Organic Matter In Tropical Soils Research Articles

Effect of Nutrient Management Practices on Carbon Pools Following 13 Year of Cropping with Soybean (Glycine max) Based Cropping Systems in Vertisol of Central India

Organic manure application has its significant impact on the soil health. Low organic matter in tropical soils is a major factor contributing to their poor productivity. Soil properties have been continuously influenced by the management practices and land uses, in which latter one has been, identified as profound influence on soil properties especially on soil organic carbon. A thirteen year experiment on soybean based cropping system in a vertisol of central india under organic farming was used for this investigation An investigation was carried out on “Soil organic carbon dynamics under long-term nutrient management in soybean based cropping system” at the Indian Institute of Soil Science, Bhopal on an on-going research project on organic farming. The effect of organic, integrated and inorganic nutrient management was assessed in three cropping systems viz. soybean (JS 335)-wheat (Malwa Shakti), soybean-mustard (Pusa Bold) and soybean-gram (JG 130) on aggregate size fractions, carbon content in aggregate as well as soil organic carbon pools dynamics on a split plot experimental design with three replications. The study relevant to dynamics of soil organic carbon pools revealed higher content of soil organic carbon, labile carbon, water soluble carbon, SMBC as well as dehydrogenase activity that varied between 1.04 and 0.86 percent; 440 and 538 mg kg-1, 52.97 and 70.43; 288 and 375 mg kg-1, 88 and 137 µg TPF g-1 soil d-1, respectively in surface 0-15 cm soil under organic nutrient management.

Evaluation of some microbiological attributes of the soil in two different management systemsEvaluation of some microbiological attributes of the soil in two different management systems

The maintenance of organic matter in tropical soils and the use of soil quality indicators that can express its changes in sustainable agricultural systems is very important for monitoring the health of these ecosystems with high productivity and longevity. The aim of this experiment was to evaluate, through enzymatic responses of microbiological activity, variations resulting from different cultivation systems under sandy soil conditions in western of São Paulo State. In this purpose, the measurement of the parameters microbial biomass carbon (MBC), microbial biomass nitrogen (NBM), dehydrogenase (DNSE), basal respiration (BR) and the metabolic quotient (qCO2) in two culture systems characterized by being a succession of annual crops with soybean/corn (annual crops) and the other under perennial pasture of the genus Urochloa (pasture), respectively. It was verified that the two systems presented different behaviors related to the evaluated microbiological attributes, showing higher values in the evaluated microbial attributes in the area where Urochloa grass was cultivated.

Residual effects of alkalized sewage sludge application on soil quality and sugarcane yield

ABSTRACT The acidification and loss of nutrients and organic matter in tropical soils are indicators of chemical degradation. In such a scenario, alkalized sewage sludge (SS) for fertilization and reclamation of soils is a promising alternative. Here, we evaluate the impact of SS on soil fertility, sugarcane nutrition and yield in three successive crops. The treatments consisted of five rates of SS (0, 10, 20, 30, and 40 t ha−1) and one treatment with mineral fertilizers. The soil characteristics, plant nutrition, and sugarcane yield were assessed. The results showed that SS increased the pH and the sum of bases, reducing exchangeable aluminum and improving chemical soil conditions. SS also increased soil organic matter (SOM), but SOM decreased over time. Likewise, the N and P contents in the soil were decreased with the successive crops. Sugarcane yield increased following SS rates and reduced with each crop cycle. The yields for plant cane, first ratoon, and second ratoon were 174, 94, and 74 t ha−1 at a rate of 40 t ha−1; these values were 75, 19, and 61% higher, respectively, than the mineral fertilization. SS can aid the reclamation of the chemically degraded soil, contributing to sugarcane nutrition and increased yields.

Effect of Organic Matter on the Behavior and Control Effectiveness of Herbicides in Soil

ABSTRACT: With extensive use of herbicides in agricultural areas, the risk of contamination of groundwater and surface water by these products has become a worldwide concern. Practices of application or maintenance of soil organic residues that have begun to be used in agriculture for soil nutrition have demonstrated other benefits besides nutrient supplementation, such as reduced mobility and increased soil degradation of herbicides. Because it is the final destination of herbicides, soil and its constituents, especially organic matter in tropical soils, play a prominent role in processes that encompass the dynamics of herbicide molecules. In this context, it is necessary to know the influence of the organic matter and its constituents on the behavior of the herbicides. This review discusses the main relationships of organic matter in the retention, transport, and transformation processes of herbicides in the soil, as well as the interference in the weed control effectiveness of these products. Because of this, knowing the influence of organic matter in the various processes related to the behavior of herbicides in the soil allows us to adopt more appropriate management practices regarding both weed control and remediation of contaminated areas. However, despite the wide range of information on the subject in the literature, each situation is distinct due to the wide variation in the behavioral response of the products to the different types of organic material present in the soil.

Analysis of soil organic matter in tropical soils with near-infrared spectroscopy (NIRS) and chemometrics

The objective of this study was to predict the concentration of soil organic matter (SOM) in tropical soils using near-infrared spectroscopy (NIRS) for samples measured within a polyethylene bag and without a bag. One hundred and fifty six soil samples from the humid tropics of Tabasco, Mexico with contrasting chemical characteristics were selected. The samples were dried, ground, and sieved through 2 mm and 5 mm screens, and their SOM contents were determined using the Walkley-Black method. The soil samples were packed in polyethylene bags, and SOM was measured directly with and without a bag using a quartz probe (FOSS 5000 model of NIRsystems, DK-3400 Hillerod,Denmark) for a range from 1100 to 2000 nm to obtain a prediction model of SOM. The model for determining SOM for bagged samples had good fit and explained 88% of the variation (0 to 10, 2% of SOM of samples). The model for determining SOM for bag-less samples was not efficient for predicting independent samples and therefore was discarded. The analysis by NIRS was reliable, more rapid, and easier for the determination of SOM in soil samples measured through a plastic bag. El objetivo del presente trabajo fue predecir la concentracion de materia organica del suelo (MOS) de regiones tropicales mediante espectroscopia de infrarrojo cercano (NIRS), en muestras medidas dentro de una bolsa de polietileno y sin esta. Fueron seleccionadas 156 muestras de suelos del tropico humedo de Tabasco, Mexico, por sus caracteristicas quimicas contrastantes. Las muestras fueron secadas, molidas y tamizadas a traves de una malla de 5 y 2 mm y su concentracion de materia organica fue determinada por el metodo de Walkley Black. Las muestras de suelos se envasaron en bolsa Infrade polietileno y se midieron directamente con y sin bolsa con una sonda de cuarzo de un NIRS, modelo FOSS 5000 de NIRsystems, en un rango de 1.100 a 2.000 nm, para obtener un modelo de prediccion del contenido de MOS en muestras dentro de la bolsa y fuera de ella. El modelo para determinar la MOS en muestras dentro de la bolsa presento buen ajuste y explico el 88% de la variacion (0 a 10,2% de SOM). El modelo para materia organica para muestras fuera de la bolsa no resulto eficiente, para predecir muestras independientes, por lo que se descarto. El analisis por NIRS es confiable, mas rapido y sencillo en la determinacion de materia organica en muestras de suelo con bolsa.

Analysis of soil organic matter in tropical soils with near-infrared spectroscopy (NIRS) and chemometrics

Analysis of soil organic matter in tropical soils with near-infrared spectroscopy (NIRS) and chemometrics

Differential response of mineral-associated organic matter in tropical soils formed in volcanic ashes and marine Tertiary sediment to treatment with HCl, NaOCl, and Na 4P 2O 7

Quantitative knowledge of the amount and stability of soil organic matter (SOM) is necessary to understand and predict the role of soils in the global carbon cycle. At present little is known about the influence of soil type on the storage and stability of SOM, especially in the tropics. We compared the amount of mineral-associated SOM resistant to different chemical treatments in soils of different parent material and mineralogical composition (volcanic ashes – dominated by short-range-order aluminosilicates and marine Tertiary sediments – dominated by smectite) in the humid tropics of Northwest Ecuador. Using 13C isotope analyses we traced the origin of soil organic carbon (SOC) in mineral-associated soil fractions resistant to treatment with HCl, NaOCl, and Na 4P 2O 7 under pasture (C 4) and secondary forest (C 3). Prior to chemical treatments, particulate organic matter was removed by density fractionation (cut-off: 1.6 g cm − 3). Our results show that: (1) independent of soil mineralogical composition, about 45% of mineral-associated SOC was resistant to acid hydrolysis, suggesting a comparable SOM composition for the investigated soils; (2) oxidation by NaOCl isolated a SOM fraction with enhanced stability of mineral-bound SOM in soils developed from volcanic ashes; while Na 4P 2O 7 extracted more SOC, indicating the importance of Al-humus complexes in these soils; and (3) recently incorporated SOM was not stabilized after land use change in soils developed from volcanic ashes but was partly stabilized in soils rich in smectites. Together these results show that the employed methods were not able to isolate a SOM fraction which is protected against microbial decay under field conditions and that the outcome of these methods is sensitive to soil type which makes interpretation challenging and generalisations to other soils types or climates impossible.

Analysis of VNIR (400–1100 nm) spectral signatures for estimation of soil organic matter in tropical soils of Thailand

The widely available laboratory spectrometers detect targets at spectral regions restricted to visible and near-infrared (VNIR). The spectral response of soils in this region is predominantly featureless and obstructs the exploitation of absorption features as diagnostic criterion. In this study, polynomial based modelling was developed as an alternative method of estimating soil organic matter (OM) from VNIR spectral region. Forty-one core samples, collected from Lop Buri, Thailand, were subjected to chemical and radiometric analysis. Computations were made across four categories of synthesized bandwidths. The selection procedure identified bands at 960, 1100 and 520 nm as OM sensitive. The widening interval of bandwidth has corresponded with diminishing predictive power, termed ‘bandwidth decay effect’. The use of polynomial models and their validations showed a higher performance than the analysis made with multiple regressions analysis. The polynomial based approach offers a fresh opportunity for modelling other non-photoactive soil nutrient parameters. Furthermore, it may form the basis for integration of spectrometers and satellite sensors, aimed at mapping of non-vegetated soils.

The role and function of organic matter in tropical soils

Soil organic matter (SOM) has many functions, the relative importance of which differ with soil type, climate, and land use. Commonly the most importantfunction of OM in soil is as a reserve of the nitrogen and other nutrients required by plants, and ultimately by the human population. Other important functions include: the formation of stable aggregates and soil surface protection; maintenance of the vast array of biological functions, including the immobilization and release of nutrients; provision of ion exchange capacity; and storage of terrestrial carbon (C). This paper considers the quantity and quality of SOM of soils in the tropics, which are estimated to contain one quarter of the C in the global pool in terrestrial soils, and supports strongly the use of analytical methods to characterizing labile SOM to develop valuable insights into C dynamics. As in other regions, the transformation of tropical lands for agriculture exploits SOM, and in particular nutrient reserves. The process of exploitation is accelerated in the tropics by the necessity to increase agricultural production, largely through agricultural intensification, to overcome inadequate nutrition, to satisfy population growth, and to cope with the limited reserves of arable land. Poverty has an overriding influence on the exploitation and degradation processes. Areas at greatest risk of land degradation are the infertile acid soils of the tropics, which, invariably, are cultivated by the poor. Soil organic matter has a central role in sustainable land management, but perspectives on the roles of SOM differ widely between farmers, consumers, scientists and policy-makers. Some consider SOM as a source of nutrients to be exploited, whereas others can afford to utilize it as a key component in the management of the chemical, biological, and physical fertility of soils. Still others see SOM as a dumping ground for excess nutrients and toxins, or as a convenient store for fossil fuel emissions, particularly CO2. Farmers need sustainable land management systems that maintain OM and nutrient reserves. Nevertheless, many available practices, whether based on indigenous or scientific knowledge, do not meet social and economic criteria that govern farmer behaviour. Much scientific knowledge about the various roles of SOM does not reach farmers and other decision-makers in a form that can be used easily. The biggest challenge to researchers is to engage with clients to pinpoint gaps in knowledge and utilize new and existing information to devise decision support Systems tailored to their needs.

FT-IR Spectroscopy of Organic Matter in Tropical Soils: Changes Induced through Deforestation

This article describes a series of transmission Fourier transform infrared (FT-IR) spectroscopy measurements of soil layers, especially organic soil layers, originating from a tropical forest and from a pasture, which was developed after deforestation of the tropical soil in 1987. Spectral information obtained from forest and pasture soil layers from central Rondônia, Brazil, was analyzed and compared. A variety of bands characteristic of molecular structures and functional groups have been identified for these complex samples. Cluster analysis revealed that such land use change affects the spectroscopic behavior of the organic soil layers. A significantly closer relationship between the pasture soil layers in comparison to the forest soil layers was obtained. This result indicates a higher homogeneity of the intoduced litter from pasture vegetation compared to forest. The application of regression models enabled the estimation of soil parameters, such as organic carbon and nitrogen; the identification and differentiation of organic forest soil horizons; and the determination of the decomposition status of soil organic matter in distinct layers. On the basis of the data presented in this study, it may be concluded that FT-IR spectroscopy is a powerful tool for the investigation of decomposition dynamics and litter quality in tropical soils.

Temperature effects on organic matter and microbial biomass dynamics in temperate and tropical soils

The aim was to investigate whether soils developed under tropical conditions had different organic matter and microbial biomass dynamics than soils developed under temperate ones. Three soils formed under temperate climatic conditions (U.K.) and three under tropical conditions (Brazilian) were selected to be as comparable as possible in terms of organic matter, clay content and pH. They were then incubated moist at 15°C or 35°C for 150 d. Carbon dioxide evolution and microbial biomass were measured at intervals during the incubation. The biomasses in the tropical soils declined more slowly at both temperatures than in the temperate soils, although at 15°C the differences were mainly small. At 35°C the decline was generally much more marked in the temperate soils (60–75% of the initial value) than in the tropical ones (15, 40 and 60%). Soil organic matter was mineralised more rapidly in the temperate than the tropical soils: at 35°C up to 9–10 times more CO 2–C was evolved than was contained in the temperate biomasses during the 150 d incubation. The comparable maximum value for the tropical soils was 4.5 times. These results seem to indicate that the organic matter in the tropical soils was more degraded, or humified, than that in the temperate soils. An attempt to quantify the extent of humification was made using differential thermal analysis (DTA) and thermogravimetric analysis (TG). Both methods also indicated that the organic matter was generally more humified in the tropical than temperate soils. It was concluded that DTA and TG may both be useful techniques in studying soil organic matter dynamics, especially when linked to studies of soil microbial dynamics.

Organic matter in tropical soils: current conditions, concerns and prospects for conservation

Soil organic matter (SOM) plays a central role in maintaining tropical soil fertility. Its conservation and maintenance in tropical cultivation systems is imperative if soil degradation is to be halted and cropping made sustainable. Around 22-23% of global carbon is present in tropical ecosystems but only 2-3% of this is present in the soil. Fluxes of CO2 to the atmosphere from tropical soils after deforestation contributes to the greenhouse effect and could represent a 1-4% increase in the overall steady-state annual CO2 release to the atmosphere. The composition of SOM is extremely diverse, with active, or labile, fractions decomposing in a matter of months while the more resistant, or nonlabile, fractions remain in soil for many years. SOM plays a central role in providing good soil structure, in supplying nutrients and in providing ion exchange capacity in tropical soils. Organic matter decomposition rates in tropical soils are generally faster than in temperate soils because decay of the nonlabile fraction is generally faster. Changes in tropical land use have profound effects on SOM status. Tropical deforestation causes significant losses of soil carbon and nitrogen which tend to decline further under continuous cultivation. Reasons for declines in soil fertility include accelerated soil erosion, loss of litter influx after canopy removal and enhanced decomposition and nutrient mineralization rates after forest clearance. A wide range of soil management techniques have been designed to conserve and improve SOM stocks in tropical cultivation systems. These include agroforestry techniques, intercropping with legumes and the use of mulches and other organic inputs. While many of these techniques look promising in terms of improved crop yields, there is urgent need for research on how these practices alter the physical, chemical and biological processes and conditions of tropical soils.

On the organic matter in tropical soils.

Light-absorption curves are given of organic matter extracted from different horizons of humus-iron podzols and brown podzolic soils on liparitic tuff and brown forest and gray-brown podzolic soils, latosols and acid brown earths on andesitic tuff, in support of theories on the role of organic matter in soil-forming processes under a humid tropical climate. (Abstract retrieved from CAB Abstracts by CABI’s permission)