JOURNAL OF TROPICAL SOILS

Spatial Distribution of Soil Properties and Soil Fertility Status in the Paddy Rice Field of Oransbari

Irena Tri Hastuti — 2025-03-25

Soil properties and soil fertility status of paddy rice fields are considered important factors related to the yield and production of rice; therefore it is essential to understand those properties across the farm. The objectives of this research is to quantify the soil properties and soil fertility status of paddy-rice soil and their spatial variability in Oransbari. Forty-two composite soil samples (0-30 cm) were taken across paddy rice fields and analyzed for soil chemical properties and fertility status. Geostatistical analysis and ordinary kriging interpolation methods were used to quantify soil variability and its fertility status across the farm. The results showed that total soil Nitrogen ranges from 0.11% to 0.17%), organic-C (1.47-6.94%), C/N ratio (11-47), total-P (13-99 mg 100 g-1), available-P (30-227 mg kg-1), total-K (27-54 mg 100 g-1), soil pH (5.83-6.93), base saturation (70-100%), and CEC is 30.51-51.23 me 100 g-1. The spatial variability of all soil characteristics exhibited medium and fit the stable model, except for available Phosphorus and Potassium. Most rice paddy fields in Oransbari showed high soil fertility status, which indicated that high-yield rice production can be achieved for this region, however, land management factors should be considered for sustainable land use.

Application of Rice-Husk Biochar to Coarse-Textured Ultisols and the Effects on Soil Fertility Indicators at Different Amendment-to-Sampling Intervals

Nancy Ekene Ebido — 2025-03-25

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 Influence of Compost and Biochar on the Physico-Chemical Properties of Soil and the Growth of Tomatoes in Sub-Optimal Land

Endriani Endriani — 2025-04-10

This study seeks to evaluate the effectiveness of coconut shell biochar (CB) and/or Leucaena compost (LC) as ameliorants in improving soil chemical and physical properties, as well as enhancing tomato yields. The goal is to identify the most effective combination of ameliorant formulations that can improve land quality and increase yield of tomato. The study was carried out over a 10-month period, spanning from March 2024 to December 2024. The research method used a Group Random Design, the treatments studied were: A0: no ameliorant + inorganic fertilizer as recommended; A1 : CB 15 Mg ha-1; A2 : LC 15 Mg ha-1; A3 : LC 5 Mg ha-1 + CB 10 Mg ha-1; A4 : LC 10 Mg ha-1 + CB 5 Mg ha-1. All treatments were repeated 5 times. The data obtained from this study were subjected to statistical analysis and further evaluated using the Duncan’s New Multiple Range Test (DNMRT). The findings reveal that applying coconut shell biochar and Leucaena compost, whether individually or in combination, markedly enhances the physical properties of the soil. These improvements include reduced bulk density (BD), increased soil organic matter SOM), total porosity (TP), and hydraulic conductivity (HC), as well as better pore distribution and water retention. Furthermore, these treatments resulted in an increase in both the tomato weight per plant and the fresh tomato weight per plot. The most effective combination for maximizing tomato yield was determined to be 10 Mg ha-1 of LC combined with 5 Mg ha-1 of CB.

Effect Application of Cellulolytic Bacteria Consortium And Palm Kernel Ash on Red Chili Plants in Peat Soil

gusmawartati gusmawartati gusmawartati — 2025-05-26

Limited agricultural land in Indonesia makes peatland an alternative land for agricultural intensification. Peat soil has a low fertility, so applying cellulolytic bacteria and palm oil shoot ash is recommended. This study aimed to determine the effect of cellulolytic bacteria consortium and oil palm shoot ash on the growth and yield of red chilies on peat soils. The research was conducted in Empat Balai Village, Kampar. The study used a factorial in a completely randomized design (3x3) and three replications. The first factor was the cellulolytic bacteria consortium (0, 20, and 30 mL polybag-1), and the second factor was palm ash (0, 3, and 6 Mg ha-1 equivalent to 0.126 and 252 g polybag-1). The application of cellulolytic bacteria consortium and its interaction with oil palm shoot ash had no significant effect on all observed variables. While, the application of palm ashes significantly affected plant height, stem diameter, number of fruits, and fruits weight.

The Dynamics of Soil Organic Matter Fractions in Cacao-Based Agroforestry Systems

Rika Ratna Sari — 2025-04-10

Soil degradation is an important problem affecting crop production, especially in cocoa agroforestry systems, where soil health is crucial for optimal results. However, the effect of land management on changes in soil organic matter (SOM) content is often not visible through measurements of total soil organic carbon (SOC) content. This study investigates the distribution of soil organic matter fractions across various land-use gradients and soil depths in cacao-based agroforestry landscapes in Southeast Sulawesi, Indonesia. Soil samples were collected from three villages representing different parts of a watershed and subjected to density fractionation to separate light (LF), intermediate (IF), and heavy (HF) fractions. Our results indicate that remnant forests (RF) maintain higher total SOM fractions, followed by cacao-based complex and simple agroforestry (CAF, SAF), particularly in the 0-10 cm soil depth. In contrast, annual crops (CR), exhibit the lowest SOM fractions. Standing litter and decomposition rates significantly influence the LF, while HF shows minimal variation across land-use systems, suggesting long-term stability. The LF also strongly correlates with SOC content, highlighting its responsiveness to recent organic inputs. The findings underscore the importance of diverse litter inputs and tree diversity in enhancing SOM fractions and SOC content in agroforestry systems. The study concludes that complex cacao-based agroforestry systems can effectively mimic natural forest conditions, promoting soil health. These insights provide valuable knowledge for sustainable land management practices to mitigate soil degradation and improve soil quality in cacao production systems.

Water Table Control Model for Maize Cultivation of C Typology Land on Tidal Lowland Reclaimed Area of South Sumatra, Indonesia

Momon Sodik Imanudin — 2025-03-25

Tidal lowland productivity in type C is still low. Most of them have only been able to cultivate rice twice a year. The third cultivation of corn often fails due to a lack of water. The research objective is to determine an operational model for water management in the field for maize cultivation at several planting times. Model area is conducted at a tertiary block of reclaimed tidal lowland, Telang Jaya Village Primer 8 Delta Telang I, of Banyuasin District. There are three planting times treatments: the fourth week of April, the second week of June, and the first week of July, 2021. A water management model was applied to control the drainage system, in which the water level in the tertiary channel is maintained at a depth of 50 cm. When groundwater drops below 70 cm, and there is no rain, pump irrigation is provided. Results of the field experiment showed that the maize crop showed similar growth quality at each phase. Land with a planting period of June and July still requires water addition using pump irrigation. It was applied on 14th and 18th August. Moreover, the maize cultivated at the end of April did not require pump irrigation. All treatments have generally similar production with an average magnitude of 8.0 Mg ha-1. The highest production is 8.73 Mg ha-1, which is planted in the first week of July.

Study of the Quality of Biogeotextile Materials as Semi-Organic Mulch on Saline Land

Fitri Wijayanti — 2025-03-25

Degraded land affects almost all ecosystems and can harm the progress and quality of human life, so it needs attention. Saline soil is a land degradation with high salt content that causes toxic effects, increases root osmotic pressure, and inhibits plant growth. One solution is using organic mulch processed into biogeotextiles because it can provide solutions for erosion control and soil stabilization while minimizing negative impacts on the ecosystem. This research was conducted from May to August 2023 in the experimental garden of the Faculty of Agriculture UPN ‘Veteran’ East Java. This study used a group randomized design with one factor, the type of geotextile material consisting of reed grass (RG), straw (ST), pandanus odorifer (PO), and sugarcane bagasse (SB). This research was conducted with a litterbox of 20x20 cm filled with 100 g of biogeotextile material. The results obtained show that pandanus odorifer biogeotextile material is the best biogeotextile material because it can last a long time on the soil surface, but can still be adequately mineralized, according to the results obtained, reducing the C/N ratio and C-Organic but increasing total nitrogen. Decomposition is closely related to the materials’ quality rather than external factors. The quality of the material, namely lignin, organic carbon, C/N ratio, and nitrogen, influences the decomposition process. Furthermore, this technology can be applied to improve soil productivity and to keep soil healthy.