Mineralogical and charge properties of volcanic ash soils from west Sumatra, Indonesia

Four volcanic ash soi1 from two toposequences along Mt Marapi and Mt Talaniau, west Sumatra were studied in order to characterize their mineralogical and charge properties. In all the soils, the silt fraction is composed mainly of gibbsite, cristobalite and feldspars, while the clay fraction is composed mainly of cristohalite, feldspars and halloysite. Gibbsite is only present in the clay fraction of the soils from Mt Talamau, while opal-A is only found in the clay of the soil from Mt Marapi. Allophane contents, computed from Si and Al extracted by ammonium oxalate and pynophosphate, are lower in the surface horizons than in the subsoil This is related to higher amounts of organic matter in the topsoil Due to higher rainfall, the soils of Mt Talamau are more weathered than those of Mt Marapi. This is reflected by lower allophane and higher ferrihydrite contents in the soils of Mt Talamau. In all the soils, the surface horizons have lower pH,, value than die under lying B-horizons. The AEC is higher in the subsoil than in the topsoil, having values of 0.3 -1.1 cmol, /kg soil

Influence of organic and inorganic soil amendments on corn root growth and soil chemical properties

One of the main constraints to corn production on a highly weathered acid soil is aluminum (Al) toxicity. High Al concentration in acid soils restricts root growth by inhibiting cell elongation and cell division. The objective of this study was to determine the effects of inorganic arid organic soil amendments on corn root growth and soil chemical properties A laboratory experiment was conducted using Bungor series soil (Typic Paleudult) surface sampled (0 - 20 cm) from Puchong farm. Aliquot of the soil (600 g) was treated with legume residues (1% w/w), chicken manure (1% w/w), GML (4 t had), gypsum (4 t ha-1) and control The treated soils were moistened at field capacity (0 25 kg H20 kg-1 soil) and allowed to react for 7 days. Corn seeds (Zea mays L.) were sown and after 5 days root length was measured The results showed that soils amended with GML or chicken manure gave relatively high root length compared to other treatments. The GML and chicken manure treatments increased soil pH and decreased both the soil exchangeable Al and Al-saturation Chicken manure had an additional ameliorative effect over lime in that it increased soil exchangeable Ca, Mg and K

Impact of agriculture on chemical properties of soils on basalt from Mindanao, the Philippines

Uncultivated and cultivated soils from Mindanao, the Philippines were sampled and studied to determine the impact of agriculture on their chemical properties The results of the study showed that cultivated soils, having lost some organic matter due to oxidation, have a lower CEC and a higher point of zero charge pH). The capacity of these soils to retain cations has decreased to a certain extent. In the subsoils of both soil types, there is a tendency for soil pH to coincide with pH, reflecting development of positive charge in the soil of that zone The sum of exchangeable bases and Al (ECEC) is found to be a good estimate of the EC of the soils

Increasing rice production using different lime sources on an acid sulphate soil in Merbok, Malaysia

Acidity is released in high amounts when pyrite-bearing sediments in the coastal plains of Malaysia are drained for development, either agriculture or otherwise. The soils formed from these materials are called acid sulphate soils, which are characterized by low pH and high exchangeable Al that adversely affect plant growth. A study was conducted with the objective of increasing rice yields on these soils under rain-fed condition in Merbok, Kedah, Malaysia, using various lime sources. The acid sulphate soil was treated with ground magnesium limestone (GML), hydrated lime and liquid lime at specified rates. Paddy variety MR 219 was tested in a field experiment as this variety is the most common variety grown in Malaysia. Prior to treatments, the pH of water sample in the rice field was 3.7, while Al concentration was 878 µM. Thus, rice plants grown under these conditions would suffer from H+ and Al3+ stress without amelioration, thus retard and/or minimize rice growth and yield. In the first season (1st season) rice plants were affected by drought during the vegetative period, while in the subsequent season (2nd season), they were infested with rice blast fungus (Magnaporthe grisea). In spite of that, however, the rice yield was 3.5 t ha-1 based on the application of 4 t GML ha-1, which was almost equivalent to the average national yield of 3.8 t ha-1. As a result, it was noted that the ameliorative effects of lime application in the 1st season had continued to the 2nd season. Liming at 4 t GML ha-1 incurs high cost to the farmers. However, the yield obtained is worth the effort and cost

FTIR and XRD analyses of highly weathered Ultisols and Oxisols in Peninsular Malaysia

For this study, four soil series with two depth levels (0-15cm, 15-30cm) were collected namely: Bungor, Kuala Brang, Segamat and Kuantan Series. The former two represent Ultisols, while the latter two represent Oxisols in Malaysia. All the samples were subjected to Fourier transmission infrared (FTIR) and X-ray diffraction analysis to determine the functional groups and mineralogical composition. All the soils were found to be acidic in nature (pH 3-5) with Al toxicity, which is an indication of low fertility. From the FTIR analysis, hydroxyl (OH-) functional group showed the presence of kaolinite [Al2Si2O5 (OH)4], halloysite and gibbsite [Al(OH)3]in both Ultisols and Oxisols. In addition, the carboxylate (C=O) stretching band (Si-O) silicate impurities confirmed the dominance of kaolinite in both soil types. The XRD analysis showed the presence of kaolinite as the major constituent in both Ultisols and Oxisols under study. Besides that, gibbsite, quartz and mica were common in the Ultisols, while mica, goethite and hematite were in trace amount in the Oxisols. Cation exchange capacity which ranged from 7.5 to 12 cmolckg-1 were low for all the soils, while exchangeable Al were above the threshold value for the growth of Al sensitive crops. This may indicate the potential of Al toxicity in the soils. Base saturation was in the range of 1.3 to 10.9%, which was very low. All soils were deficient in available P (<9.96 mg kg-1). Meanwhile, free iron (Fe2O3)contents were the lowest in Bungor (43 g kg-1) and the highest in Kuantan with the value of 419 g kg-1, indicative of hematite dominance shown supported by XRD analysis. Analysis of variance showed significant differences among exchangeable base cations, carbon, nitrogen and Fe oxides in the topsoil at p<0.05. The soils were acidic and too low in macronutrients (Ca2+, Mg2+ and K+) to sustain agricultural production. Thus, applying appropriate amendments and/or fertilizers containing necessary nutrients is required to enhance soil fertility for crop production

Increasing negative charge and nutrient contents of a highly weathered soil using basalt and rice husk to promote cocoa growth under field conditions

Technology intervention is a key success to restore properties and productivities of a highly weathered soil (Oxisols). The main challenge is to find materials with the ability to generate soil negative charge, release various nutrients and suppress toxic elements. The objective of this study was to increase negative charge and nutrient content, and suppress Al and Mn toxicities of an Oxisol using finely ground basalt and rice husk compost (RHC) to promote cocoa growth under field conditions. Factorial field experiment of 4 × 4 used finely ground basalt and rice husk compost and arranged in a randomly complete block design and planted to cocoa as a test crop. Finely ground basalt and rice husk compost were incorporated to the soil at 0–20 cm depth and rates varied from 0 to 20 t ha−1 each. Soils were periodically sampled for 24 months for analyses of soil negative charge, organic C content, various cations, pH and toxic elements. Results showed the rice husk compost (RHC) application significantly increased soil organic C content. The solid state cross polarization magic angle spinning 13carbon nuclear magnetic resonance (CP/MAS 13C NMR) indicates RHC application was able to increase soil organic C functional groups (O-alkyl, di-O-alkyl and carboxyl C), accompanied by the appearance of aromatic, alkyl and methoxyl C as new functional groups. The carboxyl C plays a major role in generating soil negative charge, suggesting RHC is suitable to restore organic C and negative charge of Oxisols. Basalt, RHC and their combination were able to increase markedly the negative charge of Oxisols as revealed by the decreases in pH0 and point zero net charge (PZNC) values. The decrease in pH0 and PZNC values resulted in the increase of net negative charge of an Oxisol from 0.8 (a control soil) to 2.8, 4.1 and 5.0 cmolc kg−1 for basalt, RHC and their combinations, respectively. In situ soil solution study (a new technique) under field conditions showed basalt and RHC applications either singly or in combination significantly increased the concentrations of Ca, Mg, K, Na and Si, while concentrations of toxic Al and Mn significantly reduced below a toxic level. Overall improvement of Oxisol chemical properties attributed by basalt and RHC applications significantly increased cocoa growth as revealed by the increase in height and stem diameter of cocoa which are two to three times faster than the control within a 24-month period

Ammonium and potassium exchange in acid tropical soil

High precipitation and low soil cation exchange capacity (CEC) of highly weathered acidic tropical soils require large amounts and many rounds of fertilization to increase the potential of these soils from leaching losses of soil ammonium (NH4+) and potassium (K+). This study was conducted to evaluate the exchange properties of natural and synthetic zeolites on soil NH4+ and K+. A Bungor Series soil (Typic Paluedults) was taken from a depth of 0 to 5 cm for this leaching experiment. Each soil treatment was added either with equal amounts of NH4+ or K+ and treated with and without zeolites. The treated soil was then leached with deionised water for 20 days and the soil leachate was collected at 5­day interval, to analyze for NH4+ and K+ concentration. The results of this study showed that all types of zeolites were able to reduce substantial leaching losses of soil NH4+ and K+. The natural zeolites were better than the synthetic zeolites in retaining these cations. The study has demonstrated that zeolites could be used as an effective soil amendment to reduce leaching losses of soil NH4+ and K+ in acid tropical soils with low CEC