Compacted Topsoil Research Articles

OPTIMIZATION OF PARAMETERS OF WORKING BODIES OF MACHINES FOR SUGAR BEET PRODUCTION

Existing technologies and modern technical means do not always provide the required quality of technological processes for growing sugar beets. Increasing requirements necessitate continuous improvement of existing and creation of new high-performance machines and units to ensure high-quality production technologies of sugar beet crops. Improved technological processes for the production of sugar beet crops are described in the article. Such technological processes include: loosening the compacted topsoil and destruction of the soil crust before the emergence of sugar beet shoots, loosening the soil after emergence, feeding sugar beets with increased soil hardness and low moisture content, inter-row soil cultivation with hilling plants in lines. As a result of research of technologies for inter-row processing of sugar beets in the system of crop care, the following ratio was established: the optimal depth and width of the strips for cutting the top layer of the soil, depending on the depth of placement of the sown seeds; the distance between the ribs of the roller, depending on the depth of cutting the soil; the maximum depth of soil loosening in the row zone and the row spacing zone, depending on the depth of sowing seeds and the placement of the root system of beets; the required depth of soil loosening in the aisles, depending on the specified optimal depth of application of mineral fertilizers in the aisles; the required distance from the conditional centerline of the beet rows to the zone of mineral fertilization in the aisles, etc. The use of optimized technological processes makes it possible to create the necessary conditions for the growth and development of sugar beet plants on heavy-textured soils and after a significant amount of precipitation and an increase in soil density. In addition, the proposed innovative technologies ensure the preservation and even increase of soil moisture, reduction of sparseness and contamination of crops, as well as losses and damage to sugar beet roots during harvesting. The research results can be used to improve and optimize zonal technologies and technical means for growing sugar beets in conditions of high density and insufficient soil moisture, as well as in the educational process in the preparation of future specialists from agricultural engineering for scientific project activities.

Impact on soil physical properties of using large-grain legumes for catch crop cultivation under different tillage conditions

Abstract In Central Europe, various plant species including large-grain legumes and their mixtures are grown as catch crops, particularly between grains harvested early and subsequent summer crops. This article investigates the question of how soil structure in the topsoil is influenced when catch cropping with large-grain legumes (experimental factor A: without catch crop, with catch crop) under different ploughless tillage conditions during catch crop seeding (experimental factor B: deep tillage/25–30 cm, shallow tillage/8–10 cm). Five one-year trials were performed using standard machinery at various sites in Germany. Soil core samples extracted from the topsoil in the spring after catch crop cultivation served to identify air capacity, saturated hydraulic conductivity and precompression stress. The above-ground and below-ground biomass yields of the catch crops were also determined at most of the sites. In addition, the soil compaction risk for the working steps in the experiments was calculated using the REPRO model. The dry matter yield of the catch crops varied considerably between the individual trial sites and years. In particular, high levels of dry matter were able to form in the case of early seeding and a sufficient supply of precipitation. The soil structure was only rarely affected positively by catch crop cultivation, and catch crops did not contribute in the short term to loosening already compacted topsoils. In contrast, mechanical soil stresses caused by driving over the ground and additional working steps used in cultivating catch crops often led to lower air capacity in these treatments. This is consistent with the soil compaction risks calculated using the REPRO model, which were higher in the treatments with catch cropping. Catch crop cultivation also only resulted in improved mechanical stability at one location. The positive effect of deep ploughless tillage on air capacity and saturated hydraulic conductivity, however, became more clearly evident regardless of catch crop cultivation. In order for catch crop cultivation with large-grain legumes to be able to have a favourable impact on soil structure, it is therefore important that cultivating them does not result in any new soil compaction. In the conditions evaluated, deep tillage was more effective at loosening compacted topsoil than growing catch crops.

Impacts of long-term chemical and organic fertilization on soil puddlability in subtropical China

Soil puddlability measures the susceptibility of a soil to puddling, and can influence transplantation and the growth of rice plants. The effects of chemical fertilizers and organic amendments on soil puddlability of paddy soils are poorly understood. This study used two 26-year field experiments (1) to compare the effects of chemical and organic fertilization on soil puddlability by measuring sinkage resistance and hard clod content after puddling, (2) to characterize physical properties of hard clods and (3) to explain the change in soil puddlability. Each of the two experiments consisted of nine treatments of chemical fertilizers alone or in combination with organic amendments. The sinkage resistance and the content of hard clods were higher in the treatments with chemical fertilization alone than in the treatments with organic amendments. The sinkage resistance was positively correlated with the content of hard clods and negatively correlated to content of soil organic C (SOC) and mean weight diameter (MWD). The bulk density, water sorptivity and apparent porosity were similar among individual hard clods from different treatments, suggesting that the hard clods were formed under the same processes. The formation of hard clods was likely attributed to the breakdown of the compacted topsoil by puddling tillage, which formed due to clogging pores by fine particles produced during previous puddling tillage and due to shrinkage upon drying during rice growth period. Compared with the organic amendment treatments, the chemical fertilization treatments contained more and larger hard clods, indicating that the compacted topsoil was thicker due to higher soil dispersibility due to N fertilization and lower SOC content in the chemical fertilization treatments than in the organic amendment treatments. The study also suggests that continuous input of organic C at an annual rate of >2.5Mgha−1 is needed to maintain SOC content and soil structure under chemical fertilization in the study region.

Dynamics of soil hydraulic properties during fallow as affected by tillage

There is limited information on the effects of tillage practices on soil hydraulic properties, especially changes with time. The objective of this study was to evaluate on a long-term field experiment the influence of conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) on the dynamics of soil hydraulic properties over 3 consecutive 16–18 month fallow periods. Surface measurements of soil dry bulk density ( ρ b), soil hydraulic conductivity ( K( ψ)) at −14, −4, −1 and 0 cm pressure heads using a tension disc infiltrometer, and derived hydraulic parameters (pore size, number of pores per unit of area and water-transmission porosity) calculated using the Poiseuille's Law were taken on four different dates over the fallow period, namely, before and immediately after primary tillage, after post-tillage rains and at the end of fallow. Under consolidated structured soil conditions, NT plots presented the most compacted topsoil layer when compared with CT and RT. Soil hydraulic conductivity under NT was, for the entire range of pressure head applied, significantly lower ( P < 0.05) than that measured for CT and RT. However, NT showed the largest mean macropore size (0.99, 0.95 and 2.08 mm for CT, RT and NT, respectively; P < 0.05) but the significantly lowest number of water-conducting pores per unit area (74.1, 118.5 and 1.4 macropores per m 2 for CT, RT and NT, respectively; P < 0.05). Overall, water flow was mainly regulated by macropores even though they represented a small fraction of total soil porosity. No significant differences in hydraulic properties were found between CT and RT. In the short term, tillage operations significantly increased K ( P < 0.05) for the entire range of pressure head applied, which was likely a result of an increase in water-conducting mesopores despite a decrease in estimated mesopore diameter. Soil reconsolidation following post-tillage rains reduced K at a rate that increased with the intensity of the rainfall events.

Evaluating the sustainability of different soil tillage practices using field measured electrical properties

Our results indicate that mechanical disturbance of soil and the corresponding structural changes influence the relationship between the field-measured soil electrical conductivity (EC) values and soil hydraulic properties. This assumes that this kind of measurements — performed on wet soils of a homogenous area — can be used to distinguish different kinds of soil tillage treatments in order to evaluate their sustainability. The EC values showed statistically significant relationship with soil hydraulic properties and quality indicators for treatments with more compacted topsoil layer. We concluded that further studies on the relationship between EC values and soil structural status should be carried out.

Root interactions between young Eucalyptus deglupta trees and competitive grass species in contour strips

To reduce soil erosion on sloping fields grass strips are commonly planted on the contours. The integration of timber trees into such strips can be economically beneficial and at the same time increase the anti-erosion effect of the strips. Root competition between grasses and trees within such strips may affect tree development, but might also reduce root competition between the trees and adjacent field crops if the grass strips restrict the lateral development of the tree root systems. The present experiment, carried out on a fertile site (Aquandic Dystrudept) in a high-rainfall region in Costa Rica (2700 mm per year), was designed to evaluate whether the lateral extension of the root system of Eucalyptus deglupta could be restricted by strips of the grasses Panicum maximum, Brachiaria brizantha or Saccharum officinarum, planted either in single, double- or triple-rows on both sides of rows of the trees. E. deglupta growth was significantly reduced in the association with P. maximum, the most competitive grass species, and to a lesser extent, by the double- and triple-row B. brizantha strips. In these treatments, the total number of lateral tree roots, as evaluated in profile walls, was reduced by up to 40% compared to the no-grass control. Furthermore, the lateral restriction of the tree root systems led to an increased density of tree roots between the grass strips. S. officinarum did not reduce the total number of tree roots and only slightly restricted lateral tree root extension. Grass strips composed of multiple grass rows appeared to restrict lateral tree root development more than strips with single grass rows but this effect was not statistically significant. None of the grasses forced the tree root systems to develop at a greater depth; on the contrary, tree roots were more superficial in the profiles beyond as well as between the grass strips in comparison to the no-grass control. There was some evidence of an increased root barrier effect of the grass strips in areas with a compacted topsoil. The barrier effect tended to decrease with increasing age of the trees. These results suggest that strips of competitive grasses can reduce the lateral root development, especially of young trees, when planted in contour strips, and this may reduce and/or delay root competition with neighboring field crops. The observed trends are likely to change as trees grow older and longer-term studies are needed.

Wirkung mechanischer Belastung auf Gefüge und Ertragsleistung einer Löss-Parabraunerde mit zwei Bearbeitungssystemen

Das Bundes-Bodenschutzgesetz von 1999 verpflichtet Landwirte zur Vorsorge. Doch immer schwerere Maschinen gefährden Produktivität und Umweltleistung unserer Ackerböden. Auf Löss-Parabraunerde wurden Auswirkungen hoher Lasten auf Bodeneigenschaften und Ertragsleistung untersucht und eine zeitabhängige Regeneration der Bodenmerkmale überprüft. Verglichen wurden zwei Bearbeitungssysteme: Lockerbodenwirtschaft (LBW) mit jährlicher Pflugfurche (25 cm) und Festbodenmulchwirtschaft (FMW) mit flacher (5—8 cm) Eingriffstiefe (Kreiselegge). Böden mit FMW gelten als stabiler und regenerationsfähiger. Belastet wurde feuchter Boden im Frühjahr 1995 in den Stufen 2 × 2,5 t (Zahl der Radeinwirkungen mal Radlast; = geringe Belastung), 2 × 5 t (= mittel) und 6 × 5 t (= hoch). Die Kontrolle blieb unbelastet. Im ersten Jahr sank bei LBW der Sommergerstenkornertrag bereits durch geringe Belastung signifikant um rund 50%, bei FMW erst durch hohe Belastung. Die Nachwirkungen bei Winterweizen und Wintergerste waren viel geringer. Lasteintrag minderte bei LBW die Gesamtwurzellänge (von 4 auf 1 km m−2) und bis ins dritte Jahr die maximale Durchwurzelungstiefe (von 70—90 auf 40—70 cm). Bei FMW war bei hohem Lasteintrag nur die Wurzellänge betroffen. Bei LBW hemmte eine Krumenbasisverdichtung (30—35 cm) die Unterbodendurchwurzelung. Bei FMW wurde die Tiefendurchwurzelung durch Regenwurmröhren gefördert. Hohe Belastung verdichtete das Bodengefüge mindestens bis in 50 cm Tiefe. An der Krumenbasis von LBW wurde ein Durchdringungswiderstand von 5 MPa und eine Lagerungsdichte von 1,65 g cm−3 erreicht. Bei FMW lag die Zone maximaler Verdichtung flacher (15—25 cm). Bei LBW wurden gesättigte Wasserleitfähigkeit (kf) und O2-Diffusionskoeffizient mit steigender Belastung gesenkt, bei FMW nur bei hoher Belastung. In den Folgejahren wurde das verdichtete Gefüge im Bearbeitungshorizont aufgebrochen. Eine endogene Gefügeregeneration an der Krumenbasis und im Unterboden war bei LBW nicht nachzuweisen. Bei FMW wurde sie durch Wiederanstieg von kf und O2-Diffusion angezeigt. Ursache hierfür waren neugebildete Wurzel- und Regenwurmgänge, dargestellt durch Computer-Tomographie. Wir folgern, dass bei Schluffböden unter Pflugwirtschaft Verdichtungszonen im Unterboden wenig regenerationsfähig sind. Böden mit Mulchwirtschaft sind stressverträglicher, dennoch nicht „extrem“ belastbar. Deshalb ist die Empfehlung von FMW als Vorsorge gegen Verdichtung beim gegenwärtigen Trend zu Schwerlast-Maschinen allein nicht ausreichend. Effect of mechanical stress on structure and productivity of a loess-derived Luvisol with conventional and conservation tillage In Germany farmers are committed to caring for the land by a soil protection law. Yet vehicles with ever increasing axle load endanger productivity and environmental quality of arable soils. In spring of 1995 a field experiment was startet on a wet silty Luvisol to test the effect of single mechanical loading on soil and crop characteristics, when managed by mouldboard ploughing (PL) or conservation tillage (CT). CT soils are considered to be more resistant against compactive stresses and to recover from degeneration more rapidly than PL soils. Beside an unwheeled control the loading treatments were light (2 × 2.5 t; number of wheel passes times wheel load); medium (2 × 5 t) and high (6 × 5 t). In 1995 even light loading of the PL soil caused a significant yield decline by 50% in spring barley, but this happened on CT soil only with high loading. In subsequent years with winter wheat and winter barley yield decline was less distinct. Loading of PL soil reduced total root length (from 4 to 1 km m−2) and rooting depth (from 70—90 to 40—70 cm), but on CT soil only root length was diminished by high loading. A tillage-traffic pan (30—35 cm) hindered subsoil rooting in PL, which was favored in CT by earthworm channels. High loading caused compaction to at least 50 cm depth. Within the pan of the PL soil, penetration resistance attained 5 MPa and bulk density 1.65 g cm−3. In the CT soil the zone of maximum compaction was closer to the surface (15—25 cm). In PL soil the saturated hydraulic conductivity and the O2-diffusion coefficient gradually decreased with loading, but in CT soil only with heavy loading. The compacted top soil was broken in subsequent years by ploughing (PL: 25 cm) or rotary implements (CT: 5—8 cm). With PL, structure in the pan layer and subsoil did not recover, and rooting depth was still limited. Some restoration, however, was indicated with CT. Here transmitting properties increased in time, which was attributed to the reconstruction of root and earthworm channels, as demonstrated by computer tomography. We conclude that in silty soils compacted layers below ploughing depth will hardly be regenerated by internal processes. CT soils are less susceptible to loading, but high stresses are harmful too. Therefore recommending CT as a measure for protecting soil from compaction would not be enough, considering the present development towards heavy field machinery.

Leaching of pesticides and a bromide tracer through lysimeters from five contrasting soils

In each of two seasons, undisturbed lysimeters 0.8 m in diameter and 1.05 m in length taken from five soil types were cropped with winter wheat. They received autumn applications of the pesticides isoproturon and linuron as well as a bromide tracer and spring applications of dimethoate and MCPA. Leachate was collected at regular intervals and concentrations of the various solutes determined. Rainfall from December to March was 290 and 191 mm in the first and second seasons, respectively. Both springs were exceptionally dry with less than 50% of the mean April-to-June rainfall of 138 mm. Total flow from the lysimeters ranged from 335 to 477 mm (and from 0.78 to 3.95 pore volumes) over the two seasons. Leaching to drainage of bromide highlighted soils where preferential flow was influential with total losses ranging from 24% of applied for a strongly structured, alluvial clay loam to 79% for an unstructured sand. Leaching to drainage of isoproturon (Koc ≈ 100 ml g−1) was observed from all but a peat soil with losses greater (0.31–1.01% of applied) from the clay loam and a deep medium loam, where patterns of leaching clearly indicated preferential flow mechanisms, than from the sand and a light loam over gravel (0.04–0.18% of applied) where a broad breakthrough curve indicated that matrix flow was more important. Linuron (Koc ≈ 500 ml g−1) was detected in occasional samples of leachate from the clay loam, the light loam over gravel and the medium loam during the first season only (maximum loss 0.12% of applied). The sandy soil, often considered most vulnerable to leaching, gave the smallest total losses of pesticide of the four mineral soils, whilst significant preferential flow in the deep, medium loam was believed to result from a compacted topsoil. Neither of the spring-applied pesticides was detected in the leachate, as flow following application was very small and relatively slow. © 2000 Society of Chemical Industry

Hydraulic Properties of Andosols Following Deforestation in the Northern Slopes of Mt. Kenya

AbstractDeterioration in soil hydraulic properties due to deforestation adversely affects the hydrology of catchments, especially those on mountain slopes. The effects of clearing natural forest (NF) for potato cultivation (PC) and livestock grazing (GL) on the hydraulic properties of an andosol (after 5 to 8 years) were investigated in the northern slopes of Mount Kenya. The two farming activities have resulted in deleterious changes in soil water flow and storage. Results obtained showed that steady infiltration rates were 65.7 in NF, 9.7 in PC and 13.4 cm h−1 in GL. Sorptivity decreased by 15% in PC and 22% in GL, while topsoil-saturated hydraulic conductivity decreased by 62% in PC and 76% in GL compared to NF. Both PC and GL topsoil had higher volumetric water content at soil matric potentials (<—25 cm) than NF. Cultivation and grazing in the area have led to compacted topsoil with lower (11%) total porosity and decreased plant available water holding capacity by 16 for PC and 19% for GL.

Forestation of Mined Lands

Green ash (Fraxinur pennrylvanica) and white pine (Pinus strobus) trees were planted on three minesoil types (graded topsoil, graded and ripped topsoil and levelled gay cast overburden) with various mixtures of masses and legumes seeded either before tree planting or at time of bee planting. Trees received weed control for either 0, 1 or 2 years. Some trees were also planted on unseeded subplots. Survival,-vigor and annual height giowth of trees were measured as well as biomass and ground cover of herbaceous species. After two growing seasons with above average precipitation, green ash had excellent survival at 98% but white pine averaged 36% survival overall and only 6% on cast overburden. However, cast overburden was a suitable soil for green ash, and biomass of seeded gasses and legumes was equal to that found on topsoiled plots in the second growing season. Treatments such as weed control, ripping compacted topsoil and delay of seeding until tree planting normally result in increased tree seedling sur...

Laboratory experiments on the effects of simulated tractor wheelings on linear soil erosion

The influence of the orientation of simulated tractor ruts on soil-erosion processes on a silty loamy topsoil with varying moisture content is studied. A sediment-transporting capacity equation is used to calculate the erosion efficiency in different experimental situations. The experiments show that the erosion resistance of wheel tracks is strongly limited. A compacted topsoil, that is rewetted at once after a long dry period, is very sensitive to severe erosion. In particular, tracks formed by tractors that have driven upslope can provoke linear erosion. Rill development in a wheel track can proceed very rapidly owing to the formation of numerous headcuts.

Effect of induced compaction by wheel traffic on soil physical properties and yield of maize in Romania

Results of field experiments with soil compaction induced by wheel traffic applied uniformly to cover the entire surface of the experimental plots are reported. Compaction was done immediately before sowing, and each year, in each location, the same treatments were repeated on the same plots. The number of tractor passes varied between 0 and 30. The experiments were conducted during the 1978–1981 period in four locations with different soil and climatic conditions. Changes in soil physical properties, as well as in the yield of maize grain, were shown to be related to the number of tractor passes according to regression formulae of the type: Y = a X b . Most of the changes were recorded between 0 and 8–10 passes, while with more than 15–20 passes changes became negligible. The average maximum increase in bulk density was 20–25% as compared with the non-compacted control plot, and the average maximum decrease in yield was 46%. Moisture content in the compacted control plot, and the was 2–3% (w/w) lower than in the control plot, except for the soils with poor drainage where the lower part of the compacted topsoil showed an increase in moisture content. Air content in the compacted plots often dropped below 10, and occasionally to nearly 0% (v/v). For three of the four locations, grain yield of maize linearly decreased by 13 kg ha −1 (or 0.18% of the control plot yield) for each 1 kg m −3 increase in bulk density.