Temporal Stability of Apparent Soil Electrical Conductivity Measured by Electromagnetic Induction Techniques

Assessing and managing the spatial variability of hydropedological properties are important in environmental,agricultural,and geological sciences.The spatial variability of soil apparent electrical conductivity(ECa) measured by electromagnetic induction(EMI) techniques has been widely used to infer the spatial variability of hydrological and pedological properties.In this study,temporal stability analysis was conducted for measuring repeatedly soil ECa in an agricultural landscape in 2008.Such temporal stability was statistically compared with the soil moisture,terrain indices(slope,topographic wetness index(TWI),and profile curvature),and soil properties(particle size distribution,depth to bedrock,Mn mottle content,and soil type).Locations with great and temporally unstable soil ECa were also associated with great and unstable soil moisture,respectively.Soil ECa were greater and more unstable in the areas with great TWI(TWI > 8),gentle and concave slope(slope < 3%; profile curvature > 0.2).Soil ECa exponentially increased with depth to bedrock,and soil profile silt and Mn mottle contents(R2= 0.57),quadratically(R2 = 0.47),and linearly(R 2 = 0.47),respectively.Soil ECa was greater and more unstable in Gleysol and Nitosol soils,which were distributed in areas with low elevation(< 380 m),thick soil solum(> 3 m),and fluctuated water table(shallow in winter and spring but deep in summer and fall).In contrast,Acrisol,Luvisol,and Cambisol soils,which are distributed in the upper slope areas,had lower and more stable soil ECa.Through these observations,we concluded that the temporal stability of soil ECa can be used to interpret the spatial and temporal variability of these hydropedological properties.

SOIL DEGRADATION IN A SEMI-ARID ENVIRONMENT IN KENYA:THE MUKOGODO CATCHMENT CASE STUDY

The objectives of this study were to assess the impact of soil erosion on the physicaland chemical characteristics and the fertility status of the soils of the catchment and to alsostudy the soil properties that have accelerated the formation and the development of gulliesand tunnels in this area. This catchment of study covers 252 hectares and the major soils covering the area

Soil and Land Suitability Assessment for Rice Cultivation at Tono Irrigation Area in the Upper East Region, Ghana

Agriculture is one of the livelihood supports for the people of Upper East Region of Ghana. Soil evaluation research was conducted at Tono Irrigation Scheme to assess soil and land suitability for rice cultivation in the irrigable area of Tono Irrigation Scheme. A total of eleven (11) soil samples were collected and analysed for their chemical and physical properties. Based on field observation and criteria for soil suitability assessment, the different soil types that were identified were classified at the series level based on their position, parent material and the observed physical characteristics. The results indicated that the pH of the soils was within the acceptable range for crop production;however, the overall fertility level of the soils was very low. Physically, the upland soils were well to moderately well-drained, consisting of coarse-grained sandy loams topsoil overlying similar sandy loams and sandy clay loams at depth. They included Leptosols and Lixisols. The soils of the Scheme under lowlands and valley bottom sites, however, included Eutric Gleysol, Calsic Vertisol, Eutric Fluvisol and Eutric Plinthosol, which were heavily textured and relatively poor drained, or medium-textured and moderately to imperfectly well-drained. They showed a low to a very low rate of water percolation losses, which is good for the current farming system of cropping rice within the lowlands and valley bottom sites of the Scheme.

Invasive Common Reed (Phragmites australis (Cav.) Trin. ex Steud.): A Serious Ecological Threat to Ladakh Tethys Himalayan Biodiversity in Changing Climate

Ladakh’s cropped and non-cropped areas suffer greatly from weedy invasion under subsistence agricultural system where weeding is not a priority but total crop + weed biomass together contribute to livestock feeding significantly. As agriculture along with livestock rearing is major activity of livelihood options, thereby contributing significantly to Ladakh economy and income generation for supporting resource poor farmers. Amongst various invasive weed species, the common reed (Phragmites australis) has become a serious ecological threat for agri-silvi-pastoral system biodiversity and accelerated its expansion in cropped lands including many wetland and salt-affected habitats of cold arid region due to its intermediate plant growth habit of C3 - C4 photosynthetic ecotypes. This character makes Phragmites a climate-resilient species, which is a major challenge for cold arid agriculture in the changing climatic patterns. Simultaneously, it is one of the best fodder substitute available under harsh climate. This paper deals with its unique characters and potential threats to the agrobiodiversity of Ladakh.

Desertification status mapping in MuttumaWatershed by using Random Forest Model

Potential of the Random Forest Model on mapping of different desertification processes was studied in Muttuma watershed of mid-Murrumbidgee river region of New South Wales,Australia.Desertification vulnerability index was developed using climate,terrain,vegetation,soil and land quality indices to identify environmentally sensitive areas for desertification.Random Forest Model(RFM)was used to predict the different desertification processes such as soil erosion,salinization and waterlogging in the watershed and the information needed to train classification algorithms was obtained from satellite imagery interpretation and ground truth data.Climatic factors(evaporation,rainfall,temperature),terrain factors(aspect,slope,slope length,steepness,and wetness index),soil properties(pH,organic carbon,clay and sand content)and vulnerability indices were used as an explanatory variable.Classification accuracy and kappa index were calculated for training and testing datasets.We recorded an overall accuracy rate of 87.7%and 72.1%for training and testing sites,respectively.We found larger discrepancies between overall accuracy rate and kappa index for testing datasets(72.2%and 27.5%,respectively)suggesting that all the classes are not predicted well.The prediction of soil erosion and no desertification process was good and poor for salinization and water-logging process.Overall,the results observed give a new idea of using the knowledge of desertification process in training areas that can be used to predict the desertification processes at unvisited areas.

Targeted yield concept and a framework of fertilizer recommendation in irrigated rice domains of subtropical India

Soil test crop response （STCR） correlation studies were carried out in Vindhyan alluvial plain during 2001 to 2004 taking IR-36 as test crop to quantify rice production in the context of the variability of soil properties and use of balanced fertilizers based on targeted yield concept. The soils were developed on gently sloping alluvial plain with different physiographic settings and notable variation in drainage condition. Soil properties show moderate variation in texture （loamy to clay）, organic carbon content （4.4 to 9.8 g/kg）, cation exchange capacity （10,2 to 22.4 cmol （p＋）/kg） and pH （5.3 to 6,4）, Soil fertility status for N is low to medium （224 to 348 kg/ha）, P is medium to high （87 to 320 kg/ha） and K ranges from medium to high （158 to 678 kg/ha）. Database regarding nutrient requirement in kg/t of grain produce （NR）, the percent contribution from the soil available nutrients [CS （%）] and the percent contribution from the applied fertilizer nutrients [CF （%）] were computed for calibrating and fbrmulating fertilizer recommendations. Validity of the yield target for 7 and 8 t/ha was tested in farmers＇ fields and yields targets varied at less than 10%. The percent achievement of targets aimed at different level was more than 90%, indicating soil test based fertilizer recommendation approach was economically viable within the agro-ecological zone with relatively uniform cropping practices and socio-economic conditions.

Effect of Salts Stress on the Growth and Yield of Wheat (Triticum aestivum L.)

In order to study the effect of salts stress on the growth and yield of wheat (cv. Inqalab), a pot experiment was conducted in the wire-house of the Department of Soil Science, Sindh Agriculture University Tando Jam. The soil was artificially salinized to a range of salinity levels i.e . EC 2.16, 4.0, 6.0, 8.0 and 10.0 dS·m-1 with different salts (MgCl2 + CaCl2 + Na2SO4). The salinized soil used for the experiment was sandy clay in texture, alkaline in reaction (pH > 7.0) and moderate in organic matter (0.95%) content. The results showed that with increasing salinity there was an increase in the ECe, Na+, Ca2+, Mg2+ and Cl- and decrease in the K+, SAR and ESP values of the soil Increasing salinity, progressively decreased plant height, spike length, number of spikelets spike-1 1000 grain weight and yield (straw and grain). Adverse effects of salts on plants were associated with the accumulation of less K+ and more Na+ and Cl- in their flag leaf sap, grains and straw. This resulted in lower K+:5Na+ ratio in flag leaf sap, grains and straw of wheat plants. These results indicated that the effects of salts stress were greater at 10 than at 8, 6 and 4 EC dS·m-1.

Correlation and Regression Analysis for Yield Traits in Wheat (Triticum aestivum L.) Genotypes

The present research work was carried out at Southern Wheat Research Station, Tandojam during the growing season 2013-14 in order to work out correlation and regression analysis for yield traits in wheat genotypes. The experiment was laid out in a Randomized Complete Block Design with three replications. Eight bread wheat genotypes such as Mehran, Sarsabz, TJ-83, SKD-1, Inqlab, A. Sattar, Sehar and Sassui were used to examine correlation and regression. Seven traits, viz.;plant height, tillers plant-1, spike length, spikelet’s spike-1, grains spike-1, seed index and grain yield plant-1 were studied. The analysis of variance revealed significant differences among the genotypes for plant height, tillers plant-1, spike length, spikelet’s spike-1, grains spike-1, seed index and grain yield plant-1. Based on mean performance, variety Sarsabz gave maximum plant height (95.46), produced maximum tillers plant-1 (4.40), gave more grain spike-1 (63.13), TJ-83 gave highest seed index (47.260), and was next ranker in spike length-1 (12.07), spikelet’s spike-1 (19.13), grains spike-1 (59.86), and grain yield plant-1 (9.86) among the genotypes. The phenotypic correlations revealed that tillers plant-1 and grains spike-1 were highly positively associated;hence these yield components can be used as reliable selection criteria to improve grain yield in wheat. Thus estimation of correlation and regression analysis among yield and yield components may provide effective selection criteria to improve wheat grain yield. The results from correlation and regression of plant height indicated significantly positive association with spikelet’s spike-1, tillers plant-1 and grains spike-1 which revealed that increase in plant height will cause corresponding increase in associated traits.

Glacier retreat, rock weathering and the growth of lichensin the Churup Valley, Peruvian Tropical Andes

The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"S;77°25’02"W)and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016),the Schmidt hammer rock test and lichenometric dating.It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05±0.1 km^2;45.0×10^6-57.4×10^6 m^3).The rate of glacier retreat is documented to vary in space(SE,SW and NW-facing slopes)and time,with the peak between 1986 and 1995.With an area of 0.045 km^2 in 2016,it is expected that the complete deglaciation of the Churup valley is inevitable in the near future.Recently(post-LIA)exposed bedrock surfaces have shown higher R-values(54.2-66.4,AVG 63.3,STDEV 2.9)compared to pre-LIA exposed surfaces(46.1-59.3,AVG 50.1,STDEV 4.9),confirming the links to the duration of rock weathering.The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l.,revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment.

Role of Organic Amendments to Mitigate Cd Toxicity and Its Assimilation in Triticum aestivum L.

In soil biota,higher and enduring concentration of heavy metals like cadmium(Cd)is hazardous and associated with great loss in growth,yield,and quality parameters of most of the crop plants.Recently,in-situ applications of eco-friendly stabilizing agents in the form of organic modifications have been utilized to mitigate the adverse effects of Cd-toxicity.This controlled experiment was laid down to appraise the imprints of various applied organic amendments namely poultry manure(PM),farmyard manure(FYM),and sugarcane press mud(PS)to immobilize Cd in polluted soil.Moreover,phytoavailability of Cd in wheat was also accessed under an alkaline environment.Results revealed that the addition of FYM(5–10 ton ha^(-1))in Cd-contaminated soil significantly increased germination rate,leaf chlorophyll content,plant height,spike length,biological and grain yield amongst all applied organic amendments.Moreover,the addition of FYM(5–10 ton ha^(-1))also reduced the phytoavailability of Cd by 73–85%in the roots,57–83%in the shoots,and 81–90%in grains of wheat crop.Thus,it is affirmed that incorporation of FYM(5–10 ton ha^(-1))performed better to enhance wheat growth and yield by remediating Cd.Thus,the application of FYM(5–10 ton ha^(-1))reduced the toxicity induced by Cd to plants by declining its uptake and translocation as compared to all other applied organic amendments to immobilize Cd under sandy alkaline polluted soil.

Pedotransfer Functions for Estimating Soil Hydraulic Properties： A Review

Characterization of soil hydraulic properties is important to environment management; however, it is well recognized that it is laborious, time-consuming and expensive to directly measure soil hydraulic properties. This paper reviews the development of pedotransfer functions （PTFs） used as an alternative tool to estimate soil hydraulic properties during the last two decades. Modern soil survey techniques like satellite imagery/remote sensing has been used in developing PTFs. Compared to mechanistic approaches, empirical relationships between physical properties and hydraulic properties have received wide preference for predicting soil hydraulic properties. Many PTFs based on different parametric functions can be found in the literature. A number of researchers have pursued a universal function that can describe water retention characteristics of all types of soils, but no single function can be termed generic though van Cenuchten （VG） function has been the most widely adopted. Most of the reported parametric PTFs focus on estimation of VG parameters to obtain water retention curve （WRC）. A number of physical, morphological and chemical properties have been used as predictor variables in PTFs. Conventionally, regression algorithms/techniques （statistical/neurM regression） have been used for calibrating PTFs. However, there are reports of utilizing data mining techniques, e.g., pattern recognition and genetic algorithm. It is inferred that it is critical to refine the data used for calibration to improve the accuracy and reliability of the PTFs. Many statistical indices, including root mean square error （RMSE）, index of agreement （d）, maximum absolute error （ME）, mean absolute error （MAE）, coefficient of determination （r2） and correlation coefficient （r）, have been used by different researchers to evaluate and validate PTFs. It is argued that being location specific, research interest in PTFs will continue till generic PTFs are developed and validated. In future studies, improved methods will be required to extract information from the existing database.

Spatially distributed modelling and mapping of soil organic carbon and total nitrogen stocks in the Eastern Mau Forest Reserve,Kenya

Detailed knowledge about the estimates and spatial patterns of soil organic carbon(SOC) and total nitrogen(TN) stocks is fundamental for sustainable land management and climate change mitigation.This study aimed at:(1) mapping the spatial patterns,and(2) quantifying SOC and TN stocks to 30 cm depth in the Eastern Mau Forest Reserve using field,remote sensing,geographical information systems(GIS),and statistical modelling approaches.This is a critical ecosystem offering essential services,but its sustainability is threatened by deforestation and degradation.Results revealed that elevation,silt content,TN concentration,and Landsat 8 Operational Land Imager band 11 explained 72% of the variability in SOC stocks,while the same factors(except silt content) explained 71% of the variability in TN stocks.The results further showed that soil properties,particularly TN and SOC concentrations,were more important than that other environmental factors in controlling the observed patterns of SOC and TN stocks,respectively.Forests stored the highest amounts of SOC and TN(3.78 Tg C and 0.38 Tg N) followed by croplands(2.46 Tg C and 0.25 Tg N) and grasslands(0.57 Tg C and 0.06 Tg N).Overall,the Eastern Mau Forest Reserve stored approximately 6.81 Tg C and 0.69 Tg N.The highest estimates of SOC and TN stocks(hotspots) occurred on the western and northwestern parts where forests dominated,while the lowest estimates(coldspots) occurred on the eastern side where croplands had been established.Therefore,the hotspots need policies that promote conservation,while the coldspots need those that support accumulation of SOC and TN stocks.

A Novel Evolutionary Genetic Optimization-Based Adaptive Neuro-Fuzzy Inference System and Geographical Information Systems Predict and Map Soil Organic Carbon Stocks Across an Afromontane Landscape

Soil organic carbon （SOC） pool has the potential to mitigate or enhance climate change by either acting as a sink, or a source of atmospheric carbon dioxide （CO2） and also plays a fundamental role in the health and proper functioning of soils to sustain life on Earth. As such, the objective of this study was to investigate the applicability of a novel evolutionary genetic optimization-based adaptive neuro-fuzzy inference system （ANFIS-EG） in predicting and mapping the spatial patterns of SOC stocks in the Eastern Mau Forest Reserve, Kenya. Field measurements and auxiliary data reflecting the soil-forming factors were used to design an ANFIS-EG model, which was then implemented to predict and map the areal differentiation of SOC stocks in the Eastern Mau Forest Reserve. This was achieved with a reasonable level of uncertainty （i.e., root mean square error of 15.07 Mg C ha-l）, hence demonstrating the applicability of the ANFIS-EG in SOC mapping studies. There is potential for improving the model performance, as indicated by the current ratio of performance to deviation （1.6）. The mapping also revealed marginally higher SOC stocks in the forested ecosystems （i.e., an average of 109.78 M C ha-1） than in the aro-ecosvstems （i.e., an average of 95.9 Mg C ha-l）.

A paleosol classification with the inclusion of ancient arctic and subarctic region soils

Paleosol identification is simplified by considering soil as a natural body withinternal organization and a history of formation. This definition assumes that we accept paleosolsas soils. In a paleosol classification, inclusion of the cold region paleosols at the suborder levelplaces temperature (climate) in balance with the other soil forming factors. Because ancienttemperatures were not recorded, we use soil and parent material properties as proxies to identifyancient soils from Arctic and Subarctic regions. The properties include permafrost andcryoturbation features as well as those resulting from glacial processes. These features generallypersist through later cycles of soil formation as climate has changed. Examples both within andbeyond the glacial borders in Wyoming, Illinois, and Indiana, USA are presented and classifiedusing an arctic paleosol suborder modifier, the formative element.

Integration of remote sensing and GIS in monitoring the dynamics of land cover in Oroba-Kibos catchment area,Kenya

Land cover in Kenya is in a state of flux at different spatial and temporal scales.This compromises environmental integrity and socioeconomic stability of the population hence increasing their vulnerability to the externalities of environmental change.The Oroba-Kibos catchment area in western Kenya is one locality where rapid land use changes have taken place over the last 30 years.The shrubs,swamps,natural forests and other critical ecosystems have been converted on the altar of agriculture,human settlement,fuel wood and timber.This paper presents the results of a study that aimed at providing spatially-explicit information for effective remedial response through(a) Mapping the land cover;(b) Identifying the spatial distribution of land cover changes;(c) Determining the nature,rates and magnitude of the land cover changes,and;(d) Establishing the drivers of land use leading to land cover changes in Oroba-Kibos catchment area.Bi-temporal Landsat TM imagery,field observation,household survey and ancillary data were obtained.Per-field classification of the Landsat TM imagery was performed in a GIS and the resultant land cover maps assessed using the field observation data.Post-classification comparison of the maps was then done to detect changes in land cover that had occurred between 1994 and 2008.SPSS was used to analyze the household survey data and attribute the detected land cover changes to their causes.The findings showed that 9 broad classes characterize the catchment area including the natural forests,swamps,natural water bodies,woodlands,shrublands,built-up lands,grasslands,bare lands and croplands.Croplands are dominant and accounted for about 65%(57122 ha) of the total land in 1994,which increased at the rate of 0.89% to 73%(64772 ha) in 2008,while natural water bodies has the least spatial coverage accounting for about 0.6%(561 ha) of the total land in 1994,which diminished at the rate of 3.57% to 0.3%(260 ha) in 2008.Climate,altitude,access and rights to land,demographic changes,poverty,political governance,market availability and economic returns are the interacting mix of proximate and underlying factors that drive the land cover changes in Oroba-Kibos catchment area.

Irrigation capability evaluation of Illushi floodplain,Edo State,Nigeria

Many irrigation projects,especially in the developing tropical regions,are embarked upon without any land capability assessment,resulting in avoidable and undesirable ecological consequences.The aim of this study is to assess the irrigation capability potentials of the soils of a rice growing Illushi/Ega community in Edo State of Nigeria.Soils of Illushi/Ega(200 ha)were studied to establish their irrigation capabilities.Water samples were collected from the rivers within and near the sites at the proposed points of intake structures and analyzed for salinity(ECw),permeability(SAR)and ion toxicity[Chlorine(Cl)and Boron(B)].Gravity irrigation suitability assessment was carried out following the guidelines of the United States Bureau for Land Reclamation(USBR,1953)and FAO(1979).Results showed that about 5.5%of the land was non-irrigable,11.5%was marginally irrigable,30.5%was moderately irrigable and 52.5%highly irrigable.Thus about 83%of the total land area was found to be irrigable.The results of analyses of irrigation water[ECw,SAR and Cl and B(ion toxicity)problems in water sources were 0.1-0.7 dS m^(-1),1.2-1.7,0.6-1.8 cmol kg^(-1) and 0.5-0.7 mg kg^(-1)]also show that there is no indication of salinity or ion toxicity problem.