Soil Surface Level Research Articles

Variation of Surface Soil Quality Parameters by Intensive Donkey-Drawn Tillage on Steep Slope

Few direct measurements are made to quantify the erosion from upslope to lower field boundaries by intensive tillage. We conducted 50 plowing operations over a 5-d period using a donkey-drawn moldboard-plow on steep backslope in the Chinese Loess Plateau. Topographic changes at different slope positions were quantified using differential global positioning system (DGPS). Soil organic matter (SOM), extractable P and N, and soil bulk density were measured along a downslope transect after each 10-tillage series. Fifty operations resulted in a decrease in maximum soil surface level (SSL) of 1.25 m in the upper slope position and an increase of 1.33 m at the bottom of the slope. Slope gradients decreased from 37 to 14° at the upper position and from 18 to 0° at the lower position. Surface soil bulk density increased from 1.14 to 1.28 Mg m−3 in the upper slope and decreased from 1.10 to 1.03 Mg m−3 in the middle slope. Mean SOM concentrations in the upper and middle positions of the slope decreased from 8.3 to 3.6 g kg−1, mineral N from 43.4 to 17.4 mg kg−1, and Olsen-P from 4.5 to 1.0 mg kg−1 Intensive tillage resulted in a short-term increase in SOM and available nutrients in the lower portion during the tillage operations. Geomorphologic evolution and landscape variability of dissected hillslopes are attributable to soil movement and resulting physical and fertility degradation induced by intensive tillage.

A Preliminary Study on Changes in Macrobenthic Assemblages in the Fenced Experimental Plots for Restoring Tidal Marsh, Hogok-ri Tidal Flat, West Coast of Korea

This preliminary study on the changes of macrobenthic assemblages in experimental sediment fences was conducted as a part of tidal marsh restoration project. Intertidal sediment fences were designed to increase the efficiency of trapping sediments on unvegetated tidal flats in order to raise sediment elevation and to allow colonization of intertidal vegetation. Although increment of soil surface level was not observed over the first three months of the study, it was possible to obtain some effects of the sediment fence. Three months later, the particle sizes of the surface sediment at experimental plots became much finer compared to unfenced areas on the natural mudflats located in the same tide level as that of the plots. The difference was much greater on the plot with drainage canals than on the plot without ones. Species diversity of the experimental plots became much higher than that of natural sites. Perinereis aibuhitensis and Glauconome chinensis which were absent from initial community appeared with high density in the plot with drainage canals. Those species were significantly different in abundance between the experimental plot and the natural mudflat. Changes in species composition were not detected in another experimental plot without drainage canals.

Controle de Acacia farnesiana e de Mimosa pteridofita em pastagem

Conduziu-se um experimento com o objetivo de estudar a eficácia agronômica e econômica de herbicidas para o controle de duas sérias plantas daninhas de pastagens: Acacia farnesiana e Mimosa pteridofita. Os produtos utilizados, por meio de pincelamento no toco, foram o óleo diesel, óleo lubrificante usado de trator, solução aquosa de 2,4-D + picloram e solução oleosa de 2,4-D + picloram. À exceção do óleo lubrificante, os herbicidas foram testados em dois tamanhos de planta daninha e duas alturas de corte. Avaliaram-se a porcentagem de controle e o vigor de brotação das plantas não-controladas. Concluiu-se que o corte das plantas só é eficiente no controle das duas espécies, quando realizado no nível do solo e seguido da aplicação de herbicida específico, como o 2,4-D + picloram. O óleo diesel também controla totalmente ambas as espécies, e com menores custos que o 2,4-D + picloram, porém apenas quando aplicado nas plantas mais jovens. Há incompatibilidade entre o óleo diesel e o 2,4-D + picloram no controle das duas espécies. O óleo lubrificante usado não apresenta nenhum efeito herbicida em plantas adultas destas espécies.

Vegetation Change and Surface Erosion in Desert Grasslands of Otero Mesa, Southern New Mexico: 1982 to 1995

Desert grasslands that skirt mountain ranges in northern Mexico and the southwestern United States were once common. These grasslands have largely been replaced by shrublands and their soils have become eroded. The most frequently cited causes of these changes are livestock overgrazing, fire and increasing aridity. Studies have not separated grazing and fire from climate effects. Our aim was to determine whether desert grasses are being replaced by shrubs and how rapidly soil surfaces are eroding on unburnt Otero Mesa desert grasslands, where livestock overgrazing has not been a significant factor in historic or recent times. In this article we describe how vegetation and soil surface levels changed from 1982 to 1995 on six permanent transects. Vegetation was measured by charting canopy cover and stem bases of perennial plants in quadrats. Soil surface levels were surveyed in reference to benchmarks placed in nearby bedrock. Vegetation quadrats and surface levels were remeasured in 1995. From 1982–1983 to 1995 the canopy cover of the desert shrubs, Larrea tridentata and Gutierrezia microcephala, declined by 1.5% and 5.8%, respectively. Canopy cover of the C4 xeric grass Bouteloua eriopoda declined by 5.3%. This decline in xeric grass cover was offset by a 1.2% increase in the C4 mesic grass Bouteloua curtipendula and a 4.0% increase in the C3 mesic grass Stipa neomexicana. From 1983–1984 to 1995 soil surfaces along transects eroded an average of 0.4 mm·y−1. Thus, desert shrubs were not replacing desert grasses, but mesic grass species were replacing xeric species. These changes were associated with a 15-y period of relatively wet cool-seasons and moist warm-seasons from 1981 through 1995. These results document that, even in the absence of livestock grazing and fire, desert grassland vegetation is very responsive to precipitation change over relatively short time periods.

The selective soil covering mechanism of weed harrows on sandy soil

Improvement of intra-row mechanical weed control is important to reduce the reliance on herbicides in arable crops and vegetables. Covering weeds by soil is an important weed control mechanism of weed harrows. A shallow post-emergence harrow cultivation controls weeds but also damages the crop to some extent. This paper explores how plants get covered by soil and how a plant’s resistance against being covered is related to its height, flexibility and shape of leaves. Seedlings of two contrasting species were sown in bins filled with a sandy soil and harrowed by a small model harrow in the laboratory. Covering selectivity (percentage covered ryegrass/percentage covered garden cress) could be influenced by soil moisture content, working depth and working speed. Differences in covering were related to spatial patterns of plant downward bending and soil surface level upheaval. These patterns are associated with soil failure patterns near tines and soil flow patterns, connected with different effects of plant height and plant flexibility. This study indicates that relationships between weed control and crop covering may not only depend on weed and crop characteristics but also on soil conditions and implement settings. As less than 10% of the covered plants were buried deeper than 15 mm, covering would mainly cause growth reduction and little killing. Limited burial depth may be an important cause for limited weed control effectiveness of harrowing.

Natural terrace formation through vegetative barriers on hillside farms in Honduras

AbstractThe effects of contour live barriers of vetiver and pennisetum on soil erosion were studied on four small farms in south central Honduras. Paired plots were installed and soil erosion measured by changes in the soil surface level of transects 0.3 and 6.0 m up the slope from the barrier. After three years, transects 0.3 m above the barriers significantly retained eroded soil compared with control transects. Soil accumulation by barriers ranged from 2.6 to 11.2 cm, and natural terrace formation (the difference between the barrier and corresponding control transect) ranged from 5.2 to 13.8 cm. No difference was detected between barrier and control for the transects 6.0 m above the barrier. Deposition in front of the barriers and reduction in surface rilling were apparent to farmers. Erosion from up slope on the barrier plots and from both transects in the control sections was not obvious. Direct measurement and farmer observation of sediment deposition by live barriers will help evaluate farmer-identified species for future use. The deposition helps farmers become aware of sheet erosion before the effects of soil degradation on crop yields become grossly apparent and soil fertility restoration becomes too costly for small-scale farmers.

Soil surface searching and transport of Euphorbia characias seeds by ants

The intensity of exploring the soil surface by ants was studied for the four species involved in the dispersal and predation of seeds of the West-Mediterranean myrmecochorous plant Euphorbia characias. During the dehiscence period (June) the whole soil surface is sccanned in 43 minutes. Not all ants that find a seed take it to the nest. For the four ant species studied ( Pheidole pallidula, Aphaenogaster senilis, Tapinoma nigerrimum, Messor barbarus) the proportion of ants that finally take the seed is 67.6%. In spite of this, the high level of soil surface searching explains the rather short time that seeds remain on the soil before being removed. The presence of an elaiosome is a key element in the outcome of the ant-seed interaction: a seed with elaiosome has a seven-fold increase in probability of being taken to the nest if found by a non-granivorous ant. The predator-avoidance hypothesis for myrmecochory is supported.

An estimation of the natural value of dune habitats using Empidoidea (Diptera)

The dune landscape along the Belgian coast was evaluated on the basis of its Empidoidea fauna by investigating the faunal composition in different habitat types. The sites selected for sampling were marram dunes, dune grassland, dune slack, scrubby vegetations and three different dune woodlands. White water traps at soil surface level were used to sample five sites from the end of April until November 1989, and four sites from April to August 1992. Data on the most abundant Dolichopodidae, Empididae and Hybotidae were analysed by means of the following multivariate analyses: detrended correspondence analysis (DCA), canonical correspondence analysis (CCA) and two-way indicator species analysis (TWINSPAN). Most sites showed a distinctive species composition, and several species were confined to particular habitat types. Empidoid communities from canopied and open habitats showed the largest contrasts during 1989. Six environmental variables were measured in July and August 1992, and correlations indicated that aerial humidity and, to a lesser extent, soil moisture were probably the main factors explaining dolichopodid distributions. In Empididae, on the contrary, the presence of canopy by scrub or trees appeared to be important for the occurrence of many species. Thus species diversity and abundance increased from dry to humid sites in dolichopodids and from open to canopied sites in empidids. On the other hand, canopied sites appeared to function as home-bases from which certain empidid species colonized more sun-exposed areas. With the Dolichopodidae it was possible to examine the recorded distribution of all species throughout Belgium. Nearly 75% of the dolichpodids appeared to be typical lowland species and in eight species, largest Belgian populations were established in the dune region. Moreover, seven species could be considered as true coastal species as they were almost entirely restricted to this region. These results clearly stress that not merely the coastal dunes themselves but the full diversity of the associated habitats needs to be maintained in order to protect the characteristic dune empidoid communities.

Differential weathering of feldspar and pyroxene in an arctic‐alpine environment

AbstractThe relative relief of adjacent plagioclase and pyroxene minerals was accurately measured on a recently‐exhumed outcrop of gabbroic rocks in Leirdalen, southern Norway. Above the level of the former soil surface the feldspars protrude above the pyroxenes whereas below that level the pyroxenes are higher. Differential relief declines with increasing depth of burial down to 80 cm. On exposed surfaces the mean loss of pyroxene relative to feldspar is 103 cm3 m−2 of rock surface. With burial down to 50 cm in an arctic‐alpine Brown Soil the mean loss of feldspar relative to pyroxene is 179 cm3 m−2. These figures represent minimum amounts of weathering over about 9000 years. The results confirm the importance of chemical weathering in arctic‐alpine environments and the techniques may provide useful physical measures of degree of weathering for use in rate studies and relative‐dating.

Field Evaluation of Soil Hydraulic Property Changes Caused by Surge Water Application

AbstractSurge flow irrigation was developed, in part, to take advantage of the property of some soils whereby irrigation water is more evenly distributed along the field by applying the water in “surges” (on and off cycles) instead of continuously. Thus, if water advances more during the second on‐time of irrigation than the first, there must be some change in soil properties during the previous off‐time. Three soils were used in this study: Nibley silty clay loam (a fine, mixed, mesic Aquic Argiustoll), Millville silt loam (a coarse‐silty, carbonatic, mesic Typic Haploxeroll), and Kidman sandy loam (a coarse‐loamy, mixed, mesic Calcic Haploxeroll). It was demonstrated by field experiments that the soil surface of the coarse and medium‐textured soils consolidated markedly (soil surface elevation decreased about 3 mm) with surge compared to continuous water application for the first irrigation following spring tillage. The saturated hydraulic conductivity (Ksat) of these soils decreased about 45% from the first to the second on‐time. The surge effect was more pronounced during the first than the second irrigation. Most of the effect measured occurred during the first 10 to 20 min of the first off‐time. Consolidation and Ksat of the fine‐textured soil was not changed significantly by the same treatment. Two simple and practical field methods to evaluate this surge effect on soil hydraulic properties were developed: (i) measurement of soil‐surface consolidation by measuring the soil‐surface elevation changes, and (ii) measurement of Ksat by the dripper method. The soil surface level decreased by more than 1 mm and Ksat changed by about 25% when the surge effect was significant. An infiltration model developed during this study showed that simulated cumulative infiltration for surge water application was similar to measured results for the three soils studied.

Survival, Growth and Reproduction of Groundsel (Senecio Vulgaris) Infected by Rust (Puccinia Lagenophorae) in the Field During Summer

(1) Seedlings of groundsel (Senecio vulgaris L.) were planted into tubs of soil sunk to the level of the normal soil surface at a field site in late spring. Plants in half the tubs were inoculated with rust fungus (Puccinia lagenophorae Cooke). (2) Infection inhibited the expansion of leaves and reduced plant dry weight. The pattern of partitioning of dry weight between organs was little changed. Senescence occurred earlier and more rapidly in rusted plants than in controls. (3) Cumulative production of capitula was inhibited by 43% in infected plants; the number of florets per capitulum was also slightly lower in infected plants than in control plants, resulting in a 46% reduction in overall floret production. (4) Little seedling mortality occurred, but mortality of mature, flowering plants began earlier and was more rapid in inoculated populations than in controls. This greater mortality, combined with the reduced growth of infected individuals, resulted in substantially lower vegetative production in rusted populations. (5) Infection reduced the percentage of plants which flowered, and cumulative production of capitula was some 60% lower in infected than in healthy populations. Cumulative floret production was 64 000 m-2 in control populations, but only 25 000 m-2 in infected populations. (6) Responses of the summer population to rust are contrasted with the previously reported responses to rust of an over-wintering population.

Preliminary observations on the effect of removal of black bluebush (Maireana pyramidata) and Pearl Bluebush (M. sedifolia) on shrub regeneration, herbage production and erosion potential.

The effects of mechanical removal of shrub tops and grazing on two bluebush communities, one with Maireana pyramidata (black bluebush)and the other with M. pyramidata and M. sedifolia (pearl bluebush) as co-dominants, were examined on the western edge of the Riverine Plain in New South Wales Measurements were made on shrub regeneration, the relationship of shrub units to a critical value for an erosion index, the change in soil surface levels, and the growth of herbaceous plants over time Shrub regeneration was slower under grazed than ungrazed conditions and occurred mainly from basal shoots of established plants rather than from seedling establishment. Herbage yields Increased on the mounds previously occupied by shrubs, whereas production between shrubs was not affected by shrub removal. After four years there was sufficient shrub growth to prevent wind erosion, except on the cleared and grazed plot at the M. sedifolia site.

Morphologische und ökologische Grundlagen der Vorlandsicherung durchPuccinellia maritima (Gramineae)

Investigations on the influence of daylength, light intensity, inundation and accretion tolerance on the morphological and ecological characteristics ofPuccinellia maritima in connection with the role of increasing salinity and temperature (results of former investigations) lead to a deeper understanding of the role this species plays in land reclamation and preservation of coastal areas. The results obtained indicate that the species exhibits a temperature — related seasonal dimorphism with short-stem growth at daylengths up to about 12 h light/day (vernal and autumnal types, caespitose growth) and a long-stem growth at daylength of about 16 h and more light/day (aestival type, stoloniferous growth). Increasing salinity (above 10‰ S) and inundation with artificial sea water (25‰ S) reduce stem and leave development. Accretion of long-stems with sand +3% peat-mixture up to 30 cm yields in 5‰ S further development of runners under long-day conditions and longation of short-stems (up to 10 cm) up to the new soil-surface level. Three shortstem types and two long-stem types can be distinguished. These results explain the natural responses of the species, the forming of the Puccinellietum maritimae within the allogene succession and its role in land preservation. The species is a facultative halophyte which occupies, due to competition from other species, the lower part of its inundation amplitude, utilising its high-salt tolerance. Its aestival long-stem and its autumnal/vernal short-stem production increases the sedimentation rate of soil particles during inundation; the following accretion leads to an elongation of short-stems up to the new soil level, and to an increased production of adventitious roots; the latter results in soil fixation.