摘要 :
Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input....
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Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input. Strategic, low application rates (112 kg ha?1) of pine and coconut feedstock biochars were tested in an established alfalfa (Medicago sativa) field. Soil inorganic N and plant growth, N concentrations, and δ15N were monitored over a growing season to follow mineral N availability, and plant N uptake and sourcing. Microbial and gene abundance and enzyme activity were measured to assess the potential for N cycling processes to occur. Biochar application had minimal effects on measured parameters. However, significant temporal dynamics in N cycling and correlations between alfalfa δ15N and soil N availability indicate differing plant N sourcing over time. Our findings indicate that low application rates of biochar in established alfalfa fields do not significantly affect N cycling, and that managing alfalfa to maximize N fixation, for example by intercropping, may be a better solution to increase N stocks and retention in this system. To determine when biochar can be beneficial for alfalfa N cycling, we need additional research to assess various economically-feasible biochar application rates at different alfalfa growth stages.
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摘要 :
Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input....
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Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input. Strategic, low application rates (112 kg ha?1) of pine and coconut feedstock biochars were tested in an established alfalfa (Medicago sativa) field. Soil inorganic N and plant growth, N concentrations, and δ15N were monitored over a growing season to follow mineral N availability, and plant N uptake and sourcing. Microbial and gene abundance and enzyme activity were measured to assess the potential for N cycling processes to occur. Biochar application had minimal effects on measured parameters. However, significant temporal dynamics in N cycling and correlations between alfalfa δ15N and soil N availability indicate differing plant N sourcing over time. Our findings indicate that low application rates of biochar in established alfalfa fields do not significantly affect N cycling, and that managing alfalfa to maximize N fixation, for example by intercropping, may be a better solution to increase N stocks and retention in this system. To determine when biochar can be beneficial for alfalfa N cycling, we need additional research to assess various economically-feasible biochar application rates at different alfalfa growth stages.
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摘要 :
Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input....
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Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input. Strategic, low application rates (112 kg ha1) of pine and coconut feedstock biochars were tested in an established alfalfa (Medicago sativa) field. Soil inorganic N and plant growth, N concentrations, and 15N were monitored over a growing season to follow mineral N availability, and plant N uptake and sourcing. Microbial and gene abundance and enzyme activity were measured to assess the potential for N cycling processes to occur. Biochar application had minimal effects on measured parameters. However, significant temporal dynamics in N cycling and correlations between alfalfa 15N and soil N availability indicate differing plant N sourcing over time. Our findings indicate that low application rates of biochar in established alfalfa fields do not significantly affect N cycling, and that managing alfalfa to maximize N fixation, for example by intercropping, may be a better solution to increase N stocks and retention in this system. To determine when biochar can be beneficial for alfalfa N cycling, we need additional research to assess various economically-feasible biochar application rates at different alfalfa growth stages.
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摘要 :
Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input....
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Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input. Strategic, low application rates (112 kg ha−1) of pine and coconut feedstock biochars were tested in an established alfalfa (Medicago sativa) field. Soil inorganic N and plant growth, N concentrations, and δ15N were monitored over a growing season to follow mineral N availability, and plant N uptake and sourcing. Microbial and gene abundance and enzyme activity were measured to assess the potential for N cycling processes to occur. Biochar application had minimal effects on measured parameters. However, significant temporal dynamics in N cycling and correlations between alfalfa δ15N and soil N availability indicate differing plant N sourcing over time. Our findings indicate that low application rates of biochar in established alfalfa fields do not significantly affect N cycling, and that managing alfalfa to maximize N fixation, for example by intercropping, may be a better solution to increase N stocks and retention in this system. To determine when biochar can be beneficial for alfalfa N cycling, we need additional research to assess various economically-feasible biochar application rates at different alfalfa growth stages.
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摘要 :
Nitrogen (N) is the most critical externally added input for any crop production system. The half of the global population directly or indirectly depends on nitrogenous fertilizers for food supply. Today, Rice, wheat, and maize ar...
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Nitrogen (N) is the most critical externally added input for any crop production system. The half of the global population directly or indirectly depends on nitrogenous fertilizers for food supply. Today, Rice, wheat, and maize are consuming more than90% of total nitrogenous fertilizer used in cereals. Underuse of nitrogen is associated with lower crop production while overuse leads to several soil and environmental related consequences. Therefore, response to applied nitrogen and its use efficiencyhave to be monitored properly for obtaining the maximum potential and sustainable yield. Efficiency of applied nitrogenous fertilizers is very low due to its various losses i.e. volatilization, leaching, surface runoff and denitrification from soil-plant system. Therefore, the proper understanding of advanced soil and plant management practices which helps in enhancement of nitrogen recovery efficiency is one of the key factors to enhance crop output, decreasing cost of cultivation, and to maintain environmental quality which ultimately adds towards the goal of achieving long term sustainable production system. In this review, an attempt has been made summarize the locally as well as scientific soil and crop management technologies used for improvinguse efficiency of applied N. This paper also discusses nitrogen cycling in soil-plant systems, various N losses pathways, present status and most possible management options at the farm level for enhancing nitrogen use in crop production system.
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The WAVE-model (Water and Agrochemicals in the soil and Vadose Environment), simulating one-dimensional transport of water, solute and heat in the unsaturated zone, was used to simulate the behaviour of water and nitrogen in soils...
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The WAVE-model (Water and Agrochemicals in the soil and Vadose Environment), simulating one-dimensional transport of water, solute and heat in the unsaturated zone, was used to simulate the behaviour of water and nitrogen in soils cropped with winter wheat and sugar beet. Soil water transport was modelled using the Richards equation, while solute transport was described with a convection equation. Soil mineral nitrogen transformations were simulated using first-order kinetics, while for the organic matter turnover three organic matter pools were considered. A summary model was used to simulate crop growth. The performance of the integrated model was evaluated in a deterministic way using field data for a three-year period. The data of the first year were used for the model calibration. The remaining set of data was used to evaluate the capacity of the model to predict soil water content, the soil nitrate-N content, the soil ammonia-N content, the soil temperature, the soil water pressure head, the leaf area development and the dry matter accumulation in different plant organs. A screening sensitivity analysis indicated that the calculated nitrogen balance was sensitive to the soil hydraulic properties and the crop K-c-factors for the given scenario. The effect of uncertainty of the sensitive hydraulic properties on the calculated nitrogen balance was investigated using Monte Carlo simulation. Taken into consideration the variability on the soil hydraulic parameters, predicted nitrate-N flux out of the soil profile at a depth of one meter ranged for the simulated period (three years) between -10 and +10 kg ha(-1). [References: 34]
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Biochar is a carbon rich product obtained from pyrolysis of biomass. The use of biochar as soil amendment has been boosted in the last years due to its possible influence on fertility, including its potential ability to lower mine...
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Biochar is a carbon rich product obtained from pyrolysis of biomass. The use of biochar as soil amendment has been boosted in the last years due to its possible influence on fertility, including its potential ability to lower mineral nitrogen losses, but specially for its potential to reduce greenhouse gases and to increase carbon sequestration in soil. However, the studies on the effects of biochar on nitrogen forms in soil are heterogeneous and contradictory. The present work aims to clarify this point by applying 6 different biochars (with different origin and production process) on 6 different soils (of different properties). The amendment corresponded to an agronomic addition rate of 30 Mg ha(-1), together with the addition of urea at a 100 kg N per ha rate. Then those mixtures were incubated for one year at a 60% of the WHC. The samples were analyzed for nitrogen forms (Kjeldahl-N, ammonium-N, nitrate-N, nitrite-N, and microbial-N) at different incubation times (1 week, 1 month, 4 months and 1 year after the addition). The results showed that the effects of different biochars on the soil nitrogen forms were variegated, mainly attributable to soil properties, and to a lesser extent to the particular biochar used. Overall, the Kjeldahl-N (KN) decreased after the incubation time, and only the mixtures with N-rich biochars achieved slightly higher KN compared to controls. Also, biochars tended to induce a decrease in NH4+-N, and, especially, in NO3--N. The biochars causing highest shifts on N inorganic forms were those produced from agronomic sources (olive and corn wastes) and the one from pine wood materials subjected to high pyrolysis temperature conditions.
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To analyze the differences in the status and processes of nitrogen saturation in Japan and northeastern United States, we examined the hydrobiogeochemistry of nitrogen of forested watersheds in these regions. Two distinct differen...
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To analyze the differences in the status and processes of nitrogen saturation in Japan and northeastern United States, we examined the hydrobiogeochemistry of nitrogen of forested watersheds in these regions. Two distinct differences were found between watersheds in Japan compared with those in US. 1) In Japanese watersheds, marked decreases of NO~- _3 concentration in surface waters during the summer growing season were not found and NO~- _3 concentrations sometimes increased especially in the summer at nitrogen nitrogen saturated sites.
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Water pollution with nutrient-based contaminants represents a special concern at national level as it may lead to the occurrence of water eutrophication affecting the properties of the water bodies. This paper presents the charact...
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Water pollution with nutrient-based contaminants represents a special concern at national level as it may lead to the occurrence of water eutrophication affecting the properties of the water bodies. This paper presents the characterisation of nitrogen distribution in water and sediments from the Plumbuita Lake (Bucharest, Romania) and the speciation of this element in the form of ammonium, nitrite, nitrate and organic nitrogen. The results of this study prove the importance of an integrated approach regarding the quantification of nutrient content with the nutrient dynamics in the evaluation of the eutrophication phenomenon.
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Natural and constructed pond ecosystems are suitable to reduce allochthonous nutrient loads discharged from point-source pollutants. An integrated water treatment system was designed by connecting aerobic ponds and surface-flow we...
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Natural and constructed pond ecosystems are suitable to reduce allochthonous nutrient loads discharged from point-source pollutants. An integrated water treatment system was designed by connecting aerobic ponds and surface-flow wetlands to utilise the advantages of both systems (Costa-Pierce 1998). The nutrient dynamics in the treatment system were examined to determine methods to enhance nutrient retention capacity. The aim of this paper is to present the nitrogen dynamics in the pond and wetland units and the nitrogen budget of the system.
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