Water repellence in sandy soils of South-Western Australia. II. Some chemical characteristics of the hydrophobic skins

Soil Research ◽  
1972 ◽  
Vol 10 (1) ◽  
pp. 35 ◽  
Author(s):  
FJ Roberts ◽  
BA Carbon

The hydrophobic organic skins on sand grains were resistant to removal by solvents such as cold water, concentrated acid, diethyl ether, ethanol, benzene, chloroform, and acetone. Prolonged treatment with hot diethyl ether, ethanol, and benzene removed part of the coating. Treatment with dilute solutions of alkali removed the skin as suspended particles. Compounds within the very stable humic fraction of the soil organic matter appeared to be mainly responsible for water repellence in soils. Deposits of fresh organic materials could also produce water repellent properties.

1981 ◽  
Vol 32 (4) ◽  
pp. 609 ◽  
Author(s):  
DA McGhie ◽  
AM Posner

Large differences in the water repellence were conferred on fired sand by adding the ground tops of a range of plant species. Contact angles of 75� to 90� were caused at 2% of most pasture and native species and at 5 % many gave contact angles > 95� The cereal crops gave contact angles of about 60� (2%) and 83�(5 %) and were more wettable than pasture and native species. The addition of ground Geraldton subterranean clover (Trifolium subteraneum cv. Geraldton) or brown mallet (Eucalyptus astrigens (Maiden)) to water-repellent sands increased the water repellence. Addition of clover to a water-repellent mallet-hill soil increased the water infiltration rate while the mallet did not change the slow rate. Wheat (Triticum aestivm), when added to water-repellent soils, always reduced the water repellence. Attention is drawn to the importance of the relative wettability of the soil and added organic matter, and therefore the type of plant cover. Soils sampled from beneath wheat/clover rotations of various lengths showed that water repellence increased in the pasture phase and was reduced during the cropping phase. The importance of the type, as well as the amount, of organic matter in the rotations is demonstrated.


Soil Research ◽  
2015 ◽  
Vol 53 (7) ◽  
pp. 786 ◽  
Author(s):  
M. M. Roper ◽  
S. L. Davies ◽  
P. S. Blackwell ◽  
D. J. M. Hall ◽  
D. M. Bakker ◽  
...  

Water-repellent (‘non-wetting’) soils are a major constraint to agricultural production in southern and south-west Australia, affecting >10 Mha of arable sandy soils. The major symptom is dry patches of surface soil, even after substantial rainfall, directly affecting agricultural production through uneven crop and pasture germination, and reduced nutrient availability. In addition, staggered weed germination impedes effective weed control, and delayed crop and pasture germination increases the risk of wind erosion. Water repellency is caused by waxy organic compounds derived from the breakdown of organic matter mostly of plant origin. It is more prevalent in soils with a sandy surface texture; their low particle surface area : volume ratio means that a smaller amount of waxy organic compounds can effectively cover a greater proportion of the particle surface area than in a fine-textured soil. Water repellency commonly occurs in sandy duplex soils (Sodosols and Chromosols) and deep sandy soils (Tenosols) but can also occur in Calcarosols, Kurosols and Podosols that have a sandy surface texture. Severity of water repellency has intensified in some areas with the adoption of no-till farming, which leads to the accumulation of soil organic matter (and hence waxy compounds) at the soil surface. Growers have also noticed worsening repellency after ‘dry’ or early sowing when break-of-season rains have been unreliable. Management strategies for water repellency fall into three categories: (i) amelioration, the properties of surface soils are changed; (ii) mitigation, water repellency is managed to allow crop and pasture production; (iii) avoidance, severely affected or poorly producing areas are removed from annual production and sown to perennial forage. Amelioration techniques include claying, deep cultivation with tools such as rotary spaders, or one-off soil inversion with mouldboard ploughs. These techniques can be expensive, but produce substantial, long-lasting benefits. However, they carry significant environmental risks if not adopted correctly. Mitigation strategies include furrow-seeding, application of wetting agents (surfactants), no-till with stubble retention, on-row seeding, and stimulating natural microbial degradation of waxy compounds. These are much cheaper than amelioration strategies, but have smaller and sometimes inconsistent impacts on crop production. For any given farm, economic analysis suggests that small patches of water repellency might best be ameliorated, but large areas should be treated initially with mitigation strategies. Further research is required to determine the long-term impacts of cultivation treatments, seeding systems and chemical and biological amendments on the expression and management of water repellency in an agricultural context.


Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 797 ◽  
Author(s):  
M Ma'shum ◽  
JM Oades ◽  
ME Tate

Water-repellency in sandy soils is determined by the amount of hydrophobic organic matter coating the sand particles and the specific surface area of the sands. The hydrophobic state can be simulated by coating hydrophilic sand with cetyl alcohol. Admixture of finely particulate materials with either naturally occurring water-repellent sands or the model cetyl alcohol-coated sand markedly reduced the water-repellency. Dispersible sodic clays were more effective than calcium saturated clays in reducing water-repellency, suggesting that the addition of dispersible, fine-grained illites and kaolinites couid play an important role in the rapid control of water-repellent soils in field situations.


2020 ◽  
Vol 156 ◽  
pp. 16087-16094
Author(s):  
Jeancy Ntuka Luta ◽  
Alasca Ekuya Lombolu ◽  
Paul Mafuka Mbe-Mpie

Objectives: In order to improve the physico-chemical characteristics of sandy soils in Kinshasa, the biochar, leaves of Ricinus communis, NPK fertilizer and their combinations were used. Okra was grown as the test plant during two growing seasons. Methodology and Results: The experimentation was carried in polyethylene bags with seven treatments and 4 replications. Each sand bag filled with sandy soil was amended with 300gms 900gms and 15gms respectively for biochar, Ricinus leaves and NPK which were only applied during the first cropping season. The soil was analysed before the trial and after each harvest. Biochar combined with mineral fertilizer and leaves of Ricinus leaves improved both Okra yield and the physico-chemical characteristics the soil. The highest yield in the first growing season was 6 times more than that of the control. In the second season, only the biochar associated with mineral fertilizer had given a satisfying yield. Conclusion and application of results. For an integrated management of fertility of the sandy soil of Kinshasa, use of mineral fertilizers should be accompanied of rational application of organic matter. Biochar appears to be very useful to solve problems of water retention and nutrients brought to this type of soil. The price of fertilizer and biochar are not any time affordable by the smallholders; therefore the use of ricinus leaves, which are very accessible and easy to collect free of charge, appears to be economically profitable. By the way, yields obtained compared with these from fertilizer and biochar are the same. Keywords: Sandy soil, biochar, pH, cation exchange capacity, organic matter, phosphorus. RESUME Objectifs : Dans la recherche de l’amélioration des caractéristiques physico-chimiques de sol sableux de Kinshasa, le biochar, les feuilles de Ricinus communis, le NPK et leurs combinaisons ont été utilisé. Le Gombo a servi de plante texte pendant deux saisons culturales. Méthodologie et résultats : L’expérimentation comprenait quatre répétitions et sept traitements. Les poquets amendés par 300gr, 900gr, et 15gr respectivement pour biochar, feuilles de ricin et NPK (17-17-17), étaient appliqués seulement à la 1ère saison culturale. Le sol était analysé avant l’expérimentation et après chaque récolte. Le biochar combiné à l’engrais minéral et aux feuilles de ricin a amélioré à la fois le rendement de Ntuka et al., J. Appl. Biosci. 2020 The effects of physico-chemical characteristics of sandy soils amended with biochar, Ricinus and NPK (17-17-17) on the Okra (Abelmoschus esculentus) in Kinshasa (DR Congo) 16088 gombo et les caractéristiques physico-chimiques étudiées du sol. Le rendement le plus élevé à la première saison était 6 fois plus que celui du témoin. A la deuxième saison, seul le biochar associé à l’engrais minéral a donné un rendement satisfaisant. Conclusion et application des résultats : Pour une gestion intégrée de la fertilité de ce sol sableux de Kinshasa, l’utilisation des engrais minéraux devrait être accompagnée d’une application adéquate de la matière organique. Le biochar s’avère très important pour améliorer le problème de la rétention en eau et des éléments nutritifs à apporter à ce type de sol. Le prix des engrais et du biochar n’étant pas tout le temps abordable par les petits fermiers, l’utilisation des feuilles de ricin qui sont accessible et facile à ramasser sans frais s’avère économiquement rentable. En outre, le rendement obtenu, comparé à ceux de la combinaison des engrais et du biochar, il n’y a pas de différence. Mots clés: Sols sableux, biochar, pH, capacité d’échange cationique, matière organique, phosphore


2016 ◽  
Vol 869 ◽  
pp. 112-115 ◽  
Author(s):  
Francisca Pereira de Araújo ◽  
Edson Cavalcanti Silva Filho ◽  
João Sammy Nery de Souza ◽  
Josy Anteveli Osajima ◽  
Marcelo Barbosa Furtini

Soil-cement bricks are good examples of environmentally friendly products. This brick is the combination of soil with compacted cement with no combustion in its production. In this work the physical chemical characteristics of the soil from Piaui for producing this material were investigated. Samples of the soil were collected in three potteries from the county of Bom Jesus and pH analysis were carried out, as well as the rate of organic matter, texture, particle density, limits of liquidity and plasticity rates. The results have shown that the soils have acid tones (pH 5,49 a 6,11), which can be neutralized by adding cement, and organic matter percentages up to 1%. The samples have shown predominantly clay-rich textures with adequate plasticity limits, however, values of liquidity limits and particle density above recommended. Altogether, these soils tend to present viability concerning soil-cement brick production, provided that corrections with additives are made in order to minimize this effect.


2013 ◽  
Vol 29 (3) ◽  
pp. 333-343 ◽  
Author(s):  
K. Jegajeevagan ◽  
S. Sleutel ◽  
N. Ameloot ◽  
M. A. Kader ◽  
S. De Neve

2014 ◽  
Vol 27 (5) ◽  
pp. 1413-1423 ◽  
Author(s):  
Nicasio T. Jiménez‐Morillo ◽  
José A. González‐Pérez ◽  
Antonio Jordán ◽  
Lorena M. Zavala ◽  
José María Rosa ◽  
...  

2012 ◽  
Vol 25 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Juliana Vanir De Souza Carvalho ◽  
Eduardo De Sá Mendonça ◽  
Newton La Scala ◽  
César Reis ◽  
Efrain Lázaro Reis ◽  
...  

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.


Author(s):  
Songyan Li ◽  
Meng Li ◽  
Guoxi Wang ◽  
Xiaolei Sun ◽  
Beidou Xi ◽  
...  

Abstract Background Exploration of composition and chemical characteristics of soil dissolved organic matter (DOM) is significant to understand its biogeochemical role in terrestrial ecosystems. A total of 43 cropped and 16 natural soils (0–20 cm) under four soil types (cinnamon, chernozem, red and paddy soils) across China were collected to investigate the spectral characteristics of DOM using UV–Vis and 3D-EEM spectroscopy. Results The chernozem soils exhibited the highest aromaticity and humification degree among the four soil types. Ranges of biological index (BIX, 0.53–1.17) and fluorescence index (FI, 1.55–2.10) were found in the investigated DOM, showing joint contribution from allochthonous and autochthonous sources. Higher BIX and FI in the DOM of the paddy and red soils indicated a greater reliance on autochthonous sources for these two soil types. The cropped soils showed no significant differences in chemical characteristics and sources from the natural soils for the cinnamon, chernozem and red soils. UVA (16.2–47.9%) and UVC fulvic-like substances (15.4–40.5%) were the prevailing DOM components, which were highest in the chernozem soils. Additionally, the cropped soils had a higher proportion of humic-like substances than the natural soils in the DOM. Conclusions Both soil type and land-use strongly affected the chemical characteristics of soil DOM, but only soil type had an impact on the DOM composition for the collected soils. These findings may contribute to the prediction of the biochemical behavior of soil DOM under different soil types and land-uses in terrestrial ecosystems.


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