Hill Soils Research Articles

Lateral Saturated Hydraulic Conductivity of Soil Horizons Evaluated in Large-Volume Soil Monoliths

Evaluating the lateral saturated hydraulic conductivity, Ks,l, of soil horizons is crucial for understanding and modelling the subsurface flow dynamics in many shallow hill soils. A Ks,l measurement method should be able to catch the effects of soil heterogeneities governing hydrological processes at the scale of interest, in order to yield Ks,l representative values over large spatial scales. This study aims to develop a field technique to determine spatially representative Ks,l values of soil horizons of an experimental hillslope. Drainage experiments were performed on soil monoliths of about 0.12 m3 volume, encased in situ with polyurethane foam. Median Ks,l of 2450 mm·h−1 and 552 mm·h−1 were estimated in the A and B horizon, respectively. In the upper part of the B horizon, the median Ks,l was 490 mm·h−1, whereas it mostly halved near the underlying restricting layer. The decline of Ks,l values with depth was consistent with the water-table dynamics observed at the same site in previous studies. Moreover, the Ks,l from the monoliths were in line with large spatial-scale Ks,l values reported from the hillslope in a prior investigation based on drain data analysis. This indicated that the large-scale hydrological effects of the macropore network were well represented in the investigated soil blocks. Our findings suggest that performing drainage experiments on large-volume monoliths is a promising method for characterizing lateral conductivities over large spatial scales. This information could improve our understanding of hydrological processes and can be used to parameterize runoff-generation models at hillslope and catchment scale.

Optimization and Production of Industrial Important Cellulase Enzyme from Penicillium citrinum in Western Ghats of Sathuragiri Hills Soil Sample Isolate

In optimization of cellulase production by different pH, substrates, nitrogen, carbon sources were detected from penicillium citrinum micro-fungal species. The maximum cellulase activity was recorded in the range of pH- 5 to 6.5 and wheat bran (91 U/ml) and rice bran (81 U/ml) is the best raw substrate for the production of cellulase. Estimation of extracellular protein was recorded in different production medium of Penicillium citrinum (1.63 mg/ml) for maltose followed by sucrose (1.46 mg/ml), fructose (1.13 mg/ml), wheat bran (1.12 mg/ml), peptone (0.88 mg/ml) and yeast extract (0.82 mg/ml). The highest extracellular protein was recorded in pH 5.5 to 6.5 followed by substrate for wheat bran (1.12 mg/ml), rice bran (1.04 mg/ml), paddy straw (1.03 mg/ml). In nitrogen sources, ammonium sulphate (141 U/ml) and ammonium nitrate (121 U/ml) is the best nitrogen source for the production of cellulase enzyme. The maximum cellulase activity was recorded in glucose (134 U/ml) and maltose (159 U/ml) was best carbon source for the production of cellulase.

Variation of Soil Fertility with Diverse Hill Soils of Chittagong Hill Tracts, Bangladesh

Variation of Soil Fertility with Diverse Hill Soils of Chittagong Hill Tracts, Bangladesh

Application of GIS in General Soil Mapping of Bangladesh

Bangladesh is a densely populated country where food crisis is one of the major issues where proper soil mapping is lacking till now. The purpose of this study is to prepare soil mapping of Bangladesh including different soil factors like pH, salinity, nutrients, texture, porosity, toxicity etc., along with general soil types and land availability through application of Geographical Information System (GIS). Q-GIS software and secondary data are used in this study. In present study, it was found that 12 types of soil texture were present in all around of Bangladesh and the maximum percentage of soil porosity values varied from 20% to 70%. A medium range of soil organic matter and strongly acidic soil was found all around the Bangladesh. It was found that the southern part of Bangladesh had slightly saline to highly saline soil. The major part of Bangladesh had medium high land which is very much preferable to agriculture. In Bangladesh, three categories of land such as highland, medium highland and low land cover 29%, 35% and 21% of total land, respectively. Agriculture land covers 9.5 million hectares in Bangladesh. The shifting rate based on agricultural use had been reported to be about 1% per year. At present, the amount of forest land covers 9.84% of total land of our country but 1976 it was 12.11%. Mangrove is now at 4.07% of total land mass of our country. In generally, 20 types of soils were found all around the country. Mapping of soil types described these 20 general soil types under 5 main categories and these are calcareous soil, non-calcareous soil, terrace soil, gray soil, peat and hill soils. This study will be helpful for the cultivator to cultivate appropriate crops in appropriate places after exploration at a glance.

Soil resource inventory for assessing soil quality and land capability using geospatial technology

Soil survey provides information about the inherent and dynamic qualities of the soil. Soil quality assessments are thus used to evaluate the effects of management on the health of the soil. The study is based on the generation of soil and land resource database of Warangal district on 1:50,000 scale using Resourcesat-1, LISS-III satellite data and Digital Elevation Model (DEM) in Geographical Information System (GIS). It was found that the study area comprised of four major physiographic regions viz. pediplain (80.9%), undifferentiated hill slopes (8.0%), pediments (6.3%), alluvial plains (4.8%) and soils were classified under Entisols, Inceptisols, Alfisols and Vertisols orders. The land capability assessment of identified mapping units showed that around 44.4% of the Total Geographical Area (TGA) which mainly falls in agriculture was classified under land capability class II and II-III and has the soil quality issues with respect to soil pH, Electrical Conductivity (E.C.) and texture. About 8.1% area found under class III in agriculture and plantation having potential limitations of unfavourable soil texture, moderate salinity, whereas, 5.4% area under open scrub was classified under class III-IV and suffers from root zone limitation, low organic carbon, unfavourable texture, susceptibility for erosion. About 8.7% area fall under open scrub/waste land placed under class IV and VI due to adverse effect of past erosion on soil quality imposed mainly due to faulty land use and unfavourable landform. It was observed that 27.5% area was covered under notified/restricted forest and 5.9% area under miscellaneous uses like settlements or water bodies etc. These areas were not studied for their land capabilities. The spatial database created in GIS will be of immense use for the academicians and planners to identify problematic areas and to suggest sustainable action plan for development of agriculture, horticulture, forestry, etc.

Soils and climate of Cul de Sac Valley, Haiti: A soil water and geomorphology perspective

Soil is an important natural resource, yet for many countries, including Haiti, the only soil inventory is a general soil map at 1:250,000 scale, which is not suitable for management planning at the farm level. A soil survey for a 3,000 ha (7,400 ac) segment of Cul de Sac Valley was conducted at 1:24,000 scale. Eleven soil types and soil map units were identified. Approximately 60% of the study area consisted of soils on Floodplains, while 40% were soils on Foothills, Hills, and Dissected Alluvial Fans. The combination of the parent material, predominantly marine sediment and limestone bedrock, and spatial-temporal precipitation patterns resulted in soils dominated by calcium carbonate (CaCO3) and sodium (Na) accumulations throughout their profile. The new soil geomorphology map derived from the detailed soil map was similar to the existing general soil map and geomorphology map. It was spatially more accurate and provided better understanding of soil and climate influence on soil water movement. Cul de Sac Valley resulted from uplifting and erosion and deposition processes. This, combined with aridic to semiaridic climate conditions, resulted in cemented CaCO3 accumulation and Na rich soils. The water management for irrigation was limited by a combination of soil properties such as high gravel and steep slopes for Dissected Alluvial Fans and Hills soil geomorphic units, presence of cemented CaCO3 for Foothills, and high Na content for Lower Flat Plains. Further studies are needed for a complete and comprehensive understanding of the soil geomorphology processes and climate interactions of this complex system.

Phosphate fertiliser application effects on seasonally dry hill country pasture and soil

ABSTRACTA grazed trial established in 1980 evaluated the effects of superphosphate fertiliser application on pasture growth on Easy (10°–20° slope) and Steep (30°–40° slope) land in the Waikato, North Island, New Zealand. Continuous and rotational grazing showed no effects on pasture responses to fertiliser. Mean annual pasture dry matter (DM) production ranged from 11,275 to 14,155 kg DM ha−1 on Easy, and 6413 to 7480 kg DM ha−1 on Steep slopes through the range of 10–100 kg ha−1 yr−1 of phosphate (P) fertiliser rates. Initial fertiliser effects on Olsen P tests were in the 0–3 cm depth only, and in the 7–15 cm soil depth only in the 100 kg ha−1 yr−1 treatment by year 4. Near maximum (97%) annual production, derived from relative yield analysis, was obtained at 0–7 cm depth soil tests of 30 on Easy slopes and at 12 on Steep slopes. Results from this trial are directly relevant to the variable fertiliser rate aerial application technology currently being developed.

Principal component analysis of soil properties in assessing erodibility indices in the Northern Brahmaputra plains of Assam

Fifty soils representing six different landscape units of the Northern Brahmaputra plains of Assam were collected for evaluating their erosional status. After estimating the soil physico-chemical and fertility related properties, various erodibility indices like clay ratio, silt/clay ratio, modified clay ratio, dispersion ratio, erosion ratio and erosion index were computed based on the measured soil data. Principal component analysis was carried out using 29 characters which included 23 soil properties and 6 erodibility indices. The principal factor analysis synthesized five factors explaining 80.38 per cent variability. The first factor which accounted for 51.79 per cent of the total variability was strongly influenced by erodibility indices and a set of related physico-chemical and fertility parameters. Based on the calculated factor scores it was found that the soils of the old flood plain are the most stable landscape unit of the studied area while, the structural hill soils are the most erodible one. The ranking of the soils appeared to be in close agreement with soil analytical and computed data.

Slope class and grazing intensity effects on microorganisms and nitrogen transformation processes responsible for nitrous oxide emissions from hill pastures

Nitrous oxide emissions are a product of soil microbial transformations such as nitrification and denitrification that are regulated by a range of biophysical factors. As the majority of farmed land in New Zealand is grazed hill country, this represents a potentially large source area for nitrous oxide (N2O) emissions nationally. In this study we investigated the impact of slope class and grazing intensity on hill soil biogeochemistry with a focus on processes leading to N2O emissions. Soils under permanent grass/legume sheep-grazed pasture on hill country in the North Island (temperate climate) of New Zealand were studied. Soil samples were collected from experimental pastures representing 3 slope gradient classes: low (0–12°), medium (13–25°), and high (>25°) slope and 2 grazing intensities which we define as extensive and intensive (mean annual standing biomass of 1900 vs.1475kgDMha−1). Soil properties, nitrifying and denitrifying enzyme activity, and abundance of soil microbial functional genes were determined.Soil physicochemical properties, nitrifying and denitrifying enzyme activity, and abundances of soil microbial functional groups were higher in the low compared to medium and high slope classes. In contrast, heterotrophic nitrification enzyme activity was marginally higher in soils from medium and high compared to low slopes. In general there were no significant effects of grazing intensity on the soil properties studied, or on autotrophic/heterotrophic nitrification enzyme activity. However, in low slopes only soil nitrate content, nirK (nitrite reductase) gene abundance and total denitrification enzyme activity were significantly higher under more intensive grazing pressure.Our results suggest that the potential for N2O emissions is higher in low compared to medium and high slope areas. At our experimental site, three years of comparatively more intensive grazing pressure did not show conclusive evidence for grazing-induced impacts on N2O emission potential. Of the microbial functional units assessed, the abundances of nirK were most closely linked with function. Our work indicates the importance of taking into consideration the effect of slope class when accounting for N2O emissions in hill country pastures in New Zealand.

Impact of fodder grasses and organic amendments on productivity and soil and crop quality in a subtropical region of eastern Himalayas, India

Agriculture in the Eastern Indian Himalayas is characterized by fragility and marginality with about 77% of the geographical area under hills and degraded plateau. Thus, field experiments were conducted for three consecutive years during 2008–2011 to assess the impact of perennial fodder grasses and sources of nutrient supply on productivity and quality of soil and fodder under terrace conditions in a subtropical degraded hill soil of Meghalaya, India (980m above sea level). The treatment consisted of four fodder crops and three sources of nutrients. Fodder crops were broom grass (Thysanolaena maxima), congosignal grass (Brachieria rosenesis), hybrid napier (Pennisetum typhoides x P. purpureum) and guinea grass (Panicum maximum). Three sources of nutrient supply were organic, inorganic and control (inherent soil fertility conditions). Farmyard manure (FYM) was used as organic source of nutrient supply on N equivalent basis and P nutrition was supplemented through rock-phosphate. Fertilizer urea, single super phosphate and muriate of potash were used as inorganic source of nutrients. The dry fodder yield increased in each successive year and three year average dry fodder yield was significantly higher with hybrid napier (28.1Mgha−1) than other grasses. Among nutrient sources, the average dry fodder yield under organic amendment (22.9Mgha−1) was 27.5 and 64.4% higher than that under inorganic fertilizer (17.9Mgha−1) and control (13.9Mgha−1), respectively. Crude fibre (35.9%) and lignin (7.02%) concentrations were the maximum in hybrid napier whereas, cellulose (39.1%) was the highest in congosignal grass. On the contrary, crude protein concentration was the maximum in broom grass (8.27%), and it was at par with that in hybrid napier. The available N, P, K and soil organic carbon (SOC) contents were significantly higher (P=0.05) under organic compared to those under other nutrient sources. The SOC concentration (17.2gkg−1) and stock (32.2Mgha−1) after three years under organic treatment was 5.3 and 2.1% and 13.3 and 8.1% higher than that recorded under inorganic and control, respectively. The study indicated suitability of fodder grasses and organic amendments in improving quality of marginal degraded hill soils.

Spatial distribution of physico-chemical properties and function of heavy metals in soils of Yelagiri hills, Tamilnadu by energy dispersive X-ray florescence spectroscopy (EDXRF) with statistical approach

Soil physico-chemical properties were thought to be important factors in obscuring clear identification of pollutant sources. In the present study physicochemical properties such as, pH, electrical conductivity, bulk density, porosity density, soil texture and color were determined to identify the pollution status using different conventional analytical methods in soils of Yelagiri Hills, Tamilnadu. Soil pH ranges from 5.39 to 8.43 which indicate that the soils are acidic to alkaline in nature. The concentrations of selected heavy metals were determined using energy dispersive X-ray florescence spectroscopy (EDXRF) technique. In all the locations Al is the most abundant metal and Co is the least amount in soil. The relationship between the physico-chemical properties and heavy metals were studied by Pearson correlation. The statistical technique shows that strong significant correlation among the heavy metals. The Chemometric approaches namely: principal component analyses (PCA), hierarchical cluster analysis (HCA), were used for identify the soil pollutant. Spatial distribution of physico-chemical properties of soil such as pH, soil texture (sand, silt, clay) electrical conductivity was studied by geo-statistical methods such as kriging identified areas. The heavy metal mapping also attempted to know the distribution pattern in soils.

Effect of long term terrace cultivation on nutrient availability and lime requirements in acid soils of Kalimpong hills under mulberry farming

This study was undertaken in 2011–12 to assess the effect of long term terrace cultivation on nutrient availability and lime (CaCO3) requirements in acid soils of Kalimpong hills under mulberry farming. Soil samples were collected from the mulberry field of Regional Sericultural Research Station (RSRS) farm, Regional Sericultural Research Station Annexure (RSRSA) farm and farmers field from eight different villages. The overall pH mean in the soils of RSRS farm and farmers field was 6.0 and 5.0 in RSRSA farm. The overall mean of OC content in the RSRS farm was 1.80% followed by 1.50% in farmers’ field and 1.30% in the RSRSA farm. The available nutrients e.g. nitrogen (N) 474.1 kg ha−1; phosphorus (P) 14.4 kg ha−1; potassium (K) 164.7 kg ha−1 and sulphur (S) 9.6 kg ha−1 were present in the soils of RSRSA research farm, however, these nutrients were 586.4 kg ha−1 (N); 17.9 kg ha−1(P); 183.6 kg ha−1(K) and 15.3 kg ha−1 (S) in the soils of RSRS research farm and 590.5 kg ha−1(N); 19.5 kg ha−1(P); 284.6 kg ha−1 (K) and 12.7 kg ha−1 (S) in the progressive farmers’ field. The overall mean of the CaCO3 requirements for reclamation of RSRSA farm soil was 2.30 mt ha−1 followed by 1.50 mt ha−1 in RSRS farm and 1.16 mt ha−1 in the farmers’ fields. These data revealed that, the long term terrace cultivation under mulberry farming in acid soils of entire Kalimpong hills, significantly affects the nutrients availability and lime requirements. The nutrients availability at RSRS research farm and farmers’ field under long term terrace cultivation was quite high than RSRSA research farm.

Measurements of Natural Gamma Radiations and Effects of Physico-Chemical Properties in Soils of Yelagiri Hills, Tamilnadu India with Statistical Approach

Human beings have always been exposed to natural radiations arising from within and outside the earth. In the present study the concentration of natural radio-nuclides 238U, 232Th and 40K and gamma radiation dose rate in soils of Yelagiri hills, Tamilnadu was determined by gamma ray spectrometry. The determined averageabsorbed dose rate value is 88.64 nGy h-1 which is slightlygreater than the world average value of 84 nGy h-1. The physico-chemical properties such as PH, soil texture, electrical conductivity, bulk density, parasite density and color of the soils was determined to assess the soil quality. The obtained radiological and physico-chemical data were treated by multivariate statistical techniques such as Pearson correlation and cluster analysis to determine the interrelation between the natural radio-nuclides and physico-chemical properties.

Statistical analysis of soil geochemical data to identify pathfinders associated with mineral deposits: An example from the Coles Hill uranium deposit, Virginia, USA

Soil geochemical anomalies can be used to identify pathfinders in exploration for ore deposits. In this study, compositional data analysis is used with multivariate statistical methods to analyse soil geochemical data collected from the Coles Hill uranium deposit, Virginia, USA, to identify pathfinders associated with this deposit. Elemental compositions and relationships were compared between the collected Coles Hill soil and reference soil samples extracted from a regional subset of a national-scale geochemical survey. Results show that pathfinders for the Coles Hill deposit include light rare earth elements (La and Ce), which, when normalised by their Al content, are correlated with U/Al, and elevated Th/Al values, which are not correlated with U/Al, supporting decoupling of U from Th during soil generation. These results can be used in genetic and weathering models of the Coles Hill deposit, and can also be applied to future prospecting for similar U deposits in the eastern United States, and in regions with similar geological/climatic conditions.

Assessment of natural radioactivity and function of minerals in soils of Yelagiri hills, Tamilnadu, India by Gamma Ray spectroscopic and Fourier Transform Infrared (FTIR) techniques with statistical approach

Gamma Ray and Fourier Transform Infrared (FTIR) spectroscopic techniques were used to evaluate the natural radioactivity due to natural radionuclides and mineralogical characterization in soils of Yelagiri hills, Tamilnadu, India. Various radiological parameters were calculated to assess the radiation hazards associated with the soil. The distribution pattern of activity due to natural radionuclides is explained by Kriging method of mapping. Using FTIR spectroscopic technique the minerals such as quartz, microcline feldspar, orthoclase feldspar, kaolinite, montmorillonite, illite, and organic carbon were identified and characterized. The extinction coefficient values were calculated to know the relative distribution of major minerals such as quartz, microcline feldspar, orthoclase feldspar and kaolinite. The calculated values indicate that the amount of quartz is higher than orthoclase feldspar, microcline feldspar and much higher than kaolinite. Crystallinity index was calculated to know the crystalline nature of quartz. The result indicates that the presence of disordered crystalline quartz in soils. The relation between minerals and radioactivity was assessed by multivariate statistical analysis (Pearson’s correlation and cluster analysis). The statistical analysis confirms that the clay mineral kaolinite and non-clay mineral quartz is the major factor than other major minerals to induce the important radioactivity variables and concentrations of uranium and thorium.

Nanocrystalline Silica from Termite Mounds

To develop a better understanding of the physical properties and microstructures of the termite hill soils, we have carried out studies on the soil samples collected from two locations: near Dehradun, Utta-rakhand and near Hauz Khas, New Delhi. Their ele-mental composition and microstructure were studied using different instrumentation techniques, such as powder X-ray diffraction, field emission scanning electron. Microscopy, transmission electron microscope (TEM) and energy-dispersive analysis of X-ray (EDAX). α-Quartz (SiO 2 ) was present in both the samples, while the sample collected from Hauz Khas, Delhi also con-tained β-cristobalite phase of SiO 2 . TEM-EDAX showed that termite hill soil consisted of silica (quartz), aluminium oxide, manganese oxide and iron oxide along with small percentage of potassium and calcium. Our studies highlight the potential to gene-rate α-quartz from all termite hills. It is also possible to obtain the less common β-cristobalite form of silica in certain termite mounds.

Soil fertility status of some mango orchards in Chittagong Hill Tracts

Major physico-chemical properties of mango orchard soils (Mangifera indica L.) in different sites of three hill districts, Rangamati, Khagrachari and Bandarban were evaluated. Soils were sandy loam in texture at all the sites except foot hill soil of Shapchari. Soil pH, organic matter, total N and available P varied from 4.76 to 5.58, 1.43 to 2.49 %, 0.10 to 0.16 %, 0.86 mg kg-1 to 2.69 mg kg-1 soil, respectively in surface soil of different sites of mango orchard. 1N NH4OAc extractable K+, Ca2+ and Mg2+ ranged from 0.35 to 0.82, 2.50 to 3.66 and 0.60 to 1.57 cmol kg-1 of soils. Soil pH, organic matter, total N and available P varied significantly among the slope positions within the sites. Similar results were found in case of 1N NH4OAc extractable K+, Ca2+ and Mg2+. The soils are generally poor in organic matter and nutrients. DOI: http://dx.doi.org/10.3329/cujbs.v6i1-2.17244 The Chittagong Univ. J. B. Sci.,Vol. 6(1&2):187-197, 2011

A study on unsaturated hydraulic conductivity of hill soil of north-east India

Hill slope hydrology in terms of surface drainage and infiltration is important for analysing its stability and understanding the possibility of landslides. The infiltrating water during rainfall is found to cause instability to the slope. The location of water table will be low in such hill slopes and the soil will be mostly unsaturated. Therefore, the subsurface drainage of infiltrating water in a slope is influenced by the unsaturated hydraulic conductivity (ku ) of soil. The hill slopes of north-east India mainly constitute unsaturated red soil. There are not many studies related to the determination of unsaturated hydraulic conductivity of this soil. Direct experimental determination of ku is a challenging task and requires costly and skilled experimentation. Therefore, the normal practice is to obtain ku based on water retention characteristic (WRC) and saturated hydraulic conductivity (ks ) of the soil. In this study, an equitensiometer, a matric potential sensor and a relative humidity sensor have been used to measure WRCs of hilly red soil. The study indicates that the measurement methodologies have significant influence on the uniqueness of WRC of red soil and, hence, the estimation of ku .

Draft Genome Sequence of Rhodococcus triatomae Strain BKS 15-14

We report the 5.8-Mb genome sequence of Rhodococcus triatomae BKS 15-14, isolated from an ant hill soil sample, collected from Bhitarkanika Mangrove Reserve Forest, Odisha, India. The draft genome of strain BKS 15-14 consists of 5,824,349 bp, with a G+C content of 69%, 5,387 protein-coding genes, and 57 RNAs.

Effect of heavy metal and nutrient uptake by soils in Indian Cardamom Hills

Indian cardamom hill soils were studied to understand nutrient and heavy metal uptake and consequent fertility level changes. Extensive cultivation of cardamom and conversion of forest land to cardamom agriculture resulted in decline of OM and lower pH. Application of chemical fertilizers in the recent past helped enhance the available phosphorus (P). This is surprisingly contrary to the general observation of low P fertility and availability of tropical humid forest soils. Available nutrient concentrations with respect to potassium (K), magnesium (Mg) and sulphur (S) were low in cardamom soils while micronutrient concentrations were well above the proposed critical limits. Agricultural intensification through use of mercurial fungicides and other pesticides in Indian cardamom hill soils has resulted in continuous loading of heavy metals in leaves, seeds and rinds. Such a situation could soon lead to a level sufficient to cause serious fertility and environmental problems. Key words: Nutrient and heavy metal uptake, soil fertility, tropical agro forest environment.