Soil management alters seedling emergence and subsequent autumn growth and yield in dryland winter wheat–fallow systems in the Central Great Plains on a clay loam soil

Stand establishment and subsequent autumn development and growth are important determinants of winter wheat (Triticum aestivum L.) yield. Soil management practices change soil properties and conditions, which alter seedling emergence, crop development and growth. Pre-plant soil management practices were studied for 6 years in a wheat–fallow rotation in eastern Colorado, USA, to isolate the impacts of pre-plant tillage (PT) and residue level on winter wheat seedling emergence and autumn development and growth. A split plot design was used with PT, using a moldboard plow that incorporated surface residue, and with no-tillage (NT). The tillage systems represented the main plots and three residue levels within each tillage treatment as subplots: no residue (0R), normal residue (1R) and twice-normal residue (2R). Residue amount had little effect on emergence or autumn growth and development. PT resulted in soil water loss from the plow zone. NT plots had more favorable soil water levels in the seeding zone which resulted in faster, more uniform and greater seedling emergence in 4 out of the 6 years. This is especially critical for stand establishment in years with low rainfall after planting. Soil or air temperature did not account for differences among treatments. Earlier and greater seedling emergence in NT treatments resulted in greater autumn development and growth. Shoot biomass, tiller density and leaf numbers were greater in NT, and again residue amount had little effect. At spring green-up, NT treatments had greater soil water in the profile. Grain yield was always equal or greater in NT than in PT, and positively correlated with earlier/greater seedling emergence and autumn growth. NT will enhance soil protection and likely increase snow catch, reduce evaporation and benefit yield in semiarid eastern Colorado.     

Biological soil crust and surface soil properties in different vegetation types of Horqin Sand Land,China

Physical and chemical properties (including coverage, thickness, hardness, moisture, particle size distribution, organic matter and nutrient contents etc.) of biological soil crust and 0–5.0 cm surface soil under the crust in three types of vegetation (semi-shrub Artemisia frigida, shrub Salix gordejevii and tree Populus simonii) were surveyed in 2005 and 2006 in Horqin Sand Land to understand the effects of different vegetation types on development of soil crust and surface soil properties under crust. The results showed that 1) no physical soil crust or biological soil crust (BSC) formed on mobile dunes without vegetation, though most ground surface in originally mobile dunes had been covered by BSC fifteen years after planted vegetation was established; 2) BSC development was best in shrub S. gordejevii sites, second in semi-shrub A. frigida sites, and weakest in tree P. simonii sites; 3) development of BSC was better in moss crust distributed mainly beneath or near plant canopies than in lichen crust distributed mainly between plant canopies in all three vegetation types; 4) surface soil properties 0–5.0 cm under BSC were improved significantly in all three vegetation types compared to those in mobile sand land. The magnitude of improvement was greater in S. gordejevii sites than in A. frigida and P. simonii sites, and greater in moss crust sites than lichen crust sites, but the magnitude of improvement decreased significantly with increasing surface soil depth; 5) based on the above-mentioned results, we suggest that S. gordejevii should be favored in future planting in Horqin Sand Land.     

Hydraulic conductivity, residue cover and soil surface roughness under different tillage systems in semiarid conditions

The objective of this study was to investigate the effect of tillage and cropping system on near-saturated hydraulic conductivity, residue cover and surface roughness to improve soil management for moisture conservation under semiarid Mediterranean conditions. Three tillage systems were compared (subsoil tillage, minimum tillage and no-tillage) under three field situations (continuous crop, fallow and crop after fallow) on two soils (Fluventic Xerochrept and Lithic Xeric Torriorthent). Soil under no-tillage had lower hydraulic conductivity (5.0 cm day⁻¹) than under subsoil tillage (15.5 cm day⁻¹) or minimum tillage (14.3 cm day⁻¹) during 1 of 2 years in continuous crop due to a reduction of soil porosity. Residue cover at sowing was greater under no-tillage (60%) than under subsoil or minimum tillage (<10%) in continuous crop. Under fallow, residue cover was low (10%) at sowing of the following crop for all tillage systems in both soils. Surface roughness increased with tillage, with a high value of 16% and decreasing following rainfall. Under no-tillage, surface roughness was relatively low (3–4%). Greater surface residue cover under no-tillage helped conserve water, despite indications of lower hydraulic conductivity. To overcome the condition of low infiltration and high evaporation when no-till fallow is expected in a cropping sequence, either greater residue production should be planed prior to fallow (e.g. no residue harvest) or surface tillage may be needed during fallow.     

The effects of long-term conservation tillage, crop residues and P fertilizer on soil conditions and responses of summer and winter crops on an Andosol in Japan

A field experiment was conducted from 1983 to 1992 in Tsukuba, Japan to investigate the effects of tillage on soil conditions and crop growth in a light-colored Andosol. Three tillage methods (NT: no-tillage, RT: no-tillage for summer cropping and moldboard plowing for winter cropping, and CT: conventional rotary tillage to a depth of 15 cm) were employed in combination with crop residue application (+R, −R) and fused magnesium phosphate (FMP) fertilization (+P, −P). Under the combination of NT and +R, diurnal variation of soil temperature at a depth of 5 cm was smaller during the summer cropping season and soil temperature in the daytime was lower during the winter cropping season than under CT. Soil inorganic N concentration at a depth of 0–30 cm was +R > −R and NT > RT > CT. The early growth of summer crops was accelerated under NT in comparison with CT, and yields were higher under NT and RT in comparison with CT. On the other hand, winter crop yields were significantly reduced under NT, while they were still higher under RT in comparison with CT. Yields were higher with +R and +P application, respectively, and these effects were more pronounced in winter cropping. The positive effect of FMP fertilization was greater in combination with NT, and that of residue treatment was greater in combination with RT and NT than with CT. In conclusion, the best tillage practice for Andosols on the Kanto Plain is RT, i.e. a combination of NT for summer cropping and CT for winter cropping. The application of NT for winter cropping is not recommended, although the application of phosphate and crop residues could reduce the risk of yield reduction, because of improved soil nutrient status and moderation of diurnal soil temperature.     

Changes in soil properties in southern Beijing Municipality following land reform

Following land reform in China in the early 1980s, farm management practices, such as the type of crops grown and their rotations, intensity of cropping and fertilizer and pesticide use, underwent drastic changes. To investigate how these changes affected soil properties and ultimately the sustainability of agricultural production, a case study was conducted in Daxing County (southern Beijing Municipality). Soil in the Daxing area was sampled in 1982 at the onset of land reform and again in 2000. Surface soil (0–20 cm) samples were collected and analyzed for organic matter (OM), total nitrogen (TN), and available N (AN), P (AP) and K (AK) contents. The soil OM, TN, AN, and AP all increased significantly while AK decreased slightly, but significantly, for the sampling area over the 18-year study period. Increased crop yield (higher biomass production) with increasing fertilizer application combined with soil conservation measures that have retained more crop residue on land, are responsible for the increases in soil OM, N and P concentrations. However, the slight decreases in AK reflect the increased cropping intensity and low AK supplying power of these coarse textured soils as well as the low K fertilizer input.     

Influence of tillage and crop residue on soil physical properties and yields of rice and wheat under shallow water table conditions

An experiment was conducted to evaluate the effects of tillage and residue incorporation on soil properties and yields of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in rotation for 4 years on a silty clay loam of an Aquic Hapludoll with natural water table fluctuating between 0.05 and 0.97 m depth The rice experiment was laid out in split plot design with four levels of tillage, viz. conventional puddling (CP), puddling by four passes of rotavator (PR), reduced puddling by two passes of rotavator (ReP), and direct seeding without puddling (DSWP) and two levels of residue, viz. residue incorporation (RI) and residue removal (RR) in four replications. The treatments for wheat were zero tillage (ZT) and conventional tillage (CT) with RI and RR superimposed over the plots of rice. Tillage for rice increased puddling index and bulk density (BD) over the years. The increase was significantly higher in CP and PR than in ReP. In wheat season, BD was higher under ZT than under CT but the differences were not significant. Puddling decreased saturated hydraulic conductivity with time, which became significantly lower in CP and PR in the fourth year than in ReP in the first year. Infiltration rate (IR) also decreased with time and was lowest in CP and PR. In wheat season, IR was at par under ZT and CT. Rice yield in PR was maximum and at par with that in ReP. But wheat yield was lowest in PR and highest in DSWP, and was at par in DSWP and ReP. Thus, rice yields were optimum under ReP, in which changes in soil properties were least, and wheat yields were optimum both under ZT and CT in the DSWP and ReP plots of rice under shallow water table conditions of the silty clay loam.     

表面电荷性质对离子在土壤胶体界面扩散的影响

采用动力学方法测定了中性紫色土胶体和砖红壤胶体的电荷性质,研究了不同pH、电解质体系、浓度条件下离子在带电土壤胶体中的扩散过程,分析了两种土壤胶体在不同条件下离子扩散通量和扩散系数的特点。结果表明:1)中性紫色土胶体和砖红壤胶体中离子平衡扩散量为2.6～3.1 mg g-1和0.26～0.51 mg g-1,前者的扩散平衡量是后者的6倍～10倍;2)中性紫色土胶体不同温度条件下,离子扩散系数为1.17×10-9～1.91×10-9cm2s-1,砖红壤胶体中在与其对应温度条件下,离子扩散系数为0.23×10-9～0.45×10-9cm2s-1,前者是后者的4倍～5倍。表面电荷性质对离子在带电土壤胶体界面扩散的影响起决定性作用。     

Soil organic carbon and nitrogen in a Minnesota soil as related to tillage, residue and nitrogen management

Soil organic carbon (SOC) and nitrogen (N) are directly influenced by tillage, residue return and N fertilization management practices. Soil samples for SOC and N analyses, obtained from a 23-year field experiment, provided an assessment of near-equilibrium SOC and N conditions. Crops included corn (Zea mays L.) and soybean [Glycine max L. (Merrill)]. Treatments of conventional and conservation tillage, residue stover (returned or harvested) and two N fertilization rates were imposed on a Waukegan silt loam (fine-silty over skeletal, mixed, superactive, mesic Typic Hapludoll) at Rosemount, MN. The surface (0–20 cm) soils with no-tillage (NT) had greater than 30% more SOC and N than moldboard plow (MB) and chisel plow (CH) tillage treatments. The trend was reversed at 20–25 cm soil depths, where significantly more SOC and N were found in MB treatments (26 and 1.5 Mg SOC and N ha⁻¹, respectively) than with NT (13 and 1.2 Mg SOC and N ha⁻¹, respectively), possibly due to residues buried by inversion. The summation of soil SOC over depth to 50 cm did not vary among tillage treatments; N by summation was higher in NT than MB treatments. Returned residue plots generally stored more SOC and N than in plots where residue was harvested. Nitrogen fertilization generally did not influence SOC or N at most soil depths. These results have significant implications on how specific management practices maximize SOC storage and minimize potential N losses. Our results further suggest different sampling protocols may lead to different and confusing conclusions regarding the impact of tillage systems on C sequestration.     

Influence of tillage on crop residue cover, soil properties and yield components of cowpea in derived savannah ectones of Nigeria

The effects of five tillage treatments: no tillage (NT), disc harrowing (DH), mouldboard ploughing followed by disc harrowing (MPH), disc ploughing followed by disc harrowing (DPH), and disc ploughing followed by two passes of disc harrowing (DPHH) on crop residue cover, soil properties and some yield parameters of cowpea were investigated for a derived savannah ectone soil. The residue left on the soil surface for NT, DH, and MPH is not significantly different. The NT left 32.1 and 44.3% more residue on the soil surface than the DPH and DPHH treatments, respectively. The NT treatment had least average value of soil bulk density of 1.01 g/cm³. The mean soil bulk densities for the DH, MPH, DPH and DPHH vary between 1.20 and 1.35 g/cm³. The soil moisture content decreased with increasing soil depth. At the soil depth of 10–30 cm, the cone penetration resistance at NT was 1.18 MPa compared with 0.92 MPa for the DH treatment, although these were not significant (p≤0.05). The tillage treatments had a significant effect on grain yield, mass of leaves and stems, root length density, and number of pods per plant of cowpea except on the germination count. DH and NT treatments gave different grain yield and number of pods per plant but these values were not statistically different and represent the highest grain yield and number of pods per plant among the other treatments were considered. The root zone exploration revealed highest root density at shallow depths with the DH and MPH treatments.     

Energy optimization for subsoilers in tandem in a sandy clay loam soil

In some maize growing regions of South Africa, conventional subsoilers are used in a tandem configuration to till up to 600 mm. The farmers believe the tandem configuration decreases the draft force per unit area tilled. If so, this probably happens because the critical depth for the rear subsoiler is increased beyond its maximum working depth of 600 mm. Such tillage systems necessitated this study with an ultimate goal of establishing the relative position of the front subsoiler at which energy utilization can be optimized.

Experiments were conducted under field conditions in a fine sandy clay loam soil and consisted of a continuous measurement of horizontal and vertical forces acting on each subsoiler at a constant speed of 1.5 kmph. The rear subsoiler was operated at a constant depth of 600 mm while that of the front subsoiler and the spacing were varied. Further more, at the end of each run the cross-sectional areas of the disturbed soil-profiles were measured at different sections and the total failure profiles constructed by a Matlab-based computer program.

The results showed that the cross-sectional area failed per unit draft force linearly increased with spacing between the subsoilers. The efficiency of the subsoilers in this configuration was maximized when the longitudinal spacing was such that the soil failed by the front subsoiler was allowed to stabilize before the rear subsoiler reached it. The maximum cross-sectional area failed per unit draft force was recorded when the depth of the front subsoiler was equal to about 80% of the operating depth of the rear subsoiler.

The knowledge contributed by this research will not only facilitate qualitative field operations and optimize energy use, but also promote better management decisions.     

Changes of surface, fine pore and variable charge properties of a brown forest soil under various tillage practices

Effects of 6 years no-tillage (NT), ploughing, disking and the two last treatments combined with loosening on surface area, water vapor adsorption energy, variable charge and fine pore properties of a brown forest soils were studied using water vapor adsorption–desorption, back-titration and mercury intrusion measurements. The studied soil properties altered markedly under mechanical tillage treatment as compared to NT soil. The radii and the volumes of cryptopores (sizes from 1 to a few tens of nanometers) decreased and the opposite was found for ultramicropores (sizes from a few tens of nanometers to around 10 μm). However, fractal dimension of cryptopores and ultramicropores had changed very slightly, indicating that general geometrical structure of the fine pore system in the studied range (ca 1 nm–10 μm) remained unaltered despite pore size-shift. Surface areas and the amount of variable surface charge were markedly lower in mechanically tilled soil. A decrease of organic matter content was observed as well. Decrease of water vapor adsorption energy and increase of the fraction of strongly acidic surface functional groups accompanied mechanical tillage treatments.     

Adaptation of soil quality indices and application to three tillage systems in southern Illinois

Sustainability of agricultural management systems has become an issue of wide public concern and international debate. One result is that soil quality assessment has been suggested as a tool for evaluating sustainability of soil and crop management practices. Our objective was to adapt a soil quality index to assess the effects of three long-term tillage systems on sloping Grantsburg silt loam soil. Soil quality was evaluated using a framework that included three soil functions: (1) resist erosion (water relations), (2) provide plant nutrients (nutrient relations), and (3) provide a favorable root environment (rooting relations). A score for each of these functions was computed using measurements (indicators) that were normalized with one of the three (more is better, optimum, or worse) scoring functions. Six different indices were developed from a basic framework. Modifications included changing the weighting factors, threshold limits, or type of scoring function applied to indicators, and the addition of air-filled and water storage porosity to the nutrient and rooting relations functions. Changing threshold limits and the type of scoring function used for surface residue improved the correlation between water relations and soil loss. The addition of porosity indicators increased the sensitivity of nutrient and rooting relations functions to yield and cone index, respectively, and resulted in a better correlation between porosity indicators and plant population. Computing soil quality indices helped to combine different soil properties and processes into a simple tool that explained changes in complex soil properties in response to different tillage practices. This supports previous studies suggesting that computing soil quality indices and functions could be useful for selecting management practices to maintain or improve soil quality. Our results demonstrated that adjusting threshold limits for local conditions can make the function ratings more or less sensitive to the management practices being evaluated.     

Using selected soil physical properties of seedbeds to predict crop establishment

Seedbed preparation can involve a wide range of tillage methods from intensive to reduced cultivation systems. The state or quality of the soil to which these tillage methods are applied for cereal crop management is not easily determined and excessive cultivations are often used. Seedbed preparation is crucial for crop establishment, growth and ultimately yield. A key aspect of the soil condition is the soil physical environment under which germination, growth and establishment occur. Crucially this affects factors such as temperature, water content, oxygen availability, soil strength and ultimately the performance of a seedbed. The dynamics of soil physical properties of a range of seedbeds and how they relate to crop establishment are considered in this paper. Significant interactions between cultivation techniques, physical properties of the seedbed in terms of penetration resistance, shear strength, volumetric water content and bulk density and the interaction with crop establishment were identified. A soil quality of establishment (SQE) model was developed for the prediction of crop establishment based upon soil bulk density and cultivation practices. The SQE significantly accounted for ca. 50% of the variation occurring and successfully predicted crop establishment to a standard error of around 20 plants per m⁻² across contrasting soil types and environmental conditions.     

Temporal changes of soil physical and hydraulic properties in strawberry fields

Even over short time intervals, soil properties are subject to variation, especially in managed soils. The objective of this study was to assess the temporal changes of soil physical and hydraulic properties in strawberry fields cultivated under surface drip fertigation in Turuçu, Brazil. Intact core samples were collected from the near surface soil layer of seedbeds to determine the total porosity (TP), macroporosity (MA), matrix porosity, bulk density (BD), available water capacity (AWC), field capacity, wilting point and Dexter’s S index. Aggregate samples were collected from the arable layer to determine the aggregate size distribution and aggregate mean weight diameter. All samples were collected from 15 strawberry fields and at four different times during the 2007–2008 strawberry growing cycle. Although soil pore‐solid relations are expected to adjust soon after seedbed construction, their variation was only evident after >13 weeks. Even though values of TP and MA decreased with time, and those of BD increased near the end of the growing cycle, all the soils maintained their capacity to support root activity as indicated by critical values of Dexter’s index (S > 0.03). The amount of relatively large aggregates (9.51–2.00 mm) and AWC increased towards the end of the strawberry cultivation cycle. With changes in soil structure improving soil physical quality, strawberry development benefitted. We showed that if farmers gradually increase the amount of water through fertigation to a maximum value occurring at the end of crop cycle instead of applying water at a constant rate, water and energy use efficiency in agriculture would improve.     

Slurry-application implement tine modification of soil hydraulic properties under different soil water content conditions for silt–clay loam soils

Tillage action associated with liquid slurry application systems/management practices can modify soil infiltration properties. The degree or nature of such modification will depend largely on the type of tillage implement used, and the soil conditions at time of tillage activity. The specific objective of this study is to evaluate differences in soil infiltration properties, as measured using pressure infiltrometers and Guelph permeameters, resulting from the immediate tine action of two commonly used slurry application tillage implements (Kongskilde Vibro-Flex (S-tine) and the AerWay SSD (rolling aerator-type tine)) over a variety of silt–clay loam soil water content conditions. The results indicated that there were consistent negative correlations between field saturated hydraulic conductivity and soil water content for all tine-disturbed and undisturbed soil treatments. For Kongskilde, field-saturated hydraulic conductivity was, on average, lower in tine-influenced furrow bottoms, relative to those measured in undisturbed conditions at similar depths for most water content conditions. Generally, the Kongskilde tine-action reduced macropore-based infiltration in the bottom of the furrow for most soil conditions, albeit, this effect was most pronounced at the higher soil water contents. For AerWay, the tine-disturbed soils had generally higher field saturated hydraulic conductivities than undisturbed soil treatments over the observed water content range. This effect was manifested to a greater degree at higher, relative to lower observed water contents.     

水耕年限对黄棕壤发育的水稻土的表面化学性质的影响

利用采自江苏省农业科学院果园的旱地黄棕壤(对照)和由黄棕壤发育水耕20年和60年的水稻土,研究了土壤黏粒和粉粒的矿物组成,胶体和土体的化学性质随水耕年限的变化.粉粒的X-射线衍射图谱表明,3种供试土壤发育母质相似,胶体的矿物组成随水耕年限的变化不大.动电电位和表面负电荷的测定结果也表明,胶体表面化学性质未发生明显变化.随水耕年限增加,土壤黏粒含量降低,导致土体性质发生明显变化,土壤CEC和结构电荷量随水耕年限增加显著减少.     

Effect of design parameters of flat tillage tools on loosening of a clay soil

Very little research has been done to investigate soil loosening as a function of the geometry of the tillage tool and of the original soil properties and moisture content. A field experiment was conducted to observe the effects of the geometric parameters of flat tillage tools on their draft, cutting efficiency and loosening of a moist clay soil. The test tool variables included rake angles to the horizontal of 30, 60 and 90°, widths of 75 and 150 mm and depths of operation of 100, 150 and 200 mm. Measurements were taken of draft, disturbed soil cross sectional profiles and the initial area of soil disturbed by the tools. The resulting draft requirement increased with width, depth and rake angle of the tool. The cross sectional area of soil disturbed did not change appreciably with rake angle, but the significant increase in draft with angle resulted in markedly diminished soil cutting efficiency (area divided by draft). The degree of soil loosening was generally smaller at a rake angle of 60° than at 30 or 90°, and tended to be higher at greater depths of operation. In addition, a larger depth to width ratio generally increased the degree of loosening. Results for the soil studied indicate that the best implement design for low draft, high cutting efficiency and superior soil loosening should have a rake angle of about 30° and should be fairly narrow with a depth to width ratio of 2 or more.     

Evaluation of tomato growth and soil properties under methods of seedling bed preparation in an alfisol in the rainforest zone of Southwest Nigeria

Tillage is expected to influence growth, yield and nutrient status of tomato (Lycopersicon esculentum, Mill.) plant, but there is scarcity of research to investigate the relationship between tillage and performance parameters of tomato. Hence the variation in soil physical and chemical properties, tomato growth, plant nutrient contents and fruit yield in response to different tillage methods and seedling bed types and positions, were investigated on an alfisol (Ferric Luvisol) at Akure in the rainforest zone of Nigeria. Different bed types for transplanted tomato seedlings were created using herbicide-based zero tillage, manual clearing (a form of zero tillage), top, side and base positions of ridges and mounds for planting seedlings of early and late season tomato crops. The soil at the top, side and base positions of ridges and mounds had lower bulk densities that was associated with greater root length, plant height, number of stems, branches and number of leaves and weight of tomato fruits, and leaf nutrient contents compared with zero tillage and manually cleared soils. Planting on ridge or mound positions increased the number of fruits and fruit weight by 200 and 100%, respectively, compared with planting on untilled soils. Soil bulk density was negatively correlated with root growth and leaf nutrient content. Tomato requires tillage for optimum productivity.     

Wear of spring tine cultivator points in sandy loam and light clay soils in southern Poland

Correct evaluation and forecasting of durability of soil cutting parts are the decisive factors for proper operation of agricultural machinery. During operation of cultivators, over two-fold difference in wear of cultivator points is observed, which makes establishing of their exchange periods extremely difficult. So, there is a need to conduct some research aimed for determination of relationship between arrangement of the points in individual cultivator rows and their wear. The presented experiments were performed under authentic farm conditions during spring soil loosening and levelling operations before sowing and planting, in sandy loam and light clay soils. Changes in length and thickness of the spring tine points, wear patterns and weight loss were measured. Loss in length of spring tine points was described by a complex function of the distance travelled or by an exponential function of the distance from the measuring point to the symmetry axis of a spring tine point; loss in thickness was described by a linear function. It was found that soil type, as well as arrangement of the points in individual cultivator rows and their position in relation to the tractor wheel track, significantly influenced their wear. It was also observed that wear of spring tine points was 40–100% higher in the sandy loam soil than in the light clay soil, and that wear within a tractor wheel track was 17–40% higher than outside the track. Moreover, wear of points positioned in the first row on the cultivator frame was 26–100% higher than wear of those in the third row. The research results emphasise the need for field experiments at compare wear of spring tine points made of different materials or of different designs to take into account differences in wear due to positioning of the points on cultivator frames.