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Soil Quality Improvement of Acidic Soil and Its Effects on The Growth and Yield of Maize

Using Biochar Derived From Rice Waste

Studienarbeit 2018 40 Seiten

Geowissenschaften / Geographie - Geologie, Mineralogie, Bodenkunde


Table of Contents


2.1. Maize: General Description
2.2. Growth requirements
2.3. Maize production constraints
2.4. Economic importance of maize
2.5. Biochar: An overview
2.6. Biochar production
2.7. Centralized, decentralized, and mobile systems
2.8. Uses of biochar
2.9. Bio-oil and synthetic gas
2.10. Direct and indirect benefits of biochar
2.11. Possible commercial use
2.12.The effect of biochar on the physical and chemical properties of the soil

3.1. Description of the experimental site
3.2. Source of materials
3.3. Field experimental layout
3.4. Data analysis






It has been reported that poor plant growth yields are strongly associated with low pH because of the deficiencies and toxicities related to a number of elements (Blamey and Chapman, 1982). Also, acidic soil with (pH < 0.5) is a wide spread problem in Agbani AreaSouth East Nigeria which has had adverse effect including decreased soil productivity and sub optimal plant growth. These acidic soils originates from acidic paren materials, mainly granite and granite gnesis that are naturally more acidic compared to the soil generated from calcerous shale or lime stone.

Moreover, atmospheric pollutant of industrial origin can increase the acidic content of soils. A gradual increase in acid deposition has occurred as a result of heavy industrialization since the 1970s. Maize belongs to the grains under the family of graminae and class of cereals. It thrives under a wide range of environmental conditions for optimum production they require a lot of sunshine, warmth and an average temperature below 14oC and a well distributed amount of rainfall. It prefers a pH of 6.5-8.0 (IITA, 1982) while a strongly acid soil is unsuitable for good yield. The soil must be deep, well drained, structured with adequate organic matter and inorganic matter like weathered minerals within the rooting depth. Biochar is a charcoal used as a soil ameliorant. It is recognized as a multifunctional material that can be used in carbon sequestration, metal immobilization and soil fertility increase. Biochar is a stable solid, rich in carbon and can endure in the soil for thousands of years. Like most charcoal, biochar is made from renewable materials via pysolysis. The alkaline nature of biochar along with the presence of a variety of other elements depending on its origin makes it a good material as a soil conditioner.

Soil quality is the ability of a soil to perform functions that are essential to plant growth and the environment. It is a reflection of how well a soil performs the functions of maintaining biodiversity and productivity. Soil quality improvement using biochar not only increases soil pH level but also affect the availability of other minerals and nutrients found in the soil (Mclean 1982). To improve the quality of an acidic soil with respect to pH, the application of biochar as an ameliorant to acidic soils is seldom. It is affordable and cost effective making it an alternative.

The main objective of this study is to use biochar derived from rice mill waste to ameliorate acidic soil and its effect on the growth and yield of maize.


2.1. Maize: General Description

Maize is a grass and it belongs to the large family called Gramineae, subfamily Andropogodeae and class of cereals. The origin of maize is still a matter of speculation because no wild forms of maize have been found. A current research showed that maize had its origin from a primitive type of corn, which have been found in caves or dwelling of early man about 7000 years old. However, it was introduced into West Africa by the Portuguese.

It is gotten throughout the tropics and in the temperate regions of the world. Maize has a fibrous root system which grows mainly from the lower nodes of the stem below ground level. There are also seminal and prop root, the prop or brace roots are adventitious roots that rise from nodes that are above the soil surface. In Nigeria, it is cultivated mostly in the southern part of the country.

Maize plant is an annual plant, the stem, culms or stalks are solid unbranched and herbaceous. Occasionally, ear bearing branches are formed. Maize stems range in height from 0.6 to 6 m and are grooved on alternating sides of each internodes. The internodes are shorter towards the tip where it contains the male inflorescence called tasel. Maize leaves have the typical grass leaf structure consisting of the main parts: the blade and the sheath surround the stalk. The leaves actematic between opposite sides of the stalk. Maize unlike other cereals has separate male and female flowers on the same plant. This implies that maize is monoecious plant. The male inflorescence, the tessel bearing staminate spikelet is produced at the apex of the main stem. Each female flower contains a single ovary terminates by a long style, the pollen-receptive organ commonly known as the silk. The silks are covered with fine hairs which trap wind-blown pollen. Each silk is a potential seed or kernel and must be pollinated for the seed to develop.

2.2. Growth requirements

Maize thrives under a wide range of environmental conditions, but for optimum production they require a lot of sunshine an warmth, average temperature below 14oC. Generally, large quantities of water well distributed are needed for high maize yields, maize uses water relatively efficiently. Most soils in Nigeria are acidic and are often deficient in essential plant nutrients (Ohiri and Ano, 1989). Maize requires a well aerated, deep, loamy, soils high inorganic matter, nitrogen, phosphorus and potassium. It can be grown successfully in soils whose pH ranges from 5.5 to 8.0. Since most soils in Nigeria is acidic, it can be improved using Biochar. Biochar not only increases soil pH but also affect the availability of other minerals and nutrients found in the soil (Mclean, 1982).

The optimum time of planting for early maize depends on the various ecological zones of Nigeria and was stated thus: forest zone (mid-March to first week of April), Sudan savanna (first to second week of June), Guinea Savanna (last week of May to first week of June), Southern Guinea Savanna (first last week of May to first week of May) Eze (2011). With the advent of global warming and climate change especially in Africa these schedules may not hold. Efforts should be geared up towards determination of time of planting for maize because of its sensitivity to this particular factor.

Complete fertilizer is applied at planting or immediately after germination. Compound fertilizer of nitrogen phosphorus and potassium, N.P.K (15: 15:15) at about 300-500 kg/hectare can be used. At about the time of tasselling, nitrogen fertilizer in the form of sulphate of ammonia (NH4)2 or Nitro Chalk Ca(NO3)2can be placed about 5-10 cm away from the plant in ring or continuous rows. Where organic manure is available, it can be spread and work in before planting.

2.3. Maize production constraints

Maize suffers from parasitic and non-parasitic disease. The parasitic diseases are caused by fungi, bacteria, viruses, nematodes and parasitic seed plant. Maize is susceptible to a number of pests which attack it either in the field or storage. Major field pests of maize includes: stem borers, Army norms (Field Army Worms, FAW), earthworms, while storage pests includes; termite, rodents and weevils.

Weed is also a problem that affects the growth of maize. The limited use of organic and inorganic fertilizer and the declining soil fertility are problems to maize production in Sub-Saharan Africa. Periodic drought caused by irregular rainfall distribution reduces maize yield by an average of 15% each year, ( Adams and Pearson, 1967).

Stalk rots are very destructive and in most cases the rots are caused by a combination of fungi and bacteria that attack plants approaching maturity. Its development is favored by dry weather early in the growing season.

Insects and birds damages to ears and seeds increase the incidence and seventy percent of rotting, all things being equal. Logged plants with the ears touching the ground expose the ears and kernels to more damage by insects and birds and consequently by rotting organisms.

Storage rots may develop on maize in cribs, bins or silos. If the moisture of the kernel (seeds) is above 12 or 15% and the surrounding air is warm enough for growth of fungi. It reduces market grade and feeding value.

2.4. Economic importance of maize

Worldwide, corn provides over 20 million tons of protein annually, used in production of alcohol (gin, whiskey, beer, industrial alcohol etc.) tooth paste, baby powder, cakes of soap, aspirin and other medicinal tablet may contain maize products, all kinds of paper must have starch treatment to give them a smooth surface and corn starch may be used for such treatment. Others are corn oil, corn flakes, corn meal flour, gums used in adhesives and sizing agents, syrup, dextrose, gluten man-power etc. Corn husks are used as filling materials whereas the corn cobs are used as fuel for making charcoal and for preparation of industrial solvents. Maize is used as feed grain and silage or green fodder for livestock. Maize consumption in Western Nigeria varies from 2.6 kg-2.8 kg per person per week (Owolabi et al., 2003).

It is also used to make chicha, a fermented beverage of South America. It is also important in pediatrics health care delivery. The predominance of glycosides of linnobic acid and high glycosides content in the unsaturated acid, render it valuable in reducing serum cholesterol level in blood. The level which is associated with arterioderasis and coronary heart diseases.

Maize feedstock used for ethanol production, somewhat exceeded direct use for livestock fee. A fraction of the maize feedstock dry matter used for ethanol production is usefully recovered as Dried Distillers Grains with Solubles (DDGS), this DDGS are fed to livestock and poultry. Because starch utilization in fermentation for ethanol production leaves other grain constituents more concentrated in the residue, the feed value per kg of DDGS, with regard to ruminant-metabolizable energy and protein, exceeds that of the grain (Hoffman and Baker, 2011).

Maize is a major source of both grain feed and fodder for livestock. It is fed to the livestock in various ways. When it is used as a grain crop, the dried kernels are used as fed. Starch from maize can also be made intro plastics, fabrics, adhesives and many other chemical products. The corn sleep liquor, a plentiful watery by product of maize wet milling process, is widely used in the biochemical industry and research as a culture medium to grow many kind of microorganisms. Maize is also increasingly used as a feedstock for the production of ethanol fuel (biofuel), (Torres et al., 2016)

2.5. Biochar: An overview

Biochar is acharcoal used as a soil ameliorant.It is recognized as a multifunctional material that can be used in carbon sequestration, metal immobilization and soil fertility increase. Biochar is a stable solid, rich in carbon and can endure in the soil for thousands of years. Like most charcoal, biochar is made from renewable materials via pyrolysis. The alkaline nature of biochar along with the presence of a variety of other elements depending on its origin makes it a good material as a soil conditioner.

Like most charcoal, biochar is made from biomass via pyrolysis. Biochar is under investigation as an approach to carbon sequestration. Biochar thus has the potential to help mitigate climate change via carbon sequestration. Independently, biochar can increase soil fertility of acidic soils (low pH soils), increase agricultural productivity, and provide protection against some foliar and soil-borne diseases. History The word "biochar" is a combination of "bio-" as in "biomass" and "char" as in "charcoal". It has been used in scientific literature of the 20thand 21st century. Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity. They seem to have produced it by smoldering agricultural waste (i.e., covering burning biomass with soil) in pits or trenches. European settlers called it terrapreta de Indio. Following observations and experiments, a research team working in French Guiana hypothesized that the Amazonian earthworm Pontoscolexcorethrurus was the main agent of fine powdering and incorporation of charcoal debris to the mineral soil.

2.6. Biochar production

Biochar is a high- carbon, fine-grained residue that today is produced through modern pyrolysis processes; it is the direct thermal decomposition of biomass in the absence of oxygen (Preventing combustion), which produces a mixture of solids (the biochar proper),liquid (bio- oil), and gas (synthesis gas) products. The specific yield from the pyrolysis is dependent on process condition, such as temperature, and can be optimized to produce either energy or biochar.

Temperatures of 400– 500 °C (673–773 K) produce more char, while temperatures above 700 °C (973 K) favor the yield of liquid and gasfuel components. Pyrolysis occurs more quickly at the higher temperatures, typically requiring seconds instead of hours. Typical yields are 60% bio-oil, 20% biochar, and 20% synthesis gas.

By comparison, slow pyrolysis can produce substantially more char (~50%); it is thiswhich contributes to the observed soil fertility of terra preta. Once initialized, both processes produce unit energy. For typical inputs, the energy required to run a “fast” pyrolyzer is approximately 15% of the energy that it outputs. Modern pyrolysis plants can use the syntheticgas created by the pyrolysis process and output 3–9 times the amount of energy required to run.

The Amazonian pit/ trench method, harvests neither bio- oil nor synthetic gas, and releases a large amount of CO2, black carbon, and other greenhouse gases (GHG)s (and potentially, toxins) into the air. Commercial-scale systems process agricultural waste, paper byproducts, and even municipal waste and typically eliminate these side effects by capturing and using the liquid and gas products. The production of biochar as an output is not a priority in most cases.

2.7. Centralized, decentralized, and mobile systems

In a centralized system, all biomass in a region is brought to a central plant for processing. Alternatively, each farmer or group of farmers can operate a lower-tech kiln. Finally, a truck equipped with a pyrolyzer can move from place to place to pyrolyze biomass. Vehicle power comes from the syntheticgas stream, while the biochar remains on the farm. The biofuel is sent to a refinery or storage site. Factors that influence the choice of system type include the cost of transportation of the liquid and solid byproducts, the amount of material to be processed, and the ability to feed directly into the power grid. For crops that are not exclusively for biochar production, the residue-to- product ratio (RPR) and the collection factor (CF) the percent of the residue not used for other things, measure the approximate amount of feed stock that can be obtained for pyrolysis after harvesting the primary product. For instance, Brazil harvests approximately 460 million tons (MT) of sugarcane annually, FAOSTAT (2006) withanRPRof0.30,andaCFof0.70forthesugarcanetops,whichnormallyareburnedinthefield. This translates into approximately 100 MT of residue annually, which could be pyrolyzed to create energy and soil additives. Adding in the biogases (sugarcane waste) (RPR=0.29 CF=1.0), which is otherwise burned (inefficiently) in boilers, raises the total to 230 MT of pyrolysis feedstock. Some plant residue, however, must remain on the soil to avoid increased costs and emissions from nitrogen fertilizers. Pyrolysis technologies for processing loose and leafy biomass produce both biochar and synthetic gas.ThermocatalyticdepolymerizationAlternatively,"thermocatalyticdepoymerizationwhichutilizesmicrowaves has recentlybeen used to efficiently convert organic matter to biochar on an industrial scale, producing~50% char. Uses Carbon sink See also: Climate engineering The burning and natural decomposition of biomass and in particular agricultural waste adds large amounts of CO2 to the atmosphere.

2.8. Uses of biochar

Biochar is a stable way of storing carbon in the ground for centuries, potentially reducing or stalling the growth in atmospheric greenhouse gas levels; at the same time its presence in the earth can improve water quality, increase soil fertility, raise agricultural productivity, and reduce pressure on old-growth forests. Biochar can sequester carbon in the soil for hundreds to thousands of years, like coal. Such a carbon-negative technology would lead to a net withdrawal of CO2 from the atmosphere, while producing consumable energy.

This technique is advocated by prominent scientists such as James Hansen, head of the NASA Goddard Institute for Space Studies, and James Lovelock, creator of the Gaia hypothesis, for mitigation of global warming by greenhouse gas remediation. Researchers have estimated that sustainable use of biocharring could reduce the global net emissions of carbon dioxide (CO2), methane, and nitrous oxide by up to 1.8 Pg CO2-C equivalent (CO2-Ce) per year (12% of current anthropogenic CO2- Ce emissions; 1Pg=1 Gt), and total net emissions over the course of the next century by 130  Pg CO2-Ce, without endangering food security, habitat, or soil conservation. Soil amendment biochar is recognized as offering a number of benefits for soil health. Many benefits area related to the extremely porous nature of biochar. This structure is found to be very effective at retaining both water and water-soluble nutrients. Soil biologist Elaine Ingham indicates the extreme suitability of biochar as a habitat for many beneficial soil micro organisms. She points out that when pre-charged with these beneficial organisms biochar becomes an extremely effective soil amendment promoting good soil, and in turn plant, health.

Biochar has also been shown to reduce leaching of E- coli through sandy soils depending on application rate, feedstock, pyrolysis temperature, soil moisture content, soil texture, and surface properties of the bacteria. For plants that require high potash and elevated pH, biochar can be used as a soil amendment to improve yield. Biochar can improve water quality, reduce soil emissions of green house gases, reduce nutrient leaching, reduce soil acidity, and reduce irrigation and fertilizer requirements. Biochar was also found under certain circumstances to induce plant systemic responses to foliar fungal diseases and to improve plant responses to diseases caused by soil borne pathogens. The various impacts of biochar can be dependent on the properties of the biochar, as well as the amount applied, and there is still a lack of knowledge about the important mechanisms and properties. Biochar impact may depend on regional conditions including soil type, soil condition (depleted or healthy), temperature, and humidity. Modest additions of biochar to soil reduce nitrous oxide N2O emissions by up to 80%and eliminate methane emissions, which are both more potent greenhouse gases than CO2. Studies have reported positive effects from biochar on crop production in degraded and nutrient–poor soils. The application of compost and biochar under FP7 project FERTIPLUS hashadpositiveeffectsinsoilhumidity,andcropproductivityandqualityindifferentcountris.

Biochar can be designed with specific qualities to target distinct properties of soils. In aColumbian savanna soil, biochar reduced leaching of critical nutrients, created a highercrop uptake of nutrients, and provide greater soil availability of nutrients. At 10% levels biochar reduced contaminant levels in plants by up to 80%, while reducing total chlordane and DDX content in the plants by 68 and 79%, respectively. On the other hand, because of its high adsorption capacity, biochar may reduce the efficacy of soil applied pesticides that are needed for weed and pest control. High- surface-area biochars may be particularly problematic in this regard; more research into the long-term effects of biochar addition to soil is needed. Slash-and- char Switching from slash-and-burn to slash-and-char farming techniques in Brazil can decrease both deforestation of the Amazon basin and carbon dioxide emission, as well as increase crop yields. Slash-and-burn leaves only 3% of the carbon from the organic material in the soil. Slash-and-char can keep up to 50% of the carbon in a highly stable form. Returning the biochar into the soil rather than removing it all for energy production reduces the need for nitrogen fertilizers, thereby reducing cost and emissions from fertilizer production and transport. Additionally, by improving the soil's ability to be tilled, fertility, and productivity, biochar– enhanced soils can indefinitely sustain agricultural production, whereas non-enriched soils quickly become depleted of nutrients, forcing farmers to abandon the fields, producing a continuous slash and burn cycle and the continued loss of tropical rainforest. Using pyrolysis to produce bio-energy also has the added benefit of not requiring infrastructure changes the way processing biomass for cellulosic ethanol does.

Additionally, the biochar produced can be applied by the currently used machinery for tilling the soil or equipment used to apply fertilizer. Water retention is hygroscopic. Thus it is a desirable soil material in many locations due to its ability to attract and retain water. This is possible because of its porous structure and high surface area. As a result, nutrients, phosphorus, and agrochemicals are retained for the plants benefit. Plants are therefore healthier, and less fertilizer leaches into surface or groundwater.



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soil quality improvement acidic effects growth yield maize using biochar derived from rice waste




Titel: Soil Quality Improvement of Acidic Soil and Its Effects on The Growth and Yield of Maize