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Gerardo Rubio - One of the best experts on this subject based on the ideXlab platform.
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long term phosphorus fertilization of wheat soybean and maize on mollisols soil test trends critical levels and balances
European Journal of Agronomy, 2018Co-Authors: Florencia Sucunza, Flavio Gutierrez H Boem, Fernando O Garcia, Miguel Boxler, Gerardo RubioAbstract:Abstract Few reports have compared the P critical level between different crops under equivalent growing conditions and the impact of P balance and P fertilization practices on the long term dynamics of soil available P. The objectives of this study were: i) to determine and compare, under similar field conditions, the P critical values for soybean, maize and wheat; and ii) to evaluate the effect of long-term application of P fertilizer on P balance and soil-test P. Results from a long-term experiment (2000/01 and 2013/14) involving soybean, maize and wheat crops in five experimental sites located at the Pampean Region (Argentina) were analyzed. Phosphorus levels included a −P treatment without P application and a +P treatment with continuous P fertilization (annual average 37 kg P ha−1). The critical Bray-P thresholds were 14.3, 12.5 and 19 mg kg−1 for soybean, maize and wheat, respectively. The rate of decline of the Bray-P pool in the −P treatments was described by an exponential decay function common to the five study sites. Obtained results indicated that a net extraction of 327 kg P per hectare is needed to reduce their initial Bray-P values by half, regardless of the initial soil Bray-P value. The soils fertilized with P showed a significant and linear increase in Bray-P. It was possible to fit a single function after pooling the data of the five sites. This combined function indicated that 3.2 kg P ha−1 were necessary to increase Bray-P in 1 mg kg−1. Obtained data on crop P critical levels and rates at which soil-test P declines or increases according to the P balance constitutes a useful tool for sustainable use of P resources in Mollisols and related soil units. They can help to monitor future changes of soil P levels and to estimate the P demand of croplands.
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soil phosphorus extracted by bray 1 and mehlich 3 soil tests as affected by the soil solution ratio in mollisols
Communications in Soil Science and Plant Analysis, 2011Co-Authors: Flavio Gutierrez H Boem, Gerardo Rubio, Daniel BarberoAbstract:Different relationships between soil-test methods results have been reported in several agricultural regions. Differences in the same soil-test procedure (e.g., soil/solution ratio) exist between soil-testing laboratories from different agricultural regions. Our objectives were to (1) determine the effect of soil/solution ratio on the amount of phosphorus removed by Bray 1 and Mehlich 3 methods, (2) compare the amounts of phosphorus removed by Bray 1 and Mehlich 3 in Mollisols from the Pampean region, and (3) determine whether soil/solution ratio affects the relationship between Bray 1 and Mehlich 3. Soil phosphorus availability was determined with two extractants (Bray 1 and Mehlich 3), using two soil/solution ratios (1:10 and 1:8, wt/v) in 72 soils (noncalcareous, loess-derived Molisolls) from the Pampean region. The amount of phosphorus removed was 20–24% greater when using 1:10 than 1:8 (wt/v) soil/solution ratio. This effect was significantly greater in Bray 1 than in Mehlich 3 (p = 0.04). When compa...
Joseph A Mason - One of the best experts on this subject based on the ideXlab platform.
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latest pleistocene to holocene loess in the central great plains optically stimulated luminescence dating and multi proxy analysis of the enders loess section nebraska usa
Quaternary Science Reviews, 2020Co-Authors: Viorica Tecsa, Joseph A Mason, William C Johnson, Xiaodong Miao, Daniela Constantin, Stelian Radu, Dana Alina Magdas, Daniel Veres, Slobodan B MarkovicAbstract:Abstract Loess deposits of the central Great Plains, USA, and their intercalated soils provide a detailed record of climatically driven changes within the aeolian system during the Pleistocene-Holocene transition and the Holocene. Here we present a detailed optically stimulated luminescence (OSL) chronology as well as multi-proxy analysis obtained for the first time on the Enders section, located in southwestern Nebraska, central Great Plains. The section records multiple episodes of rapid loess deposition alternating with soil formation. Rapid accumulation of Late Pleistocene Peoria Loess was replaced around 13–14 ka by formation of the Brady Soil until 9.5 ± 0.6 ka. The Holocene Bignell Loess then buried the Brady Soil and accumulated episodically throughout the Holocene. The loess-paleosol stratigraphy since the Late Pleistocene at the Enders site is very similar to that at other sites in western Nebraska, and the newly developed OSL chronology (based on three grain size classes) adds new confidence to earlier dating. The high-resolution grain size profile from Enders shares many features with similar data from the previously studied Wauneta site, including three peaks of fine-grained material just above and within the Brady Soil, likely representing response to millennial-scale climatic changes during the Pleistocene-Holocene transition. This study demonstrates the potential for developing high-resolution, well-dated paleoclimatic records from the loess of the central Great Plains. Contrasts between Great Plains and Eurasian loess records reflect differences in the Late Pleistocene to Holocene climatic evolution and other factors influencing the loess system.
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long term stabilization of deep soil carbon by fire and burial during early holocene climate change
Nature Geoscience, 2014Co-Authors: Erika Marinspiotta, N T Chaopricha, Alain F Plante, Aaron F Diefendorf, Carsten W Mueller, Stuart A Grandy, Joseph A MasonAbstract:The Brady soil body was buried by loess deposits as a result of early Holocene climate change. Geochemical analyses suggest that large amounts of organic carbon were trapped in this soil as a result of fire activity and slow decomposition resulting from rapid burial.
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paleopedology of soils in thick holocene loess nebraska usa
Revista Mexicana De Ciencias Geologicas, 2004Co-Authors: Peter M Jacobs, Joseph A MasonAbstract:Bignell Loess is a Holocene loess unit that has accumulated in the central Great Plains since 9,000 14 C yr BP. The Brady Soil separates Bignell Loess from last glacial Peoria Loess and thick sections, which can reach 6 m thickness, may contain four buried soils beneath the modern surface soil. The Brady Soil has A/B/C horizonation, including a thick dark A and a blocky or prismatic structured B horizon. The Brady soil is intensely burrowed, probably by nymphs of cicada species, which require woody vegetation. Secondary carbonate is present in all genetic horizons and was emplaced post burial. The Holocene soils are dominated by A horizon characteristics, namely dark colors, but blocky or prismatic structured B horizons occur in several sections. Secondary carbonate is present in most, but not all Holocene soils. Three phases of loess deposition and soil formation are evident from the thick proximal stratigraphic sections presented here. Initial rates of Bignell Loess deposition were low relative to the rate of soil formation, producing a basal aggraded A horizon above the Brady Soil, that is capped by a increment of loess with minimal pedogenic features. The middle portion of the Bignell Loess is finer textured and contains multiple dark buried soils. The final increment of loess is coarser and contains the weakly expressed modern surface soil. Climatically, termination of Brady Soil formation marks a shift to drier Holocene climates with a decrease in woody species, episodes of new loess deposition and soil formation, and secondary carbonate accumulation.
Florencia Sucunza - One of the best experts on this subject based on the ideXlab platform.
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long term phosphorus fertilization of wheat soybean and maize on mollisols soil test trends critical levels and balances
European Journal of Agronomy, 2018Co-Authors: Florencia Sucunza, Flavio Gutierrez H Boem, Fernando O Garcia, Miguel Boxler, Gerardo RubioAbstract:Abstract Few reports have compared the P critical level between different crops under equivalent growing conditions and the impact of P balance and P fertilization practices on the long term dynamics of soil available P. The objectives of this study were: i) to determine and compare, under similar field conditions, the P critical values for soybean, maize and wheat; and ii) to evaluate the effect of long-term application of P fertilizer on P balance and soil-test P. Results from a long-term experiment (2000/01 and 2013/14) involving soybean, maize and wheat crops in five experimental sites located at the Pampean Region (Argentina) were analyzed. Phosphorus levels included a −P treatment without P application and a +P treatment with continuous P fertilization (annual average 37 kg P ha−1). The critical Bray-P thresholds were 14.3, 12.5 and 19 mg kg−1 for soybean, maize and wheat, respectively. The rate of decline of the Bray-P pool in the −P treatments was described by an exponential decay function common to the five study sites. Obtained results indicated that a net extraction of 327 kg P per hectare is needed to reduce their initial Bray-P values by half, regardless of the initial soil Bray-P value. The soils fertilized with P showed a significant and linear increase in Bray-P. It was possible to fit a single function after pooling the data of the five sites. This combined function indicated that 3.2 kg P ha−1 were necessary to increase Bray-P in 1 mg kg−1. Obtained data on crop P critical levels and rates at which soil-test P declines or increases according to the P balance constitutes a useful tool for sustainable use of P resources in Mollisols and related soil units. They can help to monitor future changes of soil P levels and to estimate the P demand of croplands.
Peter Blair Henry - One of the best experts on this subject based on the ideXlab platform.
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policy watch debt relief
Journal of Economic Perspectives, 2006Co-Authors: Serkan Arslanalp, Peter Blair HenryAbstract:At the Gleneagles summit in July 2005, the heads of state from the G-8 countries—the United States, Canada, France, Germany, Italy, Japan, Russia and the United Kingdom—called on the International Monetary Fund (IMF), the World Bank and the African Development Bank to cancel 100 percent of their debt claims on the world's poorest countries. The world's richest countries have agreed in principle to forgive roughly d55 billion dollars owed by the world's poorest nations. This article considers the wisdom of the proposal for debt forgiveness, from the standpoint of stimulating economic growth in highly indebted countries. In the 1980s, debt relief under the "Brady Plan" helped to restore investment and growth in a number of middle-income developing countries. However, the debt relief plan for the Heavily Indebted Poor Countries (HIPC) launched by the World Bank and the International Monetary Fund in 1996 has had little impact on either investment or growth in the recipient countries. We will explore the key differences between the countries targeted by these two debt relief schemes and argue that the Gleneagles proposal for debt relief is, at best, likely to have little effect at all. Debt relief is unlikely to help the world's poorest countries because, unlike the middle-income Brady countries, their main economic difficulty is not debt overhang, but an absence of functional economic institutions that provide the foundation for profitable investment and growth. We will show that debt relief may be more valuable for Brady-like middle-income countries than for low-income ones because of how it leverages the private sector.
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is debt relief efficient
Journal of Finance, 2005Co-Authors: Serkan Arslanalp, Peter Blair HenryAbstract:When developing countries announce debt relief agreements under the Brady Plan, their stock markets appreciate by an average of 60% in real dollar terms—a $42 billion increase in shareholder value. There is no significant stock market increase for a control group of countries that do not sign Brady agreements. The stock market appreciations successfully forecast higher future resource transfers, investment, and growth. Since the market capitalization of U.S. commercial banks with developing country loan exposure also rises—by $13 billion—the results suggest that both borrower and lenders can benefit from debt relief when the borrower suffers from debt overhang.
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is debt relief efficient
National Bureau of Economic Research, 2004Co-Authors: Serkan Arslanalp, Peter Blair HenryAbstract:When Less Developed Countries (LDCs) announce debt relief agreements under the Brady Plan, their stock markets appreciate by an average of 60 percent in real dollar terms a $42 billion increase in shareholder value. In contrast, there is no significant stock market increase for a control group of LDCs that do not sign Brady agreements. The results persist after controlling for IMF programs, trade liberalizations, capital account liberalizations, and privatization programs. The stock market appreciations successfully forecast higher future net resource transfers, investment and growth. Creditors also benefit from the Brady Plan. Controlling for other factors, stock prices of US commercial banks with significant LDC loan exposure rise by 35 percent a $13 billion increase in shareholder value. The results suggest that debt relief can generate large efficiency gains when the borrower suffers from debt overhang.
Flavio Gutierrez H Boem - One of the best experts on this subject based on the ideXlab platform.
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long term phosphorus fertilization of wheat soybean and maize on mollisols soil test trends critical levels and balances
European Journal of Agronomy, 2018Co-Authors: Florencia Sucunza, Flavio Gutierrez H Boem, Fernando O Garcia, Miguel Boxler, Gerardo RubioAbstract:Abstract Few reports have compared the P critical level between different crops under equivalent growing conditions and the impact of P balance and P fertilization practices on the long term dynamics of soil available P. The objectives of this study were: i) to determine and compare, under similar field conditions, the P critical values for soybean, maize and wheat; and ii) to evaluate the effect of long-term application of P fertilizer on P balance and soil-test P. Results from a long-term experiment (2000/01 and 2013/14) involving soybean, maize and wheat crops in five experimental sites located at the Pampean Region (Argentina) were analyzed. Phosphorus levels included a −P treatment without P application and a +P treatment with continuous P fertilization (annual average 37 kg P ha−1). The critical Bray-P thresholds were 14.3, 12.5 and 19 mg kg−1 for soybean, maize and wheat, respectively. The rate of decline of the Bray-P pool in the −P treatments was described by an exponential decay function common to the five study sites. Obtained results indicated that a net extraction of 327 kg P per hectare is needed to reduce their initial Bray-P values by half, regardless of the initial soil Bray-P value. The soils fertilized with P showed a significant and linear increase in Bray-P. It was possible to fit a single function after pooling the data of the five sites. This combined function indicated that 3.2 kg P ha−1 were necessary to increase Bray-P in 1 mg kg−1. Obtained data on crop P critical levels and rates at which soil-test P declines or increases according to the P balance constitutes a useful tool for sustainable use of P resources in Mollisols and related soil units. They can help to monitor future changes of soil P levels and to estimate the P demand of croplands.
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soil phosphorus extracted by bray 1 and mehlich 3 soil tests as affected by the soil solution ratio in mollisols
Communications in Soil Science and Plant Analysis, 2011Co-Authors: Flavio Gutierrez H Boem, Gerardo Rubio, Daniel BarberoAbstract:Different relationships between soil-test methods results have been reported in several agricultural regions. Differences in the same soil-test procedure (e.g., soil/solution ratio) exist between soil-testing laboratories from different agricultural regions. Our objectives were to (1) determine the effect of soil/solution ratio on the amount of phosphorus removed by Bray 1 and Mehlich 3 methods, (2) compare the amounts of phosphorus removed by Bray 1 and Mehlich 3 in Mollisols from the Pampean region, and (3) determine whether soil/solution ratio affects the relationship between Bray 1 and Mehlich 3. Soil phosphorus availability was determined with two extractants (Bray 1 and Mehlich 3), using two soil/solution ratios (1:10 and 1:8, wt/v) in 72 soils (noncalcareous, loess-derived Molisolls) from the Pampean region. The amount of phosphorus removed was 20–24% greater when using 1:10 than 1:8 (wt/v) soil/solution ratio. This effect was significantly greater in Bray 1 than in Mehlich 3 (p = 0.04). When compa...