Coconut-growing soils of Kerala: 1. Characteristics and classification

Coconut plantations are the major land use systems in Kerala state. The tropical hot humid climate and soils of the state are considered suitable for the palm, with the exception of highlands occurring 600 m above MSL. However, the productivity of coconut is abysmally low in the state with an average productivity of around 40 nuts per year per palm. To find out whether the highly weathered and leached low activity clay soils developed in tropical hot humid climate is responsible for the low yield, an assessment of soil qualities in the coconut-growing soils of the state was made. Six distinct regions of coconut cultivation in the state were identified and delineated based on the variability of agro-climate and soils, viz., Central and Eastern Palakkad, Northern Kerala, Central Kerala, Southern Kerala, Onattukara sandy plains and coastal sandy plains. Soil profiles were studied at representative sites in each region. Investigated morphological features and sampled horizon-wise for the analysis of physical and chemical properties of the soil. Coconut-growing soils of Kerala state are in general deep and well drained, clayey or sandy having good structure permitting rapid transmission of water. The soils of Palakkad, Southern Kerala and Coastal Sandy Plains have near neutral reaction whereas the extensive areas of laterite soils of Northern and Central Kerala and sandy soils of Onattukara were strongly acid and had high levels of KCl extractable aluminium. The acid soils also analysed for low levels of basic cations, potassium, calcium and magnesium. Soils from all regions except Palakkad have low CEC. Surface and sub-soils base status were extremely low for soils of Northern and Central Kerala and Onattukara sandy plain. The soils of Central and Eastern Palakkad were classified as Typic Haplustalfs, Northern Kerala as Plinthic Humults, Central Kerala as Typic Plinthustults, Southern Kerala as Rhodic Kandiustults and the soils of sandy plains as Ustipsamments, according to soil taxonomy

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Not AvailableThe strategy for increasing crop production is either based on bringing new lands under cultivation or through intensive cultivation with improved management practices. Nevertheless, both the strategies require constant monitoring of soil fertility status to avoid nutrient deficiency that is one of the major constraints for crop production and it is a decisive tool for farmers and policy planners in soil nutrient management. The integrated watershed management program called SUJALA by the watershed department, Karnataka facilitated to diagnose the soil nutrient status in rainfed areas of Karnataka by collecting soil samples at grid interval from the farmer’s field. A total of 34011 georeferenced composite samples (0–15 cm) were collected at a 325x325 m grid interval to analyze the fertility status of soils. The samples were aggregated under different agro-climatic zones of Karnataka to assess the soil fertility status under each zone. The results showed that per cent sample of low soil organic carbon (<0.5 %) was high in EDZ (61%) and low available P was high in NETZ (85%), NTZ (72%), NEDZ (55%), and NDZ (53%). The soil available potassium was medium to high category. Widespread deficiency of boron (49-68%) and zinc (61-89%) was noticed in all the agro-climatic zones. Whereas, the per cent deficient of soil available Fe was high in NDZ (54%), NTZ (51%) and the deficient available sulphur was high in SDZ (57%), NEDZ (56%), and NDZ (52%). The principal component analysis revealed that organic carbon has a strong influence on the availability of Cu and Mn whereas available P, K, Fe and Zn were strongly influenced by soil pH. Soil EC has a significant effect on the availability of sulphur and boron. Hence, soil fertility management is apparent in rainfed regions to improve and sustain crop production against widespread multi-nutrient deficiency across the agro-climatic zones of Karnataka.Not Availabl

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Not AvailableAn attempt was made to assess the soil resources of Medak district and their fertility in Andhra Pradesh. Ten major soils covering 64 per cent area of the district were analysed for their physical and chemical properties. These soils were shallow to deep, calcareous with Vertic properties, medium deep red clay, medium deep red gravelly loam, shallow black gravelly clay, shallow red loam, alluvial clay and deep red clay. Soils were well to moderately well drained and differ widely in soil reaction (pH 5.0 to pH 9.3) but low in organic carbon. The CEC of soils varied from 40 cmol( + ) kg. Besides, one thousand seven hundred surface samples from 2.5 km grid interval were collected and analysed for macro and micronutrient status. About 43.2 per cent of area was low, 37.3 per cent medium and 13.2 per cent high for available nitrogen. Nearly 80.1 per cent area had low available phosphorus and 12.6 per cent as high. The available potassium was low in 41.3 per cent and medium in 50.9 per cent area. Based on the basis of soil morphology, fertility, physical and chemical properties and climate situation, suggestions were made for sustainable crop planning in the district.Not Availabl

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Not AvailableGroundwater sources are drastically changing in their quantity and quality depending on local and regional level natural andanthropogenic factors, influencing their suitability for drinking and irrigation purposes. The objective of this study is to characterizethe hydrochemistry and assess the groundwater quality in the fluvial deltaic plains of Cauvery river basin, Tamil Nadu,India. A total of 50 georeferenced groundwater samples were collected across Needamangalam block of Thiruvarur district and analyzed for major ions and hydrochemical processes. The results showed an ionic sequence of Cl− > Na+ > HCO3− > Mg2+ >Ca2+ > CO32− > SO42− > K+ based on their relative proportions. The scatter diagram indicated that groundwater chemistry wasmostly influenced by weathering dominance followed by evaporation and silicate weathering. The dominant hydro-chemical facies were Na+-Cl−-HCO3− type, Na+-Mg2+-Cl−-HCO3− type, Na+-Cl−-HCO3−-CO3 2− type and Na+-Mg2+-Cl−-HCO3−-CO3 2−type influenced by the ion-exchange reaction. Most of the groundwater samples are suitable for drinking and irrigation except few with higher Na+ and Cl− content caused by the mixing of salt from fluvio-marine sources or agriculture return flow. The high sodium content in irrigation water may affect the soil hydraulic and nutrient properties in the long runNot Availabl

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Not AvailableA detailed soil survey (1:8000 scale) was carried out in 2010-2011 to delineate homogenous soil management units in the Chikkarsinkere Hobli covering an area of 16,873 ha, out of which uplands occupy an area of about 8749 ha (52%). The survey area was divided into three major landforms namely uplands, midlands and lowlands. Based on variation in physiography and landform, eight soil series were identified in uplands. Eight typifying pedons representing the soils were analyzed for their physico-chemical properties and mapping. The soils of uplands are moderately shallow to very deep, well drained, light colored, light clayey texture developed over granite and gneissic parent materials. The pH of the upland soils ranged from 5.6 to 8.7 with a mean value of 7.52, electrical conductivity (EC) ranged between 0.02 to 0.37 dSm-1 with a mean value of 0.12 dSm-1, organic carbon (OC) varied from 0.07 to 1.3 g kg-1 with a mean value of 0.70 g kg-1, cation exchange capacity (CEC) ranged from 4.4 to 57.7 cmol (p+) kg-1 with a mean value of 17.02 cmol (p+) kg-1 and CaCO ranged between 1 to 2 g kg-1 with a mean 3 value of 1.6 g kg-1. Pedons 1, 3, 4 and 6 were classified as Typic Rhodustalfs, whereas pedons 2, 7 and 8 were classified as Rhodic Paleustalfs and pedon 5 was classified as Vertic Haplustepts.Not Availabl

Spectral assessment of soil properties in semi-arid tropical regions of southern Karnataka Plateau

International audienceThe present study assessed the visible and short wave infrared (VNIR-SWIR) laboratory spectroscopy coupled random forest regression (RF) technique for predicting soil properties in the southern Karnataka Plateau, India. The spectral data acquired for about 228 profile samples were used to predict key soil properties. The RF model fits well for the spectral prediction of clay (R-2 = 0.65), sand (R-2 = 0.60), cation exchange capacity (R-2 = 0.74), field capacity (R-2 = 0.65) and permanent wilting point (R-2 = 0.72). Wherein soil organic carbon was poorly predicted with an R-2 of 0.22 and RPD of 1.2 due to its lower content and narrow range (0.8 to 20 g kg(-1)). The spectral assessment by PCA showed that the first (50%) and third (34%) components had high spectral variation and significantly correlated with soil properties such as pH, CEC, clay, FC, and PWP related to wavelengths indicating clay minerals and iron oxides. However, the second component had less spectral variation (13%) that is related to wavelengths indicating various organic components and correlated well with SOC. Thus, the VNIR-SWIR spectroscopy could be a suitable supplementary method for rapidly predicting soil properties related to clay minerals and iron oxides

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Not AvailableIn the Western Ghats of India, the soil properties, particularly Atterberg limits, are of relevance to the landslides. Pedogenic processes in the Western Ghats and plateaus on it are regulated by parent materials, relief (topography), organisms, climate, and time. In this study, the five major soils found within the mid-part of the Western Ghats in the Idukki district of Kerala, Southern India was analyzed for elucidating physical, chemical, and geotechnical properties (Atterberg limits) on landslides potentiality or slope failure processes. The result reveals that the highly weathered lateritic soils noted with lower KCl pH (3.6–4.6), low-cation exchange capacity (3.1 to 19.6 cmol( +) kg− 1), low-effective cation exchange capacity (0.8 to 10.7 cmol( +) kg− 1) and a negative ΔpH value indicate the presence of variable charge minerals such as amorphous sesquioxides. The variable ranking of random forest revealed that the soil Atterberg limits were significantly influenced by Citrate Bicarbonate Dithionite (CBD) iron, sand fractions, and organic carbon. The layer of porous sandy soils showed lower Atterberg limits due to accentuate with clay matter, whereas the illuvial layer (Bt) have noted as higher Atterberg limits that lead to potentially collapsing gullies or triggering mass movement during heavy rainfall followed by intensive runoff due to instability of soil mass within proxy of the steeply sloping surface. Soil geotechnical properties such as liquid limit, plastic limit, and plasticity index are the main characteristics that decide the slope stability and failure in various parts of the study area, whereas the soil profile morphometry has significantly associated with the occurrence of landslides with the plastic limit value between 28.01 and 40.48. It was noticed that the failed slopes have a higher value than stable slopes along with the hill-range topography, with soil particle sizes range of silt and clay (8.79 to 36.17 and 22.31 to 57.74%) with the measurement of liquid limit (40.05 to 68.4), plastic limit (24.2 to 43.94), and plasticity index (7.81 to 24.8). This indicates that the pedogenesis of the weathering profile of soils have significantly influenced the Atterberg limits that triggering slope failure or landslides along the gullies and weathered lateritic uplands.Not Availabl

Land Resources Characterization of Kangayam Block in Tamil Nadu Uplands under Dry Semiarid Eco-region

Not AvailableA detailed soil survey was carried out to characterize and classify the soil resources of Kangayam block, Tiruppur district represented by hot dry semiarid eco-region of Tamil Nadu uplands (AESR, 8.1). Seven landform assemblages viz. isolated structural hills and ridges, local rises, upper sectors of pediplains, middle sectors of pediplains, lower sectors of pediplains, valley fringes, and the Noyyal- Amaravathi river valley floor, were identified. Typifying pedons of twelve soil series identified were analyzed for physical and chemical properties for their characterization and classification. The soils were shallow and moderately deep, well to moderately well-drained, developed from granite-gneiss and its colluvial and alluvial parent material. The sand, silt, and clay content of the soils varied from 11.2 to 88.2, 2.3 to 49.4, and 6.7 to 39.4 per cent, respectively. The soils were slightly acid to strongly alkaline (6.23 to 8.92) and non-saline (0.03 to 0.85 dS m-1). Soil organic carbon content varied from 0.09 to 0.86 per cent and the soil calcium carbonate equivalent was in appreciable quantities in sub-soils (maximum of 38.5%). The soil cation exchange capacity varied from 2.5 to 38.8 cmol (p+) kg-1. The soils were classified under Alfisols, Entisols, and Inceptisols soil orders as per USDA Soil Taxonomy.Not Availabl

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Not AvailableNatural forests and managed plantations constitute the largest land-use systems in the humid tropics of southwestern parts of Peninsular India comprising the Western Ghats and coastal plain. Soils therein are naturally acidic and the acidity is enhanced in managed land-use systems through inputs of chemical fertilizers. Plant nutrient deficiencies and mineral toxicities constrain crop production in acid soils. Surface soil and subsoil acidity in forest, coffee, rubber and coconut land-use systems was evaluated. The spatial pattern of surface soil and subsoil acidity pointed to low intensity of acidification in Malnad region of Karnataka, moderate acidity in northern Kerala and strong acidity in southern Kerala. Among the land-use systems studied, soils under natural forests and coffee plantations were only slightly acidic in surface soil and subsoil, whereas rubber-and coconut-growing soils were strongly acidic. Both natural and managed land-use systems, however, had strongly acid reaction in surface soil and subsoil in southern Kerala. Bio-mass production and crop yield are constrained in strongly acid soil by toxic levels of aluminium (Al) on soil exchange complex (>0.5 cmol ( + ) kg-1 soil) and depletion of basic cations of calcium, magnesium and potassium (base saturation less than 50% or Al saturation more than 50%). Surface soil acidity can be ameliorated by incorporating liming materials into surface soils. In case of subsoil acidity gypsum too should be incorporated. Under humid climate partial solubility of gypsum permits movement of calcium into the subsoil layers, wherein calcium replaces the aluminium on exchange complex and sulphate radical precipitates the aluminium by formation of aluminium sulphate.Not Availabl