1.1 Introduction
The use of herbicides in agriculture has contributed tremendously to both food and cash crop production all over the world. One of the challenges undermining the farming business (Ntow et al., 2006), has been the invasion of many common weed species due to favorable environmental conditions such as abundance of rainfall, adequate sunlight, fertile soil etc. in Nigeria. Hence, manufacturers have adopted flooding the market with all kinds of herbicides that are meant for the elimination of different kinds of weeds at different stages of their growth (Sebiomoet al., 2011). Perhaps, the efficacy of these herbicides in controlling the target weeds has resulted in the application of these chemicals by most farmers.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitation of the study and Definition of technical terms.
1.2 Background of Study
Herbicides use is not limited to crop production alone, its use in animal production include antibiotics administered either by injection or combined with feed; to control infectious diseases and parasites that often arise when animals are raised under extremely crowded conditions. In similar way to tractors, ploughs and other implements, herbicides have now become an integral part of the complex word of technical inputs required for modern agricultural production and are accepted as a standard tool of the trade by farmers throughout the world (Lever, 1990). For several years humans have utilized herbicides to protect their crops. The first known agrochemical was sulfur-dusting used in ancient summer about 4,500 years ago in ancient Mesopotamia. By the 15th century, toxic chemicals such as arsenic, mercury and lead were being applied to crops to kill insects. in the 17th century, nicotine sulfate was extracted from tobacco leaves for use as an insecticide. The 19th century saw the introduction of more natural agrochemicals; pesticides and pyrethrum, which are derived from chrysanthemums, and rotenone, which is derived from the roots of tropical vegetables (Miller, 2002).
However, some soil organisms use these herbicides in the process of degradation as carbon energy source for their metabolic activities. Numerous studies have shown that the level of contamination of soil with these chemicals depends on the persistency of the herbicides in the soils environment, the quantity, frequency of application and the toxicity of the chemicals. However, most of these herbicides are designed to persist longer enough to have the desired effect on the weeds (Greer et al., 1990, Wang et al., 2008 and Vandana et al., 2012).
The fate of herbicides applied onto the soil environment is governed by two major processes; transfer and degradation. The transfer process involves percolation, runoff, flora and fauna uptake, and sorption and desorption, for which the applied chemicals remain physically intact in the soil environment. The degradation processes include microbial decomposition, plant detoxification, rhizosphere chemical breakdown and photodecomposition which are chemically engineered. These two processes determine the persistency of herbicides, its efficacy for weeds, as well as its potential for soil and ground water contamination (Subhani et al., 2000). Therefore, there is the need to understand the factors affecting the degradation processes of herbicide in order to adopt effective strategies to reduce its persistent period within the soil environment. A large number of the populace in Nigeria can't read and understand herbicide label. This has resulted in the contamination of streams, rivers and ground water which is an important natural resource (Baran et al., 2007). These contaminations do not pose danger to only the non-target organisms and the environment but exposes human beings to many health implications.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Effects of the Use of Herbicide on the Soil.
1.3 Statement of Problems
Herbicide as a management tool for weed control optimum production practices had been a reality to increased yield and quality of Agriculture product. Globally world health organization estimates that at least 3 million cases of acute poisoning and 20,000 deaths occur annually due to exposure to pesticide (Orhii, 2010).
Most of the farmers are complaining of contacted diseases, acute poisoning and heath. Ill health and contacted disease include ulcer, heart pain, skin rashes respiratory condition and eyes problem. The handling of toxic chemicals has sensitive effect on soil. Field study unveiled acute decrease in bio-mass, organic matter soil degradation, low average of precipitation and water retention in the soil.
1.4 Aim and Objectives of Study
The aim of the study is to evaluate the Effects of the Use of Herbicide on the Soil. In achieving this aim, the following specific objectives were laid out as follows:
- To identify the possible effects of the herbicide usage on soil;
- To determine the factors militating poor herbicide usage on soil;
- To prolong herbicides use in the farms at Warri-South district in Delta State;
- To proffer solution that will eradicate the challenges encountered in herbicide usage on soil.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What are the possible effects of the herbicide usage on soil?
- What are the factors militating poor herbicide usage on soil?
- How can herbicides usage be prolong in the farms at Warri-South district in Delta State?
1.6 Significance of Study
This study will be of immense benefit to researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.7 Scope of Study
The study focuses on the Effects of the Use of Herbicide on the Soil in Warri-South district in Delta State.
1.8 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.9 Definition of Terms
Herbicide: A herbicide is a chemical substance used to control or eliminate unwanted plants, specifically weeds. Herbicides can be selective, targeting specific plant types, or non-selective, affecting all plants. Their use is widespread in agricultural practices to enhance crop yields by reducing competition for resources (Baker et al., 2018).
Soil Health: Soil health refers to the capacity of soil to function as a living ecosystem that supports plant growth, regulates water, filters pollutants, and cycles nutrients. Healthy soils are characterized by biological diversity, good structure, and sufficient organic matter, which contribute to their resilience against environmental changes (Doran & Zeiss, 2000).
Microbial Diversity: Microbial diversity encompasses the variety of microbial species present in a given environment, including bacteria, fungi, and archaea. In soil, microbial diversity is crucial for nutrient cycling, organic matter decomposition, and overall soil fertility, as different microbes perform distinct ecological functions (Nannipieri et al., 2018).
Soil Structure: Soil structure refers to the arrangement of soil particles and the spaces (pores) between them. Good soil structure enhances aeration, water infiltration, and root penetration, which are essential for plant growth. Compacted or poorly structured soils can lead to reduced agricultural productivity and increased erosion (Hudson, 1994).
Herbicide Residues: Herbicide residues are the remnants of herbicides left in the soil after application. These residues can persist in the environment, affecting soil health and potentially leading to contamination of water sources. The persistence of herbicide residues depends on factors like soil type, microbial activity, and climatic conditions (Zhao et al., 2021).
Biodiversity: Biodiversity refers to the variety of life forms within a given ecosystem, including the diversity of species, genetic diversity, and ecosystem diversity. High biodiversity in soil contributes to its resilience, allowing ecosystems to adapt to disturbances and maintain ecological functions (Tilman et al., 2006).
Weed Resistance: Weed resistance is the ability of weed populations to survive herbicide applications that would normally control them. This phenomenon arises from selective pressure exerted by repeated herbicide use, leading to the proliferation of resistant strains. Managing weed resistance is critical for sustainable agriculture (Gressel, 2002).
