scholarly journals CARBONO ORGÂNICO E NITROGÊNIO TOTAL NAS FRAÇÕES GRANULOMÉTRICAS E HÚMICAS EM SOLOS SOB DIFERENTES TEXTURAS

Nativa ◽  
2018 ◽  
Vol 6 (6) ◽  
pp. 575
Author(s):  
Gisele Cristina de Castro ◽  
Cristiane Ramos Vieira ◽  
Oscarlina Lúcia dos Santos Weber

A decomposição e distribuição dos componentes da matéria orgânica são influenciados diretamente pela textura do solo e podem se dar de forma diferenciada ao longo do perfil de solo. Diante disso, desenvolveu-se experimento para avaliar o teor de carbono orgânico (CO) e de nitrogênio total (NT) nas frações granulométricas e húmicas de solos sob diferentes texturas. Foram coletadas amostras em cinco quadrantes, nas profundidades de 0-20, 20-40, 40-60 e 60-100 cm. Essas amostras foram secas e passadas em peneira de 2,0 mm para os fracionamentos físico e químico. O fracionamento físico foi realizado por meio de ultrasom e as frações húmicas através da extração alcalina. O teor de CO foi determinado pela digestão sulfocrômica a quente seguida de titulação com sulfato ferroso amoniacal, enquanto o teor de nitrogênio foi obtido pela digestão seguida de destilação e titulação. Os teores de CO foram maiores na fração > 53 μm e os de NT na fração < 53 µm. A fração ácido húmico (FAH) teve o maior teor de carbono e a fração humina (FHum) teve o menor teor. A relação extrato alcalino (EA/Hum) variou de 22,09 a 24,76 g Kg-1 indicando predomínio da fração húmica na camada superficial.Palavras-chave: fracionamento físico e químico, matéria orgânica, granulometria do solo. ORGANIC CARBON AND TOTAL NITROGEN IN GRANULOMETRIC AND HUMIC FRACTIONS IN SOILS UNDER DIFFERENT TEXTURES ABSTRACT: The decomposition and distribution of the organic matter components are directly influenced by the soil texture and can occur differently along the soil profile. Therefore, an experiment was developed to evaluate the organic carbon (OC) and total nitrogen (TN) content of the granulometric and humic fractions of soils under different textures. Samples were collected on five quadrants, at depths of 0-20, 20-40, 40-60 and 60-100 cm. These samples were dried and passed through a 2.0 mm sieve to be submitted to the physical and chemical fractionations. The physical fractions were obtained by means of ultrasound and the humic fractions through the alkaline extraction. The OC content was determined by hot sulfocromic digestion followed by titration with ammoniacal ferrous sulfate, while the nitrogen content was obtained by digestion followed by distillation in semi-microdistiller and titration. The OC contents were higher in the fraction > 53 μm and TN in the fraction < 53 μm. The humic acid fraction (HAF) had the highest carbon content and the humic fraction (HUMF) had the lowest content. The alkaline extract ratio (AE /HUM) ranged from 22.09 to 24.76 g Kg-1 indicating predominance of the humic fraction in the surface layer.Keywords: physical and chemical fractionation, organic matter, soil granulometry.

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 208
Author(s):  
Małgorzata Szostek ◽  
Ewa Szpunar-Krok ◽  
Renata Pawlak ◽  
Jadwiga Stanek-Tarkowska ◽  
Anna Ilek

The aim of the study was to compare the effect of conventional, simplified, and organic farming systems on changes in the content of soil organic carbon, organic matter fractions, total nitrogen, and the enzymatic activity. The research was conducted from 2016–2018 on arable land in the south-eastern part of Poland. The selected soils were cultivated in conventional tillage (C_Ts), simplified tillage (S_Ts), and organic farming (O_Fs) systems. The analyses were performed in soil from the soil surface layers (up to 25 cm depth) of the experimental plots. The highest mean contents of soil organic carbon, total nitrogen, and organic matter fractions were determined in soils subjected to the simplified tillage system throughout the experimental period. During the study period, organic carbon concentration on surface soil layers under simplified tillage systems was 31 and 127% higher than the soil under conventional tillage systems and organic farming systems, respectively. Also, the total nitrogen concentration in those soils was more than 40% and 120% higher than conventional tillage systems and organic farming systems, respectively. Moreover, these soils were characterised by a progressive decline in SOC and Nt resources over the study years. There was no significant effect of the analysed tillage systems on the C:N ratio. The tillage systems induced significant differences in the activity of the analysed soil enzymes, i.e., dehydrogenase (DH) and catalase (CAT). The highest DH activity throughout the experiment was recorded in the O_Fs soils, and the mean value of this parameter was in the range of 6.01–6.11 μmol TPF·kg−1·h−1. There were no significant differences in the CAT values between the variants of the experiment. The results confirm that, regardless of other treatments, such as the use of organic fertilisers, tillage has a negative impact on the content of SOC and organic matter fractions in the O_Fs system. All simplifications in tillage reducing the interference with the soil surface layer and the use of organic fertilisers contribute to improvement of soil properties and enhancement of biological activity, which helps to maintain its productivity and fertility.


2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2419
Author(s):  
Marden Daniel Espinoza Guardiola ◽  
José Frutuoso Vale Júnior ◽  
Edmilson Evangelista da Silva ◽  
Celeste Queiroz Rossi ◽  
Marcos Gervasio Pereira

The crop-livestock integration (CLI) and crop-livestock-forest integration (CLFI) management systems, have been shown to be viable approaches for increasing carbon sequestration in soils, resulting in the improvement of physical and chemical soil attributes. The objective of this study was to evaluate the chemical attributes and organic matter in soils under Natural Forest (NF) converted to different uses and managed differently: rotational pasture area (PAST), crop-livestock integration (CLI), and crop-livestock-forest integration (CLIF). The research was conducted at the São Paulo farm, in Iracema, located in the south-central region of the state of Roraima, Brazil. The studied soil type was classified as Ultisol. Soil samples were taken by opening ditches and examining layers at 0.1-m depth intervals from surface to 0.60-m depth. Total organic carbon (TOC), chemical and granulometric fractionation of soil organic matter (SOM), oxidizable fractions, and light organic matter in water were analyzed. Our results showed low levels of the analyzed chemical elements, a characteristic of a soil with low natural fertility. This matches conditions inherent in source material, weathered by high rainfall, a warm and humid climate, and flat topographic relief. In the 0-0.1 m layer, the PAST and CLI systems had the highest TOC contents relative to the other systems studied. At other depths, there were no statistical differences among TOC levels. The highest concentration of C in the particulate fraction (POC) was noted in the surface layer in all management systems. The pasture system had the highest concentration POC in the top 0.10 m. Our results also showed that the upper 0.10 m of soil in NF contained the lowest content of organic carbon associated with mineral (MOC) relative to the managed agrosystems. In addition, humin provided the largest contribution to SOM in all evaluated management systems. The crop-livestock integration (CLI) and crop-livestock integration forest (CLIF) systems, emerged as a strong alternative to carbon incorporation and subsequently the improvement of physical and chemical soil attributes. The objective of this work to evaluate the chemical attributes and organic matter in soils under Natural forest (NF) converted into different use and management systems: pasture (PAST), crop-livestock Integration (CLI) and crop-livestock Integration forest (CLIF). The research was conducted at São Paulo farm in Iracema, located in the Center-South region of the State of Roraima, Brazil. The soil studied was classified as Argissolo Amarelo Distrófico. The samples were taken by the opening of trenches in layers of 0-0.10, 0.10- 0.20, 0.20- 0.40, and 0.40-0.60 m depth. Total organic carbon (TOC), chemical and granulometric fractionation of soil organic matter (SOM), oxidizable fractions and organic matter in water were analyzed. The results showed low levels of the analyzed chemical elements which characterizes soils with low natural fertility, which matches the conditions of the source material, high rainfall and regional temperature, as well as the flat local relief. In the 0-0.1 m layer, the PAST and CLI systems had the highest TOC contents when compared to the other systems studied, in the other depths there were no statistical differences between the TOC levels. The highest amount of C in the particulate fraction (COp) was verified in the surface layer in all evaluated management systems. The pasture area was the system with the greatest contribution of COp to the depth of 0-0.0 m. In relation to the carbon content associated with minerals (COam), the results showed that the depth of 0-0.05 m NF area presented the lowest levels when compared to the other systems. Regarding the humic substances, there was a larger contribution of humin in all evaluated systems.


Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 133 ◽  
Author(s):  
KL Sahrawat

The mineralizable nitrogen pool in wetland rice soils plays a dominant role in the nitrogen nutrition of rice even in fertilized paddies. There is a lack of information on how different soil properties affect ammonification of organic nitrogen in wetland rice soils. Surface samples of 39 diverse Philippine soils representing a wide range of pH, organic matter and texture were studied to determine the relationships between ammonification of organic nitrogen and soil properties. Simple correlation analysis showed that ammonium production was correlated highly significantly with total nitrogen (r = 0.94**), organic carbon (r = 0.91**) and C/N ratio (r = -0.46**), but it was not significantly correlated with cation exchange capacity, clay or pH. Multiple regression analayses showed that organic matter (organic carbon and total nitrogen) accounted for most of the variation in mineralizable nitrogen. These results suggest that organic carbon content is a good index of mineralizable nitrogen in tropical wetland rice soils.


2016 ◽  
Author(s):  
Juan Velásquez ◽  
Arístide Márquez ◽  
Ivis Fermín ◽  
Fabiola López ◽  
Deudedit Hernández ◽  
...  

This research aims to evaluate some chemical parameters of surface sediments of La Restinga coastal lagoon, located in Margarita Island, Nueva Esparta State, Venezuela. Using classical methodology for geochemical studies, grain size and texture of sediment percentage of organic carbon and total organic matter, as well as calcium carbonate were analyzed. Additionally, the concentrations of total nitrogen, total phosphorus and aliphatic hydrocarbons were determined. The results showed that in La Restinga lagoon sedimentary sandy texture dominate above sandy-loam and sandy-clay. The percentages of total organic carbon, total organic matter and calcium carbonate respectively varied as follows: 1.70-25.53%, 11.10-82.10% and 2.93-44.01%. Concentrations of 282.10-1571.80 mg kg-1 in total nitrogen, 419.50-2033.70 mg kg-1 in total phosphorus and 5.65-63.18 mg kg-1 for aliphatic hydrocarbons were determined. The total organic matter in the lagoon La Restinga is distributed based on the fine particles of sediment and the presence of mangroves, in turn calcium carbonate, was associated mainly to contributions from organisms with calcareous shell. The low values of the ratio NT/PT (under 5) suggest limitation of nitrogen in the ecosystem, and natural or anthropogenic enrichment of phosphorus in the sediment. The levels found of certain aliphatic hydrocarbons, are not considered as contamination levels as established by CARIPOL (1980), except in the eastern end of the main body of the lagoon. According to the points made in this study, we can infer that La Restinga Lagoon showed symptoms of degradation product of human intervention in the ecosystem.


2020 ◽  
Vol 119 (2) ◽  
pp. 053
Author(s):  
María Paz Salazar ◽  
Rafael Villarreal ◽  
Luis Alberto Lozano ◽  
María Florencia Otero ◽  
Nicolás Guillermo Polich ◽  
...  

Soil organic carbon (SOC) is an important factor for soil quality diagnosis. Physical and chemical fractionation of SOC are useful to characterize SOC, because some fractions are more sensitive indicators of the effects of different management practices. The aims of this study were (i) to determine values of SOC and different fractions of SOC at different depths and positions in an Argiudoll of the Argentinian Pampas under NT, and (ii) to determine the relation between physical and chemical fractions of SOC. In an experimental plot located in Chascomús, we determined SOC content, humic acids (HA), fulvic acids (FA), humins, coarse and fine particulate organic carbon (POCc and POCf) and mineral associated organic carbon (MOC), at different depths and in the row and inter-row. The content of SOC and different SOC fractions, as well as the contribution of each fraction to SOC showed a vertical variation. The contribution of HA and POCc (newer and more labile fractions) to SOC was larger in the surface than in deeper layers, while humins’ (older and more recalcitrant fraction) contribution to SOC increased with depth, and the contribution of FA, POCf and MOC to SOC remained relatively constant. There was no effect of row and inter-row in SOC content and composition. FA content was correlated to POCc, HA content to POCc and POCf and humins to MOC.


Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 263 ◽  
Author(s):  
PP Cavanagh ◽  
AJ Koppi ◽  
AB Mcbratney

Reducing cultivation may improve many soil physical and chemical properties of a red-brown earth. A trial was set up in 1986 on a red-brown earth near Forbes, N.S.W., comparing direct-drilling and conventional-cultivation crop establishment techniques. The surface soil (0-100 mm) was sampled at the end of the third year and assessed for macropore structure, infiltration characteristics, bulk density, pH, electrolytic conductivity, organic carbon and total nitrogen content. Cultivation degraded some desirable soil physical properties as indicated by data obtained from image analysis and infiltration. Bulk density did not mirror differences in macroporosity. Organic carbon, total nitrogen and electrolytic conductivity levels were higher in direct-drilled soil in comparison to conventionally tilled soil. It ib concluded that the improvement of soil chemical and physical properties afforded by a reduction in tillage would lead to an increase in soil water infiltration rate and storage.


Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 263
Author(s):  
PP Cavanagh ◽  
AJ Koppi ◽  
AB Mcbratney

Reducing cultivation may improve many soil physical and chemical properties of a red-brown earth. A trial was set up in 1986 on a red-brown earth near Forbes, N.S.W., comparing direct-drilling and conventional-cultivation crop establishment techniques. The surface soil (0-100 mm) was sampled at the end of the third year and assessed for macropore structure, infiltration characteristics, bulk density, pH, electrolytic conductivity, organic carbon and total nitrogen content. Cultivation degraded some desirable soil physical properties as indicated by data obtained from image analysis and infiltration. Bulk density did not mirror differences in macroporosity. Organic carbon, total nitrogen and electrolytic conductivity levels were higher in direct-drilled soil in comparison to conventionally tilled soil. It ib concluded that the improvement of soil chemical and physical properties afforded by a reduction in tillage would lead to an increase in soil water infiltration rate and storage.


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