CHAPTER II
Review Related Literature
Introduction
This chapter includes the ideas, finished thesis, generalization or conclusions,
methodologies and others. Those that are included in this chapter helps in
familiarizing information that are relevant and similar to the present study.
FOREIGN LITERATURE
HISTORY OF UREA FERTILIZER
Urea was first discovered in human urine by H.M. Rouelle in 1773.It was
synthesised in 1828 by Friedrich Wohler and was the first organic compound to be
synthesised from inorganic starting materials. It was found when Wohler attempted
to synthesis ammonium cyanate, to continue a study of cyanates which he had be
carrying out for several years. On treating silver cyanate with ammonium chloride
solution he obtained a white crystalline material which proved identical to urea
obtained from urine.This discovery prompted Wohler to write triumphantly to
Berzelius:-"I must tell you that I can make urea without the use of kidneys, either
man or dog. Ammonium cyanate is urea."This organic systhesis dealt a severe
blow to a widespread belief called "vitalism" which maintained that organic
chemicals could be modified by chemistry but could only be produced through the
agency of a vital force present in living plants and animals.In 1870 urea was
produced by heating ammonium carbamate in a sealed vessel. This provided the
basis of the current industrial process for its production.
Agricultural
Urea is used as a nitrogen release fertilizer as it hydrolyses back to 2NH2 and
CO2 but its most common impurity (biuret,NH2-CO-NH-CO-NH2) must be
present at less than 2% as it impairs plant growth. It is also used in many multicomponent solid fertilizer formulations.
Its action of nitrogen release is due to the conditions favouring the reagent
side of the equilibriums which produce urea.
Industrial Uses
Urea has the ability to form 'loose compounds' with many organic compounds.
The organic compounds are held in channels formed by interpenetrating helices
comprising of hydrogen bonded urea molecules. This
behaviour can be used to separate mixtures and has been used in the
production of aviation fuel and lubricating oils.
As the helices are interconnected all helices in a crystal must have the same
'handedness'. This is determined when the crystal is nucleated and can thus be
forced by seeding. This property has been used to separate racemic mixtures.
THE HISTORY OF COMPOST
The expression "older than dirt" certainly applies to compost. Nature has been
producing compost for millions of years as part of the cycle of life and death on
Earth. The first human use of animal manure, a raw form of compost, was in about
3,000 B.C. in Egypt when it was spread directly on the fields as a fertilizer. Later,
manure was mixed with dirty stable straw and other refuse and allowed to sit in
piles until it was needed. Rain kept the piles wet and aided the decomposition
process, producing a rich compost.
The Greeks and Romans knew the value of compost to boost crop production
and even used the warmth of decomposing compost to produce summer vegetables
in winter. Christian monasteries kept the art of composting alive in Europe after
the fall of the Roman Empire, and by about 1200 compost was again being used by
many farmers. Shakespeare mentions it in several of his plays written in the early
1600s.
In the United States, Presidents George Washington and Thomas Jefferson
were prominent landowners during the late-1700s and early-1800s. When they
were not involved with affairs of state, they both spent much of their time trying
innovative farming practices, including experiments with various composting
methods and materials. As years of successive crops depleted the nutrients in the
soil on the East Coast, the practice of composting became widespread. This trend
continued until the early 1900s when it was estimated that 90% of the fertilizer
used in the United States came from compost.
That all changed in 1913, when a German company began producing
synthetic nitrogen compounds, including fertilizers. These new chemical fertilizers
could be produced less expensively than messy animal manure compost, and the
farmyard compost pile quickly became a thing of the past. By 1950, it was
estimated that only 1% of the fertilizer used in the United States was derived from
compost.
One notable exception to this trend was the work started in 1942 by J.I.
Rodale, a noted pioneer in the development of the organic method of farming.
Rodale was one of the first to see the hazards of relying on synthetic fertilizers and
the benefits of using compost derived from natural sources. Composting got a
short-lived boost during the environmentally conscious era of the 1960s, but it
wasn't until the 1980s when it became a big business. This surge wasn't the result
of a renewed awareness of the positive aspects of compost, but rather a growing
concern over the negative aspects of refuse. In short, in our efforts to get rid of our
refuse, we werepolluting our air, poisoning our rivers, and quite literally burying
ourselves in it with our landfills.
In order to divert some of the municipal refuse away from landfills, several
cities established recycling centers in the early 1970s where people could bring
cans, bottles, and newspaper rather than throw them in the trash. This was followed
by curbside recycling, where people could place these recyclable materials in
separate containers for pickup in front of their houses. Finally, many citiesadded
additional curbside containers for yard wastes to be composted. By 1992, almost
1,500 cities had yard waste composting facilities.
At the same time, tough new environmental laws mandated that industries
could no longer simply dump their waste products onto the surrounding land or
discharge them into nearby rivers. To meet these laws, many industries began their
own recycling and composting programs. Environmental concerns also affected
farmers, who were being blamed for the negative health effects that chemical
fertilizers and pesticides had on humans and wildlife. As a result, many farmers
decided to cut back or eliminate chemicals in favor of using compost.
Today, most compost is processed in large facilities designed to handle a
specific type of raw material. Agricultural compost is usually produced and used
on the same farm that generated the raw materials. Industrial compost may be
bagged and sold to individual
buyers, or the raw materials may be sold in bulk to other composting facilities.
Municipal yard waste compost is usually produced in facilities operated by the city
or the refuse collection company and is sold to local landscaping companies and
garden centers.
Impact of Organic and Inorganic Fertilizers on yield, taste, and
nutritional quality of Tomatoes.
In a greenhouse experiment, tomato plants were grown in sand culture to
test whether different fertilization regimes (mineral or organic fertilizers) at low
(500 mg N plant–1 week–1) and high (750 mg N plant–1 week–1) nitrogen levels
affected yield, nutritional quality, and taste of the fruits. In the mineral-fertilizer
treatments, nitrate- or ammonium-dominated nutrient solutions were used. Organic
fertilizer was supplied as fresh cut grass-clover mulch (a total of 2.4 kg and 3.6 kg
were given per plant at low and high N level, respectively) without (orgN) and
with additional sulfur fertilization (orgN+S). Yields of red tomatoes from the
organically fertilized plants were significantly lower (1.3–1.8 kg plant–1) than
yields from plants that received mineral fertilizer (2.2–2.8 kg plant–1). At the final
harvest, yields of green tomatoes in the organic treatment with extra sulfur were
similar (1.1–1.2 kg plant–1) to the NOequation image-dominated treatments at
both nutrient levels and the NHequation image-dominated treatment at high
nutrient level. Organic fertilizers released nutrients more slowly than mineral
fertilizers, resulting in decreased S and P concentrations in the leaves, which
limited growth and yield in the orgN treatments. Analysis of tomato fruits and
plants as well as taste-test results gave no conclusive answer on the relationship
between sugar or acid contents in the fruits, macronutrient content of plant leaves
and fruits, and perceived taste. Sugar contents were higher in the fruits given
mineral fertilizer, whereas acid contents were higher in the fruits given organic
fertilizer. Preference in taste was given to the tomatoes from plants fertilized with
the nitrate-dominated nutrient solution and to those given organic fertilizer with
extra sulfur. Thus, a reduction in growth, which was expected to lead to a higher
concentration of compounds like sugars and acids, did not result in better taste.
Overall, it can be concluded that an appropriate nutrient supply is crucial to reach
high yields and good taste.
LOCAL LITERATURE
The Effects of Fertilizer Type and Application Time on Soil
Properties, Plant Traits, Yield and Quality of Tomato
The intensive agricultural practices using chemical fertilizers have helped
in increasing crop yields; however, more and more negative effects on soil quality
and environmental pollution have been found in areas where chemical fertilizers
were overused and/or used for the long-term. Therefore, organic amendments such
as crop residues, animal manures, or compost have been widely recognized as a
vital agricultural fertilizer resource to improve the soil health and grain yield in an
agroecosystem. Furthermore, organic and bio-organic amendments replace part of
the waste utilization. To promote the wide application of this technology, many
related subjects, such as the type and dosage of organic amendment, the
appropriate ratio mixed with chemical fertilizer, nitrogen application time, and
other factors such as mixing of organic amendments with different soil organisms
(e.g., phosphate-solubilizing bacteria, native free-living nematodes, and epigeic
earthworms) have been studied for various crops and vegetables in many countries
and regions. However, fewer previous studies have detected two or more factors
simultaneously, and the interactions between factors have been mostly ignored .
Furthermore, a comprehensive evaluation from soil to plant, that is, including soil
properties, plant morphological and physiological traits, yield, and quality, is
insufficient at present. Detecting the effects and comprehensive evaluations of
multiple factors are of great significance for production practice, and more detailed
work should be explored to improve the development of sustainable agriculture.
Cow manure, one of the common organic amendments, is rich in minerals and
is often used in conventional agriculture. However, organic amendments alone
may not offer sufficient nutrient supply to meet the demand for agriculture
production. Integrated soil fertility management (ISFM), a technique that makes
use of both organic and chemical fertilizer resources, is thus proposed for greater
yield response and better nutrient storage. For example, the production of tomato
and other vegetables was found to be higher when the one-third chemical fertilizer
was applied in combination with two-thirds vermicompost. Because the utilization
of nutrients by the plants to an adequate level largely depends upon the nitrogen
quantity and time of its application, there is a need to balance the nitrogen
application in terms of ratio and time of application [13]. The optimal mixed ratios
of organic and chemical fertilizers based on nitrogen have been suggested for crops,
vegetables, and fruits.However, applying nitrogen (especially the chemical form),
according to the requirements of plants at different growth stages, needs to be
taken into more consideration.
Tomato (Solanum lycopersicum L.) is one of the most important vegetable
crops, with an extensive worldwide distribution and a massive economic value. Its
global annual production is currently around 130 million tons. The yield and
quality of tomato are largely affected by the method of fertilization. Quite a
number of studies have focused on the effects of the mixed ratio of organic and
chemical fertilizers on the productivity of tomatoes and soil quality. However,
studies with nitrogen application time are much fewer for tomatoes. Furthermore,
most fertilization studies of tomato have generally only evaluated the effects on
plants or soil quality, solely. Some studies have evaluated both the plants and soil
quality but with few parameters. Exploring both the effects of mixed fertilizer and
application time, as well as conducting a comprehensive evaluation of both soil
and plant, is necessary for the technologies of sustainable agriculture practice.
According to the recommended fertilization rate for tomatoes, the total
effective nutrients (compost and fertilizer) for each fertilizer treatment were the
same: 0.12 g N per kg soil, 0.11 g/kg P2O5 per kg soil, and 0.38 K2O per kg soil.
All P, K, compost, and 25% urea for the N25 treatment (or 50% for the N50
treatment) were applied as basal fertilizer, and the remaining 75% (or 50%) urea
was applied at the flowering stage, 6 cm below the soil surface around the four
sides of the root, about 7 to 8 cm away from the root neck to avoid the root damage.
All pots were followed by a full factorial design, randomly arranged in the growth
chamber, and re-randomized weekly. Plants were watered 2–3 times a week to
compensate for evaporation losses. Weeds were controlled by hand every week
during the experimental period.
It has been widely accepted that organic fertilizers improve soil fertility and
quality better than chemical fertilizers and that different types of compost and
vermicomposting are essential for environmental sustainability and soil quality
restoration. Nutrients supplied by organic fertilizer release slowly compared with
chemical fertilizer, resulting in less loss of fertilizer and better preservation of the
soil nutrients. The compost amendment also promotes biological N-transformation
frequency in soil, which further enhances the soil’s organic and inorganic nutrients.
Furthermore, animal manure amendment may not only act as a substitute for
chemical fertilizers but also as a conditioner for soil quality. For example, one of
the most beneficial effects of compost application in soils is the increase of organic
matter content and carbon accumulation. Therefore, modern agricultural experts
recommend the use of animal excreta to improve the soil quality of field land
which has been damaged by chemical fertilizers.
We found that the soil properties, plant traits, and yield of tomato were
significantly affected by the fertilizer treatment but not by the N application time
or their interactions. No significant changes in fruit qualities were detected in this
experiment. The soil properties, plant traits, and yield of tomato with compostmixed fertilizers performed better than the CK treatment, and some parameters in
the CF30 treatment were even better than those with pure chemical fertilizer. Our
results clearly showed that the cow manure compost could be applied as a potential
source of nutrients to promote plant growth, increase tomato , and improve soil
fertility in silty loam texture soil. Establishing an optimal mixed ratio of compost
and chemical fertilizer is a critical issue for commercial tomato production, and the
chemical nitrogen application time is less important, according to our experimental
design. The implication of organic fertilizers in improving soil quality might be
greater than its impact on plant yield for sustainable agriculture practices.
REFERENCES
http://www.chm.bris.ac.uk/motm/urea/urea.html
http://www.texasorganicsoil.com/blog/2015/8/12/the-history-ofcompost#:~:text=The%20first%20human%20use%20of,piles%20until%20it%20w
as%20needed.
https://onlinelibrary.wiley.com/doi/abs/10.1002/jpln.200520553#:~:text=Preferenc
e%20in%20taste%20was%20given,not%20result%20in%20better%20taste.
https://www.mdpi.com/2071-1050/12/21/9065