High soil acidity under native shrub encroachment in the Cobar Pediplain, south-eastern Australia

2018 ◽  
Vol 40 (5) ◽  
pp. 451
Author(s):  
M. Tighe ◽  
N. Reid ◽  
B. R. Wilson ◽  
M. T. McHenry

This study investigated the chemical characteristics of shallow (0–30 cm) soil profiles under shrubs in areas of dense encroachment and compared them with shallow soil profiles under nearby large trees. Consistent patterns of high soil acidity were found under shrubs, as well as lower litter alkalinity, lower relative concentrations of calcium (Ca2+), lower effective cation exchange capacity, and higher aluminium (Al3+) and sodium (Na+) in the soil profile compared with under trees. Soil pH (CaCl2) was strongly correlated with the Ca content of surface litter. These findings suggest that shrubs (which at most sites included the shrub form of tree species) cycle alkalinity differently from large and mature trees, resulting in high acidity in the shallow soil profile acidity, and possible loss of alkalinity via surface movement of material from areas of dense encroachment.

2019 ◽  
Vol 70 (12) ◽  
pp. 1128 ◽  
Author(s):  
B. F. Hackney ◽  
J. Jenkins ◽  
J. Powells ◽  
C. E. Edwards ◽  
S. De Meyer ◽  
...  

Pasture legumes must be adequately and effectively nodulated in order to reach nitrogen-fixation targets. Of 225 pasture paddocks sampled across the Central Tablelands, Central West, Monaro and Riverina regions of New South Wales, 93% had inadequate legume nodulation. Legume content was significantly higher in the mixed faming zone (>50%, Central West and Riverina) than the permanent pasture zone (26%, Central Tablelands; 28% Monaro). Available phosphorus (P) was below critical levels in 40% of paddocks sampled and sulfur (S) in 73% of paddocks; >35% of all paddocks had soil pHCa <5.0. Deficiency of P was more prevalent in the Central Tablelands (63% of paddocks), whereas S deficiency occurred more frequently in the Central West (95% of paddocks). Legume nodule scores were associated with host legume species, soil pH, available P and/or S, and cation exchange capacity, which collectively accounted for 73% of variation. For Trifolium spp., at soil pHCa >5.55, nodulation was predicted to be near adequate (score 3.95, where adequate = 4). At pHCa <5.55, higher available S resulted in a higher nodulation score (2.42) than in paddocks where S was deficient (score 0–1.97). These results suggest that improving the capacity of legumes to supply nitrogen should focus on addressing soil acidity and plant nutrition, specifically P and S.


2015 ◽  
Vol 2 (2) ◽  
pp. 148-158
Author(s):  
Surianto

Spodosol soil of Typic Placorthod sub-group of East Barito District is one of the problem soils with the presence of hardpan layer, low fertility, low water holding capacity, acid reaction and it is not suitable for oil palm cultivation without any properly specific management of land preparation and implemented best agronomic practices. A study was carried out to evaluate the soil characteristic of a big hole (A profile) and no big hole (B profile) system and comparative oil palm productivity among two planting systems. This study was conducted in Spodosol soil at oil palm plantation (coordinate X = 0281843 and Y = 9764116), East Barito District, Central Kalimantan Province on February 2014, by surveying of placic and ortstein depth and observing soil texture and chemical properties of 2 (two) oil palm's soil profiles that have been planted in five years. Big hole system of commercial oil palm field planting on the Spodosol soil area was designed for the specific purpose of minimizing the potential of a negative effect of shallow effective planting depth for oil palms growing due to the hardpan layer (placic and ortstein) presence as deep as 0.25 - 0.50 m. The big hole system is a planting hole type which was vertical-sided with 2.00 m x 1.50 m on top and bottom side and 3.00 m depth meanwhile the 2:1 drain was vertical-sided also with 1.50 m depth and 300 m length. Oil palm production was recorded from the year 2012 up to 2014. Results indicated that the fractions both big hole profile (A profile) and no big hole profile (B profile) were dominated by sands ranged from 60% to 92% and the highest sands content of non-big hole soil profile were found in A and E horizons (92%). Better distribution of sand and clay fractions content in between layers of big hole soil profiles of A profile sample is more uniform compared to the B profile sample. The mechanical holing and material mixing of soil materials of A soil profile among the upper and lower horizons i.e. A, E, B and C horizons before planting that resulted a better distribution of both soil texture (sands and clay) and chemical properties such as acidity value (pH), C-organic, N, C/N ratio, CEC, P-available and Exchangeable Bases. Investigation showed that exchangeable cations (Ca, Mg, K), were very low in soil layers (A profile) and horizons (B profile) investigated. The low exchangeable cations due to highly leached of bases to the lower layers and horizons. Besides, the palm which was planted on the big hole system showed good adaptation and response positively by growing well of tertiary and quaternary roots that the roots were penetrable into deeper rooting zone as much as >1.00 m depth. The roots can grow well and penetrate much deeper in A profile compared to the undisturbed hardpan layer (B profile). The FFB (fresh fruit bunches) production of the non-big hole block was higher than the big hole block for the first three years of production. This might be due to the high variation of monthly rainfall in-between years of observation from 2009 to 2014. Therefore, the hardness of placic and ortstein as unpenetrable agents by roots and water to prevent water loss and retain the water in the rhizosphere especially in the drier weather. In the high rainfall condition, the 2:1 drain to prevent water saturation in the oil palm rhizosphere by moving some water into the drain. Meanwhile, the disturbed soil horizon (big hole area) was drier than un disturbance immediately due to water removal to deeper layers. We concluded that both big hole and 2:1 drain are a suitable technology for Spodosol soil land especially in preparing palms planting to minimize the negative effect of the hardpan layer for oil palm growth.


2009 ◽  
Vol 18 (7) ◽  
pp. 857 ◽  
Author(s):  
Chad T. Hanson ◽  
Malcolm P. North

With growing debate over the impacts of post-fire salvage logging in conifer forests of the western USA, managers need accurate assessments of tree survival when significant proportions of the crown have been scorched. The accuracy of fire severity measurements will be affected if trees that initially appear to be fire-killed prove to be viable after longer observation. Our goal was to quantify the extent to which three common Sierra Nevada conifer species may ‘flush’ (produce new foliage in the year following a fire from scorched portions of the crown) and survive after fire, and to identify tree or burn characteristics associated with survival. We found that, among ponderosa pines (Pinus ponderosa Dougl. ex. Laws) and Jeffrey pines (Pinus jeffreyi Grev. & Balf) with 100% initial crown scorch (no green foliage following the fire), the majority of mature trees flushed, and survived. Red fir (Abies magnifica A. Murr.) with high crown scorch (mean = 90%) also flushed, and most large trees survived. Our results indicate that, if flushing is not taken into account, fire severity assessments will tend to overestimate mortality and post-fire salvage could remove many large trees that appear dead but are not.


2016 ◽  
Vol 51 (9) ◽  
pp. 1349-1358 ◽  
Author(s):  
Diego Silva Siqueira ◽  
José Marques Júnior ◽  
Daniel De Bortoli Teixeira ◽  
Sammy Sidney Rocha Matias ◽  
Livia Arantes Camargo ◽  
...  

Abstract The objective of this work was to evaluate the use of magnetic susceptibility for characterizing the spatial variability of soil attributes and identifying areas with different potentials for sugarcane (Saccharum spp.) production. Samples were collected at 110 points (1 per 7 ha) in the layers of 0.00-0.20 and 0.20-0.40 m, to determine the magnetic susceptibility and physical and chemical attributes of the soil. Fiber content, sucrose polarization (POL), and sugarcane yield were determined in 33 points. The spatial variability model for magnetic susceptibility was 63 and 22% more accurate in delimiting soil potential for sugarcane production than soil physical and chemical attributes at the 0.0-0.2 and 0.2-0.4-m layers, respectively. The spatial variability map for magnetic susceptibility was strongly correlated with clay (0.83 and 0.89, respectively, for the layers) and sand contents (-0.84 and -0.88); moderately correlated with organic matter (-0.25 and -0.35), sum of bases (-0.46 and 0.37), cation exchange capacity (0.22 and 0.47), pH (-0.52 and 0.13), and POL (0.43 and 0.53); and weakly correlated with sugarcane yield (0.26 and 0.23). Magnetic susceptibility can be used to characterize the spatial variability of soil attributes and to identify areas with different potentials for sugarcane production.


2021 ◽  
Vol 70 (4) ◽  
pp. 369-380
Author(s):  
Marianna Ringer ◽  
◽  
Gergely Jakab ◽  
Péter Sipos ◽  
Máté Szabó ◽  
...  

This paper focuses on the vertical distribution and characterisation of pedogenic iron forms in a Gleysol- Histosol transect developed in a marshy area in the Danube-Tisza Interfluve, Hungary. Four soil profiles were investigated along a series of increasing waterlogging and spatial and temporal patterns of hydromorphic pedofeatures (characteristics of pedogenic iron forms) were recorded. Frequent and wide-range redox potential (Eh) changes caused the emergence of many types of redoximorphic iron features, including mottles, plaques and nodules. The forms of these features depended on the micro-environments determined by the vertical position in the soil profile and the presence of plant roots. The greatest iron enrichment occurred in the zone of most intensive and widest-range redox fluctuations. Increasing water saturation resulted the extension of gleyic pattern due to the existence of permanent reduction. Most of the features also showed annual variations during the varying periods of water saturation and aeration.


Author(s):  
Edmundo Rivera ◽  
Fernando Abruña ◽  
José Rodríguez

Cassava (Manihot esculenta Crantz), one of the major sources of carbohydrates throughout the tropics, was found to be very tolerant to high soil acidity in two Ultisols and one Oxisol. About 85% of maximum yields were obtained when Al saturation of the effective cation exchange capacity of the soil was around 60%, but highest yields were attained at about pH 5.3 with no exchangeable Al. Soil acidity factors did not affect the chemical composition of the cassava leaves, except for Mn, which increased with decreasing pH of the Oxisol. Tolerance of cassava to soil acidity was also confirmed by the fact that yields of 12 commercial varieties were not affected by Al saturation levels varying from 0 to 60% in an Ultisol.


1969 ◽  
Vol 69 (3) ◽  
pp. 357-365
Author(s):  
Edmundo Rivera ◽  
José Rodríguez ◽  
Fernando Abruña

The effect of acidity factors of two Ultisols and one Oxisol on yield and foliar composition of tomatoes was determined. Yields were not markedly reduced by acidity in the Ultisols until pH dropped to around 4.6 with 45% Al saturation of the cation exchange capacity (CEC), and no yield was produced at about pH 4.1 and 80% Al saturation. In the Oxisol, tomato yields dropped steadily from 39.7 t/ha, when there was no exchangeable AI, to 17.5 t/ha at the highest level of acidity, pH 4.4 and 43% AI saturation. In all soils, yields were closely correlated with soil pH, exchangeable Al and Ca and Al/Ca.


2020 ◽  
Vol 13 (10) ◽  
pp. 61
Author(s):  
A. T. Martins-Oliveira ◽  
L. E. S. Stefanello ◽  
T. M. Santos ◽  
V. R. Pinto ◽  
C. A. Souza ◽  
...  

The fluvial dynamics corresponds to the natural changes of river channels that can influence the water energy, type and morphology of the gutter, geological structure and soil types. In this context, the type of soil present on the banks of the rivers stands out, which due to their morphological, physical and chemical characteristics, will offer greater or less resistance to marginal erosive processes. Whit this study, we aim to verify the contribution of soil morphological, physical and chemical attributes in the natural dynamics of the right bank of the Paraguay River. The studied area is located in the Pantanal Matogrossense, sub-region of Cáceres, and comprises the right bank of the Paraguay River, in the region of Baia da Campina, approximately 10 km away from the municipality of Cáceres, Mato Grosso, Brazil. We carry out morphological, granulometric and chemical description of the soil. The data were tabulated in a spreadsheet, being subsequently analyzed and discussed. The vegetation occurring in the study area is of the seasonal / cerrado and alluvial forests type, with the presence of low and semi-shrub vegetation. We classified the soil profile in the section studied as Fluvic Tb Endoeutrophic Neosol, presenting medium texture and, in general, high levels of sand and low levels of clay. The values referring to the effective cation exchange capacity (CTC) obtained in this study, were classified from low to very good, a characteristic that allows the existence of low and semi-shrubby vegetation, which contributes to the resistance to erosive processes, even that the soil has a low presenting resistance physical structure.


Clay Minerals ◽  
1986 ◽  
Vol 21 (2) ◽  
pp. 149-157 ◽  
Author(s):  
S. Bouda ◽  
K. P. Isaac

AbstractBiotites from three peaty gleyed podzol soil profiles on ranite bedrock were examined to investigate the oxidation of the octahedral Fe during weathering. Oxidation of these biotites as determined by Mössbauer spectroscopy shows a good correlation with the in situ measured soil Eh values of the sampled horizons. In every soil profile the highest Eh measured is in the A horizon and the lowest in the C horizon. Similarly, biotites from the A horizons are the most oxidized compared with those from the lower horizons. In most of the samples the oxidation is accompanied by loss of K+ from the lattice, as demonstrated by a moderate degree of vermiculitization.


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