energy cycling for agricultural
production. The provision of structures providing food and shelter,
and the lack of pesticide use, attract new or re-colonizing species
to the organic area, including wild flora and fauna (e.g. birds) and
organisms beneficial to the organic system such as pollinators and
pest predators . If households are endowed with sufficient labour
to apply manure, then the probability to opt for expensive
fertilizers decreases. Other than reciprocally affecting one another,
manure and fertilizer uses are also affected by other factors in
similar or in different directions. It reveals that the likelihood of
applying both fertilizer and manure increases within increase in
parcel size .
Declines in organic matter content of soils due to cultivation
and erosion have been a major concern related to sustainability
of agriculture. Therefore, management practices that increase the
organic matter content were deemed desirable to soil quality and
productivity. Moreover, soil organic matter increases following repeated
applications of solid cattle manure. The effect of manure
on soil pH is variable. Repeated applications of N fertilizer may
lead to soil acidification due to acidity produced in the nitrification
process, while organic matter added as manure can act to
help buffer the soil against a decrease in pH, manure that is low
in organic matter and high in ammonium nitrogen may result in
a decrease in pH due to acidity produced when the ammonium
is oxidized to nitrate in the soil . Moreover, Whalen et al. 
stated that an immediate increase in the pH of two acid soils following
fresh cattle manure application and concluded that the effects
of manure on soil pH would depend on the manure source
and soil characteristics. Manures of high organic matter and carbonate
content would be most effective in raising the pH of an acid
soil and also buffering against changes in pH once in the soil. The
content of organic matter was an essential indicator of soil quality
and fertility . Organic matter was one of the three soil components
that are crucial for its physicochemical properties, such
as its sportive and buffer abilities as well as its biodiversity and
biological activity. Because of the positive influence of organic
matter on soil functionality, it was imperative that its resources
be maintained or improved . Soils that received repeated applications
of cattle manure were more friable to the feel and less
compacted under foot than those of the unmannered plots Campbell
et al. . Farmyard manure has long been known to improve
soil structure, increase porosity and water holding capacity and
decrease evaporation rates, that cattle feed manure applications
to soils increased water infiltration into the soil while reported
that additions of manure decreased crust strength. Improvements
in physical soil quality characteristics were generally indicated by
increases in water infiltration, macro porosity, aggregate size and
stability, and soil OM.
The increased consumer demand appears to be driven primarily
by the perception that organically grown produce was safer
and more nutrients to eat than produce grown conventionally
. Similarly, the use of inorganic fertilizer has been observed
to cause the destruction of soil texture and structure, which often
leads to soil erosion and acidity as a result of the leaching effect
of nutrients. All these give rise to reduced crop yields as a result
of soil degradation and nutrients imbalance . Edmeades 
concluded that manured soil had higher organic matter levels,
lower bulk density, higher porosity and hydraulic conductivity,
and greater aggregate stability than soils fertilized conventionally
Karlen and Stott, . Improvements in all of these soil quality
indicators would optimize crop growth. Thus, one of the most significant
benefits of manure as an organic nutrient source was the
potential to maintain or increase soil organic matter levels
Power and Doran,  Microbial biomass and labile organic
matter pools were often greater in organic than conventionally
managed soils. Higher organic matter content, N mineralization
potential, and microbial biomass were observed in organically
farmed plots than in those receiving commercial fertilizers. Liebig
and Doran , found greater total C and N, microbial biomass,
soil respiration, and mineralizable N in organically managed farms
than in conventional farms. In general, tissue dry matter content
was reported to be higher in organically grown leafy vegetables,
but not in fruit . Similarly, Heaton  stated that dry matter
produce from organic systems was higher than in conventionally
grown produce. High rates of K fertilization have been reported to
reduce dry matter content in some crops [26-41].
Organic and synthetic fertilizers had a role in on soil properties
and agriculture and the good points of each should be acknowledged.
But inorganic fertilizer had more demerit than organic
fertilizer. Organic fertilizers are fertilizers derived from
animal matter, human excreta or vegetable matter (compost,
manure). Organic farming is a production system that avoids or
largely excludes the use of synthetic fertilizers, pesticides, growth
regulators and livestock feed additives and rely on crop rotation,
crop residues, animal manures, legumes, green manures, off-farm
organic wastes and mineral bearing rocks. Organic farming aspires
to a combine mixture of organic, environmental, social and
ethic objectives. For instance, compost provides air, water, organic
matter, and microorganisms to your plants, thus enhancing their
growth. It also maintains a healthy atmosphere for the soil and
hence keeps insects, plant diseases, and weeds away. Many organic
materials serve as both fertilizers and soil conditioners; they
feed both soils and plants. Microbial biomass was often greater
in organic than conventionally managed soils. Organic fertilizers
are carbon-based compounds that increase the productivity and
growth quality of plants. The majority of organic fertilizers can
be prepared locally or on the farm itself. Use of these organic fertilizers
ensures that the food items produced are free of harmful
chemicals. Therefore, it is recommended that the use of organic
fertilizer or combined application is more beneficial than artificial
fertilizers in order to preserve soil properties and increase the soil
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