水稻育秧播种机钵体苗底土压实装置   总被引：1，自引：0，他引：1  

马旭  谢俊锋  齐龙  梁仲维  邝健霞  谭永炘 《农业机械学报》2014,45(8):54-60

设计了一种能实现水稻精密育秧播种机钵体软、硬秧盘穴孔底土压实的通用装置,该装置以AT89C51单片机为控制系统核心,采用步进电动机和送盘行程开关实现秧盘供送,以及限位行程开关和对准接近开关实现秧盘穴孔与压实辊指对准,压实辊指与秧盘穴孔内底土相互作用完成底土压实。通过系统的试验研究,确定了该装置的最佳工作参数。压实试验表明,该系统能满足秧盘穴孔底土压实的工作要求,实现了穴孔与压实辊指的精确对准和底土压实,当生产率在500盘/h、提前角对应弧长为1 mm时,对准率为98%,满足钵体苗穴孔底土压实的技术要求;育秧试验表明,增加穴孔底土压实深度,可提高秧苗素质,保持土壤根系坚实不散,有利于栽插作业,压实深度为6 mm时效果最佳。  相似文献   

FEM analysis of subsoil reaction on heavy wheel loads with emphasis on soil preconsolidation stress and cohesion     

M. P. Poodt  A. J. Koolen  J. P. van der Linden 《Soil & Tillage Research》2003,73(1-2):67-76

Heavy sugarbeet harvesters may compact subsoil. But it is very difficult to study this by field experiments that resemble agricultural practice. Therefore, an analysis was made by a finite element method (FEM) for a relevant calcaric fluvial soil profile, the mechanical properties of which were largely known. Measuring data of this Lobith loam soil includes preconsolidation stress, compression index and swelling index, all as a function of depth. Using these three types of soil parameters calculations have been done for tyre sizes, inflation pressures and wheel loads that occur with heaviest sugarbeet harvesters available on the European market in 1999. Because no values on soil cohesion were available, the calculations were done for several cohesion levels. The results include the detection of regions with Mohr–Coulomb plasticity and regions with cap plasticity (compaction hardening). For the soil studied—a typical soil strength profile for arable land with ploughpan in the Netherlands in the autumn of 1977—all studied combinations of wheel load and inflation pressure did not induce compaction in and below the ploughpan. The size of the region with Mohr–Coulomb plasticity decreased with increasing cohesion. It appeared from a sensitivity analysis that, although soil modelling may use a great number of soil parameters, the most important parameters seem to be: preconsolidation stress and cohesion. There is an urgent need for data of these parameters that are measured on a great range of subsoils and subsoil conditions.  相似文献   

Non-cellulosic neutral sugar contribution to mineral associated organic matter in top- and subsoil horizons of two acid forest soils     

C. Rumpel  K. Eusterhues 《Soil biology & biochemistry》2010,42(2):379-214

We investigated the polysaccharide composition of bulk and mineral-bound (density fractions >2 g cm⁻³) organic matter in topsoil and subsoil horizons of a Podzol and a Cambisol. Total sugar contents were generally higher in the Cambisol than in the Podzol. For most horizons of both soils, the sugars were enriched in the mineral-bound organic matter fraction. This fraction showed a monosaccharide distribution typical for microbial sugars, whereas in bulk soil horizons higher contributions of plant-derived sugars were observed. A strong relationship with the ¹⁴C activity of the dense fraction suggests that microbial-derived polysaccharides are most likely stabilised preferentially by mineral interactions compared to plant-derived polysaccharides.  相似文献   

水分胁迫下土壤下层水分和硼对苔期油菜的作用   总被引：2，自引：0，他引：2  

方益华 《土壤通报》2001,32(1):8-10

采用分层隔水盆栽试验 ,研究不同土壤状况下 ,表层土壤干旱 ,下层土壤湿润条件下 ,下层土壤中的水分和养分对油菜营养生理的影响 ,结果表明 ,土壤上下层干旱使油菜生长严重受抑 ,而下层湿润且硼含量充分的土壤上栽培的油菜可获得生长所需的水分和硼 ,从而改善其营养状况 ,增加其生物量 .土壤湿润情况下 ,油菜对土壤硼的利用效率增强 ,而土壤中硼各组分对油菜的有效性也有显著变化  相似文献   

Changes in chemical and biological properties of a sodic clay subsoil with addition of organic amendments     

G.J. Clark  N. Dodgshun 《Soil biology & biochemistry》2007,39(11):2806-2817

An experiment was performed to examine the chemical and biological effects on high clay sodic subsoil following the incorporation and incubation with organic amendments. The main treatments consisted of amendments with wheat shoots, lucerne pellets and peat, and these were compared to gypsum addition. Additional treatments were residues of chickpea and canola, chicken manure and sawdust. All materials were finely ground and added to crushed and sieved soil at the rate of 1% by weight. Wheat, canola and chickpea residues and chicken manure resulted in modest reductions in soil sodicity. Carbon and N mineralization were related to the soluble C/total N ratio in the amendment. The initial mineralization of wheat amendment was rapid due to its soluble C content, but then slowed to have the lowest loss, of around one third of added C, of all the plant residues after 174 days. In comparison, lucerne-amended soil increased total N and lost almost half of its C after the 174-day incubation. The canola stubble amendment showed the highest carbon loss, losing 64% of its added C. The addition of gypsum resulted in high soil electrical conductivity which suppressed respiration, compared to the control soil, indicating a detrimental effect on microbial activity due to the high electrolyte concentration in the soil. The peat amendment, with a low-soluble C content, showed a similar respiration rate to the control soil, confirming that a source of soluble C is important for the initiation of rapid biological activity. Soil pH was significantly increased (by 0.6 of a pH unit) with addition of chicken manure, and still remained higher than control soil after 174 days of incubation. Lucerne was the only plant residue to increase soil pH, with the effect being sustained for 56 days. The study demonstrated how some organic amendments can improve chemical fertility and biological activity in high clay sodic subsoil, and at the same time contribute, after 25 weeks incubation, to an increase in carbon content.  相似文献   

Technical solutions to reduce the risk of subsoil compaction: effects of dual wheels, tandem wheels and tyre inflation pressure on stress propagation in soil     

T. Keller  J. Arvidsson 《Soil & Tillage Research》2004,79(2):191-205

The use of heavy machinery is increasing in agriculture, which induces increased risks of subsoil compaction. Hence, there is a need for technical solutions that reduce the compaction risk at high total machine loads. Three field experiments were performed in order to study the effects of dual wheels, tandem wheels and tyre inflation pressure on stress propagation in soil. Vertical soil stress was measured at three different depths by installing probes into the soil horizontally from a dug pit. In one experiment, also the stress distribution below the tyre was measured. Beneath the dual wheels, vertical stresses at 0.15 and 0.3 m depth were lower between the two wheels than under the centre of each wheel, despite the gap between the wheels being small (0.1 m). At 0.5 m depth, vertical stress beneath the wheels was the same as between the two wheels. The stress interaction from the two wheels was weak, even in the subsoil. Accordingly, measured stresses at 0.3, 0.5 and 0.7 m depth were highest under the centre of each axle centre line of tandem wheels, and much lower between the axles. For a wheel load of 86 kN, tyre inflation pressure significantly affected stress at 0.3 m depth, but not at greater depths. Stress directly below the tyre, measured at 0.1 m depth, was unevenly distributed, both in driving direction and perpendicular to driving direction, and maximum stress was considerably higher than tyre inflation pressure. Calculations of vertical stress based on Boussinesq's equation for elastic materials agreed well with measurements. A parabolic or linear contact stress distribution (stress declines from the centre to the edge of the contact area) was a better approximation of the contact stress than a uniform stress distribution. The results demonstrate that stress in the soil at different depths is a function of the stress on the surface and the contact area, which in turn are functions of wheel load, wheel arrangement, tyre inflation pressure, contact stress distribution and soil conditions. Soil stress and soil compaction are a function of neither axle load nor total vehicle load. This is of great importance for practical purposes. Reducing wheel load, e.g. by using dual or tandem wheels, also allows tyre inflation pressure to be reduced. This reduces the risk of subsoil compaction.  相似文献   

A subsoil compaction database: its development, structure and content     

A. Trautner  J. J. H. van den Akker  H. Fleige  J. Arvidsson  R. Horn 《Soil & Tillage Research》2003,73(1-2):9-13

A database which holds results of field and laboratory experiments on the impact of subsoil compaction on physical and mechanical soil parameters and on crop yields and environmental impact is being developed within the EU sponsored concerted action (CA) project “Experiences with the impact of subsoil compaction on soil, crop growth and environment and ways to prevent subsoil compaction”. The database accumulates and can provide all available data from the participants of the European Union countries, and is compatible with the European Soil Database and other related databases.

More than 600 sets of data (Excel workbooks) from participants from the European Union, plus Poland, Switzerland and Norway are included in the database. Through a similar EU sponsored CA, Eastern European countries are expected to deliver 260 sets of data thus bringing the total number of Excel workbooks to approximately 860. In total, the database will contain approximately 13,500 data spreadsheets.

The objective of the database is to collect data on subsoil compaction, to store it in a structured format and to make it available for analysis and use. Thereby it will enable elucidation of the impact of subsoil compaction on soil properties, crop yields and environment and evaluate the vulnerability of soils to compaction.  相似文献   

Denitrification in intact subsoil cores     

K. Castle  J. R. M. Arah  A. J. A. Vinten 《Biology and Fertility of Soils》1998,28(1):12-18

 Intact, unamended subsoil cores taken from two contrasting field sites were incubated in the laboratory at 12  °C under aerobic (21% O₂) and anaerobic (1.1–5.5% O₂) conditions. Denitrification of ¹⁵N-NO₃ ^– diffusing into the cores across a semi-permeable membrane was estimated by: (1) direct observation of ¹⁵N-labelled N₂ and N₂O, and (2) mass balance following sectioning at the end of the experiment. The in situ denitrification potential (rates where the supply of NO₃ ^– is not limited by diffusion) was estimated using a finite-difference approximation to a diffusion reaction equation based on comparison of time and depth profiles of NO₃ ^– and Br^– in the incubated cores. Potentials between 0.2 and 2.5 mg N kg^–1 day^–1 were obtained under low O₂ and natural C concentrations. These results indicate the potential for denitrification in glacial till subsoils to reduce NO₃ ^– leaching to ground or surface waters to levels unlikely to result in a pollution hazard. The major product of NO₃ ^– reduction in these subsoils was observed to be N₂, rather than the greenhouse gas and catalyst of stratospheric O₃ removal, N₂O. Received: 31 October 1997  相似文献   

Influence of single passes with high wheel load on a structured, unploughed sandy loam soil     

M. Gysi  A. Ott  H. Flü  hler 《Soil & Tillage Research》1999,52(3-4):141-151

In a field experiment, a sandy loam was subjected to single passes with a sugar beet harvester at two different soil water potentials. Different hopper fillings resulted in ground contact pressures of 130 kPa (partial load) and 160 kPa (full load) underneath the tyre. Bulk density, macroporosity (equivalent pore radius >100 μm), penetrometer resistance, air permeability and pre-consolidation pressure were measured within and next to the wheel tracks at depths of 0.12–0.17, 0.32–0.37 and 0.52–0.57 m. Furthermore, the soil structure at two horizons (Ahp 7–24 cm, B(C) 24–38 cm) was visually assessed and classified.

The moist plot responded to a wheel load of 11.23 mg (160 kPa) with an increase in bulk density and pre-consolidation pressure as well as with a decrease in air permeability and macroporosity at a depth of 0.12–0.17 m. With a wheel load of 7.47 mg (130 kPa) on the moist plot and with both wheel load levels on the dry plot, only slight changes of the soil structure were detected. At a depth of 0.32–0.37 and 0.52–0.57 m, the measurements did not indicate any compaction. An ANOVA indicates that the factor “soil water potential” and the factor “wheel load” significantly influence the bulk density at a depth of 0.12–0.17 m. No interactions occurred between these two factors. The wheel traffic on the test plot had no effect on the yield of winter wheat planted after the experimental treatment.

Bulk density, macroporosity and pre-consolidation pressure proved to be sensitive to detect compaction because they varied only slightly and are easy to measure. In contrast, the standard deviation of air permeability is large. The soil structure determined visually in the field confirms the values measured in the laboratory. The results of the penetrometer resistance measurements were not explainable.  相似文献   

心土层肥力差异对大豆生长特性及产量的影响     

姚春雨  王秋菊  高中超  张劲松  刘峰 《大豆科学》2016,(5):776-781

采用盆栽方法研究了不同肥力心土层及不同施磷量对大豆生长特性和产量的影响。结果表明:随着心土层肥力和施磷量的增加,株高和叶绿素显著增加;干物质积累量不同肥力间无规律性变化,磷肥施用量120 kg·hm~(-2)的高肥力心土干物质积累量最高,为116.68 g·盆~(-1),中肥力心土施磷肥量180 kg·hm~(-2)的干物质积累量较高,为107.60g·盆~(-1),低肥力施用磷肥240 kg·hm~(-2)干物质积累量为103.76 g·盆~(-1),心土肥力水平与施肥量达到一定关系有利于干物质积累,处理间差异显著;不同肥力心土层大豆垂直根长差异显著,依次为高中低肥力处理,根干重、根瘤个数和根瘤干重均与不同肥力心土层和施肥量呈正相关;不同肥力心土大豆产量差异显著,高肥力心土施用120 kg·hm~(-2)磷肥大豆产量最高,达到318 g·盆~(-1);中等肥力施用180 kg·hm-2磷肥产量次之,为299.8g·盆~(-1);低等肥力施用240kg·hm~(-2)磷肥居第三,为283.5 g·盆~(-1);不同肥力心土施用适量肥料才能达到最佳效果。  相似文献