Agricultural Soil is a mixture of minerals, organic matter, gases, liquids, and countless organisms that together support life on earth. The use of compost or organic manure is currently being advocated as an option for improving soil fertility.
The method used in carrying out this analysis for cyanide, macronutrient (N,P,K) are titrimetric method, NO3 – UV spectrophotometric method, vanadomolybdo phosphorus acid method, and direct air-acetylene flame method respectively.
From the experimental analyses, the result obtained for the test of macronutrient (N,P,K) ranges from (-0.01 to 354.956) which shows that there was an increase in macronutrient before composting, after the composting process, there was a decrease in macronutrient. For cyanide it ranges from (-0.001 to 0.1) which also shows that cyanide was not found in the soil before composting, but after the composting process there was cyanide in the soil. For pH, it ranges from (3.1 to 6.72), with a mean value of 5.605 which shows that the soil was moderately acidic.
Kinetics of macronutrient (potassium) shows that there was an increase in concentration with respect to time, which has a second order reaction, with rate constant (K) of 7.14×mg/kg/day.
Conclusively, from the overall analysis it could be seen that cassava leaves compost has a bad effect on macronutrient content of agricultural soil.
1.1 Background ofthe Study
Soil is a major component of the earth's ecosystem. The world's ecosystems are impacted in far-reaching ways by the processes carried out in the soil, from ozone depletion and global warming, to rainforest destruction and water pollution. Apart from the atmosphere, the soil is the next largest carbon reservoir on earth, and it is potentially one of the most reactive to human disturbance and climate change(Bryant, 2006).
The chemistry of soil determines its ability to supply available plant nutrients and affects its physical properties and the health of its microbial population. It also determines its corrosivity, stability, and ability to absorb pollutants and to filter water. It is the surface chemistry of mineral and organic colloids that determines soil's chemical properties. "A colloid is a small, insoluble, nondiffusible particle larger than a molecule but small enough to remain suspended in a fluid medium without settling. Most soils contain organic colloidal particles called humus as well as the inorganic colloidal particles of clay." The very high specific surface area of colloids and their net charges, give soil its ability to hold and release ions.
The use of compost or organic manure is currently being advocated as an option for improving soil fertility. Organic manure or fertilizer increase the soil organic carbon pool and soil pH, improves the soil structure, decreases bulk density, provides macro- and micronutrients and enhances microbial activity. Most farmers use crop residues as feed for their livestock or as fuel. Thereby leaving only low quality plant residues for composting to generate soil humus.Humus refers to organic matter that has been decomposed by soil flora and fauna to the point where it is resistant to further breakdown. Humus usually constitutes only five percent of the soil or less by volume, but it is an essential source of nutrients and adds important textural qualities crucial to soil health and plant growth. Humus also hold bits of undecomposed organic matter which feed arthropods and worms which further improve the soil.This results in poor quality composts (Brancaet al., 2013). Therefore, the Alliance for a Green Revolution in Africa has adapted integrated soil fertility management as a base for increasing crop productivity and restoring soil fertility. This strategy aims to combine organic and inorganic fertilizers, resulting in a synchronized nutrient release and uptake by the crop (Killhamet al., 2010).
The aim of this research is to investigate the effects of cassava leaves compost on soil properties.
1.2 Problem Statement
Cassava processing produces large amount of waste (cassava leaves) and is generally considered to contribute significantly to environmental pollution (FAO, 2001). In Nigeria (Oleh community)cassava waste leaves are usually left to rot away in open (agricultural soil), thereby altering the presence of heavy metals in the soil, the pH of the soil and the content of macronutrient available for plant growth.
Cyanide is concentrated in the cassava leaves and when the cassava leaves is decompose on the soil, it reduces the power of the macro nutrient on the soil which may lead to poor fertility of the agricultural soil.
High concentrations of cyanide can inhibit respiration and affect a plant’s ability to absorb nutrients from soil, in some cases causing plant death, cyanide diminish new growth and can affect the germination of seeds. Cyanide in the soil may therefore prove fatal to plant life.
1.3 Scope of the Study
The scope of the present study is to investigate the effect of continuous application of cassava leaves compost on agricultural soil, in a selected locality of Oleh town.
1.4 Relevance of the Study
Soil tests measure the relative nutrient status of soil and are used as a basis for profitable and environmentally responsible fertilizer application. The accuracy of a soil test result is influenced by the laboratory analysis but may be influence even more by the quality of the soil sample. Sample collection is extremely important in the accuracy and repeatability of a soil test. Sample handling following collection is also important. A soil sample which does not represent the area being sampled will be misleading and result in over or under-application of fertilizer. It is therefore very important to collect and handle soil samples properly.
This work will help to direct soil Samplers in methods for determining a composite soil test, but will also introduce site-specific methods for revealing within-field nutrient levels. The challenge has been to provide meaningful information about field and within field nutrient levels with minimal cost to the Producer.
1.5 Aim and Objectives of the Study
The aim of this work is to determine the macronutrient contents of cassava leaves composted agricultural soil: experimental investigation.
Specific objectives include;
- To know the effect of cyanide present in the soil.
- To analyze the soil pH (check if it is acidic or not) and know the range.
- To measure the increase/decrease of the soil macronutrients resulting from the application of cassava leaves compost.
- To know the kinetics behind the study.