Quantification of the vertical translocation rate of soil solid-phase material by the magnetic tracer method

Approaches to the quantification of the vertical translocation rate of soil solid-phase material by the magnetic tracer method have been developed; the tracer penetration depth and rate have been determined, as well as the radial distribution of the tracer in chernozems (Chernozems) and dark gray forest soils (Luvisols) of Belgorod oblast under natural steppe and forest vegetation and in arable lands under agricultural use of different durations. It has been found that the penetration depth of spherical magnetic particles (SMPs) during their 150-year-occurrence in soils of a forest plot is 68 cm under forest, 58 cm on a 100-year old plowland, and only 49 cm on a 150-year-old plowland. In the chernozems of the steppe plot, the penetration depth of SMPs exceeds the studied depth of 70 cm both under natural vegetation and on the plowlands. The penetration rates of SMPs deep into the soil vary significantly among the key plots: 0.92–1.32 mm/year on the forest plot and 1.47–1.63 mm/year on the steppe plot, probably because of the more active recent turbation activity of soil animals.     

Modeling Water Regime of Arable Chernozems under Bare Fallow and under Corn for Two Growing Seasons with Contrasting Precipitation

Eurasian Soil Science - Water regime of arable chernozems was simulated for two plots at the Voronezh experimental station. The first plot is under continuous corn monoculture since 1966. The...     

Moisture regime of typical chernozems under the mown Steppe and plowland of Kursk oblast under the anomalous weather conditions of the last decades

The analysis of long-term (since 1947) data on the water content of the upper 3-m-thick layer in the Streletskaya Steppe chernozems under annual mowing showed that the weather changes during the last decades (from 1972–1973 to 2005–2006) resulted in an increase in the soil wetting depth during the fall-winter-spring period and the frequency of the percolation, a decrease in the water consumption from the 150- to 300-cm layer during the growing season, and a decrease in the water deficit in the fall. Therefore, the total water content of the steppe chernozems increased, although to a significantly lesser degree than that found for the steppe plot with a succession of woody-shrub vegetation. In a perennial fallow, the water content of the soil layer also increased. The water supply of the 0- to 160-cm layer of chernozems under winter wheat and corn underwent no significant changes.     

季节性冻融条件下草地入渗特性的试验研究

通过对比分析季节性冻融条件下草地与裸地入渗试验结果,得到了草地冻融条件下的入渗规律。结果表明,在冻融各阶段,地表0~40 cm深度范围内,草地地温均高于裸地,但土壤含水率低于裸地;在土壤初冻和融化阶段,草地入渗90 min累积入渗量大于裸地,但其初始入渗强度小于裸地初始入渗强度;在土壤完全处于冻结状态时,草地与裸地的入渗过程、入渗量基本相同。研究结果为草地冻融土壤入渗特性的进一步研究奠定基础,为区域水土保持与生态修复工程及季节性冻土区冬春灌溉提供参考。     

耕作方式对东北春玉米农田土壤水热特征的影响

针对东北春玉米农田春季低温冷害和季节性干旱发生频率高的问题,于2009年-2010年设置3种耕作处理,即传统垄作(LL)、平作播种中耕起垄(PL)和全生育期平作(PP),研究大田条件下耕作方式对土壤水分、土壤温度和玉米产量的影响。2a试验结果表明,耕作方式对0～40cm土层储水量有显著影响,其中PL和PP处理播种时的初始储水量比LL处理高8.7和6.0mm,而苗期则分别高4.1和3.4mm;玉米生育中后期PL和LL处理储水量则呈高于PP处理的趋势。3种耕作方式下土壤温度的差异以苗期为主,即5cm土层的平均温度PL和PP处理显著低于LL处理,但最低温度则以PL和PP处理显著高于LL处理,分别高1.6和1.2℃。总体来看,PL处理不仅可提高玉米苗期土壤的最低温度和耕层土壤储水量,而且可增加中后期土壤积蓄雨水量,促进作物生长发育,因而籽粒产量比LL和PP处理分别高7.6%和6.4%。     

冻融期灌水和覆盖对南疆棉田水热盐的影响

为了探索不同冬灌定额和地表覆盖模式对棉田水热盐的影响,该文设置了冬灌裸地(winter irrigation with bare land,WIB)、冬灌留秆(winter irrigation with high cotton stubble,WICS)、冬灌玉米秸秆覆盖(winter irrigation with corn straw mulching,WICM)、免冬灌裸地(no winter irrigation with bare land,NWIB)、免冬灌留秆(no winter irrigation with high cotton stubble,NWICS)和免冬灌玉米秸秆覆盖(no winter irrigation with corn straw mulching,NWICM)6个处理。经过2013-11-15-2014-04-04和2014-11-15-2015-04-04冬季大田试验,得到:灌水和地表覆盖可以平抑土壤温度的变幅,免冬灌或冬灌条件下,温度变异幅度均为裸地留秆玉米秸秆覆盖。玉米秸秆覆盖更有利于土壤水分保持,WICM土壤储水量比WIB和WICS分别多29.10%和10.36%,NWICM土壤储水量比NWIB和NWICS分别多14.97%和2.21%,经过两年冻融过程NWIB、NWICS和NWICM 0~100 cm土壤储水量平均减少了18.32、7.36和2.62 mm。(免)冬灌0~30 cm土壤含盐量均为裸地留秆玉米秸秆覆盖;0~100 cm土壤范围冬灌盐分淋洗率为玉米秸秆覆盖(34.86%)留秆(15.82%)裸地(7.26%);免冬灌0~100cm积盐率为裸地(10.11%)留秆(7.96%)玉米秸秆覆盖(3.01%)。研究结果可为南疆冬季休闲期棉田土壤水热盐调控提供科学依据。     

Isolation of endophytic Frankia from root nodules of Casuarina equisetifolia and infectivity of the isolate to host plants

Abstract

A method which uses the pressure head to predict unsaturated hydraulic conductivity is presented to calculate the soil water flux in a field. Hydraulic conductivities in the primary drying and wetting processes were measured with core samples in the laboratory and the hysteresis between the hydraulic conductivity and pressure head was taken into account. Hydraulic gradients were measured every hour with tensiometers installed in the field. This method was applied to analyze the water movement at 94-cm depth in Hydric Hapludands. Downward or upward flow of water by summing soil water fluxes was examined using the water balance method. Amounts of downward flow determined by our method after heavy rain in a wet soil were slightly larger in the soybean plot but smaller in the bare plot than those obtained by the water balance method due to non-uniform infiltration. Water balance equation which used values of upward flow across a 94-cm depth estimated reasonably well the evapotranspiration from the soybean plot and the evaporation from the bare plot during a dry period. Effect of initial soil water conditions on downward flux by rainfall was well monitored by our method.     

Specificity of the thermophysical status of an arable leached chernozem in the Ob region

The thermophysical status of leached chernozems in the Altai part of the Ob River basin is controlled not only by the climatic and soil features of the region but also by the method of fallow preparation for cereals. The surface treatment with a cultivator to a depth of 8–10 cm provides the best effect.     

不同覆盖措施对减少枣林休眠期土壤水分损失的影响

针对黄土丘陵半干旱区林地土壤干化缺水严重的现象,利用2012-2015年3种覆盖措施下土壤水分定位实测数据,探讨和分析全年覆盖措施对枣林休眠期土壤水分损失的影响。结果表明:休眠期是枣林地土壤水分损失的重要时期,无覆盖枣林地土壤水分损失85.64~92.34 mm,是同期降雨量的2.12倍。当地枣林地土壤水分损失的土层深度基本在0~200 cm范围。在0~200 cm范围土壤垂直剖面上,休眠期3种覆盖措施下土壤水分损失均呈现随深度增加而均匀减少的规律。休眠期0~200 cm土层秸秆覆盖、地膜覆盖和石子覆盖土壤水分总损失量分别较裸地减少38.32、50.56、40.48 mm。覆盖措施可以促进休眠期土壤水分向深层运移。     

The Effect of Contrasting Moistening Regimes on CO<Subscript>2</Subscript> Emission from the Gray Forest Soil under a Grass Vegetation and Bare Fallow

The effect of contrasting moisture regimes on the CO₂ emission from the gray forest soils (Haplic Luvisols (Loamic, Cutanic, Humic)) under a grass vegetation and bare fallow was studied in a field simulation experiment in June–September, 2015 (Moscow region). Two short soil droughts (53 and 34 days) and a long one (94 days) were simulated on plots isolated from precipitation. A variant with regular irrigation, where the soil moisture was maintained 60–70% of their water holding capacity, was used as a control. Over the whole observation period, the CO₂ emissions from the soils studied decreased by a factor of 1.8 compared to the control only in the variant with the grass vegetation under prolonged drought. During the first hours after irrigation of the dry plots, the soil respiration intensified due to the “Birch effect”. The magnitude of this effect was 84–104% in the soils under the grass vegetation and 114–133% in the fallow areas. Owing to this phenomenon, the total CO₂ emission from the soils subjected to two short droughts was equal to the CO₂ flux under regular moistening for the grass plots and exceeded it by almost 1.3 times for the fallow plots as compared to the control. However, the share of extra CO₂ flux induced by moistening of the dry soils did not exceed 8–10% of the total CO₂ emission over the whole observation period.     

秸秆覆盖对冻融期土壤墒情影响试验

为了研究秸秆覆盖对冻融期土壤墒情的影响,该文设置裸地、玉米秸秆覆盖厚度为5、10和15cm的4种地表处理,进行了冻融期的土壤水分迁移试验。结果表明,冻融期秸秆覆盖的保温效应改变了土壤冻结状,使覆盖厚度15cm田块未出现冻层,覆盖厚度5和10cm地块的土壤初冻时间比裸地分别滞后16和25d,且冻层厚度较裸地减小了29和42cm。受冻融作用的影响,裸地在40cm处出现聚墒区,秸秆覆盖田块在地表处和30～50cm处出现聚墒区。冻融期内玉米秸秆覆盖厚度为5、10和15cm田块地表水分波动幅度分别比裸地减小了1.12、6.46和8.7百分点;土壤融化后其地表0-10cm土壤平均含水率分别比裸地高9.45、9.04和8.99百分点。研究成果可为季节性冻土分布区实施秸秆覆盖措施提供参考依据。     

Long-term effect of ploughing, and organic matter input on soil moisture characteristics of a Ferric Lixisol in Burkina Faso

Soil moisture characteristic curves were determined in long-term trials at the agronomic research center of Saria (latitude 12°16′ N, longitude 2°09′ W) in West-central Burkina Faso. The agronomic treatments combined soil tillage with organic and chemical fertilizers. The twin values for soil moisture and water potential showed that on ploughed plots, moisture content was higher at low suction and lower at high suction than the hand hoed plots. Moisture contents were higher for extreme suctions (pF < 1.5 and >3) on plots that received high dose of animal manure. The bush fallow plots behaved as a ploughed plot at low suction and like a hand hoed plot at the high suction. Field capacities were around 9.50% (g/g) and 8% (g/g), respectively, for hand hoed and ploughed plots, while the wilting points for both were of 5–6% (g/g). Organic matter input improved field capacity and soil water content at wilting point but not the useful available water (UAW). The UAW ≥10 mm on the fallow and the control, while it was <9 mm on the other treatments in 0–20 cm soil layer. Soil structural modifications induced by tillage and organic matter input explained these differences in soil hydrologic regime.     

Influence of fallow, wheat and subterranean clover on pH within an initially mixed surface soil in the field

 To ascertain the cause of the decrease in pH with depth through the surface 15 cm of moderately acidic soils, pH was monitored in layers of an initially mixed surface soil (to a nominal depth of 10 cm) during two consecutive seasons under fallow, wheat, and subterranean-clover plots. Variation of pH-influencing processes within soil layers to 15 cm depth was measured during the first season. Initially, soil pH was relatively uniform within the surface 7.5 cm, although there was an average 0.53 unit decrease of pH from 0–2.5 cm to 10–15 cm depth. Under all plots, residual lime reaction, net organic anion association and oxidation, net manganese oxidation and reduction, and particularly net N mineralisation and subsequent nitrification, tended to decrease with depth through the surface 15 cm of soil. In wheat and subterranean-clover plots, the alkalinity added with the return of 3.9–4.7 t ha^–1 of plant residue dry matter was predominantly released within the surface 2.5 cm of soil. The dominant pH-influencing processes were net N mineralisation and subsequent nitrification, and the return of alkaline plant residues. In the fallow plots, the surface 10 cm of soil tended to acidify due to nitrification. However in wheat and clover plots, alkalinity added to the surface 2.5 cm of soil from plant residues exceeded acidification resulting from nitrification at this depth. The magnitude of the pH gradient through 0–15 cm depth was therefore maintained under wheat, increased under clover, and decreased under fallow. Received: 11 October 1999     

Soil physical and hydrological properties under three biofuel crops in Ohio

Abstract

While biofuel crops are widely studied and compared for their energy and carbon footprints, less is known about their effects on other soil properties, particularly hydrologic characteristics. Soils under three biofuel crops, corn (Zea mays), switchgrass (Panicum virgatum), and willow (Salix spp.), were analyzed seven years after establishment to assess the effects on soil bulk density (ρ_b), penetration resistance (PR), water-holding capacity, and infiltration characteristics. The PR was the highest under corn, along with the lowest associated water content, while PR was 50–60% lower under switchgrass. In accordance with PR data, surface (0–10 cm) bulk density also tended to be lower under switchgrass. Both water infiltration rates and cumulative infiltration amounts varied widely among and within the three crops. Because the Philip model did not fit the data, results were analyzed using the Kostiakov model instead. Switchgrass plots had an average cumulative infiltration of 69 cm over 3 hours with a constant infiltration rate of 0.28 cm min^?1, compared with 37 cm and 0.11 cm min^?1 for corn, and 26 cm and 0.06 cm min^?1 for willow, respectively. Results suggest that significant changes in soil physical and hydrologic properties may require more time to develop. Soils under switchgrass may have lower surface bulk density, higher field water capacity, and a more rapid water infiltration rate than those under corn or willow.     

A comparison of runoff and erosion rates on bare and grassed loamy sand soils

Abstract. Runoff and erosion rates on loamy sand soils were measured at the Hilton experimental site, Shropshire. Little runoff and no erosion occurred on a steep runoff plot inserted into permanent grassland. Most precipitation infiltrated into the soil and was transmitted down slope as interflow within the Ah horizon. In contrast, considerable amounts of runoff and erosion occurred on the bare arable plots. These results suggest that incorporation of strips of permanent grassland into arable systems could assist soil and water conservation. Considering the high erosion rates on bare steep plots, conversion of slopes > 12° to permanent grassland seems appropriate.     

不同地表覆盖下冻融土壤入渗能力及入渗参数（英）

为了研究不同地表覆盖下冻融土壤入渗能力的差异和入渗参数的变化规律,进行了一系列裸地、地膜覆盖地和秸秆覆盖地土壤田间入渗试验。研究表明,冻土的入渗能力主要受冻层的控制,冻层是入渗水分的控制界面,土壤冻融特征差异是影响不同地表覆盖下土壤入渗能力大小的主导因素。冻融土壤的水分入渗过程可用三参数考斯加科夫土壤入渗经验模型描述。水分入渗开始 1 min内的累积入渗量大小随着冻层厚度和密实度的增加而减小,随着土壤冻融循环次数增加而增大;入渗能力的衰减率随着冻层厚度和密实度的增加而减小;稳定入渗率大小主要取决于土壤冻结状态和入渗锋面处的水力特性。三入渗参数均与土壤含水率和冻结深度有关,不同地表覆盖下的土壤入渗参数随着冻层深度的增加而减小,随着土壤的消融解冻而增大。该研究成果对农业生产实际和水土保持具有重要的指导意义。     

The effects of different management practices on the physical properties of a sandy loam soil in Southern Nigeria

The effects of different management practices on the physical properties of a sandy loam soil in Southern Nigeria were studied for two cropping seasons. The bulk densities of the top 0–10-cm soil depths were significantly reduced in plots under 13 years of Panicum maximum and Centrosema pubescens covers. Pores of equivalent cylindrical diameter > 0.05 mm were increased significantly under the two covers. Up to 33% of the saturation water content was released between tensions of 0 and 0.06 bar in the sandy loam soil of all the treatment plots. Furthermore an average of 24% of this water was released between tensions of 0.06 and 0.33 bar. Infiltration rates, measured at the end of the growing season, ranged from 240 mm h⁻¹ under the bare fallow treatment to 1326 mm h⁻¹ under the Centrosema cover. There was no significant difference between the tilled and no-tillage plots. Saturated hydraulic conductivities were significantly higher under the Panicum and Centrosema covers. The effect of tillage on conductivity was not appreciable. The highest weekly 5-cm depth, 1.30 p.m. soil temperature (32°C) was obtained under the bare fallow treatment and the lowest (23.5°) under the Panicum cover. Tillage had no significant effect on the soil temperature. Thirteen years of continuous Centrosema and Panicum covers had a significant effect on the physical properties of the tropical sandy loam soil. Tillage effects were not significant after 2 years of cropping.     

Long‐term‐fertilization effects on soil organic carbon,physical properties,and wheat yield of a loess soil

The large dryland area of the Loess Plateau (China) is subject of developing strategies for a sustainable crop production, e.g., by modifications of nutrient management affecting soil quality and crop productivity. A 19 y long‐term experiment was employed to evaluate the effects of fertilization regimes on soil organic C (SOC) dynamics, soil physical properties, and wheat yield. The SOC content in the top 20 cm soil layer remained unchanged over time under the unfertilized plot (CK), whereas it significantly increased under both inorganic N, P, and K fertilizers (NPK) and combined manure (M) with NPK (MNPK) treatments. After 18 y, the SOC in the MNPK and NPK treatments remained significantly higher than in the control in the top 20 cm and top 10 cm soil layers, respectively. The MNPK‐treated soil retained significant more water than CK at tension ranges from 0 to 0.25 kPa and from 8 to 33 kPa for the 0–5 cm layer. The MNPK‐treated soil also retained markedly more water than the NPK‐treated and CK soils at tensions from 0 to 0.75 kPa and more water than CK from 100 to 300 kPa for the 10–15 cm layer. There were no significant differences of saturated hydraulic conductivity between three treatments both at 0–5 and 10–15 cm depths. In contrast, the unsaturated hydraulic conductivity in the MNPK plot was lower than in the CK plot at depths of 0–5 cm and 10–15 cm. On average, wheat yields were similar under MNPK and NPK treatments and significantly higher than under the CK treatment. Thus, considering soil‐quality conservation and sustainable crop productivity, reasonably combined application of NPK and organic manure is a better nutrient‐management option in this rainfed wheat–fallow cropping system.     

Structural stability of an Alfisol under various fallow management practices in southwestern Nigeria

The effects of legume‐based soil management on soil dispersion were studied on an Alfisol between 1994 and 1995 in an experiment which was established in 1989 in southwestern Nigeria. The fallow systems, which constituted the main plots in the split‐plot experiment, included natural fallow, Pueraria phaseoloides (Roxb.) Benth, and Leucaena leucocephala Lam de Wit. The subplots were 25, 33, 50 and 100 per cent cropping intensities. Apart from indices of soil dispersion such as water‐dispersible clay and dispersion ratio, the fractal theory was applied to describe the fragmentation of soil aggregates less than 4 mm under the systems and cropping intensities. Although water dispersible clay was less than 60 g kg⁻¹ in the 0–15 cm soil depth because it was inherently low in clay content, the soil dispersion ratio was generally above 50 per cent. Also, the fractal dimensions, which ranged between 2.75 and 2.89, were similar among the fallow systems with cropping intensities for the surface soil. However, the interaction of slope position with season caused significant differences in fractal parameters, suggesting that the processes of soil degradation were different for the upper and lower slopes even with similar microaggregate distribution. The soil was inherently vulnerable to soil dispersion, although, the fallow management systems with less than 100 per cent cropping intensity would maintain soil structure at similar level as the forest. Copyright © 2001 John Wiley & Sons, Ltd.     

Fallow method influences on soil water and precipitation storage efficiency

Summer fallowing is practiced in the Great Plains of the U.S.A. in order to store soil water, control weeds, make nutrients available and stabilize crop yields. Soil water storage and precipitation storage efficiencies on chemical and stubble-mulch fallow plots were compared for three 14-month fallow periods for a winter-wheat-fallow rotation (Triticum aestivum L.) and three 21-month fallow periods for spring-wheat-fallow rotation in the northern Great Plains to determine during which seasonal segment the fallow method might influence soil water storage. The experiment was conducted on a glacial till Williams loam (fine-loamy mixed, Typic Argiboroll) from July 1981 to April 1985. Soil water contents to a depth of 1.70 m were measured, using the neutron scatter technique, for seasonal segments during the fallow period. Soil water storage was similar from harvest to spring on chemical and stubble-mulch fallow plots. The over-winter to spring segment resulted in the most consistent precipitation storage efficiencies (33.3–71.1%). Soil water storage differences as a result of a fallow method are most likely to occur during summer fallow for 14-month winter-wheat-fallow rotations and during the second overwinter for 21-month spring-wheat-fallow rotations. Soil water storage for the entire fallow period was greater on chemical fallow than on stubble-mulch fallow in two out of three 14-month winter-wheat fallow periods and in one out of three 21-month spring-wheat fallow periods.