scholarly journals Model of the pression transfer apply on an alfisol from Tabuleiros Costeiros

2020 ◽  
Vol 13 (7) ◽  
pp. 1
Author(s):  
D. S. Santana ◽  
E. P. Pacheco ◽  
W. G. Vale ◽  
M. V. S. Chaves
Keyword(s):  
Negative Correlation ◽  
Plant Nutrition ◽  
Applied Pressure ◽  
Soil Surface ◽  
Agricultural Machinery ◽  
Load Bearing Capacity ◽  
Damping Effect ◽  
Ap Horizon ◽  
Subsurface Layers ◽  
Effective Depth

The cohesive subsurface horizon of the Arfisol of Tabuleiros Costeiros, reduces the effective depth of these soils, compromising the yield and longevity of the perennial crops. This pedogenetic limitation can be potentiated when the pressure applied on the surface of the Ap horizon, during the traffic of agricultural machinery is transmitted to deeper horizons, AB or Bt, at higher levels the load-bearing capacity of these layers. The objective of this research was to mathematically model the transfer of pressures applied to the surface of the Ap horizon of an Alfisol for subsurface layers, relating the pressure applied to the soil profile moisture. With the experiment developed in the Laboratory of Soils and Plant Nutrition of Embrapa Tabuleiros Costeiros, it was concluded that moisture has a damping effect on the pressure transmitted from upper layers to subsurface. The pressure transmitted to the subsurface shows an exponential function with negative correlation as a function of depth, independent of the applied pressure on the surface. The increase in the contact area for the application of pressures on the soil surface, attenuates the transmission of pressure to lower layers when compared to the same pressure applied in smaller areas

Interactions of surface drying and subsurface nutrients affecting plant growth on acidic soil profiles from an old pasture

1986 ◽  
Vol 26 (6) ◽  
pp. 681 ◽  
Author(s):  
A Pinkerton ◽  
JR Simpson
Keyword(s):  
Subsurface Layer ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Soil Profiles ◽  
Poor Growth ◽  
South Wales ◽  
Reconstituted Soil ◽  
Subsurface Layers ◽  
Surface Drying

Previous studies on soils from old pastures in southern New South Wales have demonstrated that nutrients have accumulated at the soil surface, but that the 40-100-mm depth layer in many profiles has become strongly acidic (e.g. pH 4.7), and high in extractable aluminium. Poor growth of subterranean clover has occurred on such soils during dry periods and may be associated with poor root growth in the acidic, nutrient-poor subsurface layers. Possible nutritional causes of these observations were investigated using reconstituted soil profiles. The root and shoot growth of subterranean clover, wheat, oats and lucerne were compared in unamended profiles and in profiles amended by applying nutrients or calcium carbonate (lime) to correct the more obvious deficiencies of the subsurface layers. Subterranean clover grew well as long as the surface soil remained moist, so that plants could utilise the nutrients potentially available within it. When the surface (0-40 mm) was allowed to dry but the subsurface layers remained moist, growth was poor unless phosphate was applied to the moist layer. Subsurface application of lime alone was ineffective. Nitrogen application increased clover growth in the presence of added phosphate or surface moisture, but nitrogen alone did little to alleviate the effects of surface drought. Wheat, and to a lesser extent oats, responded to subsurface lime when the surface was moist, and both responded to subsurface phosphate when the surface was dry. Lucerne responded to subsurface phosphate similarly to subterranean clover but the response was more than doubled in the presence of additional borate and lime. Lime without borate was not effective. When the surface was maintained moist, liming both the surface (0-40 mm) and subsurface layers improved the response over liming the subsurface layer only. The results suggest that declining fertility and productivity in old pastures developed on acid soils may not be rectified by liming alone, but that cultivation, ripping or drilling of phosphate, and in some cases addition of borate, may be required to improve the penetration of nutrients, particularly phosphorus, to greater depth.

The role of N transformations in the formation of acidic subsurface layers in stock urine patches

Soil Research ◽  
2004 ◽  
Vol 42 (2) ◽  
pp. 221 ◽  
Author(s):  
J. R. Condon ◽  
A. S. Black ◽  
M. K. Conyers
Keyword(s):  
Soil Surface ◽  
Urea Hydrolysis ◽  
Balance Model ◽  
Urea Solution ◽  
Nitrogen Transformations ◽  
N Transformations ◽  
Soil Layers ◽  
Subsurface Layers ◽  
Dominant Process

This study examines the role of nitrogen transformations in the acidification of soil under stock urine patches, specifically the formation of acidic subsurface layers. These are horizontal planes of acidity several centimetres below the soil surface. Glasshouse studies were conducted to relate nitrogen transformations to measured pH changes in soil treated with urine or urea solution (simulated urine). Acidic subsurface layers formed in both urine- and simulated urine-treated soil. With the development of a H+ balance model, the contribution of nitrogen transformations to changes in the H+ concentrations in simulated urine patches was determined.During the first 9 days following treatment, urea hydrolysis and NH3 volatilisation dominated changes in H+ concentration. After that, net immobilisation contributed to H+ changes; however, nitrification was the dominant process occurring. Downward movement of NH4+ originating from urea hydrolysis allowed more nitrification to occur in lower soil layers. The net result of these processes was net acidification of the 4–6, 6–8, and 8–10 cm layers by approximately 0.7, 0.6, and 0.3 pH units, respectively. Thus nitrogen transformations were responsible for the formation of acidic subsurface layers in simulated stock urine patches within 6 weeks of application.

scholarly journals Spatial variability of soil hydraulic properties on a steep slope in the loess plateau of China

2008 ◽  
Vol 65 (3) ◽  
pp. 268-276 ◽  
Author(s):  
Wei Hu ◽  
Ming An Shao ◽  
Quan Jiu Wang ◽  
Jun Fan ◽  
Klaus Reichardt
Keyword(s):  
Spatial Structure ◽  
Spatial Variability ◽  
Loess Plateau ◽  
Spatial Dependence ◽  
Hydraulic Properties ◽  
Applied Pressure ◽  
Soil Surface ◽  
Pressure Head ◽  
Steep Slope ◽  
The Loess Plateau

The understanding of the structure of the spatial variability of soil surface hydraulic properties on steep slopes is important for modeling infiltration and runoff processes. The objective of this study was to investigate the spatial variability of these properties on a steep slope of the Loess Plateau in northwest China. A 9600 m² area was systematically sampled in a grid of 106 points spaced 10 m x 10 m. Hydraulic properties were determined with a disc infiltrometer under multiple pressure heads (-15, -9, -6, -3, 0 cm) at each sample point. Classical and geo-statistical methods were used for data analysis. The results indicated that the variation of Gardner's a and hydraulic conductivities at all applied pressure heads was moderate and the heterogeneity for hydraulic conductivities increased as the applied pressure head increased. Along the slope, hydraulic conductivities generally decreased downwards, while the Gardner's a fluctuated slightly. The Gardner's a of the shaded aspect of the slope was greater than that of the sunny aspect. The hydraulic conductivities of the shaded aspect were greater at higher pressure heads as compared to the sunny aspect, but lower than those of the sunny aspect at lower pressure heads. Correlation analysis showed a negative correlation between hydraulic conductivity and soil organic matter and clay (<0.01 mm) contents. Hydraulic conductivities at pressure heads of -3, -6, -9, -15 cm varied across the slope and their spatial dependence increased as the pressure head declined. The heterogeneity and spatial dependence of hydraulic properties were larger for the areas with shaded aspect as compared to the sunny aspect, however, as pressure decreased they showed a progressively increasing spatial structure, and their spatial structure behaved increasingly similar in both the shaded and sunny aspects.

EFFECTS OF TILLAGE AND AMENDMENTS ON YIELDS AND SELECTED SOIL PROPERTIES OF TWO SOLONETZIC SOILS

1986 ◽  
Vol 66 (3) ◽  
pp. 455-470 ◽  
Author(s):  
G. R. WEBSTER ◽  
M. NYBORG
Keyword(s):  
Soil Properties ◽  
Negative Correlation ◽  
Soil Aggregates ◽  
Sodium Adsorption Ratio ◽  
The Other ◽  
Spring Season ◽  
Water Stable Aggregates ◽  
Mean Weight Diameter ◽  
Ap Horizon ◽  
Deep Plowing

Five tillage treatments in combination with two amendments and two crops were established on two Solonetzic sites and continued for 6 yr. Simulated deep plowing significantly [Formula: see text] reduced SAR values for the 0- to 15-cm depth (Ap horizon) to favorable levels of 3 to 5 at Site 1 but at Site 2 they remained in the 12 to 15 range. For the other four tillage treatments (simulated normal tillage, simulated shallow plowing, chiselling and chiselling plus simulated shallow plowing), the nonamended subplots at both sites had undesirably high SAR values in the 16 to 23 range. There was a trend for gypsum to lower SAR values of the 0- to 15-cm depth in most cases to the 10 to 15 range and was usually more effective than lime. For the 15- to 30-cm depth (Bnt) there was a trend for gypsum, and to a lesser degree lime, to lower SAR values from the 15 to 38 range to the 14 to 28 range 4 yr after the amendments had been applied. There was a negative correlation [Formula: see text] between SAR and soil aggregates < 6 mm in diameter and a positive correlation [Formula: see text] between SAR and soil clods in the 25- to 76-mm size. There was also a negative correlation [Formula: see text] between SAR and mean weight-diameter (water stable aggregates). Simulated deep plowing at Site 1 produced higher yields of alfalfa and barley than the other four tillage treatments [Formula: see text]. Alfalfa yields were considerably lower at Site 2 than at Site 1, but again simulated deep plowing produced the highest of all the tillage treatments. However, due to cloddiness of the seedbed at Site 2 in the simulated deep-plowed plots, germination of barley was poor for years when the spring season was dry. The chiselling treatment produced the highest yields of barley at this site. Gypsum, and to a lesser extent lime, lowered the SAR of the seedbed and improved aggregation but after 4 yr the 18 t ha−1 rate had only started to ameliorate the Bnt at both sites. Key words: Solonetzic soils, sodium adsorption ratio, soil aggregation, soil cloddiness

Simulated sheep urine causes the formation of acidic subsurface layers in soil under field conditions

Soil Research ◽  
2020 ◽  
Vol 58 (7) ◽  
pp. 662
Author(s):  
Jason R. Condon ◽  
A. Scott Black ◽  
Mark K. Conyers
Keyword(s):  
Subsurface Layer ◽  
Soil Surface ◽  
Bare Soil ◽  
Internal Diameter ◽  
N Transformations ◽  
Ammonium N ◽  
Subsurface Layers ◽  
Sampling Times ◽  
Sheep Urine ◽  
Treatment Application

This study aimed to ascertain whether application of sheep urine led to the development of acidic subsurface layers of a pasture soil. Deionised water or simulated urine solution delivering urea-nitrogen (N) at 44.8 g m–2 and potassium at 25 g m–2 was applied to soil in either winter or spring. Treatments were applied to the soil surface within 10.3 cm internal diameter PVC tubes inserted 20 cm into the soil either under ryegrass or kept bare. Main sampling times corresponded to the completion of various soil N transformations as determined by periodic sampling. Main samplings involved the collection of above ground plant material and soil sampling in 2 cm depth increments in 0–10 cm and 5 cm intervals in 10–20 cm depths. Following treatment application, urea and ammonium-N moved to a depth no greater than 20 cm but the extent of movement was greater in winter than spring due to the influence of initial soil moisture. Following urea hydrolysis, soil pH increased in the 0–15 cm depth. Subsequent nitrification significantly acidified soil under pasture by 0.8–1.0 pH units in the 2–8 and 2–6 cm depths in winter and spring respectively. This created a net acidic subsurface layer of 0.2–0.4 pH units compared with soil at the beginning of the experiment. Subsurface acidification was 0.5–0.7 pH units greater in bare soil compared with the presence of pasture. Transformations of N resulting from application of simulated urine solution formed acidic subsurface layers in the field regardless of the season of application.

The extent, significance and amelioration of subsurface acidity in southern New South Wales, Australia

Soil Research ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 1
Author(s):  
Jason Condon ◽  
Helen Burns ◽  
Guangdi Li
Keyword(s):  
Agricultural Land ◽  
Subsurface Layer ◽  
Organic Amendments ◽  
Soil Surface ◽  
Cost Effective ◽  
Acidic Soil ◽  
Application Rates ◽  
South Wales ◽  
Subsurface Layers ◽  
Lime Addition

Soil pH is seldom uniform with depth, rather it is stratified in layers. The soil surface (0–0.02 m) commonly exhibits relatively high pH and overlies a layer of acidic soil of 0.05–0.15 m deep, termed an acidic subsurface layer. Commercial and research sampling methods that rely on depth increments of 0.1 m either fail to detect or under report the presence or magnitude of pH stratification. The occurrence of pH stratification and the presence of acidic subsurface layers may cause the extent of acidity in NSW agricultural land to be underestimated. Though the cause of pH stratification in agricultural systems is well understood, the effect on agricultural production is poorly quantified due in part to inadequate sampling depth intervals resulting in poor identification of acidic subsurface layers. Although liming remains the best method to manage acidic soil, current practices of low pH targets (pHCa 5), inadequate application rates and no or ineffective incorporation have resulted in the continued formation of acidic subsurface layers. Regular monitoring in smaller depth increments (0.05 m), higher pH targets (pHCa &gt; 5.5) and calculation of lime rate requirements that account for application method are required to slow or halt soil degradation by subsurface acidification. If higher pH is not maintained in the topsoil, the acidification of subsurface soils will extend further into the profile and require more expensive operations that mechanically place amendments deep in the soil. Although the use of organic amendments has shown promise to enhance soil acidity amelioration with depth, the longevity of their effect is questionable. Consequently, proactive, preventative management of topsoil pH with lime addition remains the most cost-effective solution for growers.

scholarly journals Chlortoluron behavior in five different soil types

2011 ◽  
Vol 51 (No, 7) ◽  
pp. 304-309 ◽  
Author(s):  
M. Kočárek ◽  
R. Kodešová ◽  
J. Kozák ◽  
O. Drábek ◽  
O. Vacek
Keyword(s):  
Soil Profile ◽  
Preferential Flow ◽  
Soil Surface ◽  
Climatic Conditions ◽  
Soil Types ◽  
Flow Profile ◽  
Soil Database ◽  
Herbicide Transport ◽  
Subsurface Layers ◽  
High Concentrations

Chlortoluron transport was studied in five different soil types and under varying climatic conditions. The chlortoluron mobility in the monitored soils increases as follows: Albic Luvisol = Haplic Luvisol &lt; Haplic Cambisol &lt; Haplic Stagnosol &lt; Greyic Phaozem. Significantly high concentrations in the top layer of Haplic Stagnosol were observed due to the high presence of coarse gravel (30&ndash;40%) and flow profile reduction up to 60%. The content of remaining chlortoluron in the soil profile corresponds to the herbicide mobility. The percentages of remaining chlortoluron were 46.1% in Albic Luvisol, 54.6% in Haplic Luvisol, 65.0% in Haplic Cambisol, 69.6% in Haplic Stagnosol and 102.9% in Greyic Phaozem. The highest herbicide degradations were at the locations with lower observed mobility and herbicide present mainly in the top layer. Occurrence of the remaining chlortoluron percentage in Greyic Phaozem higher than 100% was caused mainly by the herbicide transport through the preferential paths and restricted degradation in subsurface layers. Variability of chlortoluron distributions in the soil profiles observed at the three positions of the same location occurred due to the heterogeneity of the soil profile and an uneven distribution of chlortoluron on the soil surface. The BPS mathematical model (Koz&aacute;k and Vacek 1996) connected with the soil database (Koz&aacute;k et al. 1996) was used to simulate chlortoluron transport. The simulated chlortoluron concentrations follow approximately the measured data except for Greyic Phaozem, where a preferential flow highly influenced solution transport. The BPS model with the soil database can be used for estimation of the chlortoluron transport.

scholarly journals Effects of pressure on the root systems of Norway spruce plants (Picea abies[L.] Karst.)

2012 ◽  
Vol 51 (No. 6) ◽  
pp. 268-275 ◽  
Author(s):  
R. Gebauer ◽  
M. Martinková
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Applied Pressure ◽  
Growth Dynamics ◽  
Soil Surface ◽  
Root Systems ◽  
Area Index ◽  
Root Area ◽  
Permanent Load ◽  
General Response

Roots are stressed quire often under natural conditions, e.g. when considering sloping terrain, layers of fluvial deposits, huge layers of melting snow, load of heavy forest machinery during logging and hauling operations, recreational activities of people, high density of deer or cattle, etc. We focused our experiments on Norway spruce (Picea abies[L.] Karst.) seedlings grown in containers with glass walls under the permanent load of 5.1 kPa during the whole growing season. The applied pressure affected roots both directly and indirectly due to the occurrence of hypoxia. Root growth ceased under such conditions. Growth dynamics and capability to occupy available soil also changed. For example, the total root area of experimental plants decreased to 52% but the root area index (RAI) was higher by 33% when compared to the control. It indicates that the pressure applied to the soil surface caused the development of only smaller root systems but more compacted into smaller volumes of soil. Mean longitudinal growth of stressed roots decreased by about 50% when compared to the control. Growth of experimental roots was also delayed, which is a typical general response to stress. However, a tendency to create dense and small root systems is in contradiction with the typical strategy of tree root systems.

scholarly journals Effect of ploughing-down of grapevine chips on soil structure when using special agricultural machinery

2012 ◽  
Vol 60 (6) ◽  
pp. 9-14 ◽  
Author(s):  
Barbora Badalíková ◽  
Jan Červinka
Keyword(s):  
Soil Structure ◽  
Soil Surface ◽  
The Other ◽  
Wood Chips ◽  
Agricultural Machinery ◽  
Waste Wood ◽  
The University ◽  
University Training ◽  
Positive Effect ◽  
Agricultural Machines

Within the period of 2008–2011, changes in soil structure were studied in two selected localities: one of them was situated in vineyards of the University Training Farm of Mendel University in Žabčice near Brno, the other was in vineyards situated in the cadastre of wine-growing municipality Velké Bílovice. Established were altogether three variants of experiments with application of crushed grapevine wood (chips): Variant 1 – control; Variant 2 – crushed grapevine wood ploughed down to the depth of 0.10 m; Variant 3 – crushed grapevine wood + grass spread on the soil surface as a mulch. Grapevine canes were crushed to chips using a special agricultural machinery while the soil in inter-rows was processed using conventional tilling machines. The obtained results showed that the best coefficient of structurality (expressing the degree of destruction of soil structure) was recorded in Variants 2 in both localities. Considering values of this coefficient it could be concluded that just this variant showed a positive effect on soil structure. This variant reduced the compaction of soil caused by the movement of agricultural machines in vineyard inter-rows Crushed grapevine waste wood can therefore compensate losses of organic matter in soil. Better values of structurality coefficient were recorded in the locality Žabčice.

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