Fertilizer

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CHAPTER II REVIEW OF RELATED LITERATURE

2.1 Fertilizers Fertilizers are substances containing the chemical elements that improve growth and productivity of plants. It is derived from a plant or animal residue or byproduct or natural material deposit which has been processed in such a way that its content of plant nutrients has not been materially changed except by purification and concentration (Meister, 2002). Sinnadurai, (1992), defines fertilizers as inorganic or organic plant food in solid or liquid forms that can be applied to soil in order to improve the quality and/or quantity of crops produced. They enhance soil fertility thus the ability of the soil to provide plant nutrients and resources that support growth, by increasing plant nutrients during the cycle. Crooke, (1972), pointed out that fertilizers have the ability to reduce the cost of production since they can raise yield with marginal increase in total cost per hectare. Although fertilizers provide nutrients to crops, they can contain elements, such as heavy metals, that are potentially harmful for the environment. They can be a major source of non-point pollution in soil and water. Eutrophication, NO3 contamination of ground water, and the accumulation of heavy metals in soil and their release to waters, together with their potential bioaccumulation in the food chain, are among the main problems mentioned by (Shokeri, 2008). Due to increasing concern regarding environmental problems related to fertilizers, previous agricultural production research aimed at optimizing fertilizer

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recommendations to maximized yields, or identifying cropping patterns that will maximize output and profit (Rola, 2004). 2.2 Kinds and nutrient composition of fertilizer There are two broad groups of fertilizers: (1) inorganic fertilizers and (2) organic fertilizers. And the nutrients in fertilizers can be grouped into two categories. These are the macro- and micronutrients. These nutrients promote plant growth (Bary, Cogger, & Sullivan, 2004). 2.2.1 Macronutrients Nitrogen (N) promotes rapid growth, increase leaf size and encourages shoots growth. It is a component of chlorophyll, and gives plant their greenness. If there is too little nitrogen, plants become stunted and pale. If plants are overdosed with nitrogen, they will grow too fast and become soft and sappy - an invitation to pests. Phosphorus (P) or phosphate encourages seed germination and early growth, stimulates blooming, enhances bud set, aids in seed formation and hastens maturity. Only small quantities are needed. A deficiency in phosphate shows as stunted growth. Potassium (K) or potash is associated with the size and quality of fruit and flowers. It toughens up plants and protects them from pests and diseases and its deficiency shows as small flowers and fruits and yellowing or browning of the leaves. Magnesium (Mg) is another greening agent and an activator of many plant enzyme required in growth processes. A deficiency shows as chlorosis, which is yellowing of the leaves starting between the veins. It is easily remedied by adding organic matter to the soil. Calcium (Ca) is a structural nutrient, it is an essential part in cell walls and membranes and helps to manufacture protein. Sulphur (S) is necessary for protein synthesis and also helps to A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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form chlorophyll. Lack of sulphur is unusual where the soil is rich in organic matter (Jokella, Magdoff, Bartlett, Bosworth, & Ross, 2004). 2.2.2 Micronutrients Micronutrients are mostly needed in minute quantities. Manganese (Mn) helps make chlorophyll and protein and acts as an activator for enzymes in plant growth process. A deficiency in Mn shows as stunting and yellowing of new leaves. Iron (Fe) serves as an activator for biological processes, such as respiration, photosynthesis, and symbiotic nitrogen fixation. Only the tiniest quantities of iron are needed. Iron deficiencies are most likely happen on chalky soils. Symptoms of lack of iron are pale leaves with brown edges and margins. Zinc (Zn) controls the synthesis of indole acetic acid, an important plant growth regulator. Copper (Cu) aids in the activation of numerous plant enzymes and plays a role in the development of plant pigments that influence color. Boron (B) is an important element for growing plant tissues. A lack of boron could cause ‘corkiness’ in fruit and vegetables. Molybdenum (Mb) is required by plants for the utilization of nitrogen. Oxygen, carbon and hydrogen are taken up from sunlight, air and water (Jokella, Magdoff, Bartlett, Bosworth, & Ross, 2004). 2.2.3 Inorganic fertilizer: Definition, advantages and disadvantages Inorganic fertilizers are fertilizers made artificially by chemical reactions. It is a fertilizer material which does not have carbon as the essential component of its basic chemical structure (Meister, 2002). They are specifically designed to feed a plant a certain amount of specific nutrients. Listed in Table 2.1 are common inorganic fertilizers. These fertilizers are extensively consumed by most of the farmers because it is widely available in the market. A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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Table 2.1 Nitrogen (N), phosphorus (P) and potassium (K) content of common chemical fertilizers* Product Ammonium nitrate

Nitrogen % Phosphate % Potash % 34

0

0

Ammonium sulphate

21

0

0

Urea

48

0

0

Ammoniated super-phosphate

3-6

48-53

0

Di-ammonium phosphate

11

48

0

Mono-ammonium phosphate

11

48

0

Super-phosphate

0

18-50

0

Triple super phosphate

0

46

0

Potassium chloride

0

0

60

Potassium nitrate

13

0

44

Potassium sulphate

0

0

50

Potassium-magnesium sulphate

0

0

22

*Food and Agriculture Organization (FAO), 2008 Due to the widespread introduction of chemical fertilizers in the mid-1990s, crop production has increased drastically (Maguire & Alley, 2009). According to (Stewart, Dibb, Johnston, & Smyth, 2005), excessive amounts of inorganic fertilizers are applied to vegetables in order to achieve a higher yield. However, imbalanced fertilization resulted in decline in the efficiency of fertilizer use overtime (Desai & Gandhi, 1989). The use of inorganic fertilizer was found to increase yield only for a few years but on long-term basis, it has not been effective (Ojeniyi, 2000). In addition to its negative effects in crop yield, chemical fertilizers generate several deleterious effects to the environment and human health. Synthetic N, P and K

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fertilizer is rapidly lost by either evaporation or by leaching in drainage water and it causes environmental pollution (Aisha, Rizk, Shaheen, & Abdel-Mouty, 2007). Jeyathilake, Reddy, Srihari, & Reddy, (2006) also added that inorganic fertilizers often leads to soil acidification, soil physical degradation, deficiency of macronutrients and decline in soil organic matter content. 2.2.4 Organic fertilizer: Definition, advantages and disadvantages, sources and production Organic fertilizer is a material that contains carbon and one or more elements beside hydrogen and oxygen that are required for plant growth (Meister, 2002). Alimi, Olubode-Awosola, & Idowu, (2006) define organic fertilizers as soil amendments that are mainly from natural organic sources or manufactured using organic materials. Compared to mineral fertilizers, the composition of organic fertilizers are usually more complex and variable. There are several researches and studies that highlighted the beneficial effects of organic waste application for crop production. These effects can be due to the intrinsic properties of the organic amendments (direct effect) or as a consequence of the beneficial effect of the organic amendments on the physical, chemical and biological properties of the soil (Stewart, Dibb, Johnston, & Smyth, 2005; Tejada, Garcia, Gonzalez, & Hernandez, 2009). In the study of Hernandez, Chocano, Moreno, & Garcia, (2014), it was stated that organic waste do several things to benefit the soil that synthetic fertilizer cannot do. They add organic matter which improves the way water interacts with the soil. And organic waste also inoculate the soil with vast numerous of beneficial microbes that promote the biological activity of the soil. A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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Crooke, (1972) also added that organic fertilizers can improve the soil by lowering bulk density and they can reduce soil erosion and improve soil fertility. These fertilizers also care for the “living soil”, which entails maintaining microbiological life in the soil in balance with the whole ecosystem without altering soil pH. Despite of its numerous benefits, utilizing organic fertilizers has also the following drawbacks such as bulkiness, offensive odor, slow acting, difficulty to transport and doubtful efficacy (Alimi, Olubode-Awosola, & Idowu, 2006). And potentially toxic heavy metals also limit the use of organic fertilizer. The nutrient composition of organic fertilizers is highly inconstant. Also, long – term or heavy usage to agricultural soils may result in salt, nutrient and heavy metal accumulation and may adversely affect plant growth, soil organisms, water quality and animal and human health (Chen, 2006). On the other hand, the utilization of organic waste in agriculture depends on several factors, including the characteristics of the waste such as its organic matter, nutrient and heavy metal content, its energy value, the odor generated by the waste, its benefits to agriculture, its availability and the transportation cost and regulatory considerations (Hernandez, Chocano, Moreno, & Garcia, 2014). 2.2.5 Potential sources of organic fertilizers Most organic fertilizers are made from diverse raw materials which can be classified into two main categories like (1) agro-industrial and (2) those derived from civil establishments. More precisely, Sharma, Canditelli, Cornacchia, & Fortuna, (1996) classified the waste into the following main groups: (1) animal waste; (2) crop residues;

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(3) fruit and vegetable waste; (4) aquatic biomass and biofertilizers; (5) fish and marine wastes; (6) industrial wastes; (7) human habitation waste, etc. Naturally occurred organic fertilizers are manure, slurry, worm castings, peat, seaweed, sewage and guano. Among the sources of organic matter, farm manure has been of major importance over the past years. Farm animals void most of the nitrogen, phosphorus and potassium that is present in the food they eat and this constitutes an enormous fertility resource (Table 2.2). Organic manures can serve as alternative to mineral fertilizers (Naeem, Iqbal, & Bakhsh, 2006), for improving soil structure (Dauda, Ajayi, & Ndor, 2008) and microbial biomass (Suresh, Sneh, Krishn, & Mool, 2004). Table 2.2 Nutrient composition of selected manure* Manure Source

N (%)

P (%)

K (%)

Chicken

3.8

1.9

1.8

Duck

2.2

1.1

1.2

Pig

2.8

1.4

1.2

Cattle

2.8

1.4

1.2

Carabao

0.3

0.1

-

Goat

0.6

0.1

0.2

Horse

2.3

0.8

1.3

Rabbit

1.7

1.3

1.1

Guano

0.6

0.4-6.6

-

*Food and Agriculture Organization (FAO), 2008 Manufactured organic fertilizers include compost, blood meal, bone meal, seaweed extract and etc. Bone meal is quite rich in phosphate to promote root growth. Blood, fish and bone for instance, is a balanced all round fertilizer. Blood meal unlike

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dried manure is very high in nitrogen. Fish meal contains nitrogen and phosphate. Dried manures have all trace elements but are quite low on NPK. Seaweed extract is also quite excellent and it is a slow releaser of nutrients. It contains cytokinins and hormones that promote photosynthesis and protein synthesis. Ash from wood is high in potassium and some phosphate which depends on the type of wood (Bary, Cogger, & Sullivan, 2004; Jokella, Magdoff, Bartlett, Bosworth, & Ross, 2004). Average nutrient concentrations of various organic materials are listed in Table 2.3. Table 2.3 NPK content of selected organic materials* Material

%Nitrogen %Phosphate %Potash

Bone meal

1-6

11-30

0

Blood meal

12

1-2

0-1

Composts

1-3

1-2

1-2

Feather meal

12

0

0

Glass clippings

1-2

0-0.5

1-2

Kelp

1-1.5

0.5-1

5-10

Leaves

1

0-0.5

0-0.5

Sawdust

0-1

0-0.5

0-1

Sewage sludge

2-6

1-4

0-1

Seaweed extract

1

2

5

Straw/corn stalks

0-0.5

0-0.5

1

Wood ashes

0

1-2

3-7

*Koenig & Johnson, 2011 Vermi compost is among the sources of organic manures. It has readily available plant nutrients, growth enhancing substances and number of beneficial microorganisms like N2 fixing, P solubilizing and cellulose decomposing organisms (Preetha, Sushama, & Marykutty, 2005). The previous study of Preetha et al., (2005) showed that waste A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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could be converted into nutrient-rich compost in a short period of ~48 days by vermicomposting with Eisenia foetida. On the other hand, compost is the end product of the composting process. Organic materials are decomposed in composting plants under controlled conditions to produce the end product which is used as fertilizer. It is produced ecologically and economically and plays a major role in the soil enrichment process, mainly through chemical, physical and biological activities (Sharma, Canditelli, Cornacchia, & Fortuna, 1996). 2.2.6 Production of organic fertilizer: Composting process As defined by Sharma et al., (1996), compost is a stabilized and sanitized product obtained from the composting of organic substances derived from urban and agroindustrial biodegradable solid waste, free from heavy metals, glass pieces, and plastic and sometimes cellulose materials with pH value around 8 and subjected to partial microbial fermentation. Composting is generally referred to as the biological oxidative decomposition of organic constituents in wastes of almost any nature under controlled condition. It requires special conditions, particularly of temperature, moisture, aeration, pH and C/N ratio, related to optimum biological activity in the various stages of the process. The main products of aerobic composting are carbon dioxide, water, mineral ions and stabilized organic matter, often called humus. Composting organic residues is an environment friendly alternative of producing fertilizer. Composting process can be done by different phases as discussed by Sharma et al., (1996). The initial phase is, during which readily degradable components are decomposed. Thermophilic phase is during which cellulose and similar materials are A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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degraded by a high bio-oxidative activity of micro-organisms. Lastly, the maturation and stabilization phase. The conventional composting method is the so-called passive method. Surprisingly, even today, a large percentage of agricultural farms practice this method. This method simply involves the storage of putrescible organic material, left undisturbed for a few months. Other composting method like using bio-reactors are in use on a wide scale. Stabilization of substrate (feedstock) using composting through reactors involves combination of different techniques for material handling and forced air ventilation in the matrix. Many variety of bio-reactors are available but rotating cylinder bioreactors, DANO, are widely used according to Sharma et al., (1996). Alternative process of composting include vermicomposting, mushroom-bed and regeneration of energy (methane, heat, etc.). But it is to be noted that the end products obtained from the last two mentioned processes are not stable biologically, and as such, their use needs further treatment. On the other hand, the main problem of vermicomposting is the production cost. The cost of earthworm cast varies from P 12.00 per kilo at the wholesale level whereas the retail price goes up to P 15 per kilo (Pilipinas.Com). Additional composting process and technologies discussed in literatures are static pile, open windrow, enclose channel and in-vessel. Static pile and open windrow are less expensive process but it will take 6-18 months to produce the compost. However, the enclosed channel and in-vessel, the finished product can be made in 3-6 months but it require high operating and capital cost.

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For in – vessel composting, the compost is confined in a building, container or vessel. This is so that air, moisture and temperature can be closely monitored and controlled. Temperature is closely monitored and compost must reach a certain temperature dependent on the process, before being applied to land. This is to kill any weed seeds that may be in the compost to prevent the germination of them onto land, and also to kill harmful pathogens within the compost (FGS Organics Ltd. 2015) 2.3 Utilization of fertilizer: Demand Over the past decades, fertilizer consumption has been increasing and punctuated by some sharp declines due to external shocks. Demands were met by imports and domestic productions (Briones, 2014). Figure 2.1 presents estimates of fertilizer consumption (Bureau of Agricultural Statistics).

Figure 2.1 Annual consumption of fertilizer in ‘000 tons, 1990-2012

The main type of fertilizer consumed has usually been nitrogen-based, until recently, next in importance are phosphate-based fertilizers. Data from Fertilizer and Pesticide Authority (FPA) provide a breakdown in fertilizer consumption by type A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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(Figure 2.2). This data set only considers the major types, namely 0-0-60 (potassium sulfate), 14-14-14 (complete NPK), 16-20-0 (ammonium phosphate), 18-46-0 (diammonium phosphate), 21-0-0 (ammonium sulfate) and

46-0-0 (urea). The

largest shares in consumption are urea and ammonium sulfate and next in rank is complete NPK fertilizer.

Figure 2.2 Utilization of fertilizer by major type, 1980-2012 The domestic production of fertilizer is sourced from five manufacturing company (Table 2.3). The largest is PHILPHOS located in the Visayas island group and the next largest capacity belongs to Soiltech in the Northern island of Luzon (FPA).

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Table 2.4 Capacity and products of fertilizer manufacturers in the Philippines (2012)* Company

Capacity (tons/year)

Products

AFC

45,000

Single superphosphate

30,000

Ammonium sulfate

80,000

Complete NPK

75,000

Ammonium phosphate

Farmfix Fertilizer

50,000

Fertilizer blends

Inchem

22,000

Potassium sulfate

PHILPHOS

1.17 million

NP fertilizer, NPK fertilizer, Ammonium sulfate

Soil Agricultural Products

1 million

NPK fertilizers: 14-14-14, 16-20-0, 6-9-15

*Briones, 2014 data from FPA & company website Moreover, the exact or appropriate amount of organic fertilizer production and utilization was not established since farmers often prepare their own organic fertilizers. Some of the largest manufacturers of organic fertilizer include Victorias Milling Company, Sagana 100 Philippines, Galactic resources Development, Sun Chemicals and Datingbayan (FAO). 2.4 Integrated use of organic and inorganic fertilizers for nutrient management Because inorganic fertilizer used in intensive agriculture is not sustainable and utilization of organic fertilizer alone is not enough in maintaining high yield, technological options are needed according to Rola, (2004). Hence, farmers often apply organic and inorganic fertilizer in combined (Law-Ogbomo, Remison, & Jombo, 2011). Integrated nutrient management or the combined use of organic and inorganic fertilizer has been proven to be a sound soil fertility management strategy (Lombion A PLANT DESIGN ON THE PRODUCTION OF INTEGRATED ORGANIC AND INORGANIC FERTILIZER

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et al., 1999) and found to be promising in maintaining stability in crop production in certain soils (Rola, 2004). Several researchers have demonstrated the beneficial effect of combined use of chemical and organic fertilizers to mitigate the deficiency of many secondary and micronutrients in fields that continuously received only N, P, and K fertilizers for a few years, without any micronutrient or organic fertilizer. Hernandez, Chocano, Moreno, & Garcia, (2014) also added that the combined use of compost and inorganic fertilizer, however produced higher yields and better fruit quality than soils that underwent the respective inorganic treatment when used alone. The conjunctive use of compost and inorganic fertilizer made it possible to reduce inorganic fertilization by about 40% while obtaining similar fruit quality and amounts in addition to improving soil characteristics. Thus, Cuevas, (1989) recommended a combined use of one-half organic and one-half inorganic fertilizer.

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