Soil-emitted nitrous oxide(N2O) and nitric oxide(NO) in crop production are harmful nitrogen(N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, su...Soil-emitted nitrous oxide(N2O) and nitric oxide(NO) in crop production are harmful nitrogen(N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, such as dicyandiamide(DCD), and urea deep placement(UDP), are considered effective approaches to reduce these emissions. This study investigated the effects of DCD and UDP, compared to urea and potassium nitrate, on emissions, nitrogen use efficiency and grain yields under direct-seeded rice. High-frequency measurements of N2O and NO emissions were conducted using the automated closed chamber method throughout the crop-growing season and during the ratoon crop. Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively. The highest emission factor(1.53% of applied N) was observed in urea, while the lowest was in UDP(0.08%). Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization. Those emission peaks contributed to 65%–98% of the total seasonal emissions. Residual effects of fertilizer treatments on the N2O emissions from the ratoon crop were not significant;however, the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions. On the other hand, cumulative NO emissions were not significant in either the rice or ratoon crops. UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea. The results suggested that the use of DCD and UDP could mitigate N2O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition.展开更多
Essential plant nutrients contained in residues and wastes generated during biofuel processing can be recovered for further production of bioenergy biomass. The objective of this study was to determine the relative ag...Essential plant nutrients contained in residues and wastes generated during biofuel processing can be recovered for further production of bioenergy biomass. The objective of this study was to determine the relative agronomic efficiency of “processed” biofuel residual (PBR). Liquid biofuel residual was “processed” by precipitating phosphate and ammonium in the residual with magnesium into a struvite-like material. Then, in a series of greenhouse experiments, we evaluated the fertility potential of PBR, using sweet sorghum (Sorghum bicolor (L.) Moench), as a test bioenergy crop. We compared the agronomic effectiveness of PBR to inorganic commercial fertilizers, biosolids, and poultry manure as nutrient sources. The sources were either applied alone or in combination with supplemental essential plant nutrients (S, K, Mg, and micronutrients). In each of the greenhouse experiments, the crop was grown for 12 wk on soil of minimal native fertility. After each harvest, sufficient water was applied to the soil in each pot over a 6-wk period to yield ~2 L (~one pore volume) of leachate to assess potential total N and soluble reactive phosphorus (SRP) losses. Dry matter yields from the PBR treatment applied alone were significantly greater than yields from inorganic fertilizers, biosolids, and poultry manure treatments applied alone, and similar to yields obtained when the supplemental essential plant nutrients were added to the inorganic fertilizer, biosolids, and manure treatments. Leachate N and SRP concentrations from the PBR treatment were significantly lower than in the treatments with inorganic fertilizers, poultry manure, and biosolids. We conclude that PBR can substitute for inorganic fertilizers and other organic sources of plant nutrients to produce bioenergy biomass cheaply, without causing offsite N and P losses in vulnerable soils.展开更多
Amidst intensifying global agricultural water demand,optimizing management practices and understanding the role of soil amendments,particularly biochar(BC),in modulating soil water dynamics are critical.Here,we review...Amidst intensifying global agricultural water demand,optimizing management practices and understanding the role of soil amendments,particularly biochar(BC),in modulating soil water dynamics are critical.Here,we review the potential impacts of BC on soil water dynamics,elucidate mechanistic underpinnings,and identify critical research gaps and prospective avenues.In general,BC modifies soil structure,hydraulic properties,surface albedo,and heat fluxes,which influence soil water storage,energy balance,and irrigation paradigms.Depending on soil texture and BC properties,BC demonstrates a greater reduction in bulk density and saturated hydraulic conductivity in coarse-textured soils compared to fine-textured soils.BC application generally increases water holding capacity(WHC)while exhibiting no consistent impact on soil water infiltration.Increased WHC of soils results from increased porosity,surface area,and soil aggregation.Increased porosity arises from a confluence of factors,encompassing new pores formation,reorganization of pores,increased soil aggregation,dilution effects of BC,reduced soil compaction,and biotic interactions,including increased population of burrowing invertebrates.BC tends to increase plant-available water in coarser soils,attributed to its hydrophilic nature,augmented specific surface area,and enhanced overall porosity.However,BC may induce soil water repellency,contingent upon variables such as feedstock composition,pyrolysis temperature,and specific soil attributes.While BC exhibits transformative potential in enhancing soil hydraulic properties,scalability concerns and economic viability pose challenges to its widespread agricultural application.Overall,BC offers promising avenues for sustainable water management.However,it is imperative to explore large-scale applications and conduct long-term field studies across different management,climate,and soil types to fully understand how different types of BC impact soil water dynamics.展开更多
基金The United States Agency for International Development provided support through the project Feed the Future Soil Fertility Technology Adoption,Policy Reform and Knowledge Management(Cooperative Agreement number AID-BFS-IO-15-00001)。
文摘Soil-emitted nitrous oxide(N2O) and nitric oxide(NO) in crop production are harmful nitrogen(N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, such as dicyandiamide(DCD), and urea deep placement(UDP), are considered effective approaches to reduce these emissions. This study investigated the effects of DCD and UDP, compared to urea and potassium nitrate, on emissions, nitrogen use efficiency and grain yields under direct-seeded rice. High-frequency measurements of N2O and NO emissions were conducted using the automated closed chamber method throughout the crop-growing season and during the ratoon crop. Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively. The highest emission factor(1.53% of applied N) was observed in urea, while the lowest was in UDP(0.08%). Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization. Those emission peaks contributed to 65%–98% of the total seasonal emissions. Residual effects of fertilizer treatments on the N2O emissions from the ratoon crop were not significant;however, the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions. On the other hand, cumulative NO emissions were not significant in either the rice or ratoon crops. UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea. The results suggested that the use of DCD and UDP could mitigate N2O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition.
文摘Essential plant nutrients contained in residues and wastes generated during biofuel processing can be recovered for further production of bioenergy biomass. The objective of this study was to determine the relative agronomic efficiency of “processed” biofuel residual (PBR). Liquid biofuel residual was “processed” by precipitating phosphate and ammonium in the residual with magnesium into a struvite-like material. Then, in a series of greenhouse experiments, we evaluated the fertility potential of PBR, using sweet sorghum (Sorghum bicolor (L.) Moench), as a test bioenergy crop. We compared the agronomic effectiveness of PBR to inorganic commercial fertilizers, biosolids, and poultry manure as nutrient sources. The sources were either applied alone or in combination with supplemental essential plant nutrients (S, K, Mg, and micronutrients). In each of the greenhouse experiments, the crop was grown for 12 wk on soil of minimal native fertility. After each harvest, sufficient water was applied to the soil in each pot over a 6-wk period to yield ~2 L (~one pore volume) of leachate to assess potential total N and soluble reactive phosphorus (SRP) losses. Dry matter yields from the PBR treatment applied alone were significantly greater than yields from inorganic fertilizers, biosolids, and poultry manure treatments applied alone, and similar to yields obtained when the supplemental essential plant nutrients were added to the inorganic fertilizer, biosolids, and manure treatments. Leachate N and SRP concentrations from the PBR treatment were significantly lower than in the treatments with inorganic fertilizers, poultry manure, and biosolids. We conclude that PBR can substitute for inorganic fertilizers and other organic sources of plant nutrients to produce bioenergy biomass cheaply, without causing offsite N and P losses in vulnerable soils.
文摘Amidst intensifying global agricultural water demand,optimizing management practices and understanding the role of soil amendments,particularly biochar(BC),in modulating soil water dynamics are critical.Here,we review the potential impacts of BC on soil water dynamics,elucidate mechanistic underpinnings,and identify critical research gaps and prospective avenues.In general,BC modifies soil structure,hydraulic properties,surface albedo,and heat fluxes,which influence soil water storage,energy balance,and irrigation paradigms.Depending on soil texture and BC properties,BC demonstrates a greater reduction in bulk density and saturated hydraulic conductivity in coarse-textured soils compared to fine-textured soils.BC application generally increases water holding capacity(WHC)while exhibiting no consistent impact on soil water infiltration.Increased WHC of soils results from increased porosity,surface area,and soil aggregation.Increased porosity arises from a confluence of factors,encompassing new pores formation,reorganization of pores,increased soil aggregation,dilution effects of BC,reduced soil compaction,and biotic interactions,including increased population of burrowing invertebrates.BC tends to increase plant-available water in coarser soils,attributed to its hydrophilic nature,augmented specific surface area,and enhanced overall porosity.However,BC may induce soil water repellency,contingent upon variables such as feedstock composition,pyrolysis temperature,and specific soil attributes.While BC exhibits transformative potential in enhancing soil hydraulic properties,scalability concerns and economic viability pose challenges to its widespread agricultural application.Overall,BC offers promising avenues for sustainable water management.However,it is imperative to explore large-scale applications and conduct long-term field studies across different management,climate,and soil types to fully understand how different types of BC impact soil water dynamics.
