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H S Gupta - One of the best experts on this subject based on the ideXlab platform.
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soil aggregation and organic matter in a Sandy Clay Loam soil of the indian himalayas under different tillage and crop regimes
Agriculture Ecosystems & Environment, 2009Co-Authors: Ranjan Bhattacharyya, A. K. Srivastva, Sandip Kundu, Ved Prakash, H S GuptaAbstract:Abstract In agricultural systems, maintenance of soil organic C (SOC) has long been recognized as a strategy to reduce soil degradation. Management practices, such as conservation tillage and legume-based cropping sequences, have the potential to enhance SOC and total soil N (TSN) content and improve soil aggregation. We examined the effects of three tillage systems [conventional tillage (CT), minimum tillage (MT) and zero tillage (ZT)] and three crop rotations [soybean–wheat (S–W), soybean–lentil (S–L) and soybean–pea (S–P)] on SOC and TSN storage and their distribution within aggregate-size fractions in Indian Himalayas, where almost all above-ground crop residues were removed. A field experiment was conducted on a Sandy Clay Loam soil (Typic Haplaquept; Eutric Cambisols) from 1999 to 2003 near Almora, India. Results indicate ZT significantly (P
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changes in soil nutrient content and enzymatic activity under conventional and zero tillage practices in an indian Sandy Clay Loam soil
Nutrient Cycling in Agroecosystems, 2008Co-Authors: B L Mina, A. K. Srivastva, Supradip Saha, Narendra Kumar, H S GuptaAbstract:For 3 years we studied the impact of different tillage practices on biological activity, major nutrient transformation potential in a Sandy Clay Loam soil and crop yield in a Himalayan subtemperate region. Field agroecosystems with a rotation of two grain crops per year (lentil-finger millet) received four different tillage practices: zero–zero (ZZ), conventional–conventional (CC), zero–conventional (ZC), and conventional–zero (ZC) tillage. Most of the chemical parameters were influenced by the type of tillage practice. ZZ increased the soil organic carbon (SOC) content in the upper soil layer from 6.8 to 7.5 mg g−1 soil. Similarly available N was increased by 6.1% in ZZ over CC. Under zero tillage soil generally had higher P and K content than under other tillage practices. Soil carbohydrate content was also increased from 3.1 to 4.9 mg g−1 and dehydrogenase activity was also increased significantly under continuous zero-tillage practice. Alkaline phosphatase, protease, and cellulase were most sensitive to changes due to tillage management. Alkaline phosphatase and protease activity was greater (by 9.3–48.1%) in the zero-tillage system over conventional practice. In contrast, cellulase activity was more (by 31.3–74.6%) in conventional practice than other management practices. We suggest that, by understanding the effects of tillage on soil biological properties, soil quality and agricultural sustainability of subtemperate hill agro-ecosystems may be improved.
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effect of tillage and crop rotations on pore size distribution and soil hydraulic conductivity in Sandy Clay Loam soil of the indian himalayas
Soil & Tillage Research, 2006Co-Authors: Ranjan Bhattacharyya, Sandip Kundu, Ved Prakash, H S GuptaAbstract:Abstract Tillage management can affect crop growth by altering the pore size distribution, pore geometry and hydraulic properties of soil. In the present communication, the effect of different tillage management viz., conventional tillage (CT), minimum tillage (MT) and zero-tillage (ZT) and different crop rotations viz. [(soybean–wheat (S–W), soybean–lentil (S–L) and soybean–pea (S–P)] on pore size distribution and soil hydraulic conductivities [saturated hydraulic conductivity ( K sat ) and unsaturated hydraulic conductivity { k ( h )}] of a Sandy Clay Loam soil was studied after 4 years prior to the experiment. Soil cores were collected after 4 year of the experiment at an interval of 75 mm up to 300 mm soil depth for measuring soil bulk density, soil water retention constant ( b ), pore size distribution, K sat and k ( h ). Nine pressure levels (from 2 to 1500 kPa) were used to calculate pore size distribution and k ( h ). It was observed that b values at all the studied soil depths were higher under ZT than those observed under CT irrespective of the crop rotations. The values of soil bulk density observed under ZT were higher in 0–75 mm soil depth in all the crop rotations. But, among the crop rotations, soils under S–P and S–L rotations showed relatively lower bulk density values than S–W rotation. Average values of the volume fraction of total porosity with pores 3 m −3 under CT, MT and ZT; and 0.592, 0.610 and 0.626 m 3 m −3 under S–W, S–L and S–P, respectively. In contrast, the average values of the volume fraction of total porosity with pores >150 μm in diameter (pores draining freely with gravity) were 0.124, 0.096 and 0.095 m 3 m −3 under CT, MT and ZT; and 0.110, 0.104 and 0.101 m 3 m −3 under S–W, S–L and S–P, respectively. Saturated hydraulic conductivity values in all the studied soil depths were significantly greater under ZT than those under CT (range from 300 to 344 mm day −1 ). The observed k ( h ) values at 0–75 mm soil depth under ZT were significantly higher than those computed under CT at all the suction levels, except at −10, −100 and −400 kPa suction. Among the crop rotations, S–P rotation recorded significantly higher k ( h ) values than those under S–W and S–L rotations up to −40 kPa suction. The interaction effects of tillage and crop rotations affecting the k ( h ) values were found significant at all the soil water suctions. Both S–L and S–P rotations resulted in better soil water retention and transmission properties under ZT.
Cimelio Bayer - One of the best experts on this subject based on the ideXlab platform.
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carbon sequestration in two brazilian cerrado soils under no till
Soil & Tillage Research, 2006Co-Authors: Cimelio Bayer, Joao Mielniczuk, Ladislau Martinneto, Aurelio Pavinato, Jeferson DieckowAbstract:Abstract A considerable proportion of the 200 million hectares of the Brazilian Cerrado is suitable for annual crops but little is known about the effects of tillage on the C dynamics of Cerrado soils. We evaluated the role of two representative Cerrado Oxisols (350 and 650 g Clay kg−1) as sources or sinks of atmospheric C when managed under three tillage systems (conventional tillage (CT), reduced tillage (RT), and no-till (NT)) in 8- and 5-year long-term experiments. A literature review was also carried out and the mean C sequestration rates in no-till soils of tropical and subtropical regions of Brazil were calculated and compared with values for soils from temperate regions of the world. The original C stocks in 0–20 cm layer of soils under native Cerrado were higher in the Clayey (54.0 Mg ha−1) than in the Sandy Clay Loam soil (35.4 Mg ha−1), suggesting a higher physical stability of organic matter associated with variable Clay minerals in the Clayey Oxisol. The original C stocks of the native Cerrado soils appear not to have decreased after 23 years of conventional tillage in the Sandy Clay Loam Oxisol, except when the soil had been subjected to erosion (15% loss of C), or after 25 years in the Clayey Oxisol. Compared to conventionally tilled soil, the C stocks in no-till Sandy Clay Loam Oxisol increased by 2.4 Mg ha−1 (C sequestration rate = 0.30 Mg ha−1 year−1) and in the Clayey Oxisol by 3.0 Mg ha−1 (C sequestration rate = 0.60 Mg ha−1 year−1). The mean rate of C sequestration in the no-till Brazilian tropical soils was estimated to be 0.35 Mg ha−1 year−1, similar to the 0.34 Mg ha−1 year−1 reported for soils from temperate regions but lower than the 0.48 Mg ha−1 year−1 estimated for southern Brazilian subtropical soils. Considering the large area (about 70 million hectares) of the Cerrado which is currently used and potentially available for cropland, the adoption of no-till systems could turn the Cerrado soils into a significant sink for atmospheric C and contribute to the mitigation of global climate change.
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organic matter storage in a Sandy Clay Loam acrisol affected by tillage and cropping systems in southern brazil
Soil & Tillage Research, 2000Co-Authors: Cimelio Bayer, Joao Mielniczuk, Telmo Jorge Carneiro Amado, Ladislau Martinneto, Sandra Beatriz Vicenci FernandesAbstract:Soil organic matter decline and associated degradation of soil and environmental conditions under conventional tillage in tropical and subtropical regions underline the need to develop sustainable soil management systems. This study aimed first to evaluate the long-term effect (9 years) of two soil-tillage systems (conventional tillage: CT, and no-tillage: NT) and two cropping systems (oat (Avena strigosa Schreb)/maize (Zea mays L.): O/M; and oatacommon vetch (Vicia sativa L.)/ maizeacowpea (Vigna unguiculata (L.) Walp): OaV/MaC without N fertilization on total organic carbon (TOC) and total nitrogen (TN) concentrations in a Sandy Clay Loam Acrisol in southern Brazil. The second objective was to assess soil potential for acting as an atmospheric CO2 sink. Under NT an increase of soil TOC and TN concentrations occurred, in both cropping systems, when compared with CT. However, this increase was restricted to soil surface layers and it was higher for OaV/MaC than for O/M. The OaV/MaC under NT, which probably results in the lowest soil organic matter losses (due to erosion and oxidation) and highest addition of crop residues, had 12 Mg ha ˇ1 more TOC and 0.9 Mg ha ˇ1 more TN in the 0‐30.0 cm depth soil layer, compared with O/M under CT which exhibits highest soil organic matter losses and lowest crop residue additions to the soil. These increments represent TOC and TN accumulation rates of 1.33 and 0.10 Mg ha ˇ1 per year, respectively. Compared with CT and O/M, this TOC increase under NT and OaV/MaC means a net carbon dioxide removal of about 44 Mg ha ˇ1 from the atmosphere in 9 years. NT can therefore be considered, as it is in temperate climates, an important management strategy for increasing soil organic matter. In the tropicals and subtropicals, where climatic conditions cause intense biological activity, in order to maintain or increase soil organic matter, improve soil quality and contribute to mitigation of CO2 emissions, NT should be associated with cropping systems resulting in high annual crop residue additions to soil surface. # 2000 Elsevier Science B.V. All rights reserved.
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effect of no till cropping systems on soil organic matter in a Sandy Clay Loam acrisol from southern brazil monitored by electron spin resonance and nuclear magnetic resonance
Soil & Tillage Research, 2000Co-Authors: Cimelio Bayer, Joao Mielniczuk, Ladislau Martinneto, Carlos Alberto CerettaAbstract:In weathered tropical and subtropical soils organic matter is crucial for soil productivity and its quantity depends heavily on soil management systems. This study evaluated the effect of no-till cropping systems on organic matter content and quality in a Sandy Clay Loam Acrisol soil (Paleudult in US taxonomy) from Southern Brazil. Ten cropping systems with varying additions of C and N were conducted for 12 years (from 1983 to 1994). The addition of crop residues increased total organic carbon (TOC) and total nitrogen (TN) in the soil at 0‐17.5 cm depth, and this increase was directly related with C and N added or recycled by the systems. The crop residues added to the soil were associated with reduced semiquinone free radical concentration, detected by electron spin resonance (ESR), in the organo-mineral aggregates <53 mm and humic acid (HA) samples, in the soil at 0‐2.5 cm depth. This showed that stable organic matter originating from crop residues was less humidified than the original soil organic matter. Results obtained from organo-mineral aggregates showed a higher amplitude (highest and lowest values were 5.47 and 2.09 10 17 spins g ˇ1 of TOC, respectively) of semiquinone free radical concentration than HA samples (highest and lowest values were 2.68 and 1.77 10 17 spins g ˇ1 of HA, respectively). These data showed that alterations due to tillage in soil organic matter characteristics, e.g., humification degree can be better identified through a combination of soil physical fractionation and spectroscopic analysis. Semiquinone content in the HA samples, detected by ESR, related significantly to aromaticity, as measured by nuclear magnetic resonance (NMR) of 13 C. Management systems including no-till and cropping systems with high C and N additions to the soil improved its quality in Southern Brazil. # 2000 Elsevier Science B.V. All rights reserved.
Ranjan Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.
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conservation tillage impacts on soil aggregation and carbon pools in a Sandy Clay Loam soil of the indian himalayas
Soil Science Society of America Journal, 2012Co-Authors: Ranjan Bhattacharyya, M D Tuti, Sandip Kundu, J K Bisht, J C BhattAbstract:1 Soil Sci. Soc. Am. J. 76:2012 Posted online 27 Dec. 2011 doi:10.2136/sssaj2011.0320 Received 13 Sept. 2011. *Corresponding author (ranjan_vpkas@yahoo.com). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Conservation Tillage Impacts on Soil Aggregation and Carbon Pools in a Sandy Clay Loam Soil of the Indian Himalayas Soil & Water Management & Conservation
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conservation tillage and fertilization impact on soil aggregation and carbon pools in the indian himalayas under an irrigated rice wheat rotation
Soil Science, 2012Co-Authors: Ranjan Bhattacharyya, M D Tuti, J K Bisht, J C Bhatt, Hari S GuptaAbstract:AbstractSoil conservation and carbon sequestration are critical issues in the Indian Himalayas. This study, conducted from 2005 through 2009 on a Sandy Clay Loam soil near Almora, India, with two tillage (conventional tillage [CT] and zero tillage [ZT]) and five fertilization management practices (1
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soil aggregation and organic matter in a Sandy Clay Loam soil of the indian himalayas under different tillage and crop regimes
Agriculture Ecosystems & Environment, 2009Co-Authors: Ranjan Bhattacharyya, A. K. Srivastva, Sandip Kundu, Ved Prakash, H S GuptaAbstract:Abstract In agricultural systems, maintenance of soil organic C (SOC) has long been recognized as a strategy to reduce soil degradation. Management practices, such as conservation tillage and legume-based cropping sequences, have the potential to enhance SOC and total soil N (TSN) content and improve soil aggregation. We examined the effects of three tillage systems [conventional tillage (CT), minimum tillage (MT) and zero tillage (ZT)] and three crop rotations [soybean–wheat (S–W), soybean–lentil (S–L) and soybean–pea (S–P)] on SOC and TSN storage and their distribution within aggregate-size fractions in Indian Himalayas, where almost all above-ground crop residues were removed. A field experiment was conducted on a Sandy Clay Loam soil (Typic Haplaquept; Eutric Cambisols) from 1999 to 2003 near Almora, India. Results indicate ZT significantly (P
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effect of tillage and crop rotations on pore size distribution and soil hydraulic conductivity in Sandy Clay Loam soil of the indian himalayas
Soil & Tillage Research, 2006Co-Authors: Ranjan Bhattacharyya, Sandip Kundu, Ved Prakash, H S GuptaAbstract:Abstract Tillage management can affect crop growth by altering the pore size distribution, pore geometry and hydraulic properties of soil. In the present communication, the effect of different tillage management viz., conventional tillage (CT), minimum tillage (MT) and zero-tillage (ZT) and different crop rotations viz. [(soybean–wheat (S–W), soybean–lentil (S–L) and soybean–pea (S–P)] on pore size distribution and soil hydraulic conductivities [saturated hydraulic conductivity ( K sat ) and unsaturated hydraulic conductivity { k ( h )}] of a Sandy Clay Loam soil was studied after 4 years prior to the experiment. Soil cores were collected after 4 year of the experiment at an interval of 75 mm up to 300 mm soil depth for measuring soil bulk density, soil water retention constant ( b ), pore size distribution, K sat and k ( h ). Nine pressure levels (from 2 to 1500 kPa) were used to calculate pore size distribution and k ( h ). It was observed that b values at all the studied soil depths were higher under ZT than those observed under CT irrespective of the crop rotations. The values of soil bulk density observed under ZT were higher in 0–75 mm soil depth in all the crop rotations. But, among the crop rotations, soils under S–P and S–L rotations showed relatively lower bulk density values than S–W rotation. Average values of the volume fraction of total porosity with pores 3 m −3 under CT, MT and ZT; and 0.592, 0.610 and 0.626 m 3 m −3 under S–W, S–L and S–P, respectively. In contrast, the average values of the volume fraction of total porosity with pores >150 μm in diameter (pores draining freely with gravity) were 0.124, 0.096 and 0.095 m 3 m −3 under CT, MT and ZT; and 0.110, 0.104 and 0.101 m 3 m −3 under S–W, S–L and S–P, respectively. Saturated hydraulic conductivity values in all the studied soil depths were significantly greater under ZT than those under CT (range from 300 to 344 mm day −1 ). The observed k ( h ) values at 0–75 mm soil depth under ZT were significantly higher than those computed under CT at all the suction levels, except at −10, −100 and −400 kPa suction. Among the crop rotations, S–P rotation recorded significantly higher k ( h ) values than those under S–W and S–L rotations up to −40 kPa suction. The interaction effects of tillage and crop rotations affecting the k ( h ) values were found significant at all the soil water suctions. Both S–L and S–P rotations resulted in better soil water retention and transmission properties under ZT.
M Paramasivam - One of the best experts on this subject based on the ideXlab platform.
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dissipation kinetics and environmental risk assessment of thiamethoxam in the Sandy Clay Loam soil of tropical sugarcane crop ecosystem
Bulletin of Environmental Contamination and Toxicology, 2020Co-Authors: Thirumalaiandi Ramasubramanian, M ParamasivamAbstract:Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the Sandy Clay Loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil.
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dissipation behavior of phorate and its toxic metabolites in the Sandy Clay Loam soil of a tropical sugarcane ecosystem using a single step sample preparation method and gc ms
IEEE Journal of Solid-state Circuits, 2016Co-Authors: Thirumalaiandi Ramasubramanian, M ParamasivamAbstract:The dissipation of phorate in the Sandy Clay Loam soil of tropical sugarcane ecosystem was studied by employing a single-step sample preparation method and gas chromatography with mass spectrometry. The limit of quantification of the method was 0.01 μg/g. The recoveries of phorate, phorate sulfoxide, phorate sulfone and phorate oxon were in the range 94.00–98.46% with relative standard deviations of 1.51–3.56% at three levels of fortification between 0.01 and 0.1 μg/g. Half-life of phorate and the total residues, which include phorate, phorate sulfoxide and phorate sulfone was 5.5 and 19.8 days, respectively at the recommended dose of insecticide. Phorate rapidly oxidized into its sulfoxide metabolite in the Sandy Clay Loam soil. Phorate sulfoxide alone accounted for more than 20% of the total residues within 2 h post-application and it was more than 50% on the fifth day after treatment irrespective of the doses applied. Phorate sulfoxide and phorate sulfone reached below the detectable level on 105 and 135 days after treatment, respectively as against 45 days after treatment for phorate residues at the recommended dose. Thus, the reasonably prolonged efficacy of phorate against soil pests may be attributed to longer persistence of its more toxic sulfoxide and sulfone metabolites. This article is protected by copyright. All rights reserved
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dissipation behavior of phorate and its toxic metabolites in the Sandy Clay Loam soil of a tropical sugarcane ecosystem using a single step sample preparation method and gc ms
Journal of Separation Science, 2016Co-Authors: Thirumalaiandi Ramasubramanian, M ParamasivamAbstract:The dissipation of phorate in the Sandy Clay Loam soil of tropical sugarcane ecosystem was studied by employing a single-step sample preparation method and gas chromatography with mass spectrometry. The limit of quantification of the method was 0.01 μg/g. The recoveries of phorate, phorate sulfoxide, phorate sulfone, and phorate oxon were in the range 94.00-98.46% with relative standard deviations of 1.51-3.56% at three levels of fortification between 0.01 and 0.1 μg/g. The Half-life of phorate and the total residues, which include phorate, phorate sulfoxide and phorate sulfone, was 5.5 and 19.8 days, respectively at the recommended dose of insecticide. Phorate rapidly oxidized into its sulfoxide metabolite in the Sandy Clay Loam soil. Phorate sulfoxide alone accounted for more than 20% of the total residues within 2 h post-application and it was more than 50% on the fifth day after treatment irrespective of the doses applied. Phorate sulfoxide and phorate sulfone reached below the detectable level on 105 and 135 days after treatment, respectively as against 45 days after treatment for phorate residues at the recommended dose. Thus, the reasonably prolonged efficacy of phorate against soil pests may be attributed to longer persistence of its more toxic sulfoxide and sulfone metabolites.
Joao Mielniczuk - One of the best experts on this subject based on the ideXlab platform.
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carbon sequestration in two brazilian cerrado soils under no till
Soil & Tillage Research, 2006Co-Authors: Cimelio Bayer, Joao Mielniczuk, Ladislau Martinneto, Aurelio Pavinato, Jeferson DieckowAbstract:Abstract A considerable proportion of the 200 million hectares of the Brazilian Cerrado is suitable for annual crops but little is known about the effects of tillage on the C dynamics of Cerrado soils. We evaluated the role of two representative Cerrado Oxisols (350 and 650 g Clay kg−1) as sources or sinks of atmospheric C when managed under three tillage systems (conventional tillage (CT), reduced tillage (RT), and no-till (NT)) in 8- and 5-year long-term experiments. A literature review was also carried out and the mean C sequestration rates in no-till soils of tropical and subtropical regions of Brazil were calculated and compared with values for soils from temperate regions of the world. The original C stocks in 0–20 cm layer of soils under native Cerrado were higher in the Clayey (54.0 Mg ha−1) than in the Sandy Clay Loam soil (35.4 Mg ha−1), suggesting a higher physical stability of organic matter associated with variable Clay minerals in the Clayey Oxisol. The original C stocks of the native Cerrado soils appear not to have decreased after 23 years of conventional tillage in the Sandy Clay Loam Oxisol, except when the soil had been subjected to erosion (15% loss of C), or after 25 years in the Clayey Oxisol. Compared to conventionally tilled soil, the C stocks in no-till Sandy Clay Loam Oxisol increased by 2.4 Mg ha−1 (C sequestration rate = 0.30 Mg ha−1 year−1) and in the Clayey Oxisol by 3.0 Mg ha−1 (C sequestration rate = 0.60 Mg ha−1 year−1). The mean rate of C sequestration in the no-till Brazilian tropical soils was estimated to be 0.35 Mg ha−1 year−1, similar to the 0.34 Mg ha−1 year−1 reported for soils from temperate regions but lower than the 0.48 Mg ha−1 year−1 estimated for southern Brazilian subtropical soils. Considering the large area (about 70 million hectares) of the Cerrado which is currently used and potentially available for cropland, the adoption of no-till systems could turn the Cerrado soils into a significant sink for atmospheric C and contribute to the mitigation of global climate change.
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organic matter storage in a Sandy Clay Loam acrisol affected by tillage and cropping systems in southern brazil
Soil & Tillage Research, 2000Co-Authors: Cimelio Bayer, Joao Mielniczuk, Telmo Jorge Carneiro Amado, Ladislau Martinneto, Sandra Beatriz Vicenci FernandesAbstract:Soil organic matter decline and associated degradation of soil and environmental conditions under conventional tillage in tropical and subtropical regions underline the need to develop sustainable soil management systems. This study aimed first to evaluate the long-term effect (9 years) of two soil-tillage systems (conventional tillage: CT, and no-tillage: NT) and two cropping systems (oat (Avena strigosa Schreb)/maize (Zea mays L.): O/M; and oatacommon vetch (Vicia sativa L.)/ maizeacowpea (Vigna unguiculata (L.) Walp): OaV/MaC without N fertilization on total organic carbon (TOC) and total nitrogen (TN) concentrations in a Sandy Clay Loam Acrisol in southern Brazil. The second objective was to assess soil potential for acting as an atmospheric CO2 sink. Under NT an increase of soil TOC and TN concentrations occurred, in both cropping systems, when compared with CT. However, this increase was restricted to soil surface layers and it was higher for OaV/MaC than for O/M. The OaV/MaC under NT, which probably results in the lowest soil organic matter losses (due to erosion and oxidation) and highest addition of crop residues, had 12 Mg ha ˇ1 more TOC and 0.9 Mg ha ˇ1 more TN in the 0‐30.0 cm depth soil layer, compared with O/M under CT which exhibits highest soil organic matter losses and lowest crop residue additions to the soil. These increments represent TOC and TN accumulation rates of 1.33 and 0.10 Mg ha ˇ1 per year, respectively. Compared with CT and O/M, this TOC increase under NT and OaV/MaC means a net carbon dioxide removal of about 44 Mg ha ˇ1 from the atmosphere in 9 years. NT can therefore be considered, as it is in temperate climates, an important management strategy for increasing soil organic matter. In the tropicals and subtropicals, where climatic conditions cause intense biological activity, in order to maintain or increase soil organic matter, improve soil quality and contribute to mitigation of CO2 emissions, NT should be associated with cropping systems resulting in high annual crop residue additions to soil surface. # 2000 Elsevier Science B.V. All rights reserved.
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effect of no till cropping systems on soil organic matter in a Sandy Clay Loam acrisol from southern brazil monitored by electron spin resonance and nuclear magnetic resonance
Soil & Tillage Research, 2000Co-Authors: Cimelio Bayer, Joao Mielniczuk, Ladislau Martinneto, Carlos Alberto CerettaAbstract:In weathered tropical and subtropical soils organic matter is crucial for soil productivity and its quantity depends heavily on soil management systems. This study evaluated the effect of no-till cropping systems on organic matter content and quality in a Sandy Clay Loam Acrisol soil (Paleudult in US taxonomy) from Southern Brazil. Ten cropping systems with varying additions of C and N were conducted for 12 years (from 1983 to 1994). The addition of crop residues increased total organic carbon (TOC) and total nitrogen (TN) in the soil at 0‐17.5 cm depth, and this increase was directly related with C and N added or recycled by the systems. The crop residues added to the soil were associated with reduced semiquinone free radical concentration, detected by electron spin resonance (ESR), in the organo-mineral aggregates <53 mm and humic acid (HA) samples, in the soil at 0‐2.5 cm depth. This showed that stable organic matter originating from crop residues was less humidified than the original soil organic matter. Results obtained from organo-mineral aggregates showed a higher amplitude (highest and lowest values were 5.47 and 2.09 10 17 spins g ˇ1 of TOC, respectively) of semiquinone free radical concentration than HA samples (highest and lowest values were 2.68 and 1.77 10 17 spins g ˇ1 of HA, respectively). These data showed that alterations due to tillage in soil organic matter characteristics, e.g., humification degree can be better identified through a combination of soil physical fractionation and spectroscopic analysis. Semiquinone content in the HA samples, detected by ESR, related significantly to aromaticity, as measured by nuclear magnetic resonance (NMR) of 13 C. Management systems including no-till and cropping systems with high C and N additions to the soil improved its quality in Southern Brazil. # 2000 Elsevier Science B.V. All rights reserved.
