Levels Of Exchangeable Cations Research Articles

Geochemical interactions between the water, suspensate and soil of the mangrove forest as a process of fertilization in Bragança, Northern Brazil

This study evaluated the changes in soil fertility mangrove after immersion in distilled water, present in the estuary of the Caeté river. In experiments, soil was immersed in distilled water, and determined periodically pH and Eh and available concentrations of Ca, K, Cu, Fe, P and organic C for a period of 132 days. The soils and suspensate had a similar composition, quartz, kaolinite, illite, and smectite, as well as anatase as an accessory mineral. Immersion provoked profound alterations in the fertility of the soil promotion the release of Fe and P, and changes in the availability of Ca, K and Cu. Carbon was consumed during the experiment, reducing its concentration. The pH changes from high acidity to medium acidity while the oxidized environment has changed for reduced environment for Eh -281.25 in 132 days of flooding. The study confirmed that the local gleisols are highly fertile, presence of 2:1 clay minerals and high levels of organic carbon who contributed to the considerable fertility of this soil. The study also indicates the importance of the suspensate for the maintenance ofthe fertility of the soil, given its high levels of exchangeable cations and available phosphorus.

Mechanisms for the successful biological restoration of the threatened African pencilcedar (Juniperus procera Hochst. ex. Endl., Cupressaceae) in a degraded landscape

Juniperus procera Hochst. ex. Endl. (Cupressaceae) is world’s largest juniper, but is currently threatened owing to multiple anthropogenic factors. This paper describes mechanisms for the successful biological restoration of African pencilcedar in a degraded landscape that had been depleted of organic matter and essential nutrient elements as a consequence of relentless deforestation, soil erosion, unsustainable farming and overgrazing. We used stecklings (= planting materials derived from rooted cuttings) of J. procera, and deployed Acacia abyssinica Hochst. ex Benth. (Fabaceae) to serve as a putative foster tree. The study was conducted for a period of 7years, with major soil fertility indicators determined at years 0, 3 and 7. We found that mean height, crown length, crown diameter, branch length, and branch numbers of J. procera trees grown in association with A. abyssinica were significantly (p=0.001) higher than those grown without the putative foster tree. Mean plant-available P (15±2.1ppm) and soil N-content (0.42±0.04%) were approximately 3- and 2-fold higher, respectively, in the A. abyssinica-treated plots than in the non-treated ones. Similarly, the levels of exchangeable cations and soil organic carbon were twice higher in the A. abyssinica-treated plots than in the non-treated ones. Cation exchange capacity improved with restoration time, both in the 0–15 and 15–30cm soil profiles, but the extent of improvement was significantly (p=0.001) higher in the 0–15cm soil profile of the A. abyssinica-treated plots than in the non-treated ones. We conclude that successful restoration of Juniperus procera in degraded landscapes and across the species’ range of habitats is feasible provided that strong and well-fortified stecklings are established along with the N2-fixing, fast-growing and drought-tolerant Acacia abyssinica.

Effects of Charcoal Production on Soil in Kiln Sites in Ibarapa Area, South Western Nigeria

In Nigeria, charcoal is a major source of energy, especially among the urban poor. However, the effects of charcoal production on the environment, especially the soil, have not been adequately documented. This study examines the effects of charcoal production in kiln sites on soil properties in the derived savanna zone of Ibarapa region, south-western Nigeria. Soils in ten kiln sites were sampled at depths of 0-10cm and 10-20cm and their characteristics were compared with those of the corresponding layers of soil in ten adjoining derived savanna sites which were used as the control. Unlike in previous studies reported for West Africa, charcoal production in the kiln sites did not result in a significant reduction in soil organic matter levels, presumably because the humid climate of the derived savanna zone, hindered a substantial rise in soil temperatures during biomass burning. Similarly, there were no significant increases in the levels of exchangeable cations in both soil layers, except for soil exchangeable sodium. There was a rise in kiln site soil pH and available phosphorus mainly due to the effects of soil heating. Biomass burning in the kiln sites did not result in significant increases in the levels of the soil micronutrients - extractable iron, copper, zinc and manganese in both the 0-10cm and 10-20cm soil layers and it had no severe deleterious effects on soil chemical status.Keywords: Charcoal production, kiln sites, macronutrients, micronutrients, Nigeria

Effect of amendment of bauxite processing sand with organic materials on its chemical, physical and microbial properties

The effects of addition of a range of organic amendments (biosolids, spent mushroom compost, green waste compost and green waste-derived biochar), at two rates, on some key chemical, physical and microbial properties of bauxite-processing residue sand were studied in a laboratory incubation study. Levels of exchangeable cations were not greatly affected by additions of amendments but extractable P was increased significantly by mushroom and green waste composts and massively (i.e. from 11.8 to 966 mg P kg −1) by biosolids applications. Levels of extractable NO 3 −–N were also greatly elevated by biosolids additions and there was a concomitant decrease in pH. Addition of all amendments decreased bulk density and increased mesoporosity, available water holding capacity and water retention at field capacity (−10 kPa), with the higher rate having a greater effect. Addition of biosolids, mushroom compost and green waste compost all increased soluble organic C, microbial biomass C, basal respiration and the activities of β-glucosidase, L-asparaginase and alkali phosphatase enzymes. The germination index of watercress grown in the materials was greatly reduced by biosolids application and this was attributed to the combined effects of a high EC and high concentrations of extractable P and NO 3 −. It was concluded that the increases in water storage and retention and microbial activity induced by additions of the composts is likely to improve the properties of bauxite-processing residue sand as a growth medium but that allowing time for soluble salts, originating from the organic amendments, to leach out may be an important consideration before sowing seeds.

Changes of Surface Soil Nutrients and Sustainability of Pastoralism on Grazed Hilly and Steep Land, South Island, New Zealand

Soil nutrients in topsoils (0-7.5 cm) on grazed hilly and steep land on 2 high country sheep farms with contrasting climate in the upper Waitaki district, South Island, New Zealand, were compared before and after a 14-15 year period. In addition, effects on soils of 2 farm management systems were compared by sampling similar soils on adjacent farms. On a farm with mean annual rainfall of 700-1,000 mm (study area A) that had been fertilised and oversown, and grazed with about 1.6 ewe equivalents per hectare for 14 years, levels of exchangeable cations (Ca, K, Mg) increased in topsoils on sunny slopes, but there was little change on shady slopes. The Ca increase on sunny slopes was the increase to be expected from the amount of Ca contained in the superphosphate applied but increases of exchangeable K and Mg could not be explained by fertiliser additions. There was an overall 29% increase of CEC, 7.5% decline of base saturation, and decline of soil pH by 0.4 units over the 14 year period. On a farm with mean annual rainfall of 500-600 mm (study area B) that had been grazed for 15 years with about 0.6 ewe equivalents per hectare but not fertilised or oversown, levels of exchangeable cations in topsoils declined. Base saturation values declined from 98% to 73% and pH declined by 0.4 units. Losses of Ca and Mg were greater than could be explained by direct effects of sheep grazing and we conclude that processes such as erosion or removal of vegetation and nutrients by rabbits are important loss pathways. In the spatial comparison on land with mean annual rainfall of approximately 1,000 mm, oversown and fertilised soils (grazed with about 1.6 ewe equivalents per hectare) had higher levels of exchangeable cations, organic C and total N than soils that had neither been oversown or fertilised (grazed with about 0.6 ewe equivalents per hectare). Questions of ecological and economic sustainability arise both on the moister and drier high country. On moister land like area A, if lime can be applied economically, and fertiliser can continue to be applied with positive financial returns, oversowing and fertilising may be sustainable on sunny slopes. The sustainability of pastoralism on shady slopes is more problematical. If on drier land losses of topsoil nutrients such as those measured on area B are widespread, they are considered to be unsustainable. Although the nutrients lost could be readily replenished using modest amounts of fertiliser and lime, the changes have occurred concurrently with declines of organic C and total N. Restoration of organic matter levels is likely to require either reduced grazing, or oversowing and application of fertiliser. Because oversowing and fertilising the drier high country is not financially viable except during periods of high commodity prices, both these options would require major changes in farm management and/or financial assistance with soil conservation measures.

Effect of an acidifying nitrogen fertiliser and lime on soil pH and wheat yields. 1. Soil effects

Three long-term trials were commenced in 1980 at Merredin, Wongan Hills, and Newdegate to investigate the effect of an acidifying fertiliser containing 17.5% nitrogen (N) and 7.6% phosphorus (P) (based on ammonium sulfate and ammonium phosphate) on soil pH, soil acidity related problems, and wheat grain yields under continuous cropping. Treatments were 3 rates (kg/ha) of N + P applied with the cereal seed (nil; 17.5 N + 7.6 P; 35 N + 15.2 P), with or without 3 t/ha of ground limestone (with or without MgSO4, KCl, Moo3) applied in 1980. Two extra treatments were 2 rates of limestone (70, 140 kg/ha) topdressed with the cereal crop each year along with the low and high N + P fertiliser treatments, respectively. This paper reports soil properties for the first 10 years of the trials. In the acidic Merredin soil (pH 4.3), there was minimal effect of N + P fertiliser on soil pH. The pH was slightly reduced at 0-10 cm depth. At Wongan Hills, soil pH at 0-10 cm depth was reduced over time by N + P application from 4.8 to 4.2. At Newdegate, only the high rate of N + P reduced pH over time, from 4.6 to 4.3 at 0-10 cm. Limestone at 3 t/ha in 1980 increased soil pH at 0-10 cm depth at all 3 sites; however, in all cases pH fell with time. Limestone applied at 70 or 140 kgha with each N + P application increased pH at 0-10 cm depth by 0.1-0.4, 0.1-0.4, and 0.3-0.9 pH units at Merredin, Wongan Hills, and Newdegate. Soil aluminium (Al) concentrations (extracted in 0.01 mol CaCl2/L) were generally low at Wongan Hills and Newdegate in the absence of N + P fertiliser. These levels rose after N + P application to 4 and 2 �g/g at 0-10 cm depth at Wongan Hills and Newdegate. Soil A1 concentrations at Merredin were high, particularly in the subsoil: 3-5, 9-13, and 23-29 �g/g in the 0-10, 10-20, and 20-40 cm depths. With the high rate of N + P, A1 concentration rose to 10 �g/g at 0-10 cm. Application of 3 t/ha of limestone reduced this to <1-2 �g/g. Application of 140 kg/ha of limestone with the high N + P fertiliser rate lowered soil A1 concentration at 0-10 cm. Extra acid that accumulated in treated plots compared with control plots varied from -34.7 kmol/ha (acid-neutralised) for the treatment at Merredin receiving only 3 t lime/ha in 1980 to 23.8 kmol/ha for the treatment at Wongan Hills receiving high N + P. With the treatments receiving lime only, the amounts of acid neutralised were only 82, 66, and 58% of those predicted at Merredin, Wongan Hills, and Newdegate, respectively. Acid accumulation in the 3 treatments receiving high N + P was within the predicted range at Wongan Hills, as it was for the treatment receiving high N + P plus 3 t lime/ha in 1980 at both Merredin and Newdegate. However, for the treatments receiving only high N + P or high N + P plus 140 kg lime/ha. year at these 2 sites, the acid accumulation rates were less than predicted. Levels of exchangeable cations in the soil were highest at Wongan Hills and lowest at Newdegate. Application of N + P decreased Ca concentration at all sites and reduced the concentration of exchangeable Mg at Wongan Hills. Lime applied at 3 t/ha increased the concentrations of exchangeable Ca and Mg at all sites. There were no effects of treatments on concentrations of exchangeable K or sodium.

Soil acidity effects on wheat seedling root growth

Abstract Soft red winter wheat (Triticum aestivum L. cv Hart) was used as a test crop in a bioassay technique to assess acid soil chemical constraints in major hill land soils of the Appalachian Region. Seedling root growth was related to amounts and forms of Al in soil solution and Al extracted by 0.01M CaCl2, 1M KC1, 0.5M CuCl2, and 0.33M LaCl3. Aluminum determined in the various extractants, total soil solution Al and soil solution Al reacting with 8‐hydroxy‐quinoline, pyrocatechol violet, and aluminon showed large differences in root growth prediction ability. In general, Al extracted by 0.01M CaCl2 was a good predictor of root growth. Root elongation was more inhibited in subsurface horizons than in surface horizons. Although surface horizons had the lowest mean pH, the presence of high levels of exchangeable cations tended to ameliorate the Al toxicity. The root bioassay technique adapted here should be useful in assessing the potential Al toxicity of diverse soil types.

Water Flow Paths and the Spatial Distribution of Soils and Exchangeable Cations in an Acid Rain‐Impacted and a Pristine Catchment in Norway

The dynamic pattern of soil water transport is a major factor in determining the chemistry of streamwater. In the acidified Birkenes catchment (southernmost Norway) the streamwater chemistry is, to a first approximation, explained by mixing solutions from the forest floor, the B horizon and the deep peat, in various proportions depending on the hydrological conditions. Paradoxically, a direct physical contact between the forest floor and the B horizon on the one hand and the stream on the other is lacking, as the stream banks largely consist of peats. To investigate this paradox, soils and their levels of exchangeable cations were studied in a 100 m × 100 m grid. Results indicate that the exchange sites of the surface peat along the stream are significantly enriched in Al, probably due to return flow of Al‐rich B horizon water. This view is supported by the similarity of the solution chemistry in surface peats and B horizons. Exchangeable base cations dominate in the forest floor upslope. Forest floor solutions, an important component of streamwater during intensive storms, are depleted in Al and may bypass the A‐enriched surface peats via ephemeral flow channels. A parallel study in a pristine catchment in mid‐Norway shows a similar accumulation of Al in return flow areas. This indicates that acid deposition is not a prerequisite for elevated levels of exchangeable Al in the surface organic layers of return flow areas.

The quantity and nature of the forest floor and topsoil under some indigenous forests and nearby areas converted toPinus radiataplantations in South Island New Zealand

Abstract In a comparative study, the quantity of accumulated organic matter in, and the nutrient composition of the forest floor and topsoil (0–20 cm) of indigenous (beech or podocarp) forests and nearby Pinus radiata plantations in five widely separated forest sites in the South Island of New Zealand were measured. Total mass of forest floors in native and radiata plantation stands ranged from 25 to 464 and 9 to 79 t/ha, respectively. Native forest stands apparently accumulated larger amounts than nearby radiata pine stands, especially in the West Coast forests. In exotic plantations, the nett accumulation was modified by management practices such as burning, during the process of converting native forests to pine plantations, and stand thinning. Except in Nelson forests, forest floors in native stands had larger contents of carbon and nutrients than those of nearby radiata pine sites. No consistent differences were found in carbon and nutrient concentrations in topsoils of native and exotic forests except in the 9-year-old radiata pine stand in the Hochstetter forest, where they were lower than those under the native forest. However, levels of exchangeable cations and Bray-P in top-soils under radiata pine stands were higher than those of native stands. Concentrations of ether-extractable components (lipids), water-soluble carbohydrates and polyphenols in the forest floors under native forest were generally higher than those under radiata pine stands. Consistent differences between concentrations of lipid components and polyphenols in the topsoil under native and exotic forest were not found.

Forest Floors in Douglas‐Fir Forests: I. Dry Weight and Chemical Properties

AbstractVarious types of understory plant communities occur in association with Douglas‐fir (Pseudotsuga menziesii [Mirb] Franco) forest in western Oregon. Dry weight and chemical properties were determined for 9 forest floor types from the Oregon Coast Range.Dry weight of forest floors varied considerably within stands. Between‐stands values ranged from 20,000 to 76,000 lb/acre. Volatile matter ranged from 69 to 86%. Ranges in values for other factors were: pH, 4.0–6.0; available P, 36–146 ppm; exchangeable K, 1.5–5.4 meq/100g; Ca, 6.5–23.5 meq/100g; Mg, 5–12.8 meq/100g; CEC, 54–76 meq/100g; total N, 0.71–1.52%; total P, 0.089–0.211%; total K, 0.115–0.323%; total Ca, 0.325–1.05%; total Mg, 0.157–0.334%; and total S, 0.081–0.163%. The types having the lowest content of metallic cations were from areas of high precipitation and soils with low base saturation. There was no apparent relationship between levels of exchangeable cations and percentage of these elements in the forest floor.