Phosphorus sorption by gyttja and its effect on pH and phosphorus in acidic soils

Phosphorus (P) is one of the primary nutrients limiting crop production. The application of phosphate fertilizers in acidic soils leads to the formation of secondary insoluble compounds that reduces the effectiveness of the fertilizer. The addition of biochar may represent a solution to the problem of nutrients bioavailability, especially P. In this study, tests were performed to determine the effects of amending soil with five different percentages of biochar (0, 5, 10, 20, and 35% w/w) on the phenomena of P sorption and desorption. The effect of soil/ biochar contact treatments on P availability was also examined. Phosphorus sorption was lower in the soils containing biochar compared to normal soil. The accumulated desorption quantity after eight consecutive extractions was 85% higher when 35% biochar was added to the soil than soil alone. Moreover, the application of 35% biochar increased the concentration of soluble P up to 38% after 30 days of incubation. Based on these results, we deduced that biochar induces changes in P retention soil properties that may be beneficial for agricultural soils.

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Evaluation of phosphate sorption capacity and external phosphorus requirement of some agricultural soils of the southwestern Ethiopian highlands

Sains Tanah - Journal of Soil Science and Agroclimatology ◽

10.20961/stjssa.v18i2.51325 ◽

2021 ◽

Vol 18 (2) ◽

pp. 136

Author(s):

Berhanu Dinssa ◽

Eyasu Elias

Keyword(s):

Sorption Capacity ◽

Crop Production ◽

Agricultural Soils ◽

Soil Characteristics ◽

Soil Samples ◽

Phosphorus Sorption ◽

Acidic Soils ◽

Ethiopian Highlands ◽

P Sorption ◽

P Sorption Capacity

One of the most soil fertility management problems for crop production on acidic soils of the Ethiopian highlands is phosphorus fixation. The research was executed to assess the P-sorption capacity and to determine the external P requirement of different acidic soils in the Southwestern highlands of Ethiopia. Phosphorus sorption capacity (Kf) and its relation with selected soil characteristics were assessed for some major agricultural soils in the Ethiopian highlands to answer the questions, ‘What are the amount of P-sorption capacity and external P requirement of Nitisols, Luvisols, Alisols, and Andosols in Ethiopia?’. Twelve surface soil samples (at depth of 0-30 cm) were gathered and the P-sorption capacity was estimated. Phosphorus-sorption data were obtained by equilibrating 1 g of the 12 soil samples with 25 ml of KH2PO4 in 0.01 M CaCl2, having 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, and 330 mg P L-1 for 24 hours. The data were adjusted to the Freundlich adsorption model and the relationship among P-sorption and soil characteristics was established by correlation analysis. Clay content and exchangeable acidity, organic matter, Al2O3, and Fe2O3 oxides have affected phosphorus-sorption at a significance level of (P < 0.05). Alisols had the highest Kf value (413 mg kg-1) but Nitisols had the lowest Kf (280 mg kg-1). The external phosphorus fertilizer requirement of the soils was in the order of 25, 30, 32, and 26 mg P kg-1 for Nitisols, Luvisols, Alisols, and Andosols sequentially. The Kf varies among different soil types of the study area. The magnitude of the soil’s Kf was affected by the pH of the soil, soil OM content, and oxides of Fe and Al. Therefore, knowledge of the soils’ P retention capacity is highly crucial to determine the correct rate of P fertilizer for crop production.

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The effectiveness of granular chalk use for growing winter wheat on grey forest soil

Agrobìologìâ ◽

10.33245/2310-9270-2020-157-1-181-191 ◽

2020 ◽

pp. 181-191

Author(s):

M. Tkachenko ◽

N. Borys ◽

Ye. Kovalenko

Keyword(s):

Winter Wheat ◽

Physicochemical Properties ◽

Forest Soil ◽

Active Substance ◽

Mass Fraction ◽

Gray Forest Soil ◽

Mineral Fertilizers ◽

Acidic Soils ◽

Grey Forest Soil

The research aims to establish the eff ectiveness of granular chalk use produced by «Slavuta-Calcium» Ltd. under growing Poliska–90 winter wheat variety, changing the physicochemical properties of grey forest soil and the wheat productivity. It also aims to establish optimal dosis of «Slavuta-Calcium» granular chalk as the meliorant and mineral fertilizer for grey forest soil in the system of winter wheat fertilization. In the temporary fi eld studies, various doses of nutrients N60–90–120P30–45–60K60–90–120 combined with «Slavuta–Calcium» granular chalk in a dose of Ca230–460–690 kg/ha of the active substance were studied against the background of secondary plowing of rotation products – soybean biomass that averaged 2.34 t/ha. Granular chalk is a modern complex highly eff ective meliorant with the content of Ca – 37.7 and Mg – 0.2 %, the mass fraction of carbonates (CaCO3 + MgCO3) makes at least 95 %. It is characterized by a high level of solubility when interacting with moisture in soil. It has a form of white granules, the mass fraction of 4.0–6.0 mm in size granules makes not less than 90 % and the one of 1.0 mm in size makes less than 5 %. Reactivity – 97 %. The granular chalk is advisable to apply on acidic soils, as a highly concentrated calcium-magnesium fertilizer, with the former as the dominant fertilizer, to optimize the physicochemical properties of the soil, as well as the plant nutrition system, in particular, increasing the availability of an element for assimilation by plants and as long-term ameliorants. The eff ectiveness of the use of mineral fertilizers, in particular acidic nitrogen on highly and medium acidic soils, after chemical reclamation is increased by 30–50 %, and slightly acidic by 15–20 %. The increase in productivity of crops from the combined eff ects of nutrients and chalk granulated is usually higher than when separately applied. The eff ectiveness of the integrated action of these elements is manifested in the growth of plant productivity and the quality of the resulting products, as well as the optimization of physical chemical properties and soil buff ering in the long term. In order to optimize the physicochemical properties of the arable layer of gray forest soil and the productive nutrition of agricultural crops, winter wheat, in particular, biogenic elements should be used in doses N60-90-120P30-45- 60K60-90-120 with granulated chalk «Slavuta-Calcium» in doses of Ca230-460-690 kg/ha of active substance. Granulated chalk obtained as a result of industrial grinding of solid sedimentary carbonate rocks of natural origin, subsequently under the infl uence of the granulation process of the starting material contains Ca and Mg carbonates of at least 95 %, dense granules which facilitates convenient mechanized application, as well as chalk suitable for accurate metered application on the quest map. Key words: granular chalk, gray forest soil, chemical reclamation, crop productivity.

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