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 Effect of Sarosate (N-Phosphonomethyl Glycine) a Non selective Herbicide on the Growth of Some Common Soil Fungi.
1.3 Statement of Problems
Investigation revealed that Herbicide as a managemhnt 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 investigate the Effect of Sarosate (N-Phosphonomethyl Glycine) a Non selective Herbicide on the Growth of Some Common Soil Fungi. In achieving this aim, the following specific objectives were laid out as follows:
- To identify the possible effects of the herbicide usage on soil fungi;
- To determine the factors militating poor herbicide usage on soil fungi;
- 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 fungi?
- What are the factors militating poor herbicide usage on soil fungi?
