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All Journal Jurnal Penelitian Pendidikan IPA (JPPIPA) Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering)
Danang Widjajanto
Tadulako University
Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Education Engineering Materials Science & Nanotechnology Physics

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Dynamics of Soil Organic Carbon at Different Elevations in Cocoa Land-Use Systems Danang Widjajanto; Rachmat Zainuddin; Rois; Abdul Rahman; Moh. Adnan Khaliq; Uswah Hasanah; Rosmaniar Gailea; Fera
Jurnal Penelitian Pendidikan IPA Vol 11 No 7 (2025): July
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v11i7.11999

Abstract

Soil organic carbon (SOC) is essential for sustaining soil quality, especially in sloped agricultural landscapes prone to erosion and degradation. This study aimed to analyze SOC dynamics across different elevations (400, 600, and 800 meters above sea level) in cocoa-based land-use systems and examine its relationships with some key physical properties. Soil sampling was conducted using a stratified random design, and laboratory analyses were carried out using standard methods. The results showed that SOC increased with elevation due to cooler temperatures, slower organic matter decomposition, and higher surface litter accumulation. Polynomial regression revealed non-linear relationships between SOC and soil properties, with significant coefficients of determination: SOC vs. bulk density (R² = 0.82), SOC vs. penetration resistance (R² = 0.44), and SOC vs. saturated hydraulic conductivity (R² = 0.37). Moderate SOC levels (around 2.3% – 3.0%) were associated with improved soil structure, lower bulk density, higher hydraulic conductivity, and reduced penetration resistance. However, excessive organic inputs beyond the optimum may reduce these benefits due to incomplete decomposition. A similar curvilinear pattern was found between surface litter and SOC content. These findings highlight the importance of optimizing organic matter management in cocoa systems on sloped lands to enhance soil physical conditions and promote sustainable agriculture.
The Use of Organic Fertilizer to Enhance Soil Water Availability and Promote the Growth of Tomatoes in Sandy Loam Soils Abdul Rahman; Danang Widjajanto
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol. 14 No. 3 (2025): June 2025
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v14i3.1034-1039

Abstract

The use of organic fertilizer has been shown to improve soil structure and promote plant root growth, particularly in critical areas with limited water resources for agricultural activities. This study aimed to evaluate the effect of organic fertilizer application on the soil’s water holding capacity and the growth performance of tomato. The experiment was conducted using a randomized complete blocs design with six treatments, each replicated three times. The treatments included P0 (0 Mg/ha), P1 (5 Mg/ha), P2 (10 Mg/ha), P3 (15 Mg/ha), P4 (20 Mg/ha), and P5 (25 Mg/ha). The findings revealed that organic fertilizer application significantly influenced soil organic carbon levels, bulk density, hydraulic conductivity, and soil water availability. Additionally, the increased soil organic carbon led to noticeable improvements in shoot dry weight, total root length, and root dry weight of tomatoes. This study found that the availability of organic carbon has very strong correlation with tomatoes growth and soil water availability. Keywords: Organic Carbon, Sandy Soils Texture, Soil Structure, Water Retention.
Co-Authors Abdul Rahman Fera Moh. Adnan Khaliq Rachmat Zainuddin Rois Rosmaniar Gailea Uswah Hasanah