摘要：This study examines the costs, returns and productivity due to fungicide use in cocoa production under the Structural Adjustment Programme (SAP) in South Western Nigeria. Budgetary (gross margins) and production function analyses are the techniques used to analyze the primary data derived from a sample survey of cocoa farmers in Osun and Ondo States of Nigeria. The data were analysed to provide estimates of economic benefits of fungicide use. The study shows that net returns to fungicide use are positive. Fungicides are efficiently utilized by the respondents. However, the efficiency of use varies from one state to the other. It is higher amongst growers in Osun than those in Ondo State but the use rate of fungicide may be increased without any adverse economic consequences in both states. var currentpos,timer; function initialize() { timer=setInterval("scrollwindow()",10);} function sc(){clearInterval(timer); }function scrollwindow() { currentpos=document.body.scrollTop; window.scroll(0,++currentpos); if (currentpos != document.body.scrollTop) sc();} document.onmousedown=scdocument.ondblclick=initialize A. A. TIJANI 64 over utilization of these chemicals while others found underutilization depending on the methodology employed. This implies the need for further research into pesticide productivity. Given the aforementioned situation, the objective of this study is to estimate costs, returns and productivity of fungicide use on cacao. This is because fungicides used in controlling black pod disease accounted for about 85% of fungicides used in Nigeria. In fact, cocoa pesticides dominate the insecticide and fungicide market in Nigeria (Ikemefuna, 1998). METHODOLOGY Primary data were used for this study. The data were sourced from a cross-sectional survey of cocoa farmers in four Local Government Areas (LGAs) each in Osun and Ondo States in the last quarter of 1997. Information was collected on the socio-economic characteristics of the farmers, output of cocoa beans per hectare, fungicide and application costs as well as information on other production costs. A three-stage random sampling procedure was adopted in collecting the data. At the first stage the LGAs were selected, then five villages were chosen from each of the LGAs; that is, a total of 20 villages were selected per state. Lastly eight farmers were selected from each chosen village, thus totaling 160 respondents per state. At the final stage, 320 respondents were interviewed for the study. Information was obtained from each farmer with the aid of a pre- tested structured questionnaire administered by the author with the assistance of trained enumera- tors. Two methods were used to estimate the economic benefits derived from chemical control of black pod disease: (i) production function analysis and (ii) budgetary analysis. A multi - factor production function investi- gated in this study is expressed mathematically as: Y = f [X 1 , X 2, X 3, X 4, X 5, X 6, X 7, X 8 , ] + e .............…….(1) Where Y is cocoa output in tonnes of har- vested cocoa beans; X 1 is amount of fungicides applied measured in kilogram; X 2 is farm size, measured in hectares; X 3 is capital consumption, measured in Naira; X 4 is labour input, measured in mandays; X 5 is the number of farm locations (diversification index); X 6 is years of formal education (management index); X 7 is number of weeding per season; X 8 is age of cocoa farm, measured in years; and e, is the error term. The relevant production function parameters, such as the marginal product and value of the marginal product are estimated. The estimated marginal value products can be compared to the unit price of the input to determine the efficient level of input use. Both Cobb-Douglas and Lichtenberg – Zilberman (1986) production models were employed in estimating the production relation contained in (1), A conceptual basis for the production models of both Cobb-Douglas and Lichtenberg – Zilberman models is provided by particular forms for (1) which are expressed as Q = Q (Z,B) …………............................................. (2) Where α is output, Z is an input, and B is the pest level.and B = B (X,B 0 ), ...........................................………… (3) Where X is the level of control agents (e.g. fungicide) and B o is the uncontrolled pest level. For example, consider the forms Q = áZ B B -y ………….......….....................…………….(4) and B = B 0 X - σ ……............…….……….......….…….(5) Where á, B, , and σ are positive parameters, and other variables are as previously defined. The reduced form for output is Q = áZ B B - b ………......................................….......….(6) Where a = áB 0 - and b = á. The model represent- ed by equation (6) is the Cobb-Douglas type. As an alternative to (6), Lichtenberg and Zilberman suggested a production model of the form. Where G(.) is the proportion of the capacity of the damaging agent abated by use of X; 0<G(X) < 1. Hence, their model makes explicit the distinction between productive (Z) and protective (X) inputs in accounting for a finite damaging capacity of a pest population. As Lichtenberg and Zilberman have argued, the nature of damage control suggests that the realized volume of output Q is a function of standard inputs (Z l …., Z n ), and a damage abatement function G (x) that gives the proportion of the destructive capacity of the damaging agent eliminated by the application of a level of control agent X. Some elements of X may be included in Z if the use of X affects potential yield. The abatement function possesses the properties of () [] () 7 ........ .......... .......... .......... .......... .......... .......... .......... γ β α X G Z Q = γ
关键词：Cocoa; pests; fungicide use rate; efficiency; blackpod disease
