The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Yakov Kuzyakov - One of the best experts on this subject based on the ideXlab platform.
-
carbon and nitrogen mineralization and enzyme activities in Soil aggregate size classes effects of biochar oyster shells and polymers
Chemosphere, 2018Co-Authors: Yakov Kuzyakov, Yasser M Awad, Yong Sik OkAbstract:: Biochar (BC) and polymers are cost-effective additives for Soil quality improvement and long-term sustainability. The additional use of the oyster shells (OS) powder in BC- or polymer-treated Soils is recommended as a nutrient source, to enhance aggregation and to increase enzyme activities. The effects of Soil treatments (i.e., BC (5 Mg ha-1) and polymers (biopolymer at 0.4 Mg ha-1 or polyacrylamide at 0.4 Mg ha-1) with or without the OS (1%)) on the short-term changes were evaluated based on a 30-day incubation experiment with respect to several variables (e.g., CO2 release, NH4+ and NO3- concentrations, aggregate-size classes, and enzyme activities in an agricultural Luvisol). The BC and BP with the addition of OS increased the portion of microaggregates (<0.25 mm) relative to the control Soil without any additions, while PAM alone increased the portion of large macroaggregates (1-2 mm). Concentrations of NO3- also increased in Soils treated with OS, OS + BC, and OS + BP as result of the increased chitinase and leucine aminopeptidase activities. The BC and BP when treated with the additional OS had significant short-term impacts on N mineralization without affecting C mineralization in Soil. Consequently, the combination of BC or BP with OS was seen to accelerate N turnover without affecting C turnover (and related C Losses) from Soil. As such, the addition of these additives contributed considerably to the improvement of Soil fertility and C sequestration.
-
Carbon and nitrogen Losses from Soil depend on degradation of Tibetan Kobresia pastures
Land Degradation & Development, 2016Co-Authors: Shibin Liu, Per-marten Schleuss, Yakov KuzyakovAbstract:© 2016 John Wiley & Sons, Ltd.Degradation of Kobresia pygmaea pastures has strongly increased on the Tibetan Plateau over the last few decades and contributed to a high loss of Soil organic carbon and nutrients. The pathways of carbon (C) and nitrogen (N) Losses from degraded K. pygmaea pastures are still unclear, but this is a prerequisite to assess the recovery of Tibetan grasslands. We investigated the response of day- and nighttime CO2 efflux and leaching of dissolved organic C and N, NH4+ and NO3- from K. pygmaea root mats in three degradation stages: living root mat, dying root mat and dead root mat. Dying root mat had the highest C loss as CO2 and as leached dissolved organic carbon. This indicates K. pygmaea pastures shift from a C sink to a C source following plant death. In contrast, living root mat had the lowest daytime CO2 efflux (0·38±0·1μgCg-1h-1) because CO2 was assimilated via photosynthesis. Nighttime CO2 efflux positively correlated with Soil moisture for living and dead root mats. It indicates that increasing precipitation might accelerate C Losses due to enhanced Soil organic carbon decomposition. Furthermore, dead root mat had the highest average NO3- loss (23±2·6mgNL-1) from leaching compared with other root mats. Consequently, leaching increases the negative impacts of pasture degradation on N availability in these often N limited ecosystems and thus impedes the recovery of K. pastures following degradation
Jennifer A J Dungait - One of the best experts on this subject based on the ideXlab platform.
-
carbon and macronutrient Losses during accelerated erosion under different tillage and residue management
European Journal of Soil Science, 2015Co-Authors: Joshua W Beniston, Martin J. Shipitalo, E A Dayton, A Joynes, F S Jones, D W Hopkins, Jennifer A J DungaitAbstract:Summary There have been many studies on the effects of tillage on erosional Losses from Soil, but rarely have Soil organic carbon (SOC), nitrogen (N) and phosphorus (P) Losses been quantified simultaneously during a single erosion event. We applied a simulated rainfall event (70 mm hour−1) to plots within a gently sloping field (6%) in Ohio, USA, on which maize (C4) cultivation had replaced C3 vegetation several decades earlier. The plots were under different tillage management: (i) no till (NT100) for 42 years; (ii) NT100 plots from which 50% (NT50) or (iii) 100% (NT0) of crop residues were removed annually for 8 years; (iv) NT100 plots tilled 24 hours previously (TNT); and (v) conventional tillage (CT) for 28 years. Relationships between SOC, N and P concentrations and natural abundance 13C : 15N stable isotope values in the topSoils and sediments suggested that eroded SOC and TN were associated with the erosion of Soil organic matter, whilst P Losses were driven by the transport of the mineral fraction. Stable 13C isotope analyses revealed that tillage and residue removal both increased the proportion of older (C3), rather than new (C4, maize-derived), SOC in eroded sediments. This study therefore demonstrated that a single tillage event after 42 years of continuous no-till caused larger erosional fluxes than 8 years of continuous removal of all maize residues, and that long-term conventional tillage resulted in the loss of a greater amount of older (> 28 years) SOC in eroded sediments, compared with continuous NT management.
Yasser M Awad - One of the best experts on this subject based on the ideXlab platform.
-
carbon and nitrogen mineralization and enzyme activities in Soil aggregate size classes effects of biochar oyster shells and polymers
Chemosphere, 2018Co-Authors: Yakov Kuzyakov, Yasser M Awad, Yong Sik OkAbstract:: Biochar (BC) and polymers are cost-effective additives for Soil quality improvement and long-term sustainability. The additional use of the oyster shells (OS) powder in BC- or polymer-treated Soils is recommended as a nutrient source, to enhance aggregation and to increase enzyme activities. The effects of Soil treatments (i.e., BC (5 Mg ha-1) and polymers (biopolymer at 0.4 Mg ha-1 or polyacrylamide at 0.4 Mg ha-1) with or without the OS (1%)) on the short-term changes were evaluated based on a 30-day incubation experiment with respect to several variables (e.g., CO2 release, NH4+ and NO3- concentrations, aggregate-size classes, and enzyme activities in an agricultural Luvisol). The BC and BP with the addition of OS increased the portion of microaggregates (<0.25 mm) relative to the control Soil without any additions, while PAM alone increased the portion of large macroaggregates (1-2 mm). Concentrations of NO3- also increased in Soils treated with OS, OS + BC, and OS + BP as result of the increased chitinase and leucine aminopeptidase activities. The BC and BP when treated with the additional OS had significant short-term impacts on N mineralization without affecting C mineralization in Soil. Consequently, the combination of BC or BP with OS was seen to accelerate N turnover without affecting C turnover (and related C Losses) from Soil. As such, the addition of these additives contributed considerably to the improvement of Soil fertility and C sequestration.
Artemi Cerdà - One of the best experts on this subject based on the ideXlab platform.
-
A review of Soil carbon dynamics resulting from agricultural practices
Journal of environmental management, 2020Co-Authors: Farhat Abbas, Hafiz Mohkum Hammad, Wajid Ishaq, Aitazaz A. Farooque, Hafiz Faiq Bakhat, Zahida Zia, Shah Fahad, Wajid Farhad, Artemi CerdàAbstract:Abstract Literature related to the carbon cycle and climate contains contradictory results with regard to whether agricultural practices increase or mitigate emission of greenhouse gases (GHGs). One opinion is that anthropogenic activities have distinct carbon footprints – measured as total emissions of GHGs resulting from an activity, in this case, “agricultural operations”. In contrast, it is argued that agriculture potentially serves to mitigate GHGs emissions when the best management practices are implemented. We review the literature on agricultural carbon footprints in the context of agricultural practices including Soil, water and nutrient management. It has been reported that the management practices that enhance Soil organic carbon (SOC) in arid and semi-arid areas include conversion of conventional tillage practices to conservation tillage approaches. We found that agricultural management in arid and semi-arid regions, which have specific characteristics related to high temperatures and low rainfall conditions, requires different practices for maintenance and restoration of SOC and for control of Soil erosion compared to those used in Mediterranean, tropical regions. We recommend that in order to meet the global climate targets, quantification of net global warming potential of agricultural practices requires precise estimates of local, regional and global carbon budgets. We have conducted and present a case study for observing the development of deep Soil carbon profile resulting from a 10-year wheat-cotton and wheat-maize rotation on semi-arid lands. Results showed that no tillage with mulch application had 14% (37.2 vs 43.3 Mg ha−1) higher SOC stocks in comparison to conventional tillage with mulch application. By implementing no tillage in conjunction with mulch application, lower carbon Losses from Soil can mitigate the risks associated with global warming. Therefore, it is necessary to reconsider agricultural practices and Soil erosion after a land-use change when calculating global carbon footprints.
Brian J. Boman - One of the best experts on this subject based on the ideXlab platform.
-
Tree growth, mineral nutrition and nutrient leaching Losses from Soil of salinized citrus
Agriculture Ecosystems & Environment, 1993Co-Authors: J.p. Syvertsen, M.l. Smith, Brian J. BomanAbstract:Abstract The effects of salinized irrigation water on tree canopy and root growth, water use, foliar nutrition and leaching Losses below the rootzone were studied during a 2-year period using single tree lysimeters. Eighteen 6-year-old ‘Valencia’ orange trees on either Carrizo citrange (CC) rootstock or sour orange (SO) rootstock were each transplanted into 7.8 m3 drainage lysimeters and irrigated with water having an electrical conductivity (EC) of 0.3, 1.6 or 2.5 dS m−1 using a 3:1 ratio of NaCl:CaCl2. To test for effects of the lysimeter tanks, six additional trees (three on each rootstock) were transplanted directly into Soil without tanks and were also irrigated with the lowest salinity water. All trees were fertilized at recommended rates in 50 split applications per year. A similar tank with no tree was also fertilized and irrigated with the lowest salinity water to determine nutrient recovery from Soils without roots. During the second year, up to 70% of the applied N and up to 80% of the applied K was recovered in the drainage water from this blank tank with no tree. At the end of the study, trees outside the tanks were smaller but were nutritionally similar to the low salinity trees in lysimeters. Trees on CC were larger, tended to have greater root densities, higher evapotranspiration (ET) and were associated with less leaching of ions and nutrients into drainage water from the tanks than trees on SO. High salinity irrigation water reduced canopy growth and ET but increased total fibrous root dry weight. Trees on CC accumulated more Cl in leaves and in fruit juice than those on SO. Overall, leaching loss of total N varied from 2 to 8% of that annually applied. Salinized trees tended to lose more N and up to twice as much K to drainage water as non-salinized trees. Based on differences between N recovered from the blank tank and tanks with trees during the second year, N uptake efficiency was as high as 68% for non-salinized trees and 64% for salinized trees.
