Aggregates Characterization and Its Associated Organic Carbon in Two Contrasting Lowland Rice Soils of West Bengal

Aims: The present study investigated the effect of lowland rice soils of two regions viz. new alluvial and red-laterite on aggregate characterization and their associated organic carbon (SOC). Study Design: Randomized block design (RBD). Place and Duration of Study: New alluvial soils were collected from Jangipara block of Hooghly, West Bengal and Red-laterite soils were collected from Raghunathpur block of Purulia, West Bengal during 2017-18. Methodology: For each soil types (New alluvial and Red-laterite) five locations were identified and soil samples were collected from three depths i.e. 0-10, 10-20 and 20-30 cm. The aggregate characteristics i.e. water-stable aggregates (WSAs), mean weight diameter (MWD), aggregate stability and aggregate size fractions along with the distribution of carbon in those aggregate size fractions were critically studied. Results: The aggregate size as well as the stability decreased with increasing soil depth from 0 to 30 cm in both soils. New alluvial soils showed higher aggregate stability than red-laterite soils. Mean weight diameter (MWD) values of new alluvial soils were 34, 29 and 87% more than red-laterite soils at 0-10, 10-20 and 20-30 cm depth, respectively. Presence of higher amount of clay and organic matter in new alluvial made the difference in structural coefficient. The surface soil (0-10 cm) had more coarse aggregate (Cmac A >2000μ) fraction, however, microaggregates (<250μ) were dominant in lower depths in both soils. Water stable aggregates (WSA) in surface soils of new alluvial and red-laterite were 57 and 36%, respectively and were decreased with depth. Red-laterite produced higher micro aggregates as compared to new alluvial soils. Coarse macro aggregate fractions (>2000μ) retained maximum amount of soil organic carbon in both soils however, coarse micro aggregate associated carbon (Cmic AC<250μ) was captured in lower depths. New alluvial soils yielded aggregates with higher in diameter and stability coefficient that is due to higher amount of carbon stored in aggregates. Conclusion: The abundance of macro aggregate of New alluvial soils indicates better soil physical quality than Red-laterite soil which was dominated in higher micro aggregates leads to poor in structure and susceptible to water erosion.

Soil Carbon and Structural Quality in Crop Rotations under No-tillage System

Abstract The no-tillage system associated with crops rotation affects the dynamics of soil organic matter, influencing the formation, reorganization and stabilization of aggregates and the carbon content (C) into soil aggregates. The aim of this study was to evaluate the effect of crop rotations under no-tillage system on C content and soil aggregation. The experiment was conducted at the Paraná Agronomic Institute in Ponta Grossa, PR, Brazil. The treatments consisted of six crop rotations, in a 3-year cycle, arranged in a randomized block design with four replications. Soil samples were collected at layers of 0-5, 5-10 and 10-20 cm. The aggregate classification was determined by the wet sieving methodology, and the Weighted Mean Diameter (WMD), Geometric Mean Diameter (GMD) and Aggregate Stability Index (ASI) were calculated. The C content in the aggregates was determined by wet oxidation. The results were submitted to analysis of variance and Tukey test at 5% probability. There was no difference among crop rotations for aggregate classes and aggregation indexes, but were higher in surface, decreasing in depth. The carbon content in the aggregates did not differ among crop rotations, but presented stratification in the soil profile, decreasing in depth. The cycle of three years with crop rotation was insufficient to express possible changes in soil C content and aggregation.

Atributos físicos e químicos de agregados pedogênicos e de coprólitos de minhocas em diferentes classes de solos da Paraíba / Physical and chemical attributes of pedogenic aggregates and earthworm casts in different soil classes of Paraíba

A estrutura do solo é constituída de agregados pedogênicos e biogênicos, formados respectivamente pela hierarquização de agregados e pela ação da macrofauna, sobretudo a das minhocas. Neste estudo, objetivou-se a comparação entre agregados do solo (pedogênicos) e coprólitos de minhocas (biogênicos) de diferentes tamanhos e classes de solos. As coletas de amostras indeformadas de solos e coprólitos de minhocas (Pontoscolex corethrurus Muller, 1857) foram realizadas em quatro solos de classes diferentes do Estado da Paraíba (Latossolo Amarelo, Argissolo Vermelho Amarelo, Luvissolo Crômico e Nitossolo Vermelho). As caracterizações físicas e químicas de agregados e coprólitos foram realizadas após secagem à sombra e separação em três classes de diâmetros (20,0 - 9,52; 9,52 - 6,35 e 6,35 - 4,76 mm). A granulometria mostrou ser similar para cada tipo de agregado (pedogênico e biogênico), independentemente do tamanho dos agregados. Em geral, os coprólitos apresentaram maiores proporções de argila, silte e areia fina e menor proporção da fração areia grossa, maior estabilidade e maiores teores de carbono orgânico e cátions trocáveis, comparativamente aos agregados pedogênicos. Os resultados refletem um processo genético peculiar e sugerem a importância dos agregados biogênicos como indicadores da qualidade do solo.

The soil structure is composed by pedogenic and biogenic aggregates, formed respectively by aggregate hierarchy and macrofauna activity, especially by earthworms. The objective of this study was to compare soil aggregates and earthworm casts with different aggregate-size classes and soil classes. The sampling of undisturbed soil and earthworm casts (Pontoscolex corethrurus, Muller, 1857) was made in four soils of different classes in the State of Paraíba (Oxisol, Ultisol, Alfisol and Nitisol). The chemical and physical evaluations of aggregates and earthworm casts were determined after dry and split into three aggregate-size classes (20.0 to 9.52, 9.52 to 6.35 and 6.35 to 4.76 mm). The particle-size distribution was similar to aggregates and earthworm casts, independent of aggregate-size classes. Earthworm casts had higher proportions of clay, silt and fine sand, lower coarse sand, higher physical stability and more organic carbon and cations contents than the pedogenic aggregates. These results show a peculiar genetic process that makes biogenic aggregates an important indicator of soil quality.

Changes in some soil properties at different incubation periods after tobacco waste application.

In this study, changes in organic carbon (OC), basal soil respiration (BSR), nitrate nitrogen (NO3-N), electrical conductivity (EC) and aggregate stability (AS) of a clay loam soil due to tobacco waste (TOW) application were monitored for 240 days. After incorporating 5% TOW into soil according to oven dry weight basis, soil samples were incubated at field capacity for 20, 40, 80, 140 and 240 days under a greenhouse condition. TOW application significantly increased all soil properties over the control treatment. Soil OC and AS values had significant positive correlations each other and with the other soil properties. Soil OC, BSR and AS values significantly increased from 0.12%, 0.03 μg CO2-C g-1 dry soil 24 hr and 20.7% in control treatment to 1.13%, 3.7 μg CO2-C g-1 dry soil 24 hr and 54.4% in TOW treatment, respectively, in 20 days. While the highest NO3-N (1780 ppm) was found in 40 days, the highest EC (3.35 dS m-1) was in 240 days after TOW application. Disaggregation occurred in all treatments after 20 days of incubation due to probably the more substrate demands of microorganisms in soil.

Propriedades físicas e teor de carbono orgânico de um latossolo vermelho-amarelo do cerrado, sob diferentes coberturas vegetais / Physical properties and organic carbon of a savannah red-yellow latossol under different plant covers

Os Latossolos têm sido largamente utilizados para a produção agrícola no Brasil. Nestes solos, cada vez mais a vegetação nativa vem sendo substituída por culturas agrícolas, pastagens e, nos últimos anos, grandes áreas têm sido plantadas com essências florestais. Este trabalho teve objetivo de avaliar o efeito de diferentes usos: cerrado, pastagem, pinus e eucalipto, nas propriedades físicas de um Latossolo Vermelho Amarelo. Foram avaliadas a estabilidade de agregados, teor de matéria orgânica, densidade do solo e de partículas e porosidade do solo. Os resultados mostraram que houve influência do uso do solo em algumas propriedades. O diâmetro médio ponderado (DMP), em geral, foi menor na camada de 20-30 cm, com exceção da área sob pinus, que apresentou resultado maior. O DMP no cerrado apresentou menor valor, a partir da camada de 10-20 cm. O teor de matéria orgânica foi maior na camada de 0-5 cm e semelhante nas outras camadas em todos os sistemas de uso. A densidade do solo (Ds) foi maior e a densidade de partículas (Dp) foi menor na área sob pastagem. Para todas as coberturas avaliadas, a Dp foi menor na camada de 0-5 cm. A porosidade do solo diminuiu a partir da camada de 10-20 cm, com exceção na pastagem que apresentou porosidade semelhante em todas as camadas estudadas.

The oxisol has been widely used for agricultural productivity in Brazil. On these soils, native vegetation has been substituted for crops, grasses and in the last years a huge area has been planted with forest plants. The aim of this paper was to evaluate the effect of different uses: savannah, grasses, pinus and eucalyptus, in different depth on soil properties of a red-yellow Latossol. The soil properties evaluated were: aggregate stability, soil organic carbon, bulk and particle density and porosity. The results showed that there was effect of the different plant covers in the depth on all soil properties studied. The mean weight diameter (DMP), in general, was lower at layer of 20-30 cm, with exception of pinus area which showed similar results in all layers. The DMP at savannah area showed lower values from layer of 10-20 cm. Soil organic carbon was higher at layer 0-5 cm and similar in the other soil layers for all plant covers. The bulk density (Ds) was higher and the particle density (Dp) was lower on soil under grasses. In layer of 0-5 cm the Dp was lower in the all plant covers. Soil porosity decreased from layer of 10-20 cm for all plant covers, with exception of grasses which had similar soil porosity at all studied soil layers.

Aplicação de dejeto suíno e estrutura de um latossolo vermelho sob semeadura direta / Pig slurry application and structure of a red latosol under no tillage

Objetivou-se, neste trabalho, estimar o efeito da aplicação de doses crescentes de dejetos suínos, em atributos físicos do solo. O experimento localizado em Campos Novos, SC, foi conduzido num Latossolo Vermelho Distroférrico, no delineamento experimental em blocos casualizados, com quatro repetições, com os tratamentos: testemunha (0); adubo solúvel (AS); combinação dejeto e adubo solúvel (DS); dejeto líquido suíno aplicado nas doses de 50, 100 e 200 m³ ha-1. Desde 2001 foi cultivado milho e aveia preta, sob sistema de semeadura direta. A amostragem do solo foi realizada em janeiro de 2006, nas camadas de 0-5; 5-10; 10-20 cm de profundidade, para determinação de carbono orgânico, densidade, estabilidade de agregados, macroporos, microporos e porosidade total. A aplicação de dejeto suíno nas doses de 50 e 100 m³ ha-1, reduziu a estabilidade de agregados do solo em relação à testemunha sem adubação. Os demais atributos físicos do solo e o teor de C orgânico não foram modificados pelos tratamentos, indicando que o uso agrícola do dejeto suíno, nas condições estudadas, mantém a qualidade física do solo.

The objective of this study was to assess the effects of crescent doses of pig slurry on physical soil properties. The experiment is carried out in Campos Novos, SC, southern Brazil, on a red distroferric latosol, with a completely random blocks experimental design and four replicates, with the following treatments: control (0); soluble fertilizer (SF); combination of pig slurry and soluble fertilizer (SS); pig slurry applications of 50, 100 and 200 m³ ha-1. Since 2001, maize and black-oat were cultivated under no tillage soil management. Soil samples were collected in January 2006, from 0-5; 5-10; 10-20 cm deep, to analyze organic carbon, soil density, aggregate stability, macro, micro and total porosity. The application of 50 and 100 m³ ha-1 of pig slurry decreased soil aggregate stability, in relation to the control treatment with no fertilization. The other physical properties and organic carbon contents had no effect on the treatments, demonstrating the pig slurry application under these tested conditions maintains the soil physical quality.

Atributos do solo sob pastagens em sistema de sequeiro e irrigado / Soil attributes under pasture system with and without irrigation

A pecuária é uma das atividades econômicas mais importantes da região do cerrado, sendo que o sucesso dessa atividade é dependente do sistema de manejo e de gramíneas forrageiras adaptadas às condições edafoclimáticas da região. Objetivou-se, neste tabalho, avaliar os atributos do solo em áreas sob pastagens com capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia) e braquiarão [Brachiaria brizantha (Hochst ex A. Rich.) Stapf. cv. Marandu], em sistema de sequeiro e irrigado no município de Rio Verde, GO. O experimento foi instalado no Centro Tecnológico Comigo, em um Latossolo Vermelho-Amarelo Distrófico típico, em 16 parcelas com 450m² cada. Adotou-se o delineamento em blocos completamente casualisados, referindo-se aos quatro tratamentos: capim-Tanzânia e braquiarão com e sem irrigação, com quatro repetições. Foram realizadas análises de atributos físicos (estabilidade de agregados) e químicas (pH, cálcio, magnésio, potássio, fósforo, acidez potencial, capacidade de troca catiônica, saturação por bases e conteúdo de matéria orgânica). Os atributos químicos variaram em ambas as profundidades, decorrentes principalmente da ação da calagem e adubação do solo independente da ausência ou presença de irrigação. Os tratamentos com capim-Tanzânia e braquiarão sem irrigação apresentaram os maiores teores de matéria orgânica e tiveram os maiores valores do diâmetro médio geométrico (DMG). A maior porcentagem dos agregados ficou retida na peneira de > 2,0mm de malha. A irrigação não afetou a produção de massa seca do capim-Tanzânia e braquiarão.

The livestock production is one of the most important economic activities in the Brazilian savanna and its success depends on the management system used as well as the use of grasses adapted to the edaphoclimatic conditions of the region. Therefore, the aim of this work was to evaluate the soil attributes under pasture with Tanzania grass (Panicum maximum Jacq. cv. Tanzania) and bread grass [Brachiaria brizantha (Hochst ex A. Rich.) Stapf. cv. Marandu], with and without irrigation, in the municipality of Rio Verde, Goiás State, Brazil. The experiment was carried out on an oxisol soil at the Comigo Technological Center, in 16 plots of 450m² each. The experimental design used was the completely randomized blocks with four replications. The treatments consisted of two grass species, Tanzania grass (Panicum maximum) and bread grass (Brachiaria brizantha) and two irrigation treatments, with and without irrigation. The following attributes were determined: aggregate stability, pH, calcium, magnesium, potassium, phosphorus, potential acidity, cation exchange capacity, base saturation, and organic matter content. The chemical attributes varied in both layers mainly due to the liming and fertilization of the soil, independently of the irrigation system. The treatments with Tanzania grass and bread grass without irrigation presented the highest organic matter content and the highest values of DMG. Most of the aggregates had a diameter larger than 2.0 mm. The irrigation management did not affect the dry mass of the grasses studied.

Recuperação da qualidade estrutural, pelo sistema plantio direto, de um Argissolo Vermelho / Soil structural quality restoration by no-tillage system of a Hapludalf

Solos com quantidades elevadas de areia no horizonte A são pouco resistentes aos processos de degradação, dependendo do sistema de cultivo utilizado. Este trabalho objetivou avaliar a degradação de um Argissolo Vermelho derivado de granito, localizado na microbacia Passo do Pilão no município de Pelotas/RS, cultivado no sistema de preparo convencional e sua recuperação pelo sistema de plantio direto, comparado ao campo e à mata nativa. Em área de lavoura, foi iniciado um experimento em abril de 1995, com a semeadura de aveia preta (Avena strigosa) + ervilhaca peluda (Vicia vilosa), para implantar os sistemas de preparo convencional e plantio direto. Uma área com campo pastejado e outra com mata nativa foram amostradas para comparar a qualidade do solo com as áreas cultivadas. Foram amostradas as camadas de 0-0,05m, 0,10-0,15m e 0,20-0,25m para determinar granulometria, porosidades, densidades, retenção de água, estabilidade e distribuição do tamanho de agregados e teor de carbono orgânico. Os sistemas de cultivo aumentam a densidade e reduzem a porosidade total, a microporosidade, a retenção e a disponibilidade de água, em relação aos sistemas campo e mata nativa. O preparo convencional reduz o teor de matéria orgânica e a estabilidade dos agregados e o plantio direto, após cinco anos, aumenta pouco o teor de matéria orgânica na camada superficial, mas aumenta sensivelmente a estabilidade de agregados para valores próximos dos sistemas campo e mata nativa. A estabilidade dos agregados teve relação direta com o teor de matéria orgânica até um patamar próximo de 25g kg-1. A densidade do solo, a macroporosidade, o parâmetro S, o teor de matéria orgânica e a estabilidade dos agregados são bons indicadores das mudanças que ocorrem entre os sistemas de uso do solo. No Argissolo derivado de granito, houve recuperação das propriedades relacionadas com a estabilidade da estrutura, mas nas relacionadas com densidade e porosidade do solo a recuperação ...

Soils with high sand content in the A horizon are prone to degradation processes, depending on management system used. This study had as objective to evaluate the degradation of a Hapludalf formed from granite, located in the Passo do Pilão watershed in Pelotas county, cultivated under conventional system, and its recovery by no-tillage system, compared to two native systems, namely grass field and forest. The experiment was setup in an agricultural area, in April of 1995, with the cultivation of Avena strigosa plus Vicia vilosa, both for conventional system and no-tillage. An area under native grasses and another with native forest were sampled for comparison. Soils samples were colleted from the layers of 0-0.05m, 0.10-0.15m and 0.20-0.25m, to determine the soil texture, porosity, densities, water retention, aggregate stability and distribution, and organic carbon content. The cultivation systems increase the soil bulk density and reduce total porosity, microporosity, water retention and availability, compared with native systems such as grass field and forest. The conventional system reduces organic carbon content and aggregate stability, whereas no-tillage, after five years, increases, somewhat, the organic carbon content in the surface layer, but increases aggregate stability to values near of those for native systems. The aggregate stability had direct relationship with organic carbon content up to an upper limit of 25g kg-1. The bulk density, macroporosity, S parameter, organic carbon content and aggregate stability are good indicators of the changes observed in the soil management systems. For the Hapludalf formed from granite, there was recovery of the properties related to soil structure stability, but in those related to soil bulk density and porosity no recovery was observed.

Evolução de propriedades físicas do solo em função dos sistemas de manejo em culturas anuais / Evolution of physical properties of soils according to tillage system on annual crops

Para assegurar a sustentabilidade do sistema produtivo, o manejo do solo deve manter as propriedades físicas do solo o mais próximo das condições originais em que este se encontrava na natureza. Esta revisão sintetiza os efeitos de três sistemas de manejo de solo (convencional, mínimo e direto) em culturas anuais sobre as propriedades físicas do solo como densidade, porosidade, resistência à penetração, velocidade de infiltração, condutividade hidráulica, compressibilidade, nível de matéria orgânica, tamanho e estabilidade de agregados. O plantio direto apresenta vantagens nos níveis de matéria orgânica, na estabilidade de agregados, na compressibilidade e na condutividade hidráulica, mas tem suas limitações quanto à densidade do solo e resitência à penetração. O preparo mínimo à base de escarificação apresenta-se especialmente eficiente na velocidade de infiltração, na condutividade hidráulica e na resistência à penetração, sendo intermediário entre convencional e direto nos demais aspectos. O preparo convencional, principalmente em condições tropicais, apresenta os indicadores menos favoráveis para propriedades físicas do solo, normalmente mais distante das condições da cobertura vegetal original e, em certas situações, aproximando-se do preparo mínimo e do plantio direto. Nesse particular, os sistemas se aproximam em alguns aspectos das condições naturais, mas não reproduzem as condições das coberturas naturais originais de mata, cerrado ou campos nativos, mesmo que estando na direção da sustentabilidade

Soil management must keep the soil physical properties next to the original conditions in natural systemsto assure the sustainability of agricultural systems. This review synthesizes the effects of conventionaltillage, minimum tillage and no-tillage systems of annual crops, on soil physical properties as bulkdensity, porosity, soil resistance to root penetration, infiltration speed, hydraulic conductivity,compressibility, organic matter level, soil aggregate size and stability. No-tillage presents advantages onorganic matter level, size and stability of aggregates, compressibility and hydraulic conductivity but has limitations on bulk density and resistance to root penetration. Minimum tillage with chisel plow isspecially efficient in relation to infiltration speed and hydraulic conductivity, and intermediate betweenconventional and no-tillage in other aspects. Conventional tillage with total pulverization of soil surface,mainly on tropical conditions, presents the less favorable scores on soil physical properties, close tominimum tillage and no-till only in few circumstances, and frequently the most different from the naturalconditions. The conservation systems by their side, despite of similarities in some aspects with naturalconditions, are not able to reproduce the conditions of natural forests, savannas or natural pastures, butare in the sustainability direction