The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Tristram O West - One of the best experts on this subject based on the ideXlab platform.
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cropland carbon fluxes in the united states increasing geospatial resolution of inventory based carbon accounting
Ecological Applications, 2010Co-Authors: Tristram O West, Craig C Brandt, Latha M Baskaran, Chad M Hellwinckel, Richard Mueller, Carl J Bernacchi, Varaprasad Bandaru, Bai Yang, Bradly Wilson, Gregg MarlandAbstract:Net annual soil carbon change, fossil fuel emissions from cropland production, and cropland net primary productivity were estimated and spatially distributed using land cover defined by the Moderate Resolution Imaging Spectroradiometer (MODIS) and by the Cropland Data Layer (CDL). Spatially resolved estimates of net ecosystem exchange (NEE) and net ecosystem carbon balance (NECB) were developed. NEE represents net on-site vertical fluxes of carbon. NECB represents all on-site and off-site carbon fluxes associated with crop production. Estimates of cropland NEE using moderate resolution (~1km2) land cover data were generated for the conterminous US and compared with higher resolution (30m) estimates of NEE and with direct measurements of CO2 flux from croplands in Illinois and Nebraska. Estimates of NEE using the CDL (30m resolution) had a higher correlation with eddy covariance flux tower estimates compared with estimates of NEE using MODIS. Estimates of NECB are primarily driven by net soil carbon change, fossil-fuel emissions associated with crop production, and CO2 emissions from the application of Agricultural Lime. NEE and NECB for US croplands were -274 and 7 Tg C yr-1 for 2004, respectively. Use of moderate to high resolution satellite-based land cover data enables improved estimates of cropland carbon dynamics.
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The contribution of Agricultural Lime to carbon dioxide emissions in the United States: dissolution, transport, and net emissions
Agriculture Ecosystems & Environment, 2005Co-Authors: Tristram O West, Allen C. McbrideAbstract:Abstract Agricultural Lime (agLime) is commonly applied to soils in the eastern U.S. to increase soil pH. AgLime includes crushed Limestone (CaCO 3 ) and crushed dolomite (MgCa(CO 3 ) 2 ). Following the supposition by the Intergovernmental Panel on Climate Change (IPCC) that all C in agLime is eventually released as CO 2 to the atmosphere, the U.S. EPA estimated that 9 Tg (Teragram = 10 12 g = 10 6 metric tonne) CO 2 was emitted from an approximate 20 Tg of applied agLime in 2001. A review of historic data on agLime production and use indicates that 30 Tg may better represent the annual U.S. consumption of agLime. More importantly, our review of terrestrial and ocean C dynamics indicates that it is unlikely that all C from agLime is released to the atmosphere following application to soils. On the contrary, the primary pathway for agLime dissolution is reaction with carbonic acid (H 2 CO 3 ) which results in uptake of CO 2 . Depending on soil pH and nitrogen fertilizer use, a fraction of agLime may react with strong acid sources such as nitric acid (HNO 3 ), thereby releasing CO 2 . Data on soil leaching and river transport of calcium (Ca 2+ ) and bicarbonate (HCO 3 − ) suggest that a significant portion of dissolved agLime constituents may leach through the soil and be transported by rivers to the ocean. Much of the fraction transported to the ocean will precipitate as CaCO 3 . Bicarbonate remaining in the soil profile is expected to release CO 2 following re-acidification of the soil over time. Our analysis indicates that net CO 2 emissions from the application of agLime is 0.059 Mg C per Mg Limestone and 0.064 Mg C per Mg dolomite. This is in contrast to IPCC estimates of 0.12 and 0.13 Mg C per Mg Limestone and dolomite, respectively. Based on our best estimate, the application of 20–30 Tg of agLime in the U.S., consisting of 80% Limestone and 20% dolomite, would have resulted in a net 4.4–6.6 Tg CO 2 emissions in 2001.
Francis M. Epplin - One of the best experts on this subject based on the ideXlab platform.
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Optimal frequency and quantity of Agricultural Lime applications
Agricultural Systems, 2003Co-Authors: Vladimir Lukin, Francis M. EpplinAbstract:Abstract Crop yields can be limited by soil pH. This study was conducted to determine the optimal level and frequency of Lime applications to low pH soils. A model was developed to reflect the dynamics of pH change in response to Lime application and continuous cropping. Data were obtained from field trials. A wheat (Triticum aestivum) grain yield response to soil pH function was estimated. An evolutionary algorithm was used to solve the discontinuous nonlinear model to determine the optimal level and frequency of Lime application. Optimal Lime application strategies that maximize net present value of returns from continuous monoculture wheat production were determined for several levels of initial soil pH.
Michael Kersten - One of the best experts on this subject based on the ideXlab platform.
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Speciation of Copper in Enriched Agricultural Lime
Soil Science Society of America Journal, 2011Co-Authors: Michael Kersten, Gerald T. Schmidt, Ka Hei Lui, Tatiana Y. Reich, Jörg GöttlicherAbstract:Agricultural liming materials are used to lower soil acidity and to improve microbial functionality and plant growth. A brownish colored Agricultural Lime was found to contain up to 180 mg kg ―1 Cu, an amount well above any fertilizing materials code threshold. The dark color of the milled material was due to ample black and brown dendrites consisting of the tectomanganate mineral romanechite (ideally (Ba,H 2 O) 2 (Mn 4+ ,Mn 3+ ) 5 O 10 ) and a mixture of the two nanocrystalline Fe oxides ferrihydrite and goethite. A four-step sequential extraction analysis of the Lime powder was not sufficient to argue whether the Cu load was contained in the carbonate matrix or in the oxide dendrites, or, in the latter case, in which of the three oxide phases identified. Electron microprobe analysis confirmed that the manganate dendrites were responsible for elevated Cu concentrations in the Limestone. Focused micro-x-ray absorption spectroscopy (μ-XAS) revealed the bonding environment of Cu in the romanechite dendrites to be octahedrally coordinated as the Jahn-Teller cation Cu 2+ bound into lattice sites of the tectomanganate phase. The Mn-Cu, Cu-Mn, and Cu-Cu shell distances indicated a subsritution of the Mn 3+ tectomanganate tunnel edge sites by the Cu 2+ cations. This structural intercalation of Cu is clearly more stable than Cu cations bound as surface adsorbate complexes. The Cu contained in the liming material is therefore not likely to be mobilized and bioavailable, and therefore the Lime poses little threat to Agricultural soils.
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Speciation and mobility of arsenic in Agricultural Lime.
Journal of environmental quality, 2009Co-Authors: Gerald T. Schmidt, Ka Hei Lui, Michael KerstenAbstract:Agricultural liming materials are used to correct soil acidity and to improve plant growth and microbial functionality. A relatively low-grade Agricultural Lime was found to contain up to 125 mg kg(-1) arsenic (As), which is above any fertilizing materials code threshold. The color of the milled material is brown due to ample oxide dendrites. Microprobe elemental maps confirmed that these accessory oxide mineral phases are responsible for the elevated As concentrations in the Limestone. The black Mn-bearing dendrites contain minor amounts of As, whereas the brown Fe-bearing dendrites contain the major part of the As inventory, with an Fe/As molar ratio around 100. Because the elemental maps represent only a few sample regions of interest (ROI), the results are corroborated by a bulk five-step sequential extraction of the Lime, which suggests that a majority of the As is bound to acid-reducible phases. Because repartitioning of the As oxyanion during extraction cannot be ruled out, X-ray absorption spectroscopy with micrometer resolution (micro-XAS) was used as a solid-state speciation analysis approach. The micro-XAS results at the Fe K-edge for the selected ROIs revealed the brown dendrites to consist of ferrihydrite and goethite, whereas those at the As K-edge revealed that the pentavalent As species arsenate predominates, with As-Fe distance and coordination indicating binding as a mononuclear inner-spheric adsorbate complex. Batch experiments with soil exposed to submerged conditions of up to 41 d revealed a negligible As release rate from the Lime (approximately 40 ng kg(-1) d(-1)). The results of this study corroborate regulatory codes that set the permissible As content in Agricultural Lime relative to the respective Fe content.
Allen C. Mcbride - One of the best experts on this subject based on the ideXlab platform.
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The contribution of Agricultural Lime to carbon dioxide emissions in the United States: dissolution, transport, and net emissions
Agriculture Ecosystems & Environment, 2005Co-Authors: Tristram O West, Allen C. McbrideAbstract:Abstract Agricultural Lime (agLime) is commonly applied to soils in the eastern U.S. to increase soil pH. AgLime includes crushed Limestone (CaCO 3 ) and crushed dolomite (MgCa(CO 3 ) 2 ). Following the supposition by the Intergovernmental Panel on Climate Change (IPCC) that all C in agLime is eventually released as CO 2 to the atmosphere, the U.S. EPA estimated that 9 Tg (Teragram = 10 12 g = 10 6 metric tonne) CO 2 was emitted from an approximate 20 Tg of applied agLime in 2001. A review of historic data on agLime production and use indicates that 30 Tg may better represent the annual U.S. consumption of agLime. More importantly, our review of terrestrial and ocean C dynamics indicates that it is unlikely that all C from agLime is released to the atmosphere following application to soils. On the contrary, the primary pathway for agLime dissolution is reaction with carbonic acid (H 2 CO 3 ) which results in uptake of CO 2 . Depending on soil pH and nitrogen fertilizer use, a fraction of agLime may react with strong acid sources such as nitric acid (HNO 3 ), thereby releasing CO 2 . Data on soil leaching and river transport of calcium (Ca 2+ ) and bicarbonate (HCO 3 − ) suggest that a significant portion of dissolved agLime constituents may leach through the soil and be transported by rivers to the ocean. Much of the fraction transported to the ocean will precipitate as CaCO 3 . Bicarbonate remaining in the soil profile is expected to release CO 2 following re-acidification of the soil over time. Our analysis indicates that net CO 2 emissions from the application of agLime is 0.059 Mg C per Mg Limestone and 0.064 Mg C per Mg dolomite. This is in contrast to IPCC estimates of 0.12 and 0.13 Mg C per Mg Limestone and dolomite, respectively. Based on our best estimate, the application of 20–30 Tg of agLime in the U.S., consisting of 80% Limestone and 20% dolomite, would have resulted in a net 4.4–6.6 Tg CO 2 emissions in 2001.
J. R. Okalebo - One of the best experts on this subject based on the ideXlab platform.
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Influence of Agricultural Lime on soil properties and wheat (Triticum aestivum L.) yield on acidic soils of Uasin Gishu county, Kenya.
American Journal of Experimental Agriculture, 2013Co-Authors: M. A. Osundwa, J. R. Okalebo, W. K. Ng'etich, J. O. Ochuodho, Caleb O. Othieno, B. Langat, V. S. OmenyoAbstract:A study was carried out to investigate the influence of Agricultural Lime (21% CaO) from Koru, Kisumu on soil properties and wheat yield on acidic soils of Uasin Gishu county. Field trials were conducted at Chepkoilel University College farm and in Kipsangui area of Uasin Gishu county. Soils were analyzed to determine their pH, available P and other nutrient levels before treatment application. The experiment was a split plot arrangement with two wheat varieties as the main plots and the Lime treatments as the subplots. The two varieties compared were ‘Njoro BW 2’ and ‘KS Mwamba’ characterized as tolerant and moderate tolerant to soil acidity, respectively. Phosphorus and nitrogen were applied as a blanket treatment at the rates of 40 kg P 205 /ha and 46 kg N/ha respectively. Lime was applied at the rates of 0.0, 0.5, 1.0, 1.5 and 2.0 t/ha. Soils from the two sites were acidic with low to
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The Potential of Increased Maize and Soybean Production in Uasin Gishu District, Kenya, Resulting from Soil Acidity Amendment Using Minjingu Phosphate Rock and Agricultural Lime
Innovations as Key to the Green Revolution in Africa, 2011Co-Authors: A.o. Nekesa, J. R. Okalebo, C.o. Othieno, M.n. Thuita, André Bationo, Boaz S. WaswaAbstract:In Kenya, soil acidity is a major contributor to declining soil fertility and 20% of the soils are acidic and are considered to be of low fertility. Most farmers are unaware of the benefits of liming acid soils. A study was carried out during the 2005 and 2006 long rain seasons at Kuinet in Uasin Gishu District of the Rift Valley Province in Kenya to delineate the effects of Minjingu phosphate rock (MPR) and Agricultural Lime as liming materials on yields of soybeans intercropped with maize. The maize responded to application of soil amendment materials for the first season with the diammonium phosphate and Lime (DAPL) treatment giving the highest maize yields of 6.19 t ha–1 compared to the control which gave 1.36 t ha–1. Soybean yields were low in the first season with the DAPL treatment and control treatment giving yields of 0.32 and 0.14 t ha–1, respectively. This, however, changed significantly after the variety was changed in the second season, with yields going up to 0.68 t ha–1 for the triple superphosphate and Lime (TSPL) treatment. From the study, it was concluded that there is potential for growing soybean in Uasin Gishu District of Kenya. However, a study and/or research is recommended to screen and identify a suitable variety for increased soybean yields in this district.
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The potential of Minjingu phosphate rock from Tanzania as a liming material: effect on maize and bean intercrop on acid soils of Western Kenya
2005Co-Authors: A.o. Nekesa, J. R. Okalebo, C.o. Othieno, M.n. Thuita, M.j. Kipsat, A. Bationo, N. Sanginga, J. Kimettu, B. VanlauweAbstract:Soil acidity in western Kenya is one of the major causes of low soil fertility and consequently low Agricultural productivity. Maize and beans are the most important staple food crops in Kenya, however, for both crops, very low yields (< 0.5 tonnes/ha/ season) are realised due to low soil fertility, which is enhanced by soil acidity. Efforts have and are being made to identify soil fertility amelioration technologies affordable and acceptable to smallhold farmers in this region. The quickest method appears to be the use of inorganic fertilisers but this practice is widely reported to be expensive, hence the search for appropriate technologies continues. The liming effect of MPR and Agricultural Lime on yields of intercropped maize and beans were tested on farm during the 2004 long and short rains seasons in Siaya district, western Kenya. Yields of maize -0.48 and 0.60 t/haand beans -0.28 and 0.29 t/hafor the first and second seasons, respectively, were extremely low from the plots where no input was made. Agricultural Lime alone (0.92 t/ha Lime) increased yields five and two folds for maize and beans, respectively in the first season. Higher rates of Lime alone (1.84 and 2.76 t/ha Lime) gave similar yields as 0.92 t/ha. MPR gave significantly higher maize yields than DAP alone except when DAP was combined with Agricultural Lime. For bean yields, MPR was significantly better than DAP alone or DAP combined with Agricultural Lime. MPR superiority to DAP alone was observed. In the second season, residual effect of Lime, MPR and DAP were studied and thus none of these was applied. However, the possible deficiency of the commonly limiting nitrogen (N) was eliminated by applying a blanket rate of 75 kg N/ha to all plots but for the control. Results in the second season due to the residual effect of Lime, MPR and DAP showed highest yields in MPR treatments with yield means of 4.78 and 0.67 t/ha for maize and beans respectively. Liming materials increased soil pH (P
