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Tissue samples from aerial biomass compartments (bark, wood, primary and secondary branches, and foliage) were taken from 16 dominant trees of teak in plantations of the Panama Canal watershed, whose volume yield ranged between 9.4 and 13.3 m3 ha-1. year-1 at ages 3 and 18 years, respectively, growing in clayey, red, and acid Ultisols. Wet and dry weight of the different tissues was measured and subsamples taken to be analyzed for macronutrients (N, K, Ca, Mg, P and S) and micronutrients (Fe, Mn, Zn, Cu and B). Regression analyses allowed to relate nutrients accumulation with tree age. Dry biomass of the wood was 59.6% (C.V. 5%) of total dry biomass, while primary branches, bark, foliage, and secondary branches represented 16.6, 9.4, 7.9, and 6.5, respectively. Larger concentrations of macronutrients were Ca (2.01%) found in the bark, and N in the foliage (1.98%). As for micronutrients, larger concentrations were found in the bark, in the order of Fe (767 mg.kg-1), Mn (60 mg.kg-1) and Zn (50 mg.kg-1). At 18 years of age accumulation of macronutrients was 15.9 kg. tree-1 (7.3 kg Ca, 3.9 kg N, 2.6 kg K, 1.0 kg Mg, 0.7 kg P and 0.4 kg S) and 124 g of micronutrients (89 g Fe, 18 g Zn, 9 g B, 5 g Mn and 3 g Cu). [ABSTRACT FROM AUTHOR]

This paper summarizes available information on soil clay mineralogy in topsoils of Costa Rica, including clay minerals described in B horizons when significantly different from predominant mineralogy in the topsoil. The soil clay suites ("predominant clay groups") emphasized are grouped as: (1) smectites and interstratified clays (Vertisols and other soils with vertic properties), and (2) oxides-hidroxides-oxihidroxides-kaolinite-gibbsite (in Alfisols, Ultisols and Oxisols). The soil clay genesis of these dominant groups is discussed when enough information is available. [ABSTRACT FROM AUTHOR]

Findings in a total of 84 research papers identifying clay minerals on 520 soil samples of Costa Rica are summarized. This review emphasizes on the clay minerals described in the topsoil samples, although clay minerals in the B horizons are also discussed when they are different to predominant mineralogy in the topsoil. Sites where soil clays information is available were geo-referenced, to observe their geographical distribution. In general most of the country possesses soil clays identified, except for the Nicoya Peninsula, the Northern Zone, and the Eastern Talamanca Range. Clay mineralogy suites ("predominant clay groups") were grouped as: (1) vitrous-amorphous-halloysitic (Andisols and other soils with andic properties; (2) smectites and interstratified clays (Vertisols and other soils with vertic properties); (3) oxides-hidroxides-oxihidroxides-kaolinite-gibbsite (Alfisols, Ultisols and Oxisols); Plus a large area of soils with mixed clay mineralogy, found in places with little or no development (Entisols and Inceptisols). The soil clay genesis of the main clay types in the country is discussed when enough information was available. [ABSTRACT FROM AUTHOR]

Foliar concentration of macro- and micronutrients in teak plantations at the Panama Canal Watershed was measured on sites classed as high, medium, and low in growth (volume.ha-1). For the same purpose, plantations where grouped by age as young (3-4 years), medium (5-6 years) and late (7-8 years). Foliar macro-nutrients concentration followed the order N (1,9%), Ca (1.1%), K (0.7%), S (0.2%) and P (0.1%), while micro-nutrients concentrations decreased in the order Mn (50), Fe (43), Al (36), B (29), Zn (28), Cu (8), and Mo (0.4) mg.kg-1. The K, P and Fe concentrations were clearly identified as low, while N, Ca, Mg and Mn values can be considered as marginal to slightly low. The Ca, Mg, N, K, Mn, Zn, Fe and Al concentrations varied statistically with plantation age in different ways; foliar concentrations of Ca, Mg, Mn, Fe and Al tend to increase with age, while those of N, K and Zn tend to diminish with age. Concentrations of Ca and Mn in the leaves of trees of sites with high and low growth differed statistically (p<0.01), with Ca values of 1.18% and 0.99%, in the high and low growth categories, respectively, and with Mn values of 41 and 65 mg.kg-1 in sites of high and low growth rates, respectively. [ABSTRACT FROM AUTHOR]

Soil-forming factors and soils distribution of the middle-upper Pirrís River watershed, Talamanca, Costa Rica. This study emphasizes on the soil-forming factors and soils distribution of the middle-upper Pirrís River watershed, Talamanca, Costa Rica, a region locally known as Los Santos. This area covers around 25 000 ha, at elevations from 1078 to 3140 m, and a range of yearly average rainfall from 1954 to 2233 mm. Geologically, rocks of the area represent a period span from Holocene to Oligocene. Four major soil units were identified: 1) recent soils developed from volcanic ash (high elevation sections); 2) soils developed from old geologic parent materials of the Talamanca Range and the Brunqueña Hills (middle elevation sections); 3) soils developed on and around intrusive volcanic buildings (medium to high elevation sections of the landscape); and 4) soils developed from recent alluvial materials deposited on valley floors (lower positions of the landscape). Soils developed on the older materials from the Pliocene to the Oligocene, present an argillic horizon as a final result of weathering and soil formation. Soils from Pleistocene to Upper Miocene intrusive materials, present a higher quartz content. Soils developed from recent alluvial deposits present a cambic horizon, but not an argillic horizon and the volcanic ash materials may present a cambic horizon or a buried argillic horizon. Six soil consociations and 22 soil associations were described in the area. Mayor soil orders in the region are Ultisols, Andisols, Inceptisols and Entisols, including 4 suborders, 6 great groups, 12 subgroups and 9 soil families. [ABSTRACT FROM AUTHOR]

Land capability for agricultural use in the middle-upper Pirrís River watershed, Los Santos, Costa Rica. Land capability for agricultural use in the middle-upper Pirrís River watershed is mainly determined by altitude belts. Between 1075 and 1700 m asl, coffee production is the main agricultural activity on clayey Ultisols with important erosion manifestations. From 1700 to 3100 m natural forest, highland fruit trees, flowers, fish ponds, pastures, some vegetables, mountain cabins, and charcoal production are the main activities on predominant Andisol, Inceptisol, and Entisol soil orders. The area consists of mountains of steep (30-60%) slopes, and a few low-relief deep valleys with recent alluvial terraces. Visible features on agricultural lands allowed to estimate that 60% of this land suffers moderate erosion (laminar and reel); 18% of this land suffers severe erosion, to very severe not considering linear erosion due to poorly-designed secondary roads, no road drainage, excavations for infrastructure, and active landslides that cause large scale soil loses. Forty four % of the soils are deep, while 38% are moderately deep, and 17% are shallow to superficial. Fertility characteristics observed on peats all over the region show that 33% the soils are of low fertility and 52% of very low fertility. Considering relief features, suffered erosion, soil fertility, and soil depth, land use capability for agricultural activities in the watershed are: 1% Class III, 2% Class V, 8% Class VIII, 26% Class VII, and 63% Classes IV and VI. [ABSTRACT FROM AUTHOR]

This paper analyses the relationship between soil clay mineralogy classes and soil fertility characteristics of soils cultivated with banana in the Caribbean lowlands of Costa Rica. The results corroborate that some fertility properties are closely related to the amount and type of dominant clay of the soils; among these characteristics the most relevant are CEC, phosphate retention and exchangeable cations. Soils belonging to the esmectitic clay mineralogy class showed greater values of CEC and exchangeable bases but lower phosphorus retention than soils of the metahalloysitic clay mineralogy class. Soil dominated by vermiculite showed lower amounts of available K and larger amounts of exchangeable Mg. [ABSTRACT FROM AUTHOR]

The effect of P additions on potato yield and nutrient absorption was studied in a Hydric Hapludands soil. P rates of 0, 150, 300, 450, and 600 kg.ha-1 of P2O5 were compared during 1 and 2 consecutive crops. Soil samples were taken before planting and after harvest; foliar samples were taken, 48 dap at flowering; aerial biomass was sampled before burning aerial biomass with chemicals, 93 dap; potato yield was estimated at harvesting, 116 dap. Tissue samples were analyzed for N, P, Ca, Mg, K, Mn, Zn, Cu, Fe, S, and B. When P was applied only to the first crop, yields were low and no residual effect of the fertilizer application was noted for any of the rates compared. The addition of P for 2 consecutive years increased yields; maximum yield obtained with 600 kg.ha-1 of P2O5 was 16.39 t.ha-1. Nutrient absorption was not affected by the P applied. Macronutrient absorption was K>>N>>Ca>P=Mg and for micronutrients Fe>>>Zn>Mn>B>>Cu. Mobile nutrients (NPK) were distributed to the tubers in 27-65%; nutrients of relative mobility, such as Cu, Mg, and Zn between 14-38%; less mobile elements (Ca, Mn, and Fe) amounted only 2-6% of the tuber weight. To maximize potato yield in Andisols, P should be applied for each crop, since the residual effect of the P-fertilizer is not enough to supply the needs of the crop in soils with high P retention capacity. [ABSTRACT FROM AUTHOR]

The residual effect of P-fertilizer applied to 2 consecutive potato crops growing in a Hydric Hapludands was studied at Hacienda Juan Viñas. Phosphorus rates compared were 0, 150, 300, 450 and 600 kg.ha-1 of P2O5, applied to the first crop and to 2 consecutive crops. To avoid fertilizer placement effects, soil samples were taken after plowing the land for planting and after digging the potatoes at harvesting. The samples were analyzed for P using modified Olsen, Bray 1 and Mehlich 3 extractants. The addition of P to the first crop only allowed to obtain low potato yields, without any significant residual effect of the P availability in the soil. After P additions for 2 consecutive crops, yields increased proportionally to the rate of P added, to attain a maximum yield of 16.39 t.ha-1 with the rate of 600 kg.ha-1 of P2O5. The Modified-Olsen method best estimated soil P changes due to P-fertilizer additions after the 2 years of fertilization and cropping. To attain measurable soil P residual rates, over 450 kg.ha-1 of P2O5 for 2 consecutive years were required; this allowed obtaining an increase of 2-3 mg.l-1. year-1 of P. Phosphorus retention in the soil was 93% during the first year of the experiment, decreasing to 91% during the second year. Among soil P extractants, the best correlation between methods was Modified Olsen and Mehlich 3 (R2=0.705). [ABSTRACT FROM AUTHOR]

This work was designed to generate sustainability indicators for the agricultural sector of the Reventado River watershed. Land use through time increased soil cations accumulation (Ca Mg y K) but decreased acidity saturation as a result of fertilizer and lime applications. Available P also increased with the period of land use, increasing at an approximated rate of 2.3 mg.l-1.year-1. The increase of P with time might allow the farmers to reduce its application to reduce costs and improve sustainability of the ago-ecosystem. Most farms suffered moderate rates of erosion. As erosion rates increased, the thickness of the A horizon and available P contents diminished, all of this while erosion rates increased from nil, to moderate to severe. Better soil structural index values were found in soil capability classes II y III, while in higher capability classes' structure was weaker and soils more susceptible to erosion. No significant differences were found between land capability classes and crop yields. Both potato and onion yields were better in irrigated fields, the fact reflected also in higher B/C ratios, particularly around Tierra Blanca. Economical and social indicators of the study were positive but environmental indicators were negative for Tierra Blanca and Llano Grande communities. However, agricultural activities are an attractive and economic possibility for farmers at the Reventado River watershed. [ABSTRACT FROM AUTHOR]

Land capability of the area of study was determined and a proposal for appropriate use was made using the Land Capability Methodology proposed by the Ministry of Agriculture and Livestock of Costa Rica. The soils of the farms sampled were being cultivated for vegetables (66.5%), pastures (22.9%), and in a lower scale by forests, fallow and flowers. The land capability consisted of 10.5% Class II, 38.1% Class III, 21.9% Class IV, 1.8% Class V, 8.9% Class VI, 17.8% Class VII and 1% Class VIII. Some 60% of the farms were in Classes III and IV, where the limitations were slope, erosion, effective depth and soil fertility. Some 25% of the farming areas showed appropriate use, 25% were slightly over-utilized and 36% were severely over-utilized. It is proposed that the conflict can be corrected by intensive management practices and soil conservation and in areas of greater slope by a change in use to high altitude fruit trees. In the lots of Class VII with grass cover, the planting of forests is recommended. For the study area, the land use potential was truck crops 57%, pastures 20%, perennial crops or fruit trees 13%, and 10% for reforestation. Water erosion in the agricultural activities in the middle watershed does not limit the productivity of the zone: some 90% of the lots showed light to moderate erosion with slopes less than 30%. Other factors that affect the soil and water deterioration were open mine extraction, natural landslides and the lack of control structures for flow and sediments in the earth roadways. [ABSTRACT FROM AUTHOR]

Release of carbon and nutrients after decomposition of harvest residues in heartof- palm plantations (Bactris gasipaes) in Costa Rica. The experiment was carried out to determine the rate of decomposition and the release of C and nutrients of heart-of-palm plantation residues. Portions of all parts of the residues were systematically introduced in nylon decomposition bags, 90×45 cm. The bags were laid on the ground of the intercrop areas of the plantation to be collected after 1, 2, 4, 8, 16, 24, 32, 40, and 48 weeks, when dry matter and nutrient contents of C, N, P, K, Ca, and Mg were measured on the remaining residues. The original plant residues showed an unfavorable C:N ratio to ensure effective short term decomposition rates. After week 16, approximately 50% of the residues in the bags were decomposed; while at week 48, 80% of the dry matter and nutrients in the litter bags had disappeared. Nutrients were released in 3 different phases: fast, decreasing, and slow. K was the element that more quickly attained the third phase, followed by Mg, P, N, and Ca. N release was strongly dependent on the C:N ratio of the fresh residues. Following the best fitting regression models, after week 16, close to 97, 80, 70, 60, and 50% of K, P, Mg, N, and Ca were already released from the decomposition material. Based on estimations, it was estimated that close to 9 t.ha-1.year-1 of dry matter, from harvesting residues, could be decomposed, releasing 4610, 87, 46, 254, 34, and 21 kg.ha-1.year-1 of C, N, P, K, Ca, and Mg, respectively. [ABSTRACT FROM AUTHOR]

Response of heart-of-palm plantations (Bactris gasipaes) to phosphorus fertilization in the Northern Zone of Costa Rica. Levels of 0, 9, 18, 33, 48, and 108 kg.ha-1.year-1 of P2O5 were applied to a soil classified as Fluvaquentic Dystrudepts, to estimate their effect on the growth and yield of heart-of-palm during the first year after planting, and twice those amounts were added during the following 24 months. Soil nutrient availability at 2 depths, and nutrient concentration in the leaves, petioles 3 and 5, and roots, were also measured. P additions to the crop did not affect plant growth, crop yield, or the concentration of other nutrients in the soil solution. However, P additions increased the number of suckers, although the quadratic regression effect was not significant. When comparing P extracting solutions, it was found that both Modified Olsen and Mehlich-3 extracted increasing amounts of P accordingly to rates of P added, but somewhat larger amounts were extracted by the Modified Olsen solution. Available P at 0-5 cm depth was higher than that extracted at 5-20 cm depth; also, in the topsoil the extracting P methodologies showed the best correlation. Of the tissues sampled (leaves 3 and 5, petioles, large roots, and dry matter) only petiole P concentration correlated with the rates of P added to the soil. Added P linearly increased petiole concentration of Ca, K, and Mg. It is recommended not to apply P fertilizer in old plantations; however 30 kg.ha-1.year-1 of P2O5 at planting should be added when densities are 10 000 plants.ha-1. To monitor P in heartof- palm plantations, it is better to sample the petiole tissue, take soil samples at 0-5 cm depth, and conduct laboratory analyses using Modified Olsen extracting solution. [ABSTRACT FROM AUTHOR]

Twenty-six soil profiles were characterized and classified as Ultisols in the middle-upper watershed of Pirrís River. These soils developed on Pleistocene to Oligocene undulated to strongly undulated mountainous landscapes, on: 1) marine sediments, 2) volcanic andesitic-basaltic materials and 3) colluvial materials, all of them covered by natural vegetation of wet to very wet tropical forest in an ustic soil moisture regime. The soils are deep, possess an argillic horizon and are of fine to very fine texture. Soil reaction is acid to strongly acid and may possess a horizon high in manganese concretions associated to ancient water levels of the Pirrís River watershed, on geologic materials high in manganese content. Clay content, CEC, particle density and bulk density of the soils vary with parent material, while base content and phosphorus fixation are not so related. According to Soil Taxonomy, 2 suborders were recognized: Humults and Ustults. Five great groups: Haplustults, Paleustults, Haplohumults, Palehumults, Rhodustults; and 9 subgroups: Typic Haplustults, Aquic Haplustults, Typic Paleustults, Andic Haplohumults, Aquic Haplohumults, Aquandic Haplohumults, Ustic Haplohumults, Andic Palehumults, Typic Rhodustults. The Andic and Aquandic subgroups exhibit, in superficial horizons, depositions of volcanic ash materials dated around 700 years of age. Buried clayey subsoils of Talamanca Ultisols are much older than their over laying horizon, being dated as old as 9000 to 65 000 years of age. [ABSTRACT FROM AUTHOR]

This experiment was conducted to evaluate the response of alder trees (Alnus acuminata (H.B.K.) O. Kuntze) to liming in Andisols of 2 sites of the Virilla River upper watershed, Costa Rica. The first experiment was set up in 2002 at the Hospicio farm, Vista de Mar, Goicoechea County, at 1542 masl; on a soil classified as Typic Udivitrands. A second experiment was carried out in 1997 at Dorval farm, Las Nubes, Vásquez de Coronado County, at 1925 masl, on a soil classified as Thaptic Udivitrands. Liming treatments were: 0 (check), 750, 1500 y 2250 kg.ha-1 of calcium and magnesium carbonate (Dolomite), 1500 kg.ha-1 of calcium carbonate (Calcita) and 1500 kg.ha-1 of calcium sulfate (Gypsum). Dasometric variables measured were diameter at breast height (DBH) at 1.3 m, total height of trees, and volume was estimated using the formula: V(m³)=2.71828 -- 10.0557 + ln(d)*2.0369 + 0.927718*ln(h) as proposed by Segura et al. (2005), where d represents DBH (cm) and h is total height (m). None of the liming treatments significantly affected DBH annual increment, total height, average height annual increment, total volume and total volume annual increment in any of the 2 farms. Nor liming affected any tree growth variable by season (dry vs. wet season). No significant differences were found among dasometric variables due to the addition of different liming sources. The lack of response to the soil amendments compared demonstrates that the soil available Ca, Mg and S was enough to provide these nutrients in quantities that allow alder optimum growth. None of the soils studies showed acidy problems large enough to adversely affect alder tree growth. [ABSTRACT FROM AUTHOR]

Andisols, Inceptisols and Entisols of the Pirrís River watershed, Los Santos, Talamanca, Costa Rica. Eight soil profiles were described and classified on volcanic ash deposits at the upper Pirrís River watershed. The soils were classified as Andisols and Inceptisols of the suborders Ustands, Udands and Ustepts; at the great group level the soils were classified as Haplustands, Placudands and Dystrustepts, belonging to the subgroups Dystric Haplustands, Humic Haplustands, Aquic Haplustands, Typic Placudands and Andic Dystrustepts. The topsoil characteristics of many of these soils are fragile, vulnerable to erosion and landslides. In general, these soils are acid, of low fertility status and present recent surface horizons (Holocene), but could be underlain by argillic horizons formed during the Pleistocene. On recent alluvial terraces from the Holocene, another group of seven soil profiles were described. These show little morphological development; major soil- forming processes in these positions include detachment in the highlands and deposition of particles through river flooding in the lowlands. These soils were classified in the orders Entisols and Inceptisols, suborders Fluvents y Ustepts, great groups Ustifluvents, Dystrustepts and Haplustepts, finally belonging to the subgroups Typic Ustifluvents, Fluventic Dystrustepts, Fluventic Haplustepts and Humic Dystrustepts. Most Entisols present coarse textures (sandy loam) while in the Inceptisols the clay content is dominant (clay loam, sandy clay loam and clayey textures). A third group of soils were described in a rim around intrusive materials of Miocene to Pleistocene origin, dated to be 8 to 11 Ma. On these metamorphic materials Inceptisols were formed, showing high rock and stone contents. Most of these soils are shallow, acid and of yellowish colors, due to the illuviation, lixiviation, humus formation, weathering and erosion dominating soil forming processes in this area. [ABSTRACT FROM AUTHOR]

Soils from 11 watersheds planted with banana in the aluvial valleys of the Caribbean zone of Costa Rica were chemically characterized and classified. Two major soil areas were identified based on their morphological and chemical properties and taxonomic criteria. One of the areas consisted mainly of Inceptisols formed from fluvio-volcanic materials with andic properties (Andic Eutrudepts, Aquandic Endoaquepts), dystric Inceptisols (Fluventic Dystrudepts) and Andisols (Typic Hapludands), most with good drainage, medium textures (sandy loam, loam, silty loam), sum of bases 10 to 19 cmol.l-1, CEC 13 to 28 cmol.l-1 and clays with permanent charge. The adjacent zone consisted mainly of Inceptisols formed from aluvial sedimentary materials deposited by frequent river floods (Fluventic Endoaquepts, Dystric Fluventic Eutrudepts, Fluvaquentic Eutrudepts, Fluvaquentic Endoaquepts), with a sum of bases 18 to 46 cmol.l-1, CEC 19 to 46 cmol.l-1, without Andic properties, textures fine to medium (clay loam, silty clay loam, clay, silty clay) and in some case with poor drainage (Endoaquepts, Epiaquepts, Fluvaquentic). Geographically, the 2 zones were separated by the watersheds of Vueltas-Silencio-Parismina Rivers; the northwest area is highly influenced by volcanic ash deposits and has its medium fertility characteristics, while the southeast area is not influenced by volcanic ejecta and has high fertility characteristics. [ABSTRACT FROM AUTHOR]

This study includes the characterization of the clay mineralogy of banana soils from 11 watersheds of the Caribbean alluvial lowlands, using RX diffraction and dissolution methods. These results confirm the abundance of montmorrillonite, metahalloisite, vermiculite and plagioclases, together with small amounts of allophane, gibbsite and iron oxides like hematite, maghemite and magnetite. Chlorite was not detected but illite was found in some samples. The use of dissolution and estequiometric techniques allowed us to identify amorphous materials, probably allophane, in soil RE-16 in the Tortuguero river basin. Soils northwest of the watershed of rivers Vueltas, Silencio and Parismina, were dominated by metahalloisite and montmorrillonite; they were classified as Inceptisols with Andic properties (Andic Eutrudepts, Aquandic Endoaquepts), Dystric Inceptisols (Fluventic Dystrudepts) and Andisols (Typic Hapludands). Soils southwest of that watershed were dominated by montmorrillonite, vermiculite and metahalloisite; they were classified as Eutric Inceptisols of alluvial origin (Fluventic Eutrudepts, Dystric Fluventic Eutrudepts, Fluvaquentic Eutrudepts, Fluventic Endoaquepts) and Inceptisols with drainage problems (Fluventic Endoaquepts, Fluvaquentic Epiaquepts). The montmorillonite, vermiculite and allophane are formed in the hillsides of the watershed (cordilleras Central and Talamanca) and later deposited in the lowlands by river flooding; metahalloisite is formed by transformation of halloisite and gibbsite developed from allophanic materials. [ABSTRACT FROM AUTHOR]

The effect of B to Andisols on tree height, diameter and volume of 5 Alnus acuminata plantations was studied. Plantation nitial ages in years were: 0.5 at Hermanas Callejas (HC), 1 at Lechería Experimental (LE), 3 at Rosa Marta Cubero (RMC), 5 at Landelina (L) and 7 at Carter (C); at the end of he experiment plantations were 3 years older. B was supplied as Boronate and broadcasted at rates of 0, 2, 4, 6 and 8 kg.ha-1; the residual effect of fertilizer was determined 14 months after its application. The fertilizer added incremented B availability in the soils, as measured with pressurized hot water and Mehlich 3 methods. R2 values obtained were higher with correlations obtained by the Mehlich 3 procedure. The B applied did not cause increments of dasometric variables measured, except for a significant increase in volume of wood at Landelina (8 year old plantation). The lack of response in growth variables to B addition are attributed to the initial B availability in the soils (0.19-1.00 mg.kg-1), most values above he critical value of 0.5 mg.kg-1 mentioned for crops in Andisols, and the low requirement of B in alder. Foliar concentration of B showed a slight tendency to increase with growing amounts of B applied to the soil, while N foliar concentration did not show any tendency after B addition to the soil. [ABSTRACT FROM AUTHOR]

The objective of the study was to characterize the middle section of the Reventado river basin socioeconomically and to estimate its contribution to the agricultural sector of the country. A survey with 106 questions was conducted; the sample included 80 producers randomly selected. It was found that the majority of producers own their farms and 50% of them did crop the land associated to other producers. Farm size ranged between 1-3 ha, this forces the system to be very efficient even though farmers classify as small and medium in size. The education level showed that 75% of the farmers had completed basic education. Knowledge acquired allowed farmers to look for new development alternatives, products, markets, and technologies; and favored some of them to move to other type of alternatives than agriculture. Irrigation availability influenced the economy of the farming systems increasing the B/C ratio of farms with access to irrigation over those without access to irrigation. Irrigation allows harvesting 3 crops per year, with lower pesticide use and the possibility of finding market windows with better prices. Tierra Blanca showed higher B/C ratios than Llano Grande, fact due to farms of larger size, more access to irrigation, lower intermediary channels, and larger agro-industrial facilities. Integrated crop management systems showed the best environmental and economical indicators, and productivity higher than the national average. The Social Development Indicator is acceptable for the area, when compared to national values. These farmers conform a highly socio-economically differentiated group with a strong cultural identity and deep roots in agriculture. [ABSTRACT FROM AUTHOR]