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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 ( B horizons (45.4 ± 2.4) > C horizons (43.8 ± 4.2) ≈ 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) ≈ 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.

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°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 (Alo and Feo) 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 Alo + 1/2Feo ≥ 20 g kg−1 (andic property criterion) at MAT

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 (

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 ( hydroxyl-Al interlayered vermiculite (HIV) ≈ 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 (pHPZNC). 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

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. Additional keywords: crop rotation, pedomorphic Mn feature, redox cycles, Si accumulation, weatherable minerals. Received 16 July 2019, accepted 12 October 2019, published online 6 November 2019, Introduction Intensive agricultural practices for crop rotations and multiple cropping systems can have profound impacts on pedological processes and soil property changes. These practices have taken place for a long [...]

About 116 million Mg of rice husk, a byproduct of rice milling, are produced worldwide annually. Rice husk could be used as a soil amendment, but little attention has been given to the effect of its application and dynamic properties in soils. A study was, therefore, conducted to determine: (i) the effect office husk compost applications on soil organic C content; and (ii) the changes in organic C functional groups with time and under different environments using solid-state cross polarization magic angle spinning (CP/MAS) [sup.13]C nuclear magnetic resonance (NMR) spectroscopy. Experiments were performed under different environments (laboratory, greenhouse, and field) for 15 to 24 mo, using an Oxisol treated with various rates of rice husk compost (RHC) and the soils were periodically sampled and analyzed. Results showed that RHC significantly increased the organic C of the Oxisol and changes in its chemistry occurred after 24 mo (laboratory) and 12 mo (greenhouse and field). Solid-state CP/MAS [sup.13]CNMR showed C types derived from RHC were dominated by cellulose, with specific characteristics of wall-ordered structure (very sharp and well- resolved peaks at O-alkyl and di-O-alk71C regions), thereby signifying stabilized organic C. The RHC decomposition was faster in the order field > greenhouse > laboratory conditions as revealed by the high values of decomposition indices (hydrophobicity/hydrophilicity ratio, alkyl/O-alkyl C ratio, and aromaticity) and the high magnitude of normalized cumulative C loss for conditions with a high decomposition rate. The cumulative C loss was 71 to 80% (depending on the application rates) in the field, 71 to 74% in the greenhouse, and 48 to 62% in the laboratory after 12 mo. Under all conditions, the remaining RHC-derived C was still significantly higher than the control treatment at the end of the experiments, implying that RHC can be used to increase organic matter in soils. doi: 10.2136/sssaj2008.0296

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%. [ABSTRACT FROM AUTHOR]

[Display omitted] • New pyrite mapping plays a crucial role for soil zonation management in swamp land. • Integrated management of pyrite, soil, water, and nutrients can support rice cultivation. • Swamp lands have low bearing capacity and are susceptible to subsidence. • Soils develop from alluvium with low pyrite overlying coastal sediment with high pyrite. • Significant Al and SO 4 increased while pH decreased from inlet to water canal networks. 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. [ABSTRACT FROM AUTHOR]

• Post-tin mining left legacy of idle land and environmental degradation. • Sandy texture, dominantly quartz minerals, and low nutrients are major crop constraints. • Cr and Sn heavy metals were mainly occluded in host-minerals and low in their available form. • Pot planting point is a new introduced system to manage post-tin mining areas. • Using innovative technology, post-tin mining areas can be suitable for forage development. 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 SiO 2 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, Cr 2 O 3 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. [ABSTRACT FROM AUTHOR]

Upland agriculture in Indonesia mainly relies on Ultisols and Oxisols, which have serious problems resulting from severe erosion and low organic-matter content. The objectives of the study were (i) to assess the effect of long-term rehabilitation techniques on soil organic carbon (SOC) and maize yields of a desurfaced Ultisol and (ii) to assess the effect of short-term rehabilitation techniques on desurfaced Oxisol properties and soybean yields. A 7-year field experiment was conducted on artificially desurfaced Ultisol grown with maize (Zea mays L.). The results showed that rehabilitation techniques using cattle manure, rice straw mulch or Mucuna sp. mulch were successful in restoring SOC content of degraded Ultisol to its initial natural state. All sources of organic-matter rehabilitations significantly increased maize yields on an Ultisol. Rehabilitations of degraded Oxisol under glasshouse conditions using phosphorus (P) fertilizer, organic matter, basic slag, and lime could increase cation exchange capacity (CEC) and nutrient availability and suppress Al toxicity. At the same time, soybean yields increased 11-14, 2-10, 1-5, and 1-3 times, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Earthquake induced-liquefaction, landslide and tsunami severely changed landscape features. • Liquefaction increased weatherable soil minerals suggesting high natural nutrient reserves. • Tsunami deposited new sediment layer and increased soluble salt and electric conductivity. • Low content of all soil nutrients are major crop limiting factors in post-disaster areas. • Heavy metals in whole soils were below a threshold limit, indicating no health risk. 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. [ABSTRACT FROM AUTHOR]

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, costeffective, 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. [ABSTRACT FROM AUTHOR]