Peter I. Ezeaku et al./ Elixir Agriculture 61 (2013) 17033-17039 17033 Introduction Appropriate land use decisions are vital in determining of suitability of land for a specific use such as irrigated or rainfed agriculture, referred as land utilization types (FAO, 1985), and to achieve optimum productivity of the land. Land suitability evaluation is one of the effective tools for an effective management of land information on which such decisions should be based. Land suitability evaluation, commonly known as ‘land evaluation’, was defined as ‘the process of assessment of land performance when the land is used for specified purpose’. FAO distinguished two general kinds of land suitability evaluation approaches: qualitative and quantitative. A qualitative approach is used to assess land potential at a broad scale, or employed as a preliminary to more detailed investigations. The results of classification are generally given in qualitative terms only, such as highly suitable (S 1 ), moderately suitable (S 2 ), currently not suitable (N 1 ) and permanently not suitability (N 2 ). The second approach is the parametric-quantitative that involves deductive, inductive or simulation modeling systems (Shields et al., 1996) to quantify the potential of land for specific uses. A deductive approach deals mainly with the estimated yield as an index relative to a standard yield, while an inductive technique utilizes land characteristics as evaluation criteria to establish land unit indices, which usually involves additive (arithmetic), multiplicative, and complex operations (Sys, 1985). Simulation modelling uses a complex of multivariate factors, and makes use of a computer based analysis system such as an expert system (Ezeaku and Agbede, 2005). However, use of a fuzzy set methodology (Burrough et al, 1992) has made a significant contribution to the refinement of land suitability analyses. Land evaluation techniques ‘predict land performance, both in terms of the expected benefits from and constraints to productive land use, as well as the expected environmental degradation due to these uses’ (Rossiter, 1996). In this case, biophysical parameters and/or socioeconomic conditions of the area are considered. Crucial to the estimation of land suitability is the matching of land characteristics with the requirements of envisaged land utilization types (Ruan, 1990). Thus, land evaluation results from a complex interaction of physical, chemical and bioclimatic processes and reliable evaluation models predict accurately the behavior of land (Sys, 1985). Physical land suitability evaluation is considered a prerequisite for land-use planning and development (FAO, 1984) as it provides information on the constraints and opportunities for the use of the land and therefore guides decisions on optimal utilization of land resources. The present study applied spatially based parametric, limiting and fuzzy set models of land suitability analysis in order to evaluate the physical land suitability for rice production along Katsina-Ala flood plains in Central region of Nigeria. Materials and methods Site description The study area is the River Katsina-Ala flood plain in Ugbema, Buruku local Government area of Benue state, Central Nigeria. It is located at latitude 07° 08.610 N, and longitude 009°16.681 E as detected by a hand held Global positioning system (GPS). Climate/Vegetation/Soil Benue State enjoys a tropical climate which manifest into two distinct seasons that begins from April to October and the dry season from November to March. The mean annual rainfall is 1,504 mm and mean temperature of 21°C (Benue River Basin Fuzzy and Parametric Methods for Land Evaluation along Katsina-Ala Flood Plains in Central Region of Nigeria: Application to Rice Production Peter I. Ezeaku* and Charles Tyav Department of Soil Science, University of Nigeria, Nsukka, Nigeria. ABSTRACT Rice is an important crop that plays a vital role in diets and economy of farmers in Katsina- Ala in northcentral Nigeria. In this study, Fuzzy set theory, parametric and limitation models were applied to determine the suitability of Katsina-Ala flood plains for rice production. Soils of two pedons were analyzed and the characteristics used as inputs in the model application. The result showed variability of suitability of the land qualities. Climate, soil depth and flood duration were highly suitable (S 1 = 95). Texture was moderate (S 2 ). Soil pH and available P ratings showed currently not suitable (N 1 =20) for both pedons. Soil organic carbon was moderately suitable (S 2 ) but most critical in the normalized pairwise comparison matrix. Salinity (EC) and CEC suitability was moderately suitable (S 2 ). Parametric and non- parametric aggregate suitability showed moderate suitability (S 2 =63.8) for current index with fertility limitations (S 2 f). The potential index was high suitability (S 2 ) for both pedons. Fuzzy regression between land index and observed rice yield was high (R 2 = 0.90). The use of the three models could serve as spatially based decision-making parameters in agricultural land use planning but fuzzy method was recommended based on its relative advantage to other predictors. © 2013 Elixir All rights reserved ARTICLE INFO Article history: Received: 28 May 2013; Received in revised form: 24 July 2013; Accepted: 6 August 2013; Keywords Model application, Land suitability index, Rice production, Central Nigeria Elixir Agriculture 61 (2013) 17033-17039 Agriculture Available online at www.elixirpublishers.com (Elixir International Journal) Tele: E-mail addresses: ezeakup@yahoo.com © 2013 Elixir All rights reserved