J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Qualitative and Economic Land Suitability Evaluation for Tea (Camellia sinensis L.) in Sloping Area of Guilan, Iran Mitra Darvishi-Foshtomi1, Mehdi Norouzi1, Mojtaba Rezaei2, Mehdi Akef1 and Ali Akbarzadeh3* 1Department of Soil Science, Faculty of Agricultural Science, University of Guilan, Rasht, IRAN 2Rice Research Institute, Rasht, IRAN 3Department of Soil Science, Faculty of Agricultural Engineering and Technology, University College of Agriculture and Natural Resources, University of Tehran, Karaj, IRAN ABSTRACT In the present study and research work, land suitability evaluation (qualitative and economic classification) has been determined for tea in an area including 5000 ha in sloping lands of Guilan province in Iran. In the study area, eight soil series and three orders (Inceptisols, Entisols and Alfisols) were identified. The simple limitation method, the limitation method regarding number and intensity and the parametric methods including the Square root and the Storie methods were used for qualitative land suitability evaluation. Results of first and second methods showed similar marginally suitability classes (S3). According to these methods, the most important limiting factors were climate, topography and physical soil characteristics. Moreover, results of Storie method showed unsuitable condition for tea cultivation (N2), except one land unit, which had non-suitable but correctable conditions (N1). In addition, results of Square root method showed unsuitable condition for one and non-suitable conditions but correctable for six land units and just one land unit had marginally suitable land classes. Economic land suitability evaluation showed that four land units had marginally suitability, three land units had moderately suitability (S2), and only one of them had the highest class (S1) and the best gross benefits. Sloping area in Guilan used to be covered by forest, but regarding to the highly destruction of plant cover and deforestation in order to tea cultivation, an intensive erosion in the area is predict to happen in future. Keywords: land suitability, qualitative and economic land evaluation, tea INTRODUCTION Land evaluation is the assessment of land performance when used for specified purposes. The principal objective of land evaluation is to select the optimum land use for each defined land unit (Sys et al. 1991). Determining land suitability for various efficiency is not only a way to prevent the destruction of agricultural lands, but one of the most important and most basic methods is to combat this problem. Agro ecological land evaluation predicts land behavior for each particular use, and soil quality evaluation predicts the natural ability of each soil to function. However, land evaluation is not the same as soil quality assessment, because biological parameters of the soil did not consider in land evaluation (Braimoh and Vlek 2008). Many studies related to various aspects of land suitability for crop cultivation have been conducted on the basis of FAO framework in different countries (Chinene and Situmbanauma 1988; Embrechts et al. 1988; Oise 1993; Habrurema and Steiner 1997). Zang et al. (2004) conducted a system for the quantitative evaluation of soil productivity developed and deployed in Gaoyou County, China. The objective of their study was to develop a new quantitative method, within the framework of a GIS. Results of this study showed soils with a bleached layer in the soil profile in sloping areas were not suitable for rice and wheat, but suitable for tea plantations, fruit trees or other kinds of cash crops. Also in several parts of Iran land suitability evaluation for some of crops has been done by Sarvari and Mahmoudi (2001), Seyed Jalali (2001), Jafarzadeh and Abbasi (2006), Jafarzadeh et al. (2008), Rahimi Lake et al. (2009), Behzad et al. (2009). Economic land evaluation is a method for predicting the micro-economic value of implementing a given land-use system on a given land area. This is a more useful prediction of land performance than a purely physical evaluation, since many land-use decisions are made on the basis of economic value (Rossiter 1995). Tea (Camellia sinensis L.) plant is an important source of different beverages, which is claimed to be the most widely consumed fluids after water, globally, and Iran as well. Lahijan region in Guilan province is considered as the major tea producing area in Iran. Tea is mainly cultivated in the hill slopes in the area (Khormali et al. 2007). The objectives of this study were land suitability evaluation (qualitative and economic classification) for tea in steep slopes of Lahijan and Langrud, as well as suitability maps within the framework of GIS.                                                              * Corresponding author: aliakbarzadeh1236@yahoo.com 135 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 MATERIALS AND METHODS Field description and Sampling The research was conducted in province of Guilan in north of Iran. The study area is about 5000 hectare in sloping areas of Lahijan and Langroud, lying between 37º 7΄ 50˝ (4109809 m in UTM system) to 37º 11΄ 36˝ (4116814 m in UTM system) northern latitude and 50º 2΄ 9˝(414420 m in UTM system) to 50º 11΄ 9˝ (424770 m in UTM system) eastern longitude (Fig. 1). The study area is a mountain physiographic unit and cultivated by tea. The average annual precipitation and temperature of the region are 1312 mm and 16.5 °C, respectively. Annual air humidity and annual evaporation rate are 77.41% and 884 mm (estimation of potential evapotranspiration by Penman-Monteith method and CROPWAT software) respectively. Climatic data were prepared from Rasht synoptic weather forecasting data station and Lahijan climatology center. After interpretation of aerial photographs and output results obtain from DEM/GIS, sixteen profiles were dug. In order to obtain a reliable soil data, the soil survey reports from the profiles inspected and then eight profiles within different land units (Fig. 2) were chosen as representative for a more detailed investigation, where parent materials in pedons were granite and phyllite (Table 1). A brief morphological characteristic of horizons for the selected profiles (Schoeneberger et al. 2002) is presented in Table 2. Figure 1. Study area in north of Iran (Guilan province) 136 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Figure 2. Study area based on land units Table 1. Environmental information and classification of the eight soil profiles Soil classification Land Profile Soil Slope Elevation Solum Parent unit number Series (%) (m) thickness material WRB systems a (cm) Soil taxonomy b 1.1 1 Koh-Bijar .5 99 50 phyllite Alisols Clayey (Fine), Mixed, Active, thermic Inceptic Haploudalfs 2.1 4 Kate shall (1) 113 75 phyllite Alisols Clayey (Fine), Mixed, Superactive, ThermicUltic Haploudalfs 3.1 15 Porush 162 90 phyllite Alisols Fine Loamy, Mixed, Superactive, Thermic Ultic Haploudalfs Fine Loamy, Mixed, Active, 4.1 16 Hajisara 43 57 granite Cambisols Thermic Typic Dystrudepts 5.1 3 Dizbon 298 100 granite Cambisols Fine Loamy, Mixed, Superactive, Thermic Typic Dystrudepts 6.1 8 Kore-kabijar 75 43 phyllite Umbrisols Sandy, Mixed, Superactive, Thermic Typic Dystrudepts 7.1 2 Kate shall (2) 71 25 phyllite Regosols Fine Loamy, Mixed, Superactive, Thermic Typic Udorthents Coarse Loamy, Skeletal, Mixed, 8.1 6 Divshall 83 25 granite Cambisols Superactive, ThermicTypic Dystrudepts a IUSS Working Group WRB (2006). b Soil Survey Division Staff (2006) classified in family level. 137 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Table 2. Abbreviated morphological properties of horizons for the selected profiles Horizon Depth a Color Consistenced (cm) Boundary Texture b Structurec Porese Dry Moist Moist wet Profile 1 Ap 0-25 aw 10YR3/6 10YR4/6 CL 2fgr fr s/p 2m Bt 25-50 cs 7.5YR5/4 7.5YR5/6 C 1vfabk-2msbk fi s/p 2f C1 50-84 cs 7.5YR5/6 7.5YR5/8 SCL m Fr ss/p 1f C2 84-125 - 7.5YR5/8 7.5YR5/8 C m Fi s/p 1vf Profile 4 Ap 0-16 aw 10YR4/3 10YR6/3 C 2fgr fi s/p 1m Bt1 16-38 gs 10YR4/6 10YR6/4 C 2mabk fi s/p 1vf Bt2 38-75 gs 10YR4/4 10YR6/4 C 2mabk fi s/p 1vf C 75-100 - 10YR5/4 10YR5/4 C m fi s/p - Profile 15 Ap 0-18 aw 10YR3/3 10YR5/6 C 2mgr fi s/p 2m AB 18-54 cs 10YR4/4 10YR5/6 CL 2mabk-2mgr fr s/p 2m Bt 54-90 gs 10YR5/4 10YR6/4 C 1mabk-m fi s/p 1f C 90~ - - - - - - - - Profile 16 Ap 0-30 aw 10YR3/4 10YR4/6 SCL 1fgr fr-lo ss/sp 2m BC 30-57 gs 7.5YR4/6 7.5YR5/6 SCL 1fabk-m fr-lo ss/sp 1m C 57-94 - 7.5YR5/6 7.5YR5/8 SCL 0 fr-lo ss/sp 1m a a = abrupt, c = clear, g = gradual; s = smooth, w = wave.b C= clay, L= loamy, SL= sandy loam, SCL= sandy clay loam, LS= loamy sand, CL= clay loam.c 0 = structureless, 1 = weak, 2 = moderate; vf = very fine, f = fine, m = medium; gr = granular, abk = angular blocky, sbk = subangular blocky, m= massive. d lo= loose, vfr = very friable, fr = friable, fi = firm; s = moderately sticky, ss = slightly sticky, sp = slightly plastic, p = plastic. e 1= few, 2= common, 3= many; vf= very fine, f= fine, m=medium. 138 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Table 2. Continued Horizon Depth Boundary a Color d (cm) Texture b Structurec Consistence Porese Dry Moist moist wet Profile 3 Ap 0-20 aw 10YR4/6 10YR5/6 SCL 2mgr vfr ss/sp 2m AB 20-50 cs 10YR5/6 10YR6/6 SCL 2mabk-2mgr fr-fi ss/sp 1f BC 50-100 cs 7.5YR4/6 7.5YR5/6 L 2mabk-m fr-fi ss/sp 1f Cr1 100-130 cs 7.5YR4/4 7.5YR5/6 SCL 0 fr-fi ss/sp 1f Cr2 130-150 - 7.5YR4/6 7.5YR5/8 SCL 0 fi s/p 1f Profile 8 Ap 0-20 aw 10YR2/2 10YR3/3 CL 2mgr fr s/p 2m Bw 20-43 cs 10YR3/3 10YR3/4 SL 2mabk-2msbk vfr-lo ss/sp 2m C 43-68 - 10YR3/6 10YR3/6 LS 0 vfr-lo ss/sp 2m Profile 2 Ap 0-25 aw 7.5YR3/4 7.5YR4/6 L 1mgr fr s/p 2m C1 25-50 cs 10YR5/8 10YR5/8 SL 0 fr ss/sp 1f C2 50-85 cs 10YR3/6 10YR5/8 SCL 0 fr ss/sp 1f C3 85-100 - 10YR4/6 10YR4/6 SCL 0 fr ss/sp 1f Profile 6 Ap 0-10 aw 10YR3/6 10YR5/8 SL 2fgr fr ss/sp 3m BC 10-25 gw 10YR4/6 10YR6/3 SL 1msbk-m fr ss/sp 2m C 25-75 - 10YR4/6 10YR6/4 SL 0 fr ss/sp 2m a a = abrupt, c = clear, g = gradual; s = smooth, w = wave.b C= clay, L= loamy, SL= sandy loam, SCL= sandy clay loam, LS= loamy sand, CL= clay loam.c 0 = structureless, 1 = weak, 2 = moderate; vf = very fine, f = fine, m = medium; gr = granular, abk = angular blocky, sbk = subangular blocky, m= massive. d lo= loose, vfr = very friable, fr = friable, fi = firm; s = moderately sticky, ss = slightly sticky, sp = slightly plastic, p = plastic. e 1= few, 2= common, 3= many; vf= very fine, f= fine, m=medium. Laboratory analysis Physical and chemical properties of the sieved soil samples (<2mm) were determined after being air-dried. Particle size analysis by hydrometer method (Gee and Or 2002), and bulk density by clod method (Blake and Hartge 1986) were measured. The samples pH values was measured in the mixture of soil/deionized water (1:1) and in the mixture of soil/CaCl2 (1:2) 0.01 M (Thomas 1996). Electrical conductivity (EC) was determined in a saturation extract of soil using conductivity meter (Rhoades 1996). Organic carbon (OC) content was measured by the Walkley–Black wet oxidation method (Nelson and Sommers 1996). Available phosphorus by Olsen method (Kuo 1996) and total nitrogen by Kjeldahl method (Bremner 1996) were determined. Cation exchange capacity (CEC) was determined using sodium acetate (NaOAc) at pH=8.2 (Sumner and Miller 1996). Exchangeable cations (Ca, Mg, Na and K) were extracted using 1 M ammonium acetate (pH=7.0) and were determined by atomic absorption and flame emission spectrometer (Suarez 1996; Helmke and Sparks 1996). Land suitability evaluation A wide range of limiting physical, economic and social factors can restrict suitability of the land for different kinds of use (FAO 2007). For qualitative land suitability investigation, simple limitation method, limitation regarding number and intensity method and parametric methods (Storie and square root) were used. Simple limitation method compares the plant requirements with its corresponding qualitative land and climatic characteristics and the most limiting characteristics defines land suitability class. The parametric land evaluation consists in numerical rating of different limitation levels of land characteristics according to a numerical scale between a maximum (normally 100) to a minimum value. Finally, the climatic index, as well as the land index, is calculated from these individual ratings. The calculation of these indices can be carried out following two procedures (Eq. 1 and Eq. 2); 139 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 1. The Storie method (Storie 1976): I  A B C   ... (Eq. 1) 100 100 Where: I = index (%) A, B, C etc. = ratings (%) 2. Square root method (Khiddir 1986): I R A B min    ... (Eq. 2) 100 100 where: I = index (%) Rmin = minimum rating (%) A, B, C etc. = remaining ratings (%) Application of these methods implies that requirement tables have to be produced for each land utilization type. We compared the land characteristics with the plant requirements tables introduced by Sys et al. (1993). For determination, the limits of land classes we used pattern introduced by Sys et al. (1991). The land suitability classes are defined as follows:  Lands having indexes >75 are in S1 (very suitable) class.  Lands having indexes 50-75 are in S2 (moderate suitable) class.  Lands having indexes 25-50 are in S3 (marginal suitable) class.  Lands having indexes < 25 are in N (non-suitable) class. Economic land evaluation calculated based on difference between gross income and variable costs. Variable costs like weeding, fertilizers, spraying and pouring herbicide and fertilizers, the cost of harvesting and collecting the yield, the cost of loading and transportation, unpredicted costs and etc were calculated (7302500 Rials in hectares-10000 Rials ~ 1 Dollar). In addition, for determination of land classes in economic land evaluation, we used pattern introduced by FAO (1983) as mentioned below:  Lands having >75 maximum gross benefit are in S1 class  Lands having 50-75 maximum gross benefit are in S2 class  Lands having 0-50 maximum gross benefit are in S3 class  Lands having <0 maximum gross benefit are in N class After determination of qualitative and economic land suitability classes, we presented the output results as georeferenced soil suitability maps using Arc GIS software version 9.2. RESULTS AND DISCUSSION Regarding to results obtained from description of the profiles and physical and chemical analysis of the samples (Table 3), soils were classified as Hapludalfs, Dystrudepts and Udorthents (Soil Survey Staff 2006) and Alisols, Cambisols, Umbrisols and Regosols in WRB system (IUSS Working Group WRB 2006). The most important feature observed, is the clay illuviation process shown as Bt horizon mainly in 1, 4 and 15 profiles. Sand content is higher in profiles with granite parent mater. 140 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 141 Table 3. Abbreviated physico-chemical properties of horizons for the selected profiles Horizon Depth Texture (g.kg -1) BDa Gravel pHb ECe OC c N P CEC d TEB e B.S f ESP g (cm) sand silt clay (g.cm-3) (%) H O CaCl (ds.m-12 2 ) (g.kg-1) ( mg.kg -1) (Cmol.kg-1) (%) Profile 1 Ap 0-25 326 327 347 1.2 25.4 4.9 3.9 0.4 24 2 5.1 18.9 4.01 21.2 1.64 Bt 25-50 326 247 427 1.24 8.8 4.6 4 0.3 3.6 0.6 2.85 19.6 7 35.7 1.77 C1 50-84 486 167 347 1.32 18.9 4.6 4.1 0.5 3.5 0.5 2.82 18.4 8.02 43.4 1.89 C2 84-125 326 267 407 1.42 - 4.6 4.1 0.7 3.4 0.4 2.79 19.4 8.99 46.3 1.33 Profile 4 Ap 0-16 206 307 487 1.25 - 4.5 3.8 0.4 25.8 2.2 7.9 34.6 12.1 35 0.8 Bt1 16-38 166 207 627 1.55 - 5.2 4.3 0.1 1.79 0.05 7.8 37.4 16.6 44.4 0.7 Bt2 38-75 166 247 587 1.64 - 5.1 4.2 0.2 1.73 0.05 7.8 32.3 16.9 52.3 1 C 75-100 206 307 487 1.41 - 5.7 4.9 0.3 1.65 0.04 7.3 21 18.2 86.7 1 Profile 15 Ap 0-18 262 333 405 1.2 1.04 5.2 4.4 0.2 23.2 2.3 3.2 29.5 8.48 28.8 2.04 AB 18-54 272 412 345 1.6 2.07 4.9 4.1 0.2 22.6 2.2 3 28.8 7.78 27.2 1.35 Bt 54-90 102 293 605 1.7 0 5.5 4.8 0.1 3.5 0.4 2.28 43.7 15.37 35.1 1.59 C 90~ - - - - - - - - - - - - - - - Profile 16 Ap 0-30 506 207 287 1.32 8.4 4.1 3.3 0.8 18.9 2 10.1 24.56 5.8 23.6 1.68 BC 30-57 486 187 327 1.4 8.4 3.9 3.4 0.6 17.8 0.5 9.3 19.12 6.7 35 2.44 C 57-94 606 127 267 1.47 10 4.4 3.8 0.4 17.4 0.5 8.4 15 6.78 44.7 2.98 a BD Bulk density; b = pH in 1:1 H2O and 1:2 CaCl c 2; OC= Organic Carbone; d CEC= Cations Exchange Capacity; e TEB= Total Exchangeable Bases; f B.S= Base Saturation; g ESP= Exchangeable sodium Percentage J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 142 Table 3. Continued Depth Texture (g.kg-1) BDa Gravel pHb ECe OC c N P CEC d TEB e B.S f ESP g Horizon (cm) sand silt clay (g.cm-3) (%) H2O CaCl2 (ds.m-1) (g.kg-1) ( mg.kg-1) (Cmol.kg-1) (%) Profile 3 Ap 0-20 518 273 209 1.24 22.5 4.1 3.5 0.8 13.6 1.7 5 19.34 4.3 22.2 2.6 AB 20-50 518 253 229 1.34 14 4.4 3.6 0.4 12.2 1.8 4.5 20.1 6 29.8 2.2 BC 50-100 438 233 329 1.36 10.6 4.8 3.8 0.18 6.5 0.5 4.5 17 5.5 32.3 3 Cr1 100-130 578 133 289 1.45 16.3 5 4.2 0.16 1.7 0.4 3.8 14.5 4.9 33.6 2.9 Cr2 130-150 538 173 289 1.52 18.7 5 4.1 0.16 1.6 0.4 3.4 14.56 4 27.5 2.6 Profile 8 Ap 0-20 406 267 327 1.33 - 5.4 5 0.5 18.9 0.9 3.3 19 5.4 28 5 Bw 20-43 566 147 187 1.46 - 5.9 5.1 0.3 14.1 0.7 2.7 14 4 28.1 4.5 C 43-68 806 87 107 1.52 - 5.9 5.1 0.2 1.4 0.3 1.3 7 2.7 38.9 4.4 Profile 2 Ap 0-25 489 313 198 1.3 - 4.8 3.8 0.1 9.2 2.2 3.5 16 3.76 23.5 3.7 C1 25-50 549 273 178 1.48 - 5.2 4.4 0.1 7.9 1.2 1.4 16 4.5 28.1 3.5 C2 50-85 509 253 238 1.45 - 5.2 4.3 0.09 1.9 0.6 1.4 20 6.01 30.1 2.3 C3 85-100 509 273 218 1.48 - 5.1 4.2 0.07 1.9 0.6 0.7 15 5.9 39.3 2 Profile 6 Ap 0-10 517 294 189 1.34 23.8 4.2 3.5 0.6 19.6 0.3 9.5 13 4.5 33.6 4.1 BC 10-25 578 234 189 1.31 34.7 4.5 3.7 0.7 18 0.3 3.8 11 3 27.3 4.4 C 25-75 737 174 89 1.5 47.4 5 4.3 0.7 17.4 0.2 3 7 2 28.7 2.3 a BD b = Bulk density; pH in 1:1 H2O and 1:2 CaCl2; c OC= Organic Carbone; d CEC= Cations Exchange Capacity; e TEB= Total Exchangeable Bases; f B.S= Base Saturation; g ESP= Exchangeable sodium Percentage J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Qualitative land suitability and climatic suitability classes for tea plantation in study area (Table 4) showed that all land units had severe climatic suitability class (S3). Main limitation in determining suitability classes were average minimum temperature in the coldest month. According to Simple limitation method, all land units had severe suitability class (S3), the most important limiting factors in whole land units were climate limitations; also 1-1, 3-1, 7-1 and 8-1 land units had topography limitations that caused by slope percentage. Only 8-1 land unit had physical soil characteristics limitation that caused by coarse fragments (high gravel percentage) (Fig. 3-a). High gravel percentage limitations comprise physical, chemical and fertility limitations. It decreased organic matter retention, number and intensity of microorganism activity, cations and anions in soil. All land units had moderate limitation levels (S2) too, for instance, 8-1 land unit had fertility limitation and the loss of nutrient caused by solum thickness and high gravel percentage in moderately suitable (S2) classes. Results of qualitative suitability class in limitation regarding number and intensity method accurately were similar to those of the simple limitation method (Fig. 3-b). Table 4. Qualitative land suitability and climatic suitability classes for tea plantation in study area Area Qualitative suitability class Land Climatic Limitation Parametric Parametric unit suitability Simple regarding (Storie) (Root square) ha (%) class limitation number and Land Land Land Land intensity index class index class 1.1 2437 31.47 S3 S3ct S3ct 5.74 N2 17.11 N1 2.1 520 6.7 S3 S3c* S3c 13.12 N1 27.57 S3 3.1 379 4.9 S3 S3ct** S3ct 5.93 N2 17.25 N1 4.1 698 9.06 S3 S3c S3c 7.43 N2 21.85 N1 5.1 2015 26.07 S3 S3c S3c 7.13 N2 21.37 N1 6.1 579 7.5 S3 S3c S3c 9.53 N2 24.71 N1 7.1 604 7.8 S3 S3ct S3ct 6.62 N2 19.45 N1 8.1 495 6.5 S3 S3cts*** S3cts 1.92 N2 9.99 N2 c* climate limitations, t** Topography limitations, s*** Physical soil characteristics limitations. Results obtained by parametric methods (Storie) showed unsuitable condition for this cultivation (N2). Only 2-1 land unit had non-suitable but correctable (N1) land classes (Fig. 3-c). Results of square root method showed unsuitable condition (N2) for 8-1 land units and non-suitable but correctable (N1) for 1-1, 3- 1, 4-1, 5-1, 6-1 and 7-1 land units. Only 2-1 land unit had marginally suitable (S3) land classes (Fig. 3-d). The accuracy of obtained results by the square root method was high and more realistic compared to limitation methods results, therefore according to the results of square root method cultivation of tea can be recommended only for soil profile 4 (2-1 land unit) where had marginally suitable (S3). 143 Figure 3. Qualitative land suitability evaluation maps of study area obtained from: (a) simple limitation method, (b) limitation regarding number and intensity method, (c) Storie parametric method, (d) Root square parametric method, and (e) Economic land suitability evaluation map (scale: 1:90000). According to results obtained by maximum gross benefit in hectare (considering maximum observed yield) the limit of land classes in economic land evaluation can be determined (Table 5). Maximum yield was observed in 2-1 land unit (12 Mg hr -1), so: 144 142 J. BIOL. ENVIRON. SCI., 2011, 5(15), 135-146 Table 5. Limit of land classes in economic land evaluation Gross benefits (Rials in hectares) Crop S1 S2 S3 N Tea > 15088125 15088125–10058750 10058750–0 <0 Gross income = yield amount × price (the prices were calculated according to the 2008-2009 cropping season) of each unit Gross incomes was obtained by tea price assessed by its quality (first class green leaves and second-class green leaves range: 3200 to 1980 Rials), as: Maximum yield (kg hr-1) × coefficient related to class green leaves × price of each unit So, 12000 (kg hr-1) × 0.25 × 3200 = 9600000 Rials And 12000 (kg hr-1) × 0.75 × 1980 = 17820000 Rials Gross income = 27420000 Rials Gross benefits = Gross income – Variable costs Gross benefits = 27420000 – 7302500 = 20117500 Rials in hectares Limit of land classes in economic land evaluation based on gross benefits were calculated. So, 20117500 × 0.75 = 15088125 Rials in hectares And 20117500 × 0.5 = 10058750 Rials in hectares After determining the economic suitability class (Table 6), it was revealed that 1-1, 3-1, 7-1 and 8-1 land units had marginally suitability (S3) and 4-1, 5-1 and 6-1 had moderately suitability (S2), but 2-1 land unit lying Kate-e-Shall (1) has the highest class and the best gross benefits (Fig. 3-e). Comparison between qualitative and economic land suitability evaluation for tea showed that economic suitability class were in a higher levels. Table 6. Gross benefits amount and economic suitability class Area Land unit Gross benefits Economic ha (%) (Rials in hectares) suitability class 1.1 2437 31.47 9149500 S3 2.1 520 6.7 20117500 S1 3.1 379 4.9 6407500 S3 4.1 698 9.06 13262500 S2 5.1 2015 26.07 10977500 S2 6.1 579 7.5 10063500 S2 7.1 604 7.8 8692500 S3 8.1 495 6.5 2980000 S3 With comparing climate information and product requirements, the results of this study showed that climatic suitability classes in three methods were S3. According to the high amount of annual rainfall in the region (>1312 mm), at the first look, it seemed that it was enough to fulfill tea water requirement and no irrigation was needed. A detailed study of the rainfall showed that it unequally distributed during the year, and mostly happens in non-cultivation months of the year in winter, when tea is in hibernation period. Considering that about 50 percent of tea production is in summer, so, water balance in this season is negative and the cultivation of tea in the time of the year needs supplementary irrigation. Since the severe topography problem that affects feasibility of effective irrigation system, obtaining a high yield was restricted. Sloping area in Guilan used to be covered by forest, but regarding to the highly destruction of plant cover and deforestation in order to tea cultivation, an intensive erosion in the area is predict to happen in future. 145 ACKNOWLEDGEMENTS The authors would like to thank gratefully Mr. Fadaei and Ansari, managers of the soil science laboratory of faculty of agriculture, University of Guilan, and Mr. Bahemmat, Fatemi, Maskani, and Lahijan Tea Research Center for their supports. REFERENCES Behzad M, Albaji M, Papan P, Boroomand Nasab S, Naseri AA, and Bavi A (2009). Qualitative Evaluation of land suitability for principal crops in Gargar region, Khuzestan province, southwest Iran. Asian J. Plant Sci. 8: 28-34. Blake GR and Hartge KH (1986). Bulk Density. In: Methods of soil analysis, Part 1-Physical and mineralogical methods, 2nd ed. Agronomy Monograph, vol. 9. (Ed. A Klute), ASA and SSSA, Madison, WI, pp. 363-375. Braimoh AK and Vlek PLG (2008). Land Use and Soil Resources. Springer Inc. p. 253. Bremner JM (1996). Nitrogen-total. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Eds. Sparks DL), ASA and SSSA, Madison, WI, pp. 1085-1121. Chinene VR and Situmbanauma W (1988). Land evaluation of the proposed Musaba state farm in Samfya district Zambia. Soil Surv. Land Eval. 8: 176-182. Embrechts J, Zulkanian P, and Sys C (1988). Physical land evaluation. Using a parametric method application to oil palm plantation in north-sumatra, Indonesia. Soil Surv. and Land Eval. 8: 111-122. FAO (1983) Guidelines: Land evaluation for rainfed agriculture. Soil Bull, No. 52, FAO p. 237. FAO (2007) Land evaluation towards a revised framework. Land & Water Discussion Paper 6. FAO, Rome, p. 124. Gee GW and Or D (2002). Particle-size analysis. In: Methods of soil analysis, Part 4- Physical methods, 2nd ed. Agronomy Monograph, vol. 9. (Eds. JH Dane, GC Topp), ASA and SSSA, Madison, WI, pp. 255-293. Habrurema E and Steiner K (1997). Soil suitability classification by farmers in southern Rwanada. Geoderma 75: 75-87. Helmke PA and Sparks DL (1996). Lithium, Sodium, Potassium, Rubidium and Cesium. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 551-574. IUSS Working Group WRB (2006). World reference base for soil Resources: 2nd edition. World Soil Resources Reports No. 103.FAO, Rome. Jafarzadeh AA and Abbasi G (2006). Qualitative land suitability evaluation for the growth of onion, potato, maize, and alfalfa on soils of the Khalat pushan research station. Biologia 19: 349-352. Jafarzadeh AA, Alamdari P, Neyshabouri MR, and Saedi S (2008). Land Suitability Evaluation of Bilverdy Research Station for Wheat, Barley, Alfalfa, Maize and Safflower. Soil & Water Res. 3: 81-88. Khiddir SM (1986). A statistical approach in the use of parametric systems applied to the FAO framework for land evaluation. Ph.D. Thesis. State University Ghent. Khormali F, Ayoubia Sh, Kananro Foomani F, Fatemi A, and Hemmati Kh (2007). Tea yield and soil properties as affected by slope position and aspect in Lahijan area, Iran. Int. J. Plant Prod. 1: 98-111. Kuo S (1996). Phosphorus. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol. 9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 869-920. Nelson DW and Sommers LE (1996). Total carbone, organic carbone, and organic matter. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 961-1010. Osie BA (1993). Evaluation of some soils in south-western Nigeria for arable crop production. Commun. Soil Sci. Plant Anal. 24: 757- 773. Rahimi Lake H, Taghizadeh Mehrjardi A, Akbarzadeh A, and Ramezanpour H (2009). Qualitative and Quantitive land suitability evaluation for Olive (Olea europaea L.) production in Roodbar Region, Iran. Agric. J. 4: 52-62. Rhoades JD (1996). Salinity: Electrical conductivity and total dissolved solids In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 417-435. Rossiter DG (1995). Economic land evaluation, Why and how. Soil Use Manage 11: 132-140. Sarvari SA and Mahmoudi SH (2001). Qualitative land suitability evaluation for irrigated sugar beet in Ghazvin region. Iranian Journal of Soil and Water. Special issue on soil surv land eval pp. 66-75. Schoeneberger PJ, Wysocki DA, Benham EC, and Broderson WD (2002). Field book for describing and sampling soils. Version 2.0.. Natural resources conservation service. National soil survey center, Lincoln, NE. Seyed Jalali SA (2001). Comparison of land suitability classification methods for irrigated winter wheat. Iranian Journal of Soil and Water. Special issue on soil surv land eval pp. 56–65. Soil Survey Staff (2006). Keys to Soil Taxonomy, (10th ed.), U.S. Dep. Agric., Soil Conserv. Serv., Washington, DC. Storie RE (1976). Storie Index Soil Rating (revised 1978). Spec. Publ. Div. Agric. Sci. No. 3203, University of California, Berkeley. Suarez DL (1996). Berylium, Magnesium, Calcium, Strontium, and Barium. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 575-601. Sumner ME and Miller WP (1996). Cations exchange capacity and Exchange Coefficients. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol.9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 1201-1230. Sys C, Vanranst E, and Debaveye J (1991). Land evaluation. Part I. Principles in land evaluation and crop production calculations. International training center for post graduate soil scientists. Ghent University. Gent. p. 237. Sys C, Vanranst E, and Debaveye J (1993). Land evaluation. Part III: Crop requirement. International training center for post graduate soil scientists. Ghent university. Gent, p. 195. Thomas GW (1996). Soil pH and soil acidity. In: Methods of soil analysis, Part 3- chemical methods. Agronomy Monograph, vol. 9. (Ed. DL Sparks), ASA and SSSA, Madison, WI, pp. 475-490. Zhanga B, Zhanga Y, Chenb D, Whiteb RE, and Lib Y (2004). A quantitative evaluation system of soil productivity for intensive agriculture in China. Geoderma 123: 319-331.   146 142