Soil slips on weathering-limited slopes underlain by coarse-grained granite or fine-grained gneiss near Seoul,Republic of Korea

The chemical, mineral, physical, and mechanical properties of two soil layers on soil-slip scars in slopes underlain by coarse-grained granite and fine-grained granitic gneiss near Seoul, Republic of Korea, were examined. Our aim is to study the effect of the mineral grain size of the bedrock on the soil layer structure and the return period of shallow soil slips. Because of the coarser slope materials in granite resulting from weathering, the permeability is larger and the weathering front has a copious water supply; also, because of the smaller specific surface area of the minerals, restricted leaching produces grus from the bedrock, so that the rate of formation of soil (and in particular the slip plane) due to chemical weathering is faster. Since, on granite slopes, the leaching proceeds toward the surface, the sliding plane is deeper with coarser soft grus, resulting in the existence of a minimum c value in the soil layer. On gneiss slopes, by contrast, leaching cannot proceed with decreasing soil depth, and the sliding plane is deeper with finer soft grus just above hard grus and has similar c and ϕ values as the upper soft grus because the grain size of both soils is the same. In the granite soil layers, the sliding plane corresponds to the minimum shearing resistance, whereas in the gneiss soil layers, the shearing resistance increases gradually with soil depth, and the sliding plane is formed when the weathering front is located deeper. Because of the faster soil formation rate and the shallower slip depth in granite slopes, the return period of occurrence of soil slips should be shorter in granite slopes than in gneiss slopes.     

不同土壤坡面细沟侵蚀差异与其影响因素

采用室内纯净水人工模拟降雨试验,在坡度为10°、15°、20°、25°坡面,土槽为5 m、10 m两种规格,对两种土壤((土娄)土与黄绵土)分别进行雨强为1.5 mm min-1,的降雨实验,利用三维激光扫描仪对每一场降雨后的坡面进行监测,分析不同坡度对细沟侵蚀的影响,比较两种土壤坡面细沟侵蚀的差异,以及其差异的影响因子.结果表明:(土娄)土土壤颗粒以粉粒与黏粒为主,粉粒占总质量的64.12％,黏粒为28.42％.黄绵土的土壤颗粒以粉粒为主占总质量的67.95％,黏粒与沙粒含量较少,黏粒占14.52％,沙粒占17.53％.在相同条件下,(土娄)土降雨过程中人渗缓慢,产流时间、坡面流速均快于黄绵土,跌坎出现时间也较早,使其更容易产生细沟.(土娄)土的径流量高于黄绵土,在降雨过程中,径流稳定时间较早.(土娄)土侵蚀量高于黄绵土,(土娄)土产沙率呈增加趋势,黄绵土含沙量变化不明显.从坡面细沟发育来看,(土娄)土坡面细沟成平行状分布,黄绵土细沟为较宽树枝状.     

The 137Cs technique applied to steep Mediterranean slopes (Part I): the effects of lithology,slope morphology and land use

Concentrations in the soil of anthropogenic and natural radionuclides have been investigated in order to assess the applicability of the ¹³⁷Cs technique in an area of typical Mediterranean steep slopes. This technique can be used to estimate net soil redistribution rates but its potential in areas with shallow and stony soils on hard rock lithology have not been evaluated so far. In this research, the validity of using this technique in stony shallow soils at very steep slopes is discussed together with the relations between radionuclide concentrations and other soil properties, lithology, slope morphology and land use in a Mediterranean environment. Both natural Potassium-40 (⁴⁰K), Uranium-238 (²³⁸U), Thorium-232 (²³²Th) and anthropogenic Caesium-137 (¹³⁷Cs) radionuclides have been determined in samples taken along slope transects on uncultivated serpentinite soils and cultivated gneiss soils. In addition to the radionuclide concentrations, parameters such as slope position, slope angle, aspect, soil depth, surface stone cover, moss, litter, vegetation cover, soil crust, stone content and bulk density have been quantified.All the natural radionuclides ⁴⁰K, ²³⁸U, ²³²Th show significantly higher concentrations in the gneiss than in the serpentinite soils, opposed to the ¹³⁷Cs concentration, which is found significantly higher in the serpentinite soils probably because of the difference in clay mineralogy. The exponential decreasing depth distribution of ¹³⁷Cs and its homogeneous spatial distribution emphasise the applicability of the ¹³⁷Cs technique in this ecosystem.Lithology determines the concentration of natural and anthropogenic radionuclides. Land use determines the relations between ¹³⁷Cs concentration/inventory and some soil characteristics. Higher ¹³⁷Cs concentration and inventory are associated with higher percentages of vegetation cover, higher percentage of stones in the soil and higher values of soil bulk density in cultivated gneiss soils. Slope morphology and land use influence the soil redistribution at slope scale. The gneiss slopes show a zonation of four to five areas of differential erosion/accumulation processes corresponding with more regular slopes and soil redistribution due to water erosion and to tillage translocation and erosion. The serpentinites, as an example of a more unstable slope type, show more erosion areas with less accumulation downslope and soil redistribution due to water erosion.     

Dry Matter and Nutrient Partitioning of Selected Pineapple Cultivars Grown on Mineral and Tropical Peat Soils

The pineapple cultivars ‘Moris’ (Queen cultivar), ‘N‐36’ (‘Sarawak’ × ‘Gandul’ hybrid), ‘Gandul’ (Singapore Spanish cultivars), and ‘Josapine’ (‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid) are mostly grown on peat soils in Malaysia, whereas ‘Sarawak’ (‘Smooth Cayenne’ cultivar) is more commonly grown on mineral soils. To obtain good yields of fruit of high quality, it is important to understand the differences in nutrient requirements for these cultivars in the different soils in which they are grown. Therefore, the objectives of the study were to determine the biomass and nutrient partitioning of the different pineapple cultivars and to determine the plant variables affecting fruit yield and quality. Plants of each of the pineapple cultivars were randomly sampled from different locations of the major pineapple‐growing areas in Malaysia. Only plants having A‐grade fruit of marketable quality at harvest were selected. The cultivars and respective field sites were as follows: ‘Sarawak,’ Bukit Tandak farm, Kelantan (5° 55.274′ N, 102° 00.608′ E); ‘Moris,’ ‘N‐36,’ and ‘Gandul,’ Peninsula Pineapple Plantations, Simpang Renggam, Johor (1° 49.909′ N, 103° 14.053′ E); and ‘Josapine,’ Goh Swee Eng Pineapple Farm, Simpang Renggam, Johor (1° 48.441′ N, 103° 11.935′ E). Plants were partitioned into roots, stem, leaves, peduncle, fruit, and crown, and fresh and dry weights were recorded. Total biomasses for the different cultivars were 733.46 ± 22.83 g for ‘Gandul,’ 842.34 ± 43.26 g for ‘N‐36,’ 927.38 ± 53.10 g for ‘Moris,’ 434.77 ± 16.82 g for ‘Josapine,’ and 2446.94 ± 156.00 g for ‘Sarawak.’ Leaves accounted for the greatest proportion of dry matter (48.5%), followed by fruit (22.9%) and stem (21.6%), and a smaller proportion (1.2–2.5%) was roots, peduncle, and crown. The proportions of the dry‐matter accumulation in leaves and stem for the cultivars were 53.5 ± 0.7 and 16.7 ± 0.9% for ‘Gandul’; 45.1 ± 0.5 and 17.7 ± 0.7% for ‘N‐36’; 51.9 ± 1.6 and 16.8 ± 0.6% for ‘Moris’; 56.5 ± 1.0 and 12.0 ± 0.9% for ‘Josapine’; and 54.2 ± 5.1 and 27.7 ± 4.4% for ‘Sarawak.’ The proportion of the macro‐ and micronutrients in pineapple parts differed widely between cultivars. Potassium (K) showed the greatest proportion (7.96 ± 0.6 to 29.73 ± 1.17%) in leaves and (4.46 ± 0.70 to 9.35 ± 0.28%) in fruit followed by nitrogen (N) and phosphorus (P) with lower proportions. Most pineapple cultivars grown showed variation in nutrient‐use efficiency (NUE) with respect to the elements measured with values of <1.0 g dry matter g^?1 nutrient. The NUE values of >1.0 g dry matter g^?1 nutrient were observed for magnesium (Mg) in ‘Gandul’ and ‘N‐36’ and for calcium (Ca) and copper (Cu) in ‘N‐36.’ Total nutrient accumulation in the plant components differed approximately according to their cultivar origins (‘Smooth Cayenne,’ ‘Queen,’ ‘Singapore Spanish’). It is interesting that the results for the ‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid Josapine were more similar to the ‘Singapore Spanish’ cultivars than being between the parents. Partitioning of biomass and nutrients in pineapple provides a means to categorize them and makes it possible to use a cultivar‐based fertilization program.     

Residue management for reducing evaporation in relation to soil type and evaporativity1

Abstract. Usual residue-management options are to remove the residue, use it as mulch with or without undercutting or to incorporate it into the soil. While the role of surface mulch in evaporation has been widely studied, the information on the effect on evaporation of mulch with undercutting or residue incorporated into soil, particularly in relation to soil type and evaporativity (E_o) is lacking. We studied the effect of wheat straw used in various ways on the course of evaporation loss from soil columns with three soils at Ludhiana, India and one soil at Bushland, Texas, USA, under two E_o's Energy-limited evaporation rates under mulch (E_om) followed the soil-specific relation E_om/E_o= a e^(bRes+cEo), where Res is residue rate t/ha and a, b and c are constants; E_o, is expressed in mm/d. In an effort to model the total evaporation (CE) during the energy-limited stage ‘U’ was obtained from appropriate CE versus time curves and (CE-U) was regressed over (t - ti)^0.5 to obtain the slope ‘α’ (Ritchie 1972) for the soil-limited evaporation stage. The observed ‘U’ was independent of mulch rate and E_o but was strongly affected by soil type, Values of ‘α’ decreased with increase in mulch rate and decrease in E_o and coarseness of soil. The otherwise short lived benefit of evaporation reduction with mulch per se, which peaked after a few days was maintained when residue was mixed with soil at the stage when evaporation reduction reached a maximum; this benefit continued for several weeks. Cumulative evaporation values computed from ‘U’ and ‘α’ agreed closely with the observed values under straw mulch for loamy sand and clay loam soils and for ‘undercut’ and ‘residue mixed’ treatments on all soils regardless of E_o, and for all situations under small E_o. However, for sandy loam and silt loam soils under E_o of 10 mm/d, the modified square root of the time function of Jalota et al. (1988) gave a better fit.     

Effect of rainfall intensity and slope steepness on the development of soil erosion in the Southern Cis-Ural region (A model experiment)

The effect of rainfall intensity on the erosion of residual calcareous agrogray soils and clay-illuvial agrochernozems in the Southern Cis-Ural region on slopes of different inclination and vegetation type has been studied by simulating with a small-size sprinkler. It has been shown that soil loss linearly depends on rainfall intensity (2, 4, and 6 mm/min) and slope inclination (3° and 7°). When the rainfall intensity and duration, and the slope inclination increase, soil loss by erosion from agrogray soils increases higher than from agrochernozems. On the plowland with a slope of 3°, runoff begins 12, 10, and 5 min, on the average, after the beginning of rains at these intensities. When the slope increases to 7°, runoff begins earlier by 7, 6, and 4 min, respectively. After the beginning of runoff and with its increase by 1 mm, the soil loss from slopes of 3° and 7° reaches 4.2 and 25.7 t/ha on agrogray soils and 1.4 and 4.7 t/ha on agrochernozems, respectively. Fallow soils have higher erosion resistance, and the soil loss little depends on the slope gradient: it gradually increases to 0.3–1.0 t/ha per 1 mm of runoff with increasing rainfall intensity and duration. The content of physical clay in eroded material is higher than in the original soils. Fine fractions prevail in this material, which increases their humus content. The increase in rainfall intensity and duration to 4 and 6 mm/min results in the entrapment of coarse silt and sand by runoff.     

TYPES OF SOIL DEGRADATION ON LOESS NEAR KRAKOW

Humus content, thickness of the accumulation horizon, soil texture, and depth of decalcification are all related to the slope of the soil surface in loess soils near Kraków. For example, humus content declines from 75 to 65 tonnes/ha as slope increases from 2 to 12°. Depth of decalcification which is about IOO cm on soils with slopes less than 2° is only about 50 cm on slopes of 12°. Such observations may prove helpful in the evaluation of the intensity of soil erosion processes on other loess areas physiographically similar to the region near Kraków.     

Prolonged survival of an environmental Escherchia coli in laboratory soil microcosms

The survival, persistence, and dispersal of bacteria in soil raises serious water quality questions for rural areas of the world especially where podzol-type soils dominate. To determine survival characteristics of an environmentally derived multiple-antibiotic resistant E. coli, it was added to laboratory containers containing sandy-loam podzol soils taken from two different locations (‘Webb’, pH 6.8–8.3 and ‘Rich’, pH 5.5–7.2). This was done in order to study the stability of the tracer bacterium under conditions designed to mimic those that might be encountered during subsequent field mini-plot studies. Sets of microcosms consisting of three replicates of each soil received 10¹² or 10¹³ colony forming units per g of soil and were incubated at four temperatures (5, 10, 20, and 37 °C) and two moisture levels (15% i.e. average field capacity and saturation) for 160 days. The microcosm data gave estimated maximum survical times for the ‘Webb’ soil of 23.3 months at 5 °C under saturating moisture conditions and 20.7 months for the ‘Rich’ soil under the same conditions using exponential regression analysis of the data.     

Characterizing soil surface roughness using a combined structural and spectral approach

The ability to quantitatively and spatially assess soil surface roughness is important in geomorphology and land degradation studies. This paper describes the results of an experiment designed to investigate whether hyperspectral directional reflectance factors can describe fine‐scale variations in soil surface roughness. A Canadian silt loam soil was sieved to an aggregate size range of 1–4.75 mm and exposed to five different artificial rainfall durations to produce soils displaying progressively decreasing levels of surface roughness. Each soil state was measured using a point laser profiling instrument at 2 mm spatial resolution, in order to provide information on the structure and spatial arrangement of soil particles. Hyperspectral directional reflectance factors were measured using an Analytical Spectral Devices FieldSpec Pro Spectroradiometer (range 350–2500 nm), at a range of measurement angles (θ_r=?60° to +60°) and illumination angle conditions (θ_i= 28°–74°). Directional reflectance factors varied with illumination and view angles, and with soil structure. Geostatistically‐derived indicators of soil surface roughness (sill variance) were regressed with directional reflectance factors. The results showed a strong relationship between directional reflectance and surface roughness (R²= 0.94 where θ_r=?60°, θ_i= 67°–74°). This fine‐scale quasi‐natural experiment allowed the control of slope, initial aggregate size and rainfall exposure, permitting an investigation into factors affecting a soil’s bidirectional reflectance response. This has highlighted the relationship between fine‐scale variations in surface roughness, illumination angle and reflectance response. The results show how the technique could provide a quantitative measure of surface roughness at fine spatial scales.     

Establishing permissible erosion rates for various landforms in Delhi State,India

Permissible erosion rate also known as soil loss tolerance (‘T’ value) is defined as maximum erosion that can take place on a given soil without degrading its long‐term productivity. In India, default ‘T’ value of 11·2 Mg ha⁻¹ y⁻¹ is used for devising land restoration strategies for different types of soils. However, ability of soil to resist degradation varies with soil type, depth and physico‐chemical characteristics. Therefore, the present investigation was undertaken to determine ‘T’ value of different landforms of Delhi State by taking into account the soil saturated hydraulic conductivity (SHC), bulk density (BD), organic carbon, erodibility and soil pH. Soil state was defined by a quantitative model and scaling functions were used to convert soil parameters to a 0–1 scale. The normalised values were multiplied by appropriate weighting factors based on relative importance and sensitivity analysis of each indicator. Categorical rankings of I, II or III were assigned to soil groups based on overall aggregate score. ‘T’ value of different landforms of Delhi State was computed using the guideline of USDA‐Natural Resource Conservation Services. Majority of landforms of Delhi had ‘T’ value of 12·5 Mg ha⁻¹ y⁻¹, except for the soils of hill terrain, dissected hill, pediment and piedmont plain, where ‘T’ value ranged from 5 to 10 Mg ha⁻¹ y⁻¹. These ‘T’ values could be used for conservation planning and will help the planners in devising suitable land restoration strategies. Copyright © 2008 John Wiley & Sons, Ltd.     

Interrelationship among slope steepness,tillage practice and rainfall properties with surface runoff and soil loss on Mollisols in Northeast China

ABSTRACT

Soil erosion and rainfall-induced runoff are well studied yet remain somewhat unpredictable from one natural rainfall to the next, due to interactions between erosion parameters. This study quantified the relationship between annual (2011–2016) and individual (2016) rain events with overland flow (runoff) and soil loss in China’s northern ‘corn-belt’. Two tillage practices and slopes were evaluated (no-till and conventional till, 5° and 7° slopes). Results showed 54 rainfall events for a total of 394 mm precipitation ranging between May and October 2016. Runoff occurred 13 times in the conventional till with 7° slope, accounting for 25.9% of the precipitation volume and caused 15.6 t ha^?1 erosion. It occurred twice in the no-till with 5° slope plot and caused 0.2 t ha^?1 erosion., Thus the no-till with 5° slope treatment is the best tillage system to protect soil in Mollisols in Northeast China. Broad analysis coupled with a detail review of three rainfall events demonstrates that water either runs off plots quickly or rapidly infiltrates while sediment moves in a pulsing manner.     

Remediation of Perfluorooctane Sulfonate in Contaminated Soils by Modified Clay Adsorbent—a Risk-Based Approach

Perfluorooctane sulfonate (PFOS), which has numerous uses besides being an ingredient in the formulation of aqueous film-forming foams, is considered as an emerging pollutant of increasing public health and environmental concern due to recent reports of its worldwide distribution, environmental persistence and bioaccumulation potential. In an attempt to recommend a ‘risk-based’ remediation strategy, this study investigates the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent (MatCARE?, patent number 2009905953). Batch adsorption tests demonstrated a much faster adsorption kinetics (only 60 min to reach equilibrium) and remarkably higher PFOS adsorption capacity (0.09 mmol g^?1) of the MatCARE? compared to a commercial activated carbon (0.07 mmol g^?1). Treatability studies, performed by treating the PFOS-contaminated soils with the MatCARE? (10 % w/w) and then incubating at 25 and 37 °C temperatures maintaining 60 % of the maximum water holding capacity of the soils for a period of a year, demonstrated a negligible release (water extractable) of the contaminant (only 0.5 to 0.6 %). The fixation of PFOS in soils by the new adsorbent was exothermic in nature. Soils with higher clay and organic matter content, but lower pH values, retained PFOS to a much greater extent. A cost analyses confirmed that the MatCARE^TM could be an economically viable option for the ‘risk-based’ remediation of PFOS in contaminated waters and soils.     

Micronutrient Contents of Citrus Orchard Soils in Southern China

Investigations were carried out on the micronutrient contents,of major citrus orchard soils (involving seven soil great groups in 8 provinces and an autonomous region of southern China),and an evaluation on the abundance and deficiency of available micronutrients in these soils was made in this paper.In southern China,citrus orchard soils derived from sandstone,sandy shale,Quaternary red clay,diluvial deposit,granite gneiss and neritic deposit were deficient in available Mo and B and low in Zn.Those developed on purple sandy shale,limestone and slope deposit were all in short supply of available Zn,B and Mo.Coastal solonchak was fairly abundant in B,but its available Fe,Zn and Mo contents were rather low.     

Runoff sediment particle sizes associated with soil erosion in the Lake Tahoe Basin,USA

Runoff sediment from disturbed soils in the Lake Tahoe Basin has resulted in light scattering, accumulation of nutrients, and subsequent loss in lake clarity. Little quantified information about erosion rates and runoff particle‐size distributions (PSDs) exists for determining stream and lake loading associated with land management. Building on previous studies using rainfall simulation (RS) techniques for quantifying infiltration, runoff, and erosion rates, we determine the dependence and significance of runoff sediment PSDs and sediment yield (SY, or erodibility) on slope and compare these relationships between erosion control treatments (e.g., mulch covers, compost, or woodchip incorporation, plantings) with bare and undisturbed, or ‘native’ forest soils. We used simulated rainfall rates of 60–100 mm h⁻¹ applied over replicated 0·64 m² plots. Measured parameters included time to runoff (s), infiltration and runoff rates (mm h⁻¹), SY (g mm⁻¹ runoff), and average sediment concentration (SC, g L⁻¹) as well as PSDs in runoff samples. In terms of significant relationships, granitic soils had larger particle sizes than volcanic soils in bulk soil and runoff samples. Consequently, runoff rates, SCs, and SYs were greater from bare volcanic as compared to that from bare granitic soils at similar slopes. Generally, runoff rates increased with increasing slope on bare soils, while infiltration rates decreased. Similarly, SY increased with slope for both soil types, though SYs from volcanic soils are three to four times larger than that from granitic soils. As SY increased, smaller particle sizes are observed in runoff for all soil conditions and particle sizes decreased with increasing slope. Copyright © 2008 John Wiley & Sons, Ltd.     

全风化花岗岩管沟回填土坡面侵蚀影响因素及交互作用

为了查明全风化花岗岩地区输油气管道作业边坡坡面水土流失问题,通过野外典型边坡边界条件测量、坡面侵蚀特征冲沟沟深、冲沟截面积数据采集、岩土体取样测试,并结合室内模型降雨试验等方法。结果表明：降雨、坡长、坡度、汇水面积、岩土体特性5种因素均影响全风化花岗岩管沟回填土坡面侵蚀。产沙率和产流率随着降雨强度的增大而增大。坡长、坡度、汇水面积与冲沟沟深和冲沟截面积呈正相关关系,且随着坡长、坡度、汇水面积的增大,冲沟沟深和冲沟截面积也在增大。通过取样测试发现,原状土与回填土的颗粒组成相对含量具有较大差异,初始回填土粒度级配为良好土。降雨冲刷初期回填土坡面径流主要携带粉粒和黏粒。5年回填土相对于原状土,孔隙率增加到原来的1.13倍,土体渗透系数增大1个数量级,饱和状态下黏聚力降低为原状土的67.6%,内摩擦角降低为原状土的87.5%。通过查明全风化花岗岩管沟回填土坡面侵蚀影响因素及其作用,为后续的边坡治理提供依据。     

Release Kinetics of Nonexchangeable Potassium by Different Extractants from Soils of Varying Mineralogy and Depth

Abstract

Nonexchangeable potassium (K) release kinetics of six major benchmark soil series of India as affected by mineralogy of clay and silt fractions, soil depth and extraction media was investigated. The cumulative release of nonexchangeable K was greater in smectitic soils (353 mg K kg^?1 at 0‐ to 15‐cm depth and 296 mg K kg^?1 at 15‐ to 30‐cm depth, averaged for 2 soils and 3 extractants) than in illitic (151 mg K kg^?1 at 0‐ to 15‐cm depth and 112 mg K kg^?1 at 15‐ to 30‐cm depth) and kaolinitic (194 mg K kg^?1 at 0‐ to 15‐cm depth and 167 mg K kg^?1 at 15‐ to 30‐cm depth) soils. Surface soils exhibited larger cumulative K release in smectitic and illitic soils, whereas subsurface soils had larger K release in kaolinitic soils. Among the extractants, 0.01 M citric acid extracted a larger amount of nonexchangeable K followed by 0.01 M CaCl₂ and 0.01 M HCl. The efficiency of citric acid extractant was greater in illitic soils than in smectitic and kaolinitic soils. Release kinetics of nonexchangeable K conformed fairly well to parabolic and first‐order kinetic models. The curve pattern of parabolic diffusion model suggested diffusion controlled kinetics in all the soils, with a characteristic initial fast rate up to 7 h followed by a slower rate. Greater nonexchangeable K release rates in smectitic soils, calculated from the first‐order equation (b=91.13×10^?4 h^?1), suggested that the layer edge and wedge zones and swelling nature of clay facilitated the easier exchange. In contrast to smectitic soils, higher release rate constants obtained from parabolic diffusion equation (b=39.23×10^?3 h^?1) in illitic soils revealed that the low amount of exchangeable K on clay surface and larger amount of interlayer K allowed greater diffusion gradients, thus justifying the better fit of first‐order kinetic equation in smectitic soils and parabolic diffusion equation in illitic soils.     

The influence of slope aspect on soil weathering processes in the Springerville volcanic field,Arizona

A comparison was made between soils on north- and south-facing slopes of six cinder cones in the Springerville volcanic field (SVF), Arizona, in order to determine the influence of slope aspect on soil weathering processes. Twenty-four soil pedons were sampled on different aspects of six cinder cones. To control for the influence of slope on pedogenesis, all sample sites possessed slopes of 17±2°. Soil weathering processes were characterized by solum depth, texture, and Ca:Zr chemical weathering indices. Quartz and mica were used to identify eolian additions to the volcanic soils. Accelerated rates of weathering and soil development were found to occur in soils on south-facing slopes while no trend with aspect was found for eolian additions. Accelerated rates of weathering and soil development may influence cinder cone degradation and cone morphology.     

不同雨强和坡度下侵蚀性风化花岗岩母质坡地产流产沙特征

为研究解决南方侵蚀性风化花岗岩地区的水土流失问题,该文采用室内人工模拟降雨方法研究了不同降雨强度(30,60,90,120,150 mm/h)和不同坡度(5°,8°,15°,25°)条件下的风化花岗岩残积坡地的土壤侵蚀过程。结果表明:1)坡面径流的初始产流产沙时间都随着坡度和雨强的增大而提前;2)坡面径流量与坡度之间不呈简单的正相关关系,径流系数随雨强的变化呈现指数相关关系,入渗率在雨强为30~120 mm/h之间在坡度8°左右出现极大值;3)侵蚀产沙量随坡度和雨强的增大而增大,其与坡度之间的关系可以用幂函数表示,决定系数均达到0.815,与雨强之间为指数函数关系,决定系数均达到0.889以上;4)水力侵蚀对泥沙具有分选性,径流侵蚀挟带泥沙中的粉粒、黏粒以及细砂粒含量较多;5)坡度和雨强对于侵蚀产沙量的综合影响可以用线性相关方程来比较准确地描述,对产沙量的影响权重排序为:含沙量雨强径流系数坡度。     

BORON NUTRITION OF PEANUT GROWN IN BORON-DEFICIENT CALCAREOUS SOILS: GENOTYPIC VARIATION AND PROPOSED DIAGNOSTIC CRITERIA

Field studies were conducted to assess boron (B) requirement, critical concentrations in diagnostic parts based on yield response curves and genotypic variation by growing three peanut (Arachis hypogaea L.) cultivars (‘Golden’, ‘BARD-479’, ‘BARI-2000’) on two B-deficient calcareous soils. Boron application significantly increased pod yield of all the cultivars over control. Maximum pod yield increases were: ‘Golden’, 16?23%; ‘BARD-479’, 21?27%; and ‘BARI-2000’, 25?31%. The cultivars varied in B efficiency and cv. ‘Golden’ was the most B efficient (81?86%) while cv. ‘BARI-2000’ was the least efficient (76?80%). Boron requirements for near-maximum (95%) dry pod yield were 0.65 kg ha^?1 for ‘Golden’, 0.75 kg ha^?1 for BARD-479 and 0.80 kg ha^?1 for BARI-2000. Critical B concentrations in shoots and seeds were: ‘Golden’, 33 mg kg^?1 and 26 mg kg^?1; ‘BARD-479’, 38 mg kg^?1 and 31 mg kg^?1; and ‘BARI-2000’, 42 mg kg^?1 and 33 mg kg^?1.     

Effect of saline irrigation on the biomass yield,and the protein,nitrogen, phosphorus,and potassium composition of alfalfa in a pot experiment

During 1994–1995, field experiments were conducted in six apple orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Lobo’, ‘Aroma’, and ‘Åkero’. Fruit samples were picked at about one week before commercial maturity and stored for three to six months at 2 to 4°C and 85–95% relative humidity. During storage the percentage of physiological disorders was visually recorded. Fruit nitrogen (N) and calcium (Ca), firmness, diameter, juice titratable acidity (TA), and soluble solids concentrations (SSC) were determined at harvest. Nitrogen and Ca in the soil and leaves collected during fruit development were determined. The ranges in fruit N were 296–624 and Ca 27–68 mg kg^‐1 fresh weight, and in the leaves N 15–23 and Ca 9–19 g kg^‐1 dry matter. The N/Ca ratio was 5 and 16 and 0.9 and 2.3 in fruit and leaves, respectively. There was more variation between years in N and Ca contents of leaves than that of fruit. Other fruit quality characteristics varied between seasons and cultivars. Leaf N correlated positively with fruit diameter and negatively with fruit dry matter. The incidence of physiological disorders on apples after three month storage was 2 to 13% and after six months 10 to 95%. Fruit with Ca content below 45 mg kg^‐1 fresh weight were susceptible to bitter pit ('Aroma’ and ‘Åkero') and Jonathan spot ('Red Atlas'). The cultivar ‘Melba’ was susceptible to bruising damages and ‘Raike’ and ‘Red Atlas’ were affected more with internal breakdown and core browning.