Coarse Textured Sand Research Articles

Soil dependence of biochar composts in mitigating greenhouse gas emissions: An overlooked biophysical mechanism

Biochar-manure co-compost (BM) has garnered considerable attention as a promising soil amendment for improving nutrient retention and mitigating the emission of greenhouse gases (GHGs). However, its efficacy often varies largely from one soil to another. By comparing soil CO2 and N2O effluxes, solution chemistry, enzyme activities, and the abundances of N-cycle genes between BM and manure compost (M) across three soils of different texture classes through microcosm incubations, we aimed to develop biophysical mechanics to untangle the soil-dependent efficacy of BM in mediating soil carbon and nitrogen transformation processes. Compared to M addition, BM addition significantly reduced soil CO2 and N2O emissions, but its effectiveness was soil texture-dependent, being strongest for CO2 and N2O in fine-textured clay loam and coarse-textured sand, respectively. Such soil texture-dependent effects of BM versus M were also observed in soil enzyme activities and gene copy numbers of ammonia-oxidizing bacteria and denitrifiers. Our datasets suggest that BM interacted strongly with soil texture to modulate the pore scale-based diffusion of oxygen, thereby creating divergence in the aeration status among soils. Sequentially, soil phenol oxidase activity was greater in BM than in M under more aerobic conditions but no difference between BM and M in oxygen-limited soils. The balance between oxygen depletion due to microbial respiration of organic amendments and oxygen diffusion through soil/biochar pores also shaped the activities of nitrifying and denitrifying prokaryotes differently between coarse- and fine-textured soils. This logic model well-explained the magnitude of change in soil-dependent CO2 and N2O emissions from organic amendments. The knowledge gained in this work will likely have profound practical ramifications for optimizing BM efficacy in mitigating the GHGs emission.

The University of West Florida Campus Ecosystem Study: effects of forest vegetation on light availability and soil processes.

College and university campuses with a notable arboreal component provide unique opportunities for carrying out ecological research. The University of West Florida Campus Ecosystem Study (UWF CES) was established in 2019 as interconnected research to take advantage of the extensive arborescent nature of the UWF campus, particularly concerning longleaf pine (Pinus palustris). One of these investigations established permanent plots in forested sites of two contrasting types, one dominated by longleaf pine ("pine site") and the other dominated by hardwoods ('hardwood site'). This study used these plots to examine the influence of forest vegetation on light availability and soil processes. Light was measured as photosynthetically active radiation (and expressed as photon flux density-PFD) with a handheld meter in each plot. Soil was sampled to 5 cm in each plot; texture was measured with the hydrometer method. Identical sampling methods were carried out in a persistent canopy opening to assess light and soil conditions under maximum solar radiation. Mean PFD was ~4× higher in pine stands than in hardwood stands; PFD was 12.8 and 3.5% of full light in the pine and hardwood stands, respectively. All soils were dominated by coarse-textured sands, but silt was significantly higher in pine stand soil and higher still in the canopy opening. Among forest stand plots, sand was negatively related to PFD, whereas clay was positively related to PFD. Across the three sites, silt was positively related to PFD. These relationships are consistent with the importance of solar radiation as one of many drivers of soil weathering.

Plasticity of pine tree roots to podzolization of boreal sandy soils

AimsThe morphological traits of fine roots change with forest succession and soil weathering. However, low tree species diversity in boreal forests may limit plastic responses of the roots to soil nutrient loss. We tested whether pine trees (Pinus sylvestris L.) exhibit root plasticity to change fine root allocation to deeper soil horizons in response to varying degree of podzolization.MethodsWe compared root biomass in two sand dune chronosequences (aluminium (Al)/iron (Fe) oxide-poor coarse-textured sand vs. oxide-rich fine-textured sand) in Estonia.ResultsWe found that faster podzolization in coarse-textured soil promotes migration of Al/Fe oxides and phosphorus (P) into deeper horizons and reshapes the depth distribution of fine root biomass. A decrease in P availability in the coarse-textured soil profile increases fine root biomass and length in both the organic and mineral horizons. In the fine-textured old soil, fine root distribution increases in the mineral soil (especially, spodic horizon) rich in oxide-bonded P.ConclusionPine roots exhibit two forms of plasticity in low-diversity boreal forests – changing root morphological traits and changing depth distribution of root biomass, depending on the abundance of Al and Fe oxides and the depth distribution and dominant form of P.

Unsaturated flow effects on solute transport in porous media

A major contaminant transport process in soils is hydrodynamic dispersion by affecting the spreading and arrival of surface-applied pollutants at underlying groundwater reservoirs. When a soil is unsaturated, hydrodynamic dispersion is very much affected by soil water saturation. Centimeter- and decimeter-scale column experiments were carried out to explore the effects of fluid saturation and particle size on the unsaturated solute dispersivity. Measured in-situ breakthrough curves were analyzed in terms of both classical advection–dispersion and dual-porosity (mobile-immobile) type transport equations. A clear non-monotonic relationship was found between the dispersivity and soil water saturation. The extent of non-monotonicity was more pronounced for a relatively coarse-textured sand compared to a finer sand. This finding has been reported rarely before; it explains some of the inconsistencies of saturation-dispersivity relationships in the literature.

Effect of biochar addition on hydraulic functions of two textural soils

Land degradation reduces soil productivity and exacerbates the problem of food security. Thus, there is an increasing need to look for sustainable farming practices aimed to water and soil conservation. In this regards, conditioning the soil with biochar has been identified as a possible means on improving water conservation and soil biochemical, physical, i.e. mechanical and hydraulic characteristics. Many studies demonstrate these effects of biochar. However, the extended number of variables influencing its impact require further measurements. The objective of this study is to determine the effect of wood-based biochar on two different textured soils and to evaluate their influence on some hydrological properties: water retention, shrinkage behavior and the effect of wetting and drying periods on the hydraulic conductivity. Test samples were prepared by adding 2.5 and 5% (by dry mass) of pyrolyzed mango-wood biochar to a sand and a sandy loam. Soil water retention and soil shrinkage curves were measured. Additionally, extra core samples were exposed to four intense cycles of wetting and drying, by drying the samples at 30 °C for three consecutive days. Biochar amendments increased water retention in the coarse textured sand compared to the unamended soil. Pore size distribution was significantly altered in the sandy substrate, reducing the fraction of wide coarse pores and increasing meso porosity. Repeated wetting and drying cycles enhanced the structural stability of the pore system increasing the saturated hydraulic conductivity. Soil rigidity, especially in the sandy mixtures, was enhanced by the addition of biochar, forming an internal pore structure able to resist better hydraulic deformation due to drying. These results confirm the suitability of biochar to overcome extreme hydrological conditions.

Edaphic properties enable facilitative and competitive interactions resulting in fairy circle formation

Millions of generally regularly spaced, roughly circular barren patches called fairy circles occur in a narrow band ca 100 km inland of the south‐west African coast. These generally have conspicuously taller peripheral grasses in a shorter grass matrix. The origins of these fairy circles are controversial, but one possibility is that they are self‐organizing emergent vegetation patterns that are the consequence of interplay between positive (facilitative) and negative (competitive) interactions between grasses. We hypothesized that the coarse textured sand on which fairy circles occur creates a hydraulically and nutritionally connected landscape, in which neighbouring fairy circles competitively influence each other over several metres, while providing opportunity for focusing of resources around the peripheral grasses. To test our hypotheses we conducted three main groups of analyses: 1) we measured grass biomass to assess facilitative and competitive effects of the component grasses; 2) across a region with fairy circles we measured the size and density of fairy circles and correlated that with water infiltration rates into soil; 3) we measured the capacity of soil to conduct water pulses and 15N tracers. We found evidence of facilitative interactions in the periphery of the fairy circles and competitive suppression of the matrix grass proximal to the periphery. Across the region, fairy circle size was positively correlated with soil infiltration rates and negatively with precipitation. This suggests that fairy circles emerge in soils with high capacity for water flux that enables landscape hydraulic connectivity. Water‐ and 15N‐pulse experiments showed that edaphic resources were highly mobile, moving up to 7.5 m over a period of 1–3 weeks. We concluded that the evidence is consistent with an emergent vegetation pattern explanation for the origins of fairy circles and that the circles are more closely associated with a highly connective edaphic environment, rather than with particular biota.

Effect of soil texture and wheat plants on N2O fluxes: A lysimeter study

Agricultural soils are a major source of nitrous oxide (N2O) emissions and an understanding of factors regulating such emissions across contrasting soil types is critical for improved estimation through modelling and mitigation of N2O. In this study we investigated the role of soil texture and its interaction with plants in regulating the N2O fluxes in agricultural systems. A measurement system that combined weighing lysimeters with automated chambers was used to directly compare continuously measured surface N2O fluxes, leaching losses of water and nitrogen and evapotranspiration in three contrasting soils types of the Riverine Plain, NSW, Australia. The soils comprised a deep sand, a loam and a clay loam with and without the presence of wheat plants. All soils were under the same fertilizer management and irrigation was applied according to plant water requirements. In fallow soils, texture significantly affected N2O emissions in the order clay loam>loam>sand. However, when planted, the difference in N2O emissions among the three soils types became less pronounced. Nitrous oxide emissions were 6.2 and 2.4 times higher from fallow clay loam and loam cores, respectively, compared with cores planted with wheat. This is considered to be due to plant uptake of water and nitrogen which resulted in reduced amounts of soil water and available nitrogen, and therefore less favourable soil conditions for denitrification. The effect of plants on N2O emissions was not apparent in the coarse textured sandy soil probably because of aerobic soil conditions, likely caused by low water holding capacity and rapid drainage irrespective of plant presence resulting in reduced denitrification activity. More than 90% of N2O emissions were derived from denitrification in the fine-textured clay loam—determined for a two week period using K15NO3 fertilizer. The proportion of N2O that was not derived from K15NO3 was higher in the coarse-textured sand and loam, which may have been derived from soil N through nitrification or denitrification of mineralized N. Water filled pore space was a poorer predictor of N2O emissions compared with volumetric water content because of variable bulk density among soil types. The data may better inform the calibration of greenhouse gas prediction models as soil texture is one of the primary factors that explain spatial variation in N2O emissions by regulating soil oxygen. Defining the significance of N2O emissions between planted and fallow soils may enable improved yield scaled N2O emission assessment, water and nitrogen scheduling in the pre-watering phase during early crop establishment and within rotations of irrigated arable cropping systems.

Characterizing water fingering phenomena in soils using magnetic resonance imaging and multifractal theory

Abstract. The study of water movement in soils is of fundamental importance in hydrologic science. It is generally accepted that in most soils, water and solutes flow through unsaturated zones via preferential paths or fingers. This paper combines magnetic resonance imaging (MRI) with both fractal and multifractal theory to characterize preferential flow in three dimensions. A cubic double-layer column filled with fine and coarse textured sand was placed into a 500 gauss MRI system. Water infiltration through the column (0.15×0.15×0.15 m3) was recorded in steady state conditions. Twelve sections with a voxel volume of 0.1×0.1×10 mm3 each were obtained and characterized using fractal and multifractal theory. The MRI system provided a detailed description of the preferential flow under steady state conditions and was also useful in understanding the dynamics of the formation of the fingers. The f(α) multifractal spectrum was very sensitive to the variation encountered at each horizontally-oriented slice of the column and provided a suitable characterization of the dynamics of the process identifying four spatial domains. In conclusion, MRI and fractal and multifractal analysis were able to characterize and describe the preferential flow process in soils. Used together, the two methods provide a good alternative to study flow transport phenomena in soils and in porous media.

Harvest treatment, scarification and competing vegetation affect jack pine establishment on three soil types of the boreal mixed wood of northwestern Quebec

A split–split-plot sowing experiment was undertaken on the effects of seedbed and competing vegetation on jack pine ( Pinus banksiana Lamb.) establishment in the boreal mixed wood of northwestern Quebec. Between 3 and 33% of sown seeds germinated and survived as seedlings after two growing seasons. Negligible jack pine seeds or seedlings came from residual seed trees. Scarification had a lesser effect on pine seed germination on clay soil than on till or sand. This difference could be explained by lower soil surface temperatures. Vegetation control and absence of forest cover had a strong positive effect on seedling survival. Nothing indicates that jack pine regeneration would be more difficult on clay than on more typical coarse-textured sands. However, competing vegetation, mainly aspen ( Populus tremuloides Michx.), on sites with clay soils could be a critical factor affecting jack pine seedling mortality because of its abundance and persistence through time. Jack pine regeneration after cutting is less abundant than after fire, probably because of the delay between the opening of the stand and seed dispersal.

Dryland mediterranean farming systems in Australia

The mediterranean region of Australia extends from Geraldton in Western Australia across southern Australia into western and northern Victoria. This region experiences hot, dry summers and cool, wet winters, with 300-600 mm annual rainfall. In the dryland farming zone, the cereal-livestock farming system dominates and produces 30-35% of Australia's total agricultural production. The major soils in the region are deep, coarse-textured sands and sandy loams, duplex soils with coarse-textured sands over clay (generally low in nutrients and organic matter), and fine-textured red-brown earths of low hydraulic conductivity. Major soil problems in the region include sodicity, salinity, soil structural degradation, nutrient deficiencies, boron toxicity, acidity, waterlogging, inadequate nitrogen nutrition, water-repellence, and root diseases. These problems have been exacerbated by excessive clearing of trees, increased frequency of cropping, reduced area sown to pastures, declining pasture production, and a decline in nutrient levels. With improved soil management there is potential for increased productivity from dryland farming areas of the region and improved ecological sustainability.

Self‐Sealing of Earthen Liquid Manure Storage Ponds: I. A Case Study

AbstractA monitoring system was established on an unlined, earthen storage pond near Kitchener, ON prior to the addition of liquid manure from a 4500‐head beef (Bos taurus) feeding operation. The bottom of the pond, which had a surface area when full of 2 ha, was a coarse textured sand. This material, with some gravel layers, extended below the water table, which was initially at 13.7 m below the ground surface. A platform, at which soil moisture measurement and groundwater sampling tubes were installed, was constructed within the pond. Additional groundwater sampling tubes were installed at several points surrounding the pond. Moisture content of the soil immediately below the pond reached saturation when liquid manure was first added but began to decrease within 2 weeks and reached a steady state at a water potential of about −0.03 MPa within 90 d. The infiltration rate at this time was estimated to be less than 10−8 m s−1, a value considered to indicate that the bottom was effectively sealed. There was a rapid increase in Cl content of the groundwater within 2 weeks of manure addition but the concentration declined to initial values within 12 weeks. There was no evidence of elevated Cl concentrations in groundwater outside the boundaries of the pond. The NO3‐N content of groundwater below the pond decreased to non‐detectable values very shortly after addition of manure but returned to background values within 12 weeks except in the upper portions of the groundwater. A similar depression of NO3‐N was observed at one sampling position within a few meters of the pond but not at more distant points. It was concluded that the NO3‐N depression was due primarily to denitrification in the groundwater as it passed below the pond. It is concluded that, with some limitations, unlined earthen manure ponds are environmentally acceptable, even in sandy material.

Field Evaluation of Sweet Potato Clones for Reaction to Root-Knot and Stubby Root Nematodes in California

Abstract Clones of ‘Jewel’, ‘Eureka’, ‘Pope’, ‘Oklamex’, ‘Garnet’, L5-19, NC-719, and W-152 sweet potato [Ipomoea batatas (L.) Lam] were tested for 1 to 3 seasons in field plots of coarse-textured sand soils. The soils were infested with Meloidogyne incognita (Kofoid & White) Chitwood and Paratrichodorus minor (Colbran) Siddiqui that included 1,3-dichloropropene fumigated and nonfumigated subplots. ‘Jewel’, followed by ‘Pope’, was the highest-yielding copper-skinned type and the least affected by nematode infection; however, it supported large numbers of M. incognita. Yields of ‘Eureka’ were lowest in nonfumigated plots in the presence of P. minor. Significantly greater P. minor population increase occurred on ‘Eureka’ than on other clones. Yield of red-skinned W-152 was greater than ‘Garnet’ on fumigated plots, but W-152 showed no greater yield when nematode-infected. ‘Oklamex’, L5-19, and NC-719 were discontinued after 1 year because of poor yield or quality. M. incognita resistance in all clones prevented damage to the appearance of sweet potatoes, but plant growth and yield were increased significantly in fumigated plots compared with yields from nonfumigated plots. M. incognita reproduced on all lines, especially when soil temperature was high in 1981.

Species distribution and community organization in a Nebraska Sandhills mixed prairie as influenced by plant/soil-water relationships.

Plant and soil water relationships in a typical nebraska Sandhills prairie were examined to 1) explain the observed distribution patterns of several dominant grasses along a topographic gradient, and 2) show how spatial and temporal variations in soil moisture are critical to community organization on a sandy substrate. An experimental transect encompassing the major community and soil types along a steep, west-facing vegetated dune was established. Maximum available water was shown to be significantly higher in the fine textured surface soils of the lowland sites than the coarse textured sands of the dune sites. Seasonal (1979) patterns of available soil moisture of the sampling sites on the transect showed that in the upper elevation dune sands, moisture was available in the entire profile with surface depletions not occurring until mid to late summer. In contrast, moisture in the surface 60-80 cm in the fine textured lowland soils was exhausted by early to mid-summer with the entire profile nearly dry by late summer. Deep-rooted, C4 species, Andropogon hallii and Calamovilfa longifolia which are common on upper, coarser sandy soils showed significantly greater water stress on fine textured soils than on dune sands. C3, shallowrooted species, Agropyron smithii, Stipa comata, and Koeleria cristata always experienced lower mid-day and predawn leaf water potentials than the C4 species. The C3 species, with the exception of Koeleria are most abundant on finer textured soils that provide substantial moisture during their peak activity in the spring. It appears that the C4 species show more conservative water use patterns than the C3 species as significantly lower leaf conductances in the C4's were measured when soil water was abundant. The C3 species appear to be opportunistic with available water and rapidly deplete surface soil moisture as a result of high transpiration rates. These data suggest that the temporal and spatial distribution of available water along this gradient controls species distribution according to rooting morphology, photosynthetic physiology, and water deficits, incurred by transpirational losses. Competitive interactions between species that utilize soil moisture differently may be an important factor in community organization.

Nitrogen accumulation in kaolin mining wastes in cornwall

Nitrogen accumulation was studied in mica and sand mining wastes of Cornwall after twelve forage legume varieties were established with the use of lime and fertilizers containing phosphorus and potassium. In the finetextured mica waste legume productivity and nitrogen accumulation were similar to those for upland pastures in Cornwall; but legume growth was limited by summer drought on the coarse-textured sand waste. Native perennial legumes well adapted to the British climate were the most productive and showed the highest potential for nitrogen fixation. More than 500 kg N/ha accumulated during the 2-year period whenTrifolium pratense andLotus corniculatus were established on mica waste, and more than 250 kg N/ha was accumulated by these legumes on sand waste.Trifolium pratense andLotus corniculatus were persistent on both the mica and sand waste, andMedicago lupulina showed an unusually high tolerance for competition from invading and sown grass on the sand waste.Trifolium repens andT. hybridum are recommended for waste sites where grazing is a part of management. Nitrogen accumulation on mica waste was consistent with N fixation rates expected from climatic conditions. Nitrogen fixation by free-living bacteria is limited by the low organic matter content of the wastes. The nitrogen fixation potential by legumes on sand wastes has been underestimated because leaching losses were not adequately evaluated. Since nitrogen accumulation rates by earlyTrifolium pratense andT. repens were 70 percent higher than the maximum rate estimated for natural legumesi.e. (Ulex europaeus) on sand waste, the use of forage legumes should reduce reclamation time considerably. re]19760512

The influence of subterranean clover pastures on soil fertility. III. The effect of applied phosphorus and sulphur

The total nitrogen content of the soil was significantly increased at each of four levels of superphosphate applied to a densely sown subterranean clover pasture on a coarse-textured sand at Kojonup, W.A. During the first 4 years of the experiment nitrogen build-up was similar for all four treatments, but over the 11 year term the build-up was significantly slower at the lowest level of superphosphate. The relationship between the age of the pasture and soil nitrogen was linear at the lowest level of fertilizer but curvilinear at all other levels. The relationship between total superphosphate applied and soil nitrogen was curvilinear. There were no differential effects of the fertilizer treatments on either the bulk density or the pH of the soil. At the two lower levels of superphosphate a high percentage of both phosphorus and sulphur was retained in the major plant root zone (0–10 cm) of the soil. At the two higher levels most of the phosphorus was retained but there were heavy losses of sulphur. The results of pot trials with soil taken from the experiment at the end of the 11 year period showed that the different levels of superphosphate had induced large differences in the phosphorus status of the soil but had had much smaller effects on the sulphur status. The possible effect of this loss of sulphur on the accumulation of soil organic matter is discussed.