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All Journal Journal of Tropical Soils SAINS TANAH - Journal of Soil Science and Agroclimatology
Obalum, Sunday E.
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Agriculture, Biological Sciences & Forestry Education Environmental Science

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Application of Rice-Husk Biochar to Coarse-Textured Ultisols and the Effects on Soil Fertility Indicators at Different Amendment-to-Sampling Intervals Ebido, Nancy Ekene; Awaogu, Chukwuebuka Ebuka; Akubue, Jacinta Chinonso; Ozongwu, Ogorchukwu Valeria; Unagwu, Benedict Onyebuchi; Obalum, Sunday E.; Igwe, Charles Arizechukwu
JOURNAL OF TROPICAL SOILS Vol 30, No 2: May 2025
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2025.v30i2.69-83

Abstract

The low fertility status of the highly weathered tropical soils offers the opportunity to study the potential and optimum application rate of biochar as an organic soil amendment, especially for the dominant coarse-textured Ultisols. Despite the relatively fast mineralisation of organics in these soils and the need to synchronise nutrient release crops critical stages of nutrient requirement, the time corresponding to peak effects of biochar remains unclear. The effects of rice-husk biochar (RHB) on the soil fertility of sandy-loam Ultisols at 0, 7.5, 15, 30, and 60 Mg ha-1 equivalents in 2-kg soils were assessed at 0, 2, 4, 8, and 12 weeks of incubation (WOI). Treatments were prepared in batches to enable concurrent sampling for all five incubation intervals. The RHB enhanced soil fertility across the incubation intervals, with optimal rates as 15 Mg ha-1 for soil pH and 30 - 60 Mg ha-1 for macronutrients availability. Relative to the its non-application, RHB increased soil pH-H2O, total N, available P, exchangeable bases, exchangeable acidity, apparent CEC and base saturation by 4-30%, 43-100%, 30-202%, 13-240%, 14-675%, 21-126% and 7-82%, respectively. Soil pH tended to decrease after, while available P progressively decreased before 8 WOI, when treatment effects were generally most pronounced. At an all-encompassing optimal rate range of 30-60 Mg ha-1, RHB could reduce soil acidity and enhance the macronutrient status of coarse-textured Ultisols over at least 12 weeks, soil fertility restoration effects of which are likely to be most pronounced around 8 weeks.
Application of Rice-Husk Biochar to Coarse-Textured Ultisols and the Effects on Soil Fertility Indicators at Different Amendment-to-Sampling Intervals Ebido, Nancy Ekene; Awaogu, Chukwuebuka Ebuka; Akubue, Jacinta Chinonso; Ozongwu, Ogorchukwu Valeria; Unagwu, Benedict Onyebuchi; Obalum, Sunday E.; Igwe, Charles Arizechukwu
JOURNAL OF TROPICAL SOILS Vol. 30 No. 2: May 2025
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2025.v30i2.69-83

Abstract

The low fertility status of the highly weathered tropical soils offers the opportunity to study the potential and optimum application rate of biochar as an organic soil amendment, especially for the dominant coarse-textured Ultisols. Despite the relatively fast mineralisation of organics in these soils and the need to synchronise nutrient release crops critical stages of nutrient requirement, the time corresponding to peak effects of biochar remains unclear. The effects of rice-husk biochar (RHB) on the soil fertility of sandy-loam Ultisols at 0, 7.5, 15, 30, and 60 Mg ha-1 equivalents in 2-kg soils were assessed at 0, 2, 4, 8, and 12 weeks of incubation (WOI). Treatments were prepared in batches to enable concurrent sampling for all five incubation intervals. The RHB enhanced soil fertility across the incubation intervals, with optimal rates as 15 Mg ha-1 for soil pH and 30 - 60 Mg ha-1 for macronutrients availability. Relative to the its non-application, RHB increased soil pH-H2O, total N, available P, exchangeable bases, exchangeable acidity, apparent CEC and base saturation by 4-30%, 43-100%, 30-202%, 13-240%, 14-675%, 21-126% and 7-82%, respectively. Soil pH tended to decrease after, while available P progressively decreased before 8 WOI, when treatment effects were generally most pronounced. At an all-encompassing optimal rate range of 30-60 Mg ha-1, RHB could reduce soil acidity and enhance the macronutrient status of coarse-textured Ultisols over at least 12 weeks, soil fertility restoration effects of which are likely to be most pronounced around 8 weeks.
The concept of bio-economic mulching in droughty tropical agroecosystems and its trans-season effects on soil hydro-thermal regime and okra performance Okorie, Benedict Odinaka; Obi, Justina O.; Chioke, Geraldine U.; Obalum, Sunday E.; Onah, Chinaza J.; Nnadi, Adaobi L.; Igwe, Charles A.; Obi, Martin E.
SAINS TANAH - Journal of Soil Science and Agroclimatology Vol 21, No 2 (2024): December
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/stjssa.v21i2.83285

Abstract

Mulching is an effective soil-water conservation technique in high-evaporative-demand tropical climates. Because of the drawbacks in bulk application of organic mulches, we introduce the concept of bio-economic mulching (BEM), a one-time low-rate application of organic mulch to improve soil productivity while sustaining economic viability. The study evaluated the effects of BEM (dry-grass mulching at 0, 2, 4, and 6 t ha–1) on soil hydrothermal properties of sandy-loam Ultisols using okra growth during 4–9 weeks after sowing in successive rainy-to-dry/partially rainfed season (PRS) and rainy/completely rainfed season (CRS). During the PRS, soil volumetric moisture content (q) increased (10.02%–25.50%), but soil temperature decreased (37.67–26.67°C) as BEM rate increased. A similar q trend (8.71%–18.37%) occurred during the CRS. Soil thermal conductivity (0.78to 4.88 W m–1 K–1), thermal diffusivity (3.95 × 10–7 to 35.97 × 10–7 m2 s–1), and heat flux (15.00 to 85.56 W m–2) generally decreased as q increased with BEM application rate particularly during the PRS; the reverse prevailed for volumetric heat capacity (1.33 × 106 to 2.25 × 106 J m–3 K–1). Okra plant height differed (BEM-6 > BEM-4 > BEM-2/BEM-0) in the PRS, but BEM-6 and BEM-4 gave the tallest and shortest plants, respectively in the CRS. Fruit yield was 1.8- and 9.5-fold higher in BEM-6 than BEM-4 in PRS and CRS, respectively. Mulch treatment-induced temporal variations in soil q influenced okra performance indices of plant height (r2 = 0.85) and total fresh fruit yield (r2 = 0.69). In droughty tropical environments, BEM implementation at 6 t ha−1 could engender soil hydrothermal regime favoring vegetable production beyond the ‘drier’ first season and even more pronouncedly in the second season.
Co-Authors Akubue, Jacinta Chinonso Awaogu, Chukwuebuka Ebuka Chioke, Geraldine U. Ebido, Nancy Ekene Igwe, Charles A. Igwe, Charles Arizechukwu Nnadi, Adaobi L. Obi, Justina O. Obi, Martin E. Okorie, Benedict Odinaka Onah, Chinaza J. Ozongwu, Ogorchukwu Valeria Unagwu, Benedict Onyebuchi