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Author: Henry Michael Wilson Publisher: ISBN: Category : Languages : en Pages : 118
Book Description
As the atmospheric CO2 concentration continues to increase, more attention is being focused on the soil as a possible sink for atmospheric CO2. This study was conducted to examine the short-term effects of N fertilization and tillage on soil carbon dynamics. There were two main objectives in this study. Objective one was to determine the impact of N fertilization on soil CO2 emission and soil carbon (C) fractions change in central Iowa soils. Objective two was to determine the impact of tillage on changes in soil C fractions in Iowa soils. Soil CO2 emissions were measured during the growing seasons of 2003 and 2004 from plots fertilized with three N rates in continuous corn (Zea mays L.) and a corn-soybean (Glycine max L.) rotation. Soil samples were collected in the spring of 2002 and 2004 to determine soil C and N contents in different soil C fractions. A laboratory soil incubation and a soil microbial biomass determination were conducted to examine the effects of N fertilization on microbial biomass and microbial activity. Objective two was accomplished by collecting soil samples in the spring of 2002 and 2004 from no-tillage and chisel plow plots at six sites to determine soil C and N fractions changes. Nitrogen fertilization increased soil CO2 emissions by 25% in the corn-soybean rotation in 2003. The laboratory soil incubation produced contrary results with the highest N rate producing the greatest CO2 evolution. This was attributed to the increased N in the soil at the start of the soil incubation. Even though N fertilization consistently increased crop biomass and had minimal effects on soil CO2 emission, the soil C fractions only showed small increases. Tillage had minimal effects on the soil C fractions. No-tillage treatment had 7-17% greater SOC content than that of the chisel plow treatment in the Marshall, GPS, and CNW soil associations. Soil C fractions were most affected in the Marshall and GPS soil associations. We hypothesize these soils are more sensitive to tillage intensity due to more well balanced soil air and moisture conditions than the poorly drained soils in Iowa.
Author: Henry Michael Wilson Publisher: ISBN: Category : Languages : en Pages : 118
Book Description
As the atmospheric CO2 concentration continues to increase, more attention is being focused on the soil as a possible sink for atmospheric CO2. This study was conducted to examine the short-term effects of N fertilization and tillage on soil carbon dynamics. There were two main objectives in this study. Objective one was to determine the impact of N fertilization on soil CO2 emission and soil carbon (C) fractions change in central Iowa soils. Objective two was to determine the impact of tillage on changes in soil C fractions in Iowa soils. Soil CO2 emissions were measured during the growing seasons of 2003 and 2004 from plots fertilized with three N rates in continuous corn (Zea mays L.) and a corn-soybean (Glycine max L.) rotation. Soil samples were collected in the spring of 2002 and 2004 to determine soil C and N contents in different soil C fractions. A laboratory soil incubation and a soil microbial biomass determination were conducted to examine the effects of N fertilization on microbial biomass and microbial activity. Objective two was accomplished by collecting soil samples in the spring of 2002 and 2004 from no-tillage and chisel plow plots at six sites to determine soil C and N fractions changes. Nitrogen fertilization increased soil CO2 emissions by 25% in the corn-soybean rotation in 2003. The laboratory soil incubation produced contrary results with the highest N rate producing the greatest CO2 evolution. This was attributed to the increased N in the soil at the start of the soil incubation. Even though N fertilization consistently increased crop biomass and had minimal effects on soil CO2 emission, the soil C fractions only showed small increases. Tillage had minimal effects on the soil C fractions. No-tillage treatment had 7-17% greater SOC content than that of the chisel plow treatment in the Marshall, GPS, and CNW soil associations. Soil C fractions were most affected in the Marshall and GPS soil associations. We hypothesize these soils are more sensitive to tillage intensity due to more well balanced soil air and moisture conditions than the poorly drained soils in Iowa.
Author: Marc Louis Kruse Publisher: ISBN: Category : Languages : en Pages : 186
Book Description
The increase in atmospheric carbon dioxide (CO2) over the last century has led to an increased interest in soil C dynamics and sequestering C in soil. The focus of this study is to investigate CO2 emissions and soil C changes with various N application rates in a corn-soybean rotation. The study consists of seven sites across Iowa. Each experiment consists of four selected N rates of 0, 90, 180 and 225 kg ha−1 replicated four times in a randomized complete block design in a corn-soybean rotation. Soil samples were collected at 0-5, 5-10, 10-15, 15-30 and 30-60 cm increments for soil organic carbon (SOC), total soil N (TN), particulate organic matter carbon (POMC), and associated mineral fraction C (MFC). Field soil CO2 emissions from the same N rate treatments were measured during the growing season using a Li-Cor 6400 Infrared Gas Analyzer every seven to 10 days at the Boone, Floyd, and Warren sites in 2002, and Tama site in 2003. Soil laboratory incubation, microbial biomass, and N mineralization studies were conducted on the soils from Boone, Floyd, and Tama sites. Results indicated cumulative soil CO2-C emissions varied in response to N fertilization. Higher N rate treatments had lower cumulative CO2-C than the 0 kg ha−1 N rate treatment when N fertilizer was applied to the corn crop. However, N fertilizer rates of 90, 180 and 225 kg ha−1 N applied to corn the previous year showed higher cumulative CO2-C emissions than the 0 kg ha−1 N rate treatment in the soybean season. In a laboratory soil incubation study, N fertilized soils emitted significantly less CO2-C than the non-fertilized soils. Nitrogen fertilization significantly increased inorganic soil N concentration prior to a 56-day laboratory incubation. After the 56-day incubation period, inorganic soil N concentration was significantly lower for the 0 kg ha−1 N rate treatments than the higher N rate treatments. Nitrogen fertilization did not have a significant effect on microbial biomass carbon (MBC). Results indicate N fertilization does not significantly affect soil SOC, POMC, or MFC at the 0-5, 5-10, and 15-30 cm depths. Nitrogen fertilization had variable effects on crop biomass production along with TC and TN potentially returned to the soil via biomass. Overall, after 2 years of N fertilizer application to corn and one year of soybean with no N fertilizer application, no significant changes in soil SOC, POMC, and MFC were observed in the short period of time.
Author: Fugen Dou Publisher: ISBN: Category : Languages : en Pages :
Book Description
Management practices that may increase soil organic matter (SOM) storage include conservation tillage, especially no till (NT), enhanced cropping intensity, and fertilization. My objectives were to evaluate management effects on labile [soil microbial biomass (SMB) and mineralizable, particulate organic matter (POM), and hydrolyzable SOM] and slow (mineral-associated and resistant organic) C and N pools and turnover in continuous sorghum [Sorghum bicolor (L.) Moench.], wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.], sorghum-wheat/soybean, and wheat/soybean sequences under conventional tillage (CT) and NT with and without N fertilization. A Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochepts) in southern central Texas was sampled at three depth increments to a 30-cm depth after wheat, sorghum, and soybean harvesting. Soil organic C and total N showed similar responses to tillage, cropping sequence, and N fertilization following wheat, sorghum, and soybean. Most effects were observed in surface soils. NT significantly increased SOC. Nitrogen fertilization significantly increased SOC only under NT. Compared to NT or N addition, enhanced cropping intensity only slightly increased SOC. Estimates of C sequestration rates under NT indicated that SOC would reach a new equilibrium after 20 yr or less of imposition of this treatment. Labile pools were all significantly greater with NT than CTat 0 to 5 cm and decreased with depth. SMB, mineralizable C and N, POM, and hydrolyzable C were highly correlated with each other and SOC, but their slopes were significantly different, being lowest in mineralizable C and highest in hydrolyzable C. These results indicated that different methods determined various fractions of total SOC. Results from soil physical fractionation and 13C concentrations further supported these observations. Carbon turnover rates increased in the sequence: ROC
Author: Maria Angeles Munoz Publisher: Academic Press ISBN: 0128121297 Category : Science Languages : en Pages : 398
Book Description
Soil Management and Climate Change: Effects on Organic Carbon, Nitrogen Dynamics, and Greenhouse Gas Emissions provides a state of the art overview of recent findings and future research challenges regarding physical, chemical and biological processes controlling soil carbon, nitrogen dynamic and greenhouse gas emissions from soils. This book is for students and academics in soil science and environmental science, land managers, public administrators and legislators, and will increase understanding of organic matter preservation in soil and mitigation of greenhouse gas emissions. Given the central role soil plays on the global carbon (C) and nitrogen (N) cycles and its impact on greenhouse gas emissions, there is an urgent need to increase our common understanding about sources, mechanisms and processes that regulate organic matter mineralization and stabilization, and to identify those management practices and processes which mitigate greenhouse gas emissions, helping increase organic matter stabilization with suitable supplies of available N. - Provides the latest findings about soil organic matter stabilization and greenhouse gas emissions - Covers the effect of practices and management on soil organic matter stabilization - Includes information for readers to select the most suitable management practices to increase soil organic matter stabilization
Author: Molefi Jacob Mpheshea Publisher: ISBN: Category : Cotton growing Languages : en Pages : 95
Book Description
Effective soil management requires a deeper understanding of how internal soil carbon (C) works. This is vital as cycling is tightly linked with nutrient cycling processes. This study evaluated the effect of agronomic practices including tillage (no-till and tilled), cover crops (no cover, hairy vetch - Vicia villosa L, and winter wheat - Triticum aestivum. L ) and different N fertilizer rates ( 0, 34 and 101 kg N per hectare ) on soil microbial C dynamics as measured by soil microbial biomass C (SMBC) along with soil microbial respiration over the 2013 cotton growing season at Jackson, West Tennessee. The study was set as split -split plot with N fertilizer rates as the whole plot, cover crops as the split plot and tillage as the split-split plot. Sampling was carried out four times; in June, July, September and October. Both SMBC and soil respiration responded similarly to the treatment factors. Early in the season, June and July, N fertilizer rate affected SMBC with 101N fertilizer rate having greater SMBC. In July, in addition to N fertilizer rate, tillage affected SMBC with tilled-vetch treatment at 34N and 101N fertilizer rate having a significantly greater levels of SMBC while soil respiration was greater under the no-till no cover treatment across all N fertilizer rates. However in September, tillage and cover crop affected SMBC and soil microbial respiration. The no-till no cover and no-till wheat treatments had greater SMBC and soil microbial respiration compared with no-till vetch at 0N and 34N fertilizer rate. At the end of the growing season prior to harvest, the no-till no cover treatment still had effect on soil microbial respiration while none of the treatment factors affected SMBC. Early in the season N fertilizer influences microbial activities while later in the season tillage and cover crop become the dominating factors. Overall the effects of N fertilizer, tillage and cover crops on these soil properties were season dependent.
Author: Werner L. Kutsch Publisher: Cambridge University Press ISBN: 1139483161 Category : Technology & Engineering Languages : en Pages : 301
Book Description
Carbon stored in soils represents the largest terrestrial carbon pool and factors affecting this will be vital in the understanding of future atmospheric CO2 concentrations. This book provides an integrated view on measuring and modeling soil carbon dynamics. Based on a broad range of in-depth contributions by leading scientists it gives an overview of current research concepts, developments and outlooks and introduces cutting-edge methodologies, ranging from questions of appropriate measurement design to the potential application of stable isotopes and molecular tools. It includes a standardised soil CO2 efflux protocol, aimed at data consistency and inter-site comparability and thus underpins a regional and global understanding of soil carbon dynamics. This book provides an important reference work for students and scientists interested in many aspects of soil ecology and biogeochemical cycles, policy makers, carbon traders and others concerned with the global carbon cycle.
Author: Lei Sun Publisher: ISBN: Category : Greenhouse gases Languages : en Pages : 158
Book Description
Improving soil carbon (C) sequestration through land management practices is of great interest due to concerns over global climate change caused by increased atmospheric greenhouse gas (GHG) concentrations. Soil disturbance by conventional tillage (CT) generally accelerates soil organic carbon (SOC) mineralization, and changing from CT to no tillage (NT) has been shown to reduce GHG emissions and increase soil C sequestration in western Canada. However, long-term NT may cause crop residue accumulation and weed infestation. Reversing NT to CT, a process called tillage reversal, may be needed to address those issues but it may markedly alter soil C dynamics in agricultural ecosystems. The effects of tillage reversal and nitrogen (N) fertilization on soil GHG emissions during the growing season, soil C and N concentrations, and C stability in top- and subsoils were studied in two long-term field experimental sites: a Malmo silty clay loam (an Orthic Black Chernozem) at Ellerslie and a Breton loam (an Orthic Gray Luvisol) at Breton. This study used a split-plot design with two levels of N (since 1979) - 0 (N0) vs. 100 kg N ha-1 yr-1 (N100) and two levels of tillage - long-term NT (since 1979) vs. tillage reversal (TR) (since 2009 at Ellerslie and 2010 at Breton) - treatments. Straw was retained in each plot. The results are: (1) tillage reversal increased area-scaled GHG emissions but decreased yield-scaled GHG emissions at Ellerslie while N fertilization increased area-scaled GHG emissions but decreased yield-scaled GHG emissions at Breton; (2) soil heterotrophic respiration (Rh) was stimulated by tillage reversal only at Ellerslie but was stimulated by N fertilization only at Breton; (3) tillage reversal and N fertilization only increased soil C and N concentrations in the topsoil at Breton; (4) nitrogen fertilization increased water-extractable organic carbon (WEOC) concentrations at both sites but the stability of WEOC was increased by N fertilization only at Breton; (5) Nitrogen fertilization increased soil aggregation and aggregate-associated C in the topsoil at both sites; and (6) physical protection for C in the subsoil was decreased by N fertilization and tillage reversal only at Ellerslie. In conclusion, with straw retention, long-term N fertilization with short-term tillage reversal is recommended to increase soil C sequestration, improve soil aggregation, and decrease yield-scaled GHG emissions in the Gray Luvisol. In the Black Chernozem, short-term tillage reversal is recommended to improve soil aggregation and decrease yield-scaled GHG emissions.
Author: Henry Michael Wilson
Author: Henry Michael Wilson
Author: Marc Louis Kruse
Author: Fugen Dou
Author: Maria Angeles Munoz
Author: Molefi Jacob Mpheshea
Author: Werner L. Kutsch
Author: Howard J. Haas
Author: 
Author: Percy Edgar Brown
Author: Lei Sun