Inorganic fertilizers, which provide nutrients, such as nitrogen (N), phosphorus (P), and potassium (K), are recognized for their rapid-release properties; therefore, the future of rice cultivation will require the development of smart fertilizers (SF). This study focused on creating an NPK-coated fertilizer using ameliorant materials to slow nutrient release and improve rice growth, yield, and Relative Agronomic Efficiency (RAE) in vertisol paddy fields. The research involved soil analysis, fertilizer formulation, and N release tests. Field tests at two locations included 12 treatments, with eight NPK-coated formulas and four controls, each replicated thrice. Fertilizer was applied once before planting or each planting cycle. Observations covered soil properties, NO3- and NH4+ release, agronomic parameters, RAE, and grain nutrient content. Results showed that NPK-coated fertilizers released nutrients more slowly than inorganic ones. Four formulas, T4, T5, T6, and T8, were suitable for the further development, demonstrating RAE values exceeding 104

Background and Aim: Rice straw, a widely available agricultural byproduct globally, has significant potential as a basal diet for livestock. The major challenge lies in obtaining high-protein foliage that can be easily extracted using natural water rather than chemical solvents. This study aimed to assess the ability of distilled water to extract protein concentrate from Indigofera leaves (Indigofera zollingeriana Miq.) and to evaluate its effectiveness in enhancing rumen feed fermentation and digestibility in low-quality rice straw basal diets. Materials and Methods: The study was conducted in two experimental series. Experiment 1 was designed to explore the ability of distilled water to extract protein concentrate from fresh and dry Indigofera leaves by comparing it with the 0.1 N NaOH standard solvent. Experiment 2 focused on the in vitro digestibility of protein concentrates extracted from fresh Indigofera leaves based on optimal findings from experiment 1. Five treatments consisting of 0.5% and 1.0% protein concentrate and two extractants (distilled water and 0.1 N NaOH) were used to extract protein from Indigofera leaves. These extracts were then added to rice straw-based diets. Rice straw without supplements was used as a control. The treatments were arranged using a randomized complete design with five replicates. Results: The results of experiment 1 showed that distilled water was superior to 0.1 N NaOH for extracting protein concentrate from fresh Indigofera leaves, as revealed by higher dry matter, protein yield, total amino acids (AA), and total essential AA (EAA) production. For in vitro experiment 2, supplementation with distilled water-extracted protein concentrates successfully increased rumen fermentation and digestibility in rice straw basal diets, as indicated by higher gas production, total volatile fatty acid, and microbial protein levels compared with 0.1 N NaOH. Conclusion: Findings from this study confirm that Indigofera leaf protein concentrate offers a new alternative for enhancing rumen feed fermentation and the digestibility of low-quality rice straw diets. This study implies that it is an easy, cost-effective, and environmentally friendly approach, particularly beneficial for smallholders, to extract protein concentrate from fresh Indigofera leaves using distilled water and use it to enhance the quality of rice straw for ruminant feed. The limitation of this study is that the Indigofera supplement was established using in vitro digestibility under controlled laboratory conditions, which does not reflect real rumen conditions. Therefore, further studies using in vivo digestibility in ruminant animals are required to confirm the ability of the protein extracted from indigofera to enhance rumen feed fermentation in low-protein basal diets.

The development of digital technology changed the technique of making maps based on manual digitization into automatic digitization. A variety of software that is equipped with additional programs (plug-ins) makes the mapping process even easier because it cuts down on a long series of procedures. This research examines the effectiveness of using 4 machine learning in the Dzetsaka plug-ins on QGIS software, which is open-source software. The four machine learnings are The Gaussian Mixture Model (GMM), Random Forest (RF), Support Vector Machine (SVM), and K-Nearest Neighbors (K-NN). A total of 110 polygons containing 10 training data in each class were created manually based on RGB Sentinel 2 images taken throughout 2019. Next, the training data is divided by 50% for the training model and validation test. Overall, the accuracy of the validation test with confusion matrix by Dzetsaka for 4 machine learning in 2 districts, Rumpin and Kemang (Bogor Regency) reached 90%. Virtual validation resulted in RF consistency producing the best machine learning for the classification of cropland, scarce vegetation, dense vegetation, fallow land, building area, and water body with a total accuracy of more than 74%. These results provide opportunities for the use of the open source for independent mapping of land use and land cover at the district level. The prediction maps are also adequate for describing land use and land cover at the district level.

The idle swamp land of the former mega rice project in Indonesia has the potential for development of paddy field as a response to the global food crisis. Mapping of pyrite (FeS 2 ) in swamp land as the key driver of soil degradation and poor water quality has not been made to establish a strategy for sustainable paddy field practices. The objective of the study was to assess the spatial distribution of pyrite (FeS 2 ) through detailed mapping, and to evaluate soil and water properties associated with the adverse effects of pyrite. Detailed conventional pyrite mapping with a grid system at 1:10,000 scale, covering a large area of 26,588 ha, had been made. A comprehensive analysis of soil chemical, physical and mineralogical properties, pyrite content, and water properties was conducted. The detailed pyrite mapping showed that spatial distribution of pyrite was delineated into six depth classes, in the order of decreasing extent: P3 -moderately deep (>50 - 75 cm) > P4 -deep (>75 - 100 cm) >> P5 -very deep (>100 - 150 cm) > P2 -shallow (>25 - 50 cm) > P6 -exceptionally deep (>150 cm) > P1 -very shallow (0 - 25 cm). These pyrite classes allow zonation management strategy of soils and water table into different depths to avoid pyrite oxidation and its harmful effect. Soils have limited easily weathered minerals (<16 %), implying low inherited soil nutrients. In the topsoils, chemical properties exhibited extreme acidity (pH 3.8 - 4.2), imbalanced cations with excess Mg, low in K and P and Zn, Cu, and Mn micronutrients. The dynamic changes of water properties in network canals showed a drop in pH from 6.0 at the inlet and primary canal to 2.9 and 3.5 in the canal network (secondary > tertiary > quaternary > pyrite collector), as well as the increased Al and SO 4 ions suggests the decrease in quality throughout the canal network. We propose the management strategy for the sustainable establishment of paddy field in pyritic swamp areas including: (i) performing detailed mapping of pyrite classes to guide depth -based pyrite zonation to control water table, (ii) implementing controlled drainage water flow from inlet to various canal networks corresponds to pyrite depth zonation, (iii) applying lime with Ca -rich materials but not dolomite (containing Mg) to improve cation balance, reduce acidity, increase soil pH and suppress ion toxicity, (iv) utilizing adaptive/tolerant rice cultivars to acidity, and (v) application of NPK fertilizer to alleviate nutrient deficiencies. These strategies can be implemented to ensure the sustainability of paddy fields and avoid soil degradation in swamp land.

Early-stage pedogenic processes and formation rates on completely obliterated volcanic landscapes, such as the super explosive 1815 Mount Tambora eruption, have not previously been robustly explored. The objectives of this study were to determine (i) the mineralogical composition of the sand fraction, selected physical and chemical soil properties and potential nutrient reserves after 200 years of pedogenesis, and (ii) chemical weathering indices, rate of soil formation, and rates of C and N accretion. Soil formation was examined for five soil profiles on stable plain/foot slope positions representing the diversity of soils in these landscape positions, which are important for agricultural production. Results showed that the soil mineralogical composition of the sand fraction was dominated by easily weatherable minerals (e.g., labradorite and augite volcanic glass) indicating high potential nutrient reserves (e.g., Ca2+, Mg2+, K+, P) as confirmed by X-ray fluorescence (XRF) analyses. Allophanic material formation was minimal (<2.3%) owing to the preferential accumulation of Al3+ into Al-humic complexes. The low contents of allophanic materials and metal-humus complexes resulted in low Pretention (17.5-43.4%) within the soil solum, with the highest value in surface horizons (33-43%). Morphological features showed rapid solum (A + B horizons) development of 22 to 107 cm. Shallow soils occurred on shallow eruption deposits (consisting of pyroclastic flow underlain by pumice), whereas the deepest soils were found on thick deposit consisting of either trachyandesite pyroclastic or basaltic andesite materials. The chemical index of alteration (CIA) followed the order of A horizons (48.4 +/- 4.6) > B horizons (45.4 +/- 2.4) > C horizons (43.8 +/- 4.2) approximate to tephra/lava (43.1), indicating accumulation of Al oxides and depletion of base cations in the upper horizons. Similarly, the base depletion index (BDI) showed a trend of A horizons (1.13 +/- 0.18) < B horizons (1.25 +/- 0.09) < C horizons (1.34 +/- 0.20) approximate to tephra/lava (1.35), indicating depletion of base cations (Ca2+, Mg2+, K+, Na+) from the soil surface to C horizons. Based on solum depths (A + B horizons) and 200 years of post-eruption soil development, the solum formation rate ranged from 1.2 to 5.3 mm yr(-1). Appreciable stocks of SOC (2.3-12.8 kg C m(-2)) and SON (0.21-0.77 kg m(-2)) accumulated over the 200 year period. Eruption materials from the Mt. Tambora eruption with a precisely known timescale contributed new pedological insights documenting rapid soil formation rates from pyroclastic materials leading to a rapid recovery of soil functions to support agricultural production.

Gender equality is one of the UN sustainable development goals less discussed in soil science in Indonesia. There is limited information regarding soil science education, and the role of women in Indonesia. This study aimed to provide an overview of the issue of gender equality in Indonesian soil science. We surveyed the number of women soil science students, lecturers, and researchers from 2016 to 2020. Twenty-seven soil science undergraduate programs were identified across government-owned universities in Indonesia. The number of students in soil science is steadily increasing in the last five years, each year with about 1500 new students enroll in soil science. The number of female students also increased with an average proportion of 55% in 2020. However, the number of women academics was only 30%, representing a disproportion of gender equity. The Indonesian soil science society had 35% women members. Students still perceive soil science would be better taught by men lecturers as it involves fieldwork. Nevertheless, more students preferred to be supervised by women lecturers. Our data also revealed that women academics had less opportunity to receive Ph.D. degrees, became professors, and occupied leadership positions in the university. We discuss barriers that hinder women's academics careers in Indonesia, including social and cultural values and organizational barriers. Soil science academics should prepare a gender-equal soil science workforce to the growing population. Thus, supporting the Indonesian soil scientists' women and achieving a more gender balance target is vital for accelerating soil science education, enhancing research opportunities, and managing agriculture to support economic growth.

The physical and chemical properties of refused materials in post-mining areas have received in-depth attention, while the mineralogy as a driver of the potential nutrient reserve has been ignored in reclamation practices. The objective of the study was to evaluate mineralogical, chemical, and physical properties and heavy metals of refused materials (spoil and tailings) as the basis for reclamation. Seven representative soil profiles were described and sampled to a depth of 130 cm for various soil analyses and to assess soil limiting factors for crop growth. Eleven forage species were tested in a field plot trial and their adaptability and biomass production against extreme limiting soil properties were evaluated for two consecutive growing seasons. Results showed that tin mining has drastically altered the soil texture from sandy clay loam under native conditions to loamy sand and sand under post-tin mining, resulting in serious unfavourable conditions for crop growth. Potential nutrient reserves have been depleted as revealed by the dominance of quartz minerals with small amounts of tourmaline, opaque minerals, zircon and garnet. Total elemental analysis using X-ray fluorescence (XRF) showed extreme high SiO2 content (92-96%) associated mainly with the dominance of quartz in the mineral constituents, and extremely low contents of Ca, Mg, P, K and S expressed as oxides (< 0.2% altogether). This suggests that all nutrients are a severe constraint for crop growth. Among the analyzed total heavy metals, Cr2O3 contents were high (204-286 mg kg(-1)), while SnO contents were low (0-153 mg kg(-1)). However, the health risk is negligible because they were preserved in the structure of host minerals. Rehabilitation of post-tin mining was successfully performed using various forage types by implementing "a pot planting point system " accompanied by animal manure and complete fertilizer applications. Six out of the eleven forages tested, namely Cynodon dactylon, Pennisetum purpureum cv Mott, Brachiaria decumbens cv Humidicola, Pennisetum purpureum cv Taiwan, Brachiaria decumbens cv Mulato, and Paspalum atratum were recommended based on their high adaptability and significantly higher fresh biomass production (varying from 16.5 to 24.7 ton ha-1 season-1). Findings from this study provide alternatives for forage production systems to support livestock establishment. Soil mineralogy provides important information on nutrient reserves and should be considered part of an integral soil characterization including physical and chemical properties, and heavy metal contents of post-tin mining sites to ensure successful reclamation.

•Newly developed Andisols, fragile Histosols, Inceptisols, Ultisols and Oxisols are dominated soils in Indonesia.•Andisols located at the most densely populated, farmers regard them as the most fertile soils.•Andisols and Histosols can be a carbon sink, potentially removing CO2 from the atmosphere to mitigate climate change.•Ecosystem services of soils in Indonesia are often overlooked, water storage and filter, nutrient cycling, and habitat for microorganisms.•Food estates in Indonesia need soil science knowledge to ensure biomass production.

This study aimed to identify the characteristics of Andisols under tea plantations affected by different Oldeman's agro-climatic zones, of different ages, and containing different types of volcanic ash material. For this study, three tea plantation estates were chosen, the Ciater Site (CTR), Sinumbra Site (SNR), and Sedep Site (SDP), having Oldeman's agro-climatic zones of A, B1, and B2, respectively. Three profiles (CTR-A, CTR-B, and SNR-A) were created from andesitic volcanic ash, and three profiles (SNR-B, SDP-A, and SDP-B) were created from basaltic volcanic ash materials. The CTR-A, SNR-B, and SDP-B profiles were obtained from Holocene parent materials, while the CTR-B, SNR-A, and SDP-A profiles were derived from Pleistocene parent materials. Soil samples were taken from the soil profiles from depths of 0 to 153 cm incrementally, dependent on each soil horizon thickness. The findings of the study reveal that the age of parent materials and the variance in agro-climatic zones result in considerable differences in soil chemical characteristics, such as pH (H2O), base saturation (BS), and organic C, while the qualities of the basaltic and andesitic volcanic ash parent materials were also shown to be unaffected. All Andisol profiles went through cambic weathering processes. Moreover, the key pedogenetic strategies were the production of short-range-order minerals through the leaching of easily dissolved elements and the coprecipitation of SiO2 and Al2O3 gels. Halloysite was formed by the resilication of short-range-order minerals, while gibbsite was formed by desilication. The XRD analysis indicated that amorphous materials predominated with some HIV and kaolinite minerals were also present.

The serious problems of sandy soils for crop development are low water-holding capacity, nutrient retention, and low content of all nutrients. The objective of the study was to increase the nutrient content of sandy soil and evaluate nutrient types that mostly affect the high shallot yield with reasonable economic values. The field experiment was conducted on the upland sandy loam soil. Six treatments consisting of complete nutrients, N-, P-, K-, Mg- and S-omission tests were arranged in a randomly completed block design with four replicates. The observed parameters included soil physicochemical properties, tissue nutrient content, growth, yield, and input-output of shallot cultivation. The results showed that N, P, K, Mg and S application successfully increased shallot bulb, achieving 11.43 t ha−1 on sandy soil. The order of shallot tissue content was K > N > P~Mg > S, where the S, P, N, and Mg are limiting factors, as revealed by significantly lower relative yield (varying from 79 to 88%). The highest weight loss during storage occurred for S-omission treatment (40 to 60%), indicating insufficient S tissue is the most responsible for the quality of shallot. The complete nutrient treatment gave the highest income (7446.09 USD ha−1) with a revenue cost ratio of 2.41 compared to other treatments. The tolerance limit for price reductions that do not cause losses was 58.59%.

Rice production in the karst dryland is still low, due to soil characteristics that lack nutrient availability. Meanwhile, upland rice has received less attention, and it has not been used to its full potential. This study aimed to evaluate the effect of various combinations of inorganic fertilizers, poultry manure, and upland rice varieties on the production and economic value of karst dryland in Gunungkidul, Yogyakarta. This experiment was arranged in a factorial design, with inorganic fertilizers, poultry manure, and upland rice varieties set in a randomized block design with three replications. The first factor was a combination of inorganic and organic fertilizer rates: 72 N kg ha−1 + 26 P2O5 kg ha−1 + 25 K2O ha−1 + 3 t ha−1 organic, 92 N kg ha−1 + 36 P2O5 kg ha−1 + 30 K2O kg ha−1 + 2 t ha−1 organic, 112 N kg ha−1 + 46 P2O5 kg ha−1 + 35 K2O kg ha−1 + 1 t ha−1 organic. The second factor is the upland varieties of Inpago 8, Inpago 10, and Inpago 12 and lowland variety Inpari 42 Agritan GSR, as checked. Based on the study, we concluded that the combination of 92 N kg ha−1 + 36 P2O5 kg ha−1 + 30 K2O kg ha−1 + 2 t ha−1 poultry manure fertilizers with Inpago 8 resulted in an IDR profit of 23,586,000 ha−1, and it is the most recommendable fertilizer and variety combination to be developed in the karst dryland, in consideration of land fertility and sustainability.

Climate and parent material are considered the primary factors determining the distributions of soil clay (secondary) minerals, but their influence has not been rigorously elucidated for tropical volcanic soils. Herein, we investigated soil secondary mineral distributions in volcanic regions of Java and Sumatra islands representing large variations in climatic (mean annual temperature (MAT): 13 to 27 degrees C; precipitation: 1910 to 3950 mm) and parent material conditions (rhyolitic-to-basaltic tephra). Soil secondary minerals were assessed by selective extractions, X-ray diffraction analysis, and differential thermal analysis. Moreover, the thermodynamic stabilities of minerals were evaluated based on the ion activities of equilibrated soil-water suspensions. Factor analysis of climate and soil geochemical (e.g., total Si, Fe and K) properties identified temperature, dry season intensity, and parent material as the primary factors regulating secondary mineral distributions. A negative correlation between oxalate extractable Al and Fe (Al-o and Fe-o) and the temperature factor indicates low temperature promoted the formation and preservation of short-range-order (SRO) minerals and organo-Al/Fe complexes, which resulted in Al-o + 1/2Fe(o) >= 20 g kg(-1) (andic property criterion) at MAT <21 degrees C. Desiccation in the dry season, represented by excess precipitation for the driest quarter of the year, was related to soil H4SiO40 activity of soil-water suspensions. High H4SiO40 activity resulting from intense seasonal desiccation coincided with a higher Si/Al ratio of SRO aluminosilicates (Si-rich allophane) and smectite. In contrast, low H4SiO40 activity enhanced the formation of SRO aluminosilicates with a low Si/Al ratio (Al-rich allophane) and gibbsite. The influence of parent materials was evident in high free Fe(hydr) oxide content in soils derived from mafic materials and the occurrence of mica, which altered to hydroxy-Al interlayered vermiculite under continuous leaching conditions, in soils from felsic materials. Overall, we demonstrated strong temperature and seasonal desiccation controls on secondary mineral distributions in the humid, tropical volcanic soils of Java and Sumatra islands.

Unprecedented terrible and catastrophic disasters on September 28, 2018 triggered by earthquake-induced liquefaction, tsunami and landslide hit Palu, Central Sulawesi, Indonesia. The objective of the study was to assess and evaluate soil mineralogical compositions, properties, heavy metals, and water quality in the areas of post-earthquake-induced liquefaction, tsunami and landslide to provide the basis for agricultural and ecosystem rehabilitation. The soil samples were collected by digging pits after 12-days of disaster at liquefied soils, tsunami sediments, and soil mass motion/landslide for analyses. Water samples for analysis were collected from soil pits, surface flow and new spring. Results showed that the earthquake-induced liquefaction, tsunami and landslide completely reshape the ecosystem landscape and reset the initial soil formation as revealed by the formation of sand boil microrelief, accumulation of tsunami sediment on initial soil surfaces, and redistribution of soil through mass movement on landscapes. Liquefaction increased the number of weatherable minerals in the sand fraction, varying from 28 to 58% as compared to natural soils (17-42%), indicating the high nutrient reserve of pristine liquefied soils in the long-term. The clay minerals were dominated by smectite followed by illite and kaolinite and were not affected by earthquake impacts. The liquefaction increased soil pH and sand fraction and decreased all soil nutrients, which collectively became severe limiting factors for crop establishment. The tsunami resulted in new material deposits of 5-10 cm thick overlain the natural soils in coastal areas. The deposits did not increase the number of weatherable minerals but resulted in the highest electrical conductivity of soil and water, and high concentrations of Ca, Na, Mg and K ions. The concentration of total and availability of all types of heavy metals is below the threshold limits, indicating no potential heavy metal risks in post-earthquake-induced disaster areas. Information of high weatherable minerals and pristine soil properties, water and heavy metals from this study may provide a strong effective basis for rehabilitation and management of agriculture and the environment in post-disaster areas in the long-term period of time.

A detailed spatial inventory of the extent and depth distribution for tropical peatlands is not currently available; however, there is a critical need for new detailed peatland information at national, regional and global scales. Hence, the objective of this study was to provide a rigorous assessment of the extent and depth distribution of tropical peatlands in Indonesia. Data were acquired using a standard method protocol of semi-detailed peatland mapping programs (1:50 000 scale) from 2013 to 2019 for all Indonesian peatlands. Arc-GIS and multi-source satellite images (Landsat ETM-7, Landsat 8 OLI, ALOS, SPOT-5 and SPOT-6/7, and DEM/SRTM) were used to delineate soil-mapping units (polygons) which were supported by depth observation points derived from databases of soil maps 1:50 000 and peatland maps 1:250 000, and then subsequently verified with rigorous groundtruthing. Field transects were made between rivers using systematic distances to observe peat morphological features and thickness resulting in a total of 18,232 data points that included 14,185 new observations and 4,047 legacy points. Our results provide the first systematic census for all Indonesian peatlands and showed that peatlands occupied 13.43 million ha distributed on four islands (million ha): Sumatera (5.85) > Kalimantan (4.54) > Papua (3.01) > Sulawesi (0.024). Peat depth was classified into six categories: D1(50-<100 cm), D2 (100-<200 cm), D3 (200-<300 cm), D4 (300-<500 cm), D5 (500-<700 cm) and D6 (=700 cm), which represented (million ha/peatlands%) 3.17 (24%), 3.44 (26%), 2.61 (19%), 2.32 (17%), 1.29 (10%) and 0.59 (4%), respectively. Exceptionally deep (=700 cm) peatlands occurred on Kalimantan and Sumatera Islands, but were not found on Papua and Sulawesi Islands. The present peatland extent (13.43 million ha) was smaller than previous estimates (pre-2012) that varied from 14.9 to 27.0 million ha. The smaller peatland extent in the present semi-detailed mapping inventory (1:50 000) than previous estimates (pre-2012) may result primarily from (i) segregation of mineral soil inclusions previously considered as peatland, (ii) improved remote sensing and GIS tools (e.g., DEM/SRTM) that prevented misclassification of peatland areas, and (iii) extensive field observation for verification of peatland boundaries and thickness requirements (>50 cm) that eliminated peatlands lost to enhanced decomposition from agricultural management and drainage practices. Our study on peatland extent and thickness provides new detailed information of tropical peatlands in Indonesia (a major region of tropical peatlands) to serve as a baseline for future inventories. The information provided by this study updates peat information for Indonesia (extent and depth), fills a critical knowledge gap for accurately determining regional/global organic C stocks, and informs future directions for the sustainable use and management of tropical peatlands.

Short-term changes in tropical rainforest soil properties and their impact on C cycling following land-use conversion to agriculture have received intensive study. However, long-term, land-use changes have not been explored for tropical Andisols, whose high carbon stocks and several distinctive properties may differ in their response to land-use conversion. Thus, the primary objective of this study was to assess changes in selected soil properties of Andisols in response to long-term (>100 years) changes of land use from tropical rainforests to agriculture. Soils were sampled by horizon to a depth of 110-140 cm in pine forests (PF), tea plantation (TP) and horticultural crops with either intensive cultivation (IH) or bare fallow (FH) cropping systems. Selected physical, chemical and biological soil properties were characterized, including microbial biomass carbon (MBC) and laboratory CO2 mineralization rates. Results showed that land-use change from rainforest to agriculture resulted in increased soil bulk density and meso/micropores that contributed to increased plant-available water retention capacity. Soil carbon and nitrogen stocks in the upper 1 m of soil were higher in agricultural soils (25-29 kg C m(-2); 1.7 - 2.3 kg N m(-2)) than pine forest soil (17 kg C m(-2); 1 kg N m(-2)) with a redistribution of organic matter from topsoil to subsoil horizons. Organic matter quality was also affected by land-use conversion with the horticultural soils having lower rates of carbon mineralization per unit soil carbon (PF > TP > IH > FH) and lower microbial biomass, especially in topsoil horizons. The MBC sharply decreased in the topsoil horizon due to land-use change from forest (330 mg kg(-1)) to agricultural production (<118 mg kg(-1)). The intensive horticultural soil receiving recent additions of horse manure had higher extractable mineral N (especially NO3), reduced P fixation, increased available P, higher pH, and higher concentrations of exchangeable base cations (Ca2+, Mg2+ and K+) and micronutrients (Zn, Mn and Cu). The Andisols in this study demonstrated strong resilience to long-term degradation of soil properties following conversion from rainforest to agronomic land use. Further, this study demonstrates the ability of these Andisols to sequester additional C upon conversion to selected agriculture practices, thereby providing a positive impact on C mitigation.

Effect of long-term wet and dry (redox) cycles attributed to seasonally flooded soils in rotation of rice and upland food crops on soil characteristics is not yet available in modern agriculture. The objective of this study was to assess soil morphological features, mineralogical compositions and dynamic pedogenic processes under rotation of rice and honey-taste sweet potato. Four profiles that experienced redox cycles and one that did not (as a control) were sampled for soil analyses. Results showed that all soil profiles, irrespective of redox cycles, derived from similar parent materials as revealed by the same type of weatherable mineral contents (hornblende, labradorite, hypersthene, and olivine or muscovite), ranging within 27–84%. High proportions of easily weatherable minerals corresponded to the high availability of Ca, Mg, Si, Fe, Mn and Cu nutrients, suggesting the release of nutrient reserves from weatherable minerals. In all soils, the clay fraction contained only the one mineral, halloysite. Long-term redox cycles due to rotation of rice–honey-taste sweet potato resulted in a remarkable pedomorphic feature, i.e. discrete large soft black Mn segregation with the highest accumulation in the middle part of soil profiles. Other pedogenic processes were Ca, Mg, and Si translocation from the upper to lower layers of soil profiles, but Fe was retained in the uppermost two horizons. We proposed a new soil classification ‘Manganic Eutrudept’ as a subgroup category to accommodate the soil property of high soft Mn segregation.

Characteristics of refused materials are prerequisite information required to determine the strategic reclamation of extreme land degradation in post-tin mining areas. The objective of the study was to evaluate mineralogical, chemical, and physical properties and heavy metals of spoil and tailing as the basis for reclamation measures. Seven representative soil profiles were made and sampled to a depth of 130 cm for various soil analyses. Results showed that tin mining has drastically altered the soil texture from sandy clay loam under native conditions to loamy sand and sand under post-tin mining. Mineralogical constituents of refused materials were mainly mineral resistant to chemical weathering, consisting of predominant quartz with small amounts of tourmaline, opaque, zircon and garnet. Total X-ray fluoresce elemental analysis showed extreme high SiO2 content (92-96%) associated mainly with quartz mineral, and extremely low oxides of Ca, Mg, P, K and S (< 0.2% altogether). This suggests all nutrients are severe problems for crops. Type of total heavy metals showed the Cr2O3 was high in sandy tailing (204 - 286 mg kg-1), while the SnO was low (0 -153 mg kg-1) and they were preserved in the structure of host minerals, thereby the health risk is negligible. Based on many serious constraints of soils, the strategic reclamation to recover soil productivity and ecological function was the building up soil organic matter, establishing “pot planting point” technique, complete fertilizer application, and selection of crops with an ability to fix N nutrient from the atmosphere, and adaptive to low soil nutrients.

Extensive areas of Andosols in tropical Indonesia have been subjected to long-term (>100 years) alterations from native forest to agricultural land use. This study assessed the mineralogical and surface charge characteristics of Andosols in West Java, Indonesia and assessed their resilience upon conversion from rainforest (PF1) to tea plantation (TP1) and horticultural practices. Soils developed in basaltic-andesite volcanic ash (<15,000 years B.P.) under an isothermic/perudic soil climate and were classified as Silandic Andosols. The colloidal fraction of all soils was dominated by nanocrystalline/paracrystalline materials (e.g., allophone, imogolite, ferrihydrite) and Al/Fe-humic complexes. Crystalline minerals were a minor component of the clay fraction and followed kaolinite > hydroxyl-Al interlayered vermiculite (HIV) approximate to gibbsite. The colloidal fraction appeared relatively resilient to changes in land use, except for the tea plantation in which allophanic material content decreased and Al-humus complexes increased due to strong soil acidification, and decreased ferrihydrite in the horticultural soils, possibly due to liming and increased organic matter. In spite of the abundance of allophanic materials, Fe (hydr)oxides and organic matter appeared to regulate surface charge characteristics of the colloidal fraction. Net soil charge in PF1 and TP1 soils was positive (pH PZNC). Horse manure and lime amendments to the horticultural soils lowered the PZNC, increased negative charge (CEC) and decreased positive charge (AEC). At ambient soil conditions, CEC increased from <1.2 cmol(c)kg(-1)in PF1 and TP1 soils to 6-20 cmol(c)kg(-1)in soils under horticultural management, while positive charge (AEC) was appreciably higher (0.7-4.3 cmol(c)kg(-1)) in PF1 and TP1 soils than in horticultural soils (<0.6 cmol(c)kg(-1)). This study demonstrated that the colloidal fraction is relatively resilient to land-use change; however, charge characteristics of the variable-charged colloids can be readily altered by soil management practices.

Indonesia produces normal and “honey taste sweet potatoes” (HTSP), but soil properties and climate factors that govern the unique honey taste and its sugar content have not yet comprehensively evaluated. The objective of the study was to assess and evaluate the soil nutrients and climate factors generating honey taste of Cilembu Rancing cultivar. Soils and plant tissues were sampled at different elevations for various macro- and micro-nutrient analyses and that tubers for sugar analysis. Results showed that the most suitable climate to produce the highest vine and tuber weight, and total tuber sugar of the HTSP was monthly temperature of 21–22oC occurring at 870–917 m soil elevation with monthly rainfall of 96-199 mm. The K nutrient was responsible in part to the high production and total sugar as revealed by significantly positive correlation between soil available K against K content of leaves and tubers, fresh weight of vines and tubers, and total sugar of tubers. The honey taste was driven by type of dominant sugar: fructose > sucrose > glucose. The balance of N, P, K, Ca and Mg to support generation of HTSP for Rancing cultivar was 2,067, 25, 304, 1,824 and 260 mg kg-1 soil, respectively. Further, the content of Fe, Mn, Cu and Zn micronutrient was 29, 177, 4 and 2 mg kg-1, respectively. Findings of climate factors and soil nutrients required by HTSP in this study could be used as a guidance to select the new areas for massive development of honey-taste sweet potato.