Background: The objective of this study was to examine the adsorption-de- sorption phenomena of heavy metals in an agricultural Ferralsol treated with sewage solid waste at rates usually applied for soil fertility man...Background: The objective of this study was to examine the adsorption-de- sorption phenomena of heavy metals in an agricultural Ferralsol treated with sewage solid waste at rates usually applied for soil fertility management. Methods: The study was carried out under laboratory conditions, using a Ferralsol sourced from Makerere University Agricultural Research Institute, Kabanyolo (MUARIK). Soil and sewage solid waste were analysed for pH, organic matter, cation exchange capacity and heavy metals (copper, zinc, chromium and lead). Soil was treated with sewage solid waste at input rates of 0, 50, 100, and 150 g per pot (equivalent to 0, 2.5, 5.0 and 7.5 metric tones·ha﹣1?respectively);and supplemented with phosphorus. The phosphorus was applied at rates of 0, 0.795, 1.591 and 2.385 g per pot (equivalent to 0, 25, 50 and 75 kg·ha﹣1, respectively). Batch adsorption was used to study the sorption-desorption of heavy metals on the treated soil and the Langmuir and Freundlich models were used to analyse the data. Results: Adsorption and desorption isotherms fitted better to Freundlich equation than Langmuir model. Chromium was the most sorbed and retained metal;while lead was the least retained overall. The desorption process was virtually irreversible, considering the low amounts of the metals desorbed. Chromium fitted relatively better to both models than the copper, zinc and lead. All the four metals were less desorbed at high metal concentrations. Conclusion: The four metals would not be available at high metal concentrations especially when the application rate used is ≥ 5.0 tones·ha﹣1 of the sewage solid waste. Thus, the metals would not be available for plant uptake and the chance to contaminate groundwater is very limited especially for chromium.展开更多
The amount of OH- replaced by sulfate, i.e., sulfate-exchange alkalinity, from the electric double layer of ferralsol colloid was measured quantitatively in different conditions with an automatic titration equipment.T...The amount of OH- replaced by sulfate, i.e., sulfate-exchange alkalinity, from the electric double layer of ferralsol colloid was measured quantitatively in different conditions with an automatic titration equipment.The amount of OH- release increased with the amount of Na2SO4 added and decreased with raising pH in the suspension of ferralsol colloid. The exchange acidity was displayed as PH was higher than 5.6. If the negative effect of sodium ions was offset, the amount of OH- replaced by sulfate was larger than the original amount of OH- released in the PH range of lower than 5.8. The amount of OH- released decreased rapidly as PH was higher than 6.0 and dropped to zero when PH reached 6.5. In the solution of 2.0 mol L-1 NaClO4, the amount of OH- replaced by sulfate from the surface of ferralsol colloid could be considered as the amount of OH- adsorbed by ligand exchange reaction. The amount of OH- released in the solution of NaClO4 concentration below 2.0 mol L-1 from which the amount o f OH- adsorbed by ligand exchange reaction was subtracted could be considered as the OH- adsorbed by electrostatic force. The OH- adsorbed by electrostatic force decreased with increases in the concentration of NaClO4 and PH and increased almost linearly with the increasing amount of Na2SO4 added. The percentages of OH- adsorbed by electrostatic force in water and in the electrolyte solutions of 0.05 and 0.5 mol L-1NaClO4 in the total OH- released were calculated, respectively.展开更多
There is immobilization of inorganic P （phosphorus） fertilizer becoming unavailable to plants and declining yield over cropping seasons is occurring in rice agro-ecology of humid forest. The performances of indigeno...There is immobilization of inorganic P （phosphorus） fertilizer becoming unavailable to plants and declining yield over cropping seasons is occurring in rice agro-ecology of humid forest. The performances of indigenous PR （rock phosphates） from Ma （Mali）, Burkina Bu （Faso）, Ni （Niger）, To （Togo） and Senegal including that of Pa （Thies） and Ta （Taiba） were tested applying 200 kg.P2O5.ha-1 and 400 kg.P2O5.ha-1 once for three cropping seasons while TSP （triple super phosphate） was applied every season at 60 kg.P2O5.ha-1 and 120 kg-P2O5.ha-1. No P-fertilizer treatment was the control plot and WAB 56-104 was sown as rice variety. No significant difference was observed between the overall mean values of plant height, tiller and panicle numbers according to P-sources likewise for the grain yield when comparing that of 60 kg.P2O5.ha-1 （TSP） vs. treatments of PR while, the treatments Pa, Ta and To significantly induced greater grain yield than 120 kg.P2O5.ha-1 as TSP. Moreover, declining yield in the third cropping year was greater （75%） with TSP than for To, which was not significantly impacted by the number of cropping seasons. Applying 200 kg.P2O5.ha-1 of To was suggested as strategy for sustaining rice production on Ferralsol of west Africa.展开更多
In Côte d’Ivoire, the decline in soil fertility strongly impacts the productivity of maize (Zea mays L.) on heavily leached ferralitic soil. In this study, the general objective was therefore to improve the prod...In Côte d’Ivoire, the decline in soil fertility strongly impacts the productivity of maize (Zea mays L.) on heavily leached ferralitic soil. In this study, the general objective was therefore to improve the productivity of maize EV87-28 on the Ferralsols in pre-forested areas during different cropping seasons. Eight (8) micro-plots were set up according to a total randomization device with three repetitions. Two factors were studied: nitrogen fertilizer modalities (main factor) and crop season (secondary factor). Growth, flowering and yield parameters were measured and analyzed. The results showed that there was no interaction between the nitrogen fertilizer factor and the cropping season factor. In addition, this study showed the short rainy season had the most positive impact on growth, flowering and yield parameters than the long rainy season. The results also showed that the different nitrogen fertilizer modalities had no statistically different effects on growth, flowering and yield parameters. However, quantitative differences were reported, highlighting one nitrogen fertilizer modality, which is the combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure). The combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure) had the best effect on corn grain yield. So, the combination of urea (75%) and manure (25%), that resulted in yield gain, could be recommended for corn fertilization during the small rainy season.展开更多
Despite an abundance of short-term studies focusing on biochar’s effects on annual plants,the long-term effects of biochar on perennial plants and the effects of the biochar on the mobility and speciation changes of ...Despite an abundance of short-term studies focusing on biochar’s effects on annual plants,the long-term effects of biochar on perennial plants and the effects of the biochar on the mobility and speciation changes of metals/metalloids not limited to main plant nutrients in soils are poorly constrained.This study reports on the amelioration a sloped orthic ferralsol by biochar from Tibouchina wood and the resulting effects on perennial crops and microbiota,including a comprehensive analysis of metals/metalloids speciation changes.Fields were amended with biochar and urine-amended biochar(2 kg/m^(2))and were planted with papaya,banana,and manioc.Soil and plant materials were analyzed using acid digestions,sequential extractions,and 16S rRNA gene sequencing.Biochar applications led to decreased soil acidity,shifted the cation exchange capacity from being Al-influenced to being Mg/K/Ca-dominated,and elevated the concentrations of Mg,K,Ca,Zn,and Ba in soils.The exchangeable/acid-soluble fraction of Ca,P,and S notably increased.The soil microbial biome became more species rich and diverse in the biochar-amended fields.Manioc benefited from biochar applications,demonstrating increased growth,which resulted in generally decreased concentrations of trace elements in most plant parts,however,with an increased total elemental uptake.Urine amendment contributed to higher concentrations of P,S,and K in soils,but did not further increase plant growth.Biochar was shown to be a promising soil amendment for agricultural use of orthic ferralsols of the Brazil’s Atlantic forest region,but the accumulation of potentially harmful metals needs to be considered.展开更多
The study was to investigate the adsorption behavior of arsenite （As（HI）） and arsenate （As（V）） on two variable charge soils, i.e., Haplic Acrisol and Rhodic Ferralsol at different ionic strengths and pH with b...The study was to investigate the adsorption behavior of arsenite （As（HI）） and arsenate （As（V）） on two variable charge soils, i.e., Haplic Acrisol and Rhodic Ferralsol at different ionic strengths and pH with batch methods. Results indicated that the amount of As（HI） adsorbed by these two soils increased with increasing solution pH, whereas it decreased with increasing ionic strength under the acidic condition. This suggested that As（Ⅲ） was mainly adsorbed on soil positive charge sites through electrostatic attraction under the acidic condition. Moreover, intersects of As（Ⅴ） adsorption-pH curves at different ionic strengths （a characteristic pH） are obtained for both soils. It was noted that above this pH, the adsorption of As（Ⅴ） was increased with increasing ionic strength, whereas below it the reverse trend was true. Precisely the intersect pH was 3.6 for Haplic Acrisol and 4.5 for Rhodic Ferralsol, which was near the values of PZSE （soil point of zero salt effect） of these soils. The effects of ionic strength and pH on arsenate adsorption by these soils were interpreted by the adsorption model. The results of zeta potential suggested that the potential in adsorption plane becomes less negative with increasing ionic strength above soil PZSE and decreases with increasing ionic strength below soil PZSE. These results further supported the hypothesis of the adsorption model that the potential in the adsorption plane changes with ionic strength with an opposite trend to surface charge of the soils. Therefore, the change of the potential in the adsorption plane was mainly responsible for the change of arsenate adsorption induced by ionic strength on variable charge soils.展开更多
Maize production in Kenya is constrained by weed infestation and nutrient deficiencies. Field studies were conducted during the 2008/2009 cropping seasons to investigate weeds in maize fields on three dominant soil ty...Maize production in Kenya is constrained by weed infestation and nutrient deficiencies. Field studies were conducted during the 2008/2009 cropping seasons to investigate weeds in maize fields on three dominant soil types in Western Kenya. Weeds were inventoried and their composition was compared using Jaccard＇s index. The economic importance of weed species （potential to reduce yields and the difficulty to control them by manual weeding） was assessed through participatory surveys. Finally, field trials assessed the effects of management options （farmer＇s practice, clean weeding, green manure, zero-tillage ＋ cover crop and zero-tillage） on weed biomass and species composition. Across the three soil types, 55 weed species in 21 families were identified. Soil types influenced species composition as confirmed by Jaccard＇s similarity indices of 0.50, 0.58 and 0.62 for Nitisol vs. Acrisol, Ferralsol vs. Acrisol and Nitisol vs. Ferralsol, respectively. The economically important weeds were Commelina benghalensis, Cynodon nlemfuensis, Bidens pilosa, Galinsoga parviflora and Leonotis nepetifolia. Management options significantly （P 〈 0.05） reduced weed biomass, irrespective of soil type and seasons. Maize biomass response was highest （7-16 Mg ha1） in zero-tillage and zero-tillage ＋ cover crop and lowest （2-8 Mg ha1） in farmer＇s practice. Significantly negative relationships （P 〈 0.01, r2 = 0.37 - 0.51） were established between leaf area index of maize and weed biomass across the soils. Zero-tillage combined with the use of a cover crop had the lowest weed biomass （〈 30% of the farmer practice） and thus appears to be a promising strategy combining soil fertility improvement with weed suppression in smallholder maize farming systems of Western Kenya.展开更多
Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar appl...Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar application is a promising approach to lower soil greenhouse gas emissions,particularly under high soil moisture conditions where denitrification is the primary N-transformation pathway.In a replicated field trial,we evaluated the effects of two contrasting biochars derived from poul-try litter and from hardwood on soil N_(2)O emissions,soil ammonium(NH4^(+))and nitrate(NO3^(−))status,pasture productivity and herbage nutrient content.A liming treatment to mimic the liming equivalence of the poultry litter biochar was used to separate any effects observed from changes in soil pH.To further separate the effects of biochars on soil N status,N_(2)O emissions and pasture N uptake,high and low N fertiliser doses(annual application of 672 kg N ha^(−1),336 kg N ha^(−1))were superimposed across all of the treatments.The N fertiliser dose had no significant impact on pasture yield.Application of poultry litter biochar resulted in significant increases in pasture productivity under both high and low N inputs.This was achieved by alleviating soil P,and possibly K nutritional constraints that are typical in Australian Ferralsols.Under the high N fertiliser dose,emissions of N_(2)O from the treatments and control were not significantly different(p>0.05)and ranged between 1.14 and 1.78 kg N_(2)O-N ha^(−1)across the 11-month study.The low N dose resulted in significantly lower emissions of N_(2)O of between 0.80 and 0.84 kg N_(2)O-N ha^(−1),but biochar had no significant effect on net emissions across the season.The lack of impact of biochar on N_(2)O emissions was attributed to the relatively dry conditions over the trial period resulting in nitrification being the most likely N-transformation pathway.During brief episodes of high soil moisture,peak emissions from the biochar plots were lower than from the control or lime treatment,but these differences did not impact on the emis-sion budget over the 11-month sampling campaign.展开更多
文摘Background: The objective of this study was to examine the adsorption-de- sorption phenomena of heavy metals in an agricultural Ferralsol treated with sewage solid waste at rates usually applied for soil fertility management. Methods: The study was carried out under laboratory conditions, using a Ferralsol sourced from Makerere University Agricultural Research Institute, Kabanyolo (MUARIK). Soil and sewage solid waste were analysed for pH, organic matter, cation exchange capacity and heavy metals (copper, zinc, chromium and lead). Soil was treated with sewage solid waste at input rates of 0, 50, 100, and 150 g per pot (equivalent to 0, 2.5, 5.0 and 7.5 metric tones·ha﹣1?respectively);and supplemented with phosphorus. The phosphorus was applied at rates of 0, 0.795, 1.591 and 2.385 g per pot (equivalent to 0, 25, 50 and 75 kg·ha﹣1, respectively). Batch adsorption was used to study the sorption-desorption of heavy metals on the treated soil and the Langmuir and Freundlich models were used to analyse the data. Results: Adsorption and desorption isotherms fitted better to Freundlich equation than Langmuir model. Chromium was the most sorbed and retained metal;while lead was the least retained overall. The desorption process was virtually irreversible, considering the low amounts of the metals desorbed. Chromium fitted relatively better to both models than the copper, zinc and lead. All the four metals were less desorbed at high metal concentrations. Conclusion: The four metals would not be available at high metal concentrations especially when the application rate used is ≥ 5.0 tones·ha﹣1 of the sewage solid waste. Thus, the metals would not be available for plant uptake and the chance to contaminate groundwater is very limited especially for chromium.
文摘The amount of OH- replaced by sulfate, i.e., sulfate-exchange alkalinity, from the electric double layer of ferralsol colloid was measured quantitatively in different conditions with an automatic titration equipment.The amount of OH- release increased with the amount of Na2SO4 added and decreased with raising pH in the suspension of ferralsol colloid. The exchange acidity was displayed as PH was higher than 5.6. If the negative effect of sodium ions was offset, the amount of OH- replaced by sulfate was larger than the original amount of OH- released in the PH range of lower than 5.8. The amount of OH- released decreased rapidly as PH was higher than 6.0 and dropped to zero when PH reached 6.5. In the solution of 2.0 mol L-1 NaClO4, the amount of OH- replaced by sulfate from the surface of ferralsol colloid could be considered as the amount of OH- adsorbed by ligand exchange reaction. The amount of OH- released in the solution of NaClO4 concentration below 2.0 mol L-1 from which the amount o f OH- adsorbed by ligand exchange reaction was subtracted could be considered as the OH- adsorbed by electrostatic force. The OH- adsorbed by electrostatic force decreased with increases in the concentration of NaClO4 and PH and increased almost linearly with the increasing amount of Na2SO4 added. The percentages of OH- adsorbed by electrostatic force in water and in the electrolyte solutions of 0.05 and 0.5 mol L-1NaClO4 in the total OH- released were calculated, respectively.
文摘There is immobilization of inorganic P （phosphorus） fertilizer becoming unavailable to plants and declining yield over cropping seasons is occurring in rice agro-ecology of humid forest. The performances of indigenous PR （rock phosphates） from Ma （Mali）, Burkina Bu （Faso）, Ni （Niger）, To （Togo） and Senegal including that of Pa （Thies） and Ta （Taiba） were tested applying 200 kg.P2O5.ha-1 and 400 kg.P2O5.ha-1 once for three cropping seasons while TSP （triple super phosphate） was applied every season at 60 kg.P2O5.ha-1 and 120 kg-P2O5.ha-1. No P-fertilizer treatment was the control plot and WAB 56-104 was sown as rice variety. No significant difference was observed between the overall mean values of plant height, tiller and panicle numbers according to P-sources likewise for the grain yield when comparing that of 60 kg.P2O5.ha-1 （TSP） vs. treatments of PR while, the treatments Pa, Ta and To significantly induced greater grain yield than 120 kg.P2O5.ha-1 as TSP. Moreover, declining yield in the third cropping year was greater （75%） with TSP than for To, which was not significantly impacted by the number of cropping seasons. Applying 200 kg.P2O5.ha-1 of To was suggested as strategy for sustaining rice production on Ferralsol of west Africa.
文摘In Côte d’Ivoire, the decline in soil fertility strongly impacts the productivity of maize (Zea mays L.) on heavily leached ferralitic soil. In this study, the general objective was therefore to improve the productivity of maize EV87-28 on the Ferralsols in pre-forested areas during different cropping seasons. Eight (8) micro-plots were set up according to a total randomization device with three repetitions. Two factors were studied: nitrogen fertilizer modalities (main factor) and crop season (secondary factor). Growth, flowering and yield parameters were measured and analyzed. The results showed that there was no interaction between the nitrogen fertilizer factor and the cropping season factor. In addition, this study showed the short rainy season had the most positive impact on growth, flowering and yield parameters than the long rainy season. The results also showed that the different nitrogen fertilizer modalities had no statistically different effects on growth, flowering and yield parameters. However, quantitative differences were reported, highlighting one nitrogen fertilizer modality, which is the combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure). The combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure) had the best effect on corn grain yield. So, the combination of urea (75%) and manure (25%), that resulted in yield gain, could be recommended for corn fertilization during the small rainy season.
基金This study was financially supported by the Natural Sciences and Engineering Research Council of Canada(Discovery Grant RGPIN-04134 to D.S.A.)the Graduate Student Association(travel Grant to K.v.G.)the Faculty of Graduate Studies and Research(travel Grant to M.H.)。
文摘Despite an abundance of short-term studies focusing on biochar’s effects on annual plants,the long-term effects of biochar on perennial plants and the effects of the biochar on the mobility and speciation changes of metals/metalloids not limited to main plant nutrients in soils are poorly constrained.This study reports on the amelioration a sloped orthic ferralsol by biochar from Tibouchina wood and the resulting effects on perennial crops and microbiota,including a comprehensive analysis of metals/metalloids speciation changes.Fields were amended with biochar and urine-amended biochar(2 kg/m^(2))and were planted with papaya,banana,and manioc.Soil and plant materials were analyzed using acid digestions,sequential extractions,and 16S rRNA gene sequencing.Biochar applications led to decreased soil acidity,shifted the cation exchange capacity from being Al-influenced to being Mg/K/Ca-dominated,and elevated the concentrations of Mg,K,Ca,Zn,and Ba in soils.The exchangeable/acid-soluble fraction of Ca,P,and S notably increased.The soil microbial biome became more species rich and diverse in the biochar-amended fields.Manioc benefited from biochar applications,demonstrating increased growth,which resulted in generally decreased concentrations of trace elements in most plant parts,however,with an increased total elemental uptake.Urine amendment contributed to higher concentrations of P,S,and K in soils,but did not further increase plant growth.Biochar was shown to be a promising soil amendment for agricultural use of orthic ferralsols of the Brazil’s Atlantic forest region,but the accumulation of potentially harmful metals needs to be considered.
基金supported by the Knowledge Innovation Program Foundation of the Chinese Academy of Sciences (No. KZCX2-YW-409)the National Natural Science Foundation of China (No. 20577054)
文摘The study was to investigate the adsorption behavior of arsenite （As（HI）） and arsenate （As（V）） on two variable charge soils, i.e., Haplic Acrisol and Rhodic Ferralsol at different ionic strengths and pH with batch methods. Results indicated that the amount of As（HI） adsorbed by these two soils increased with increasing solution pH, whereas it decreased with increasing ionic strength under the acidic condition. This suggested that As（Ⅲ） was mainly adsorbed on soil positive charge sites through electrostatic attraction under the acidic condition. Moreover, intersects of As（Ⅴ） adsorption-pH curves at different ionic strengths （a characteristic pH） are obtained for both soils. It was noted that above this pH, the adsorption of As（Ⅴ） was increased with increasing ionic strength, whereas below it the reverse trend was true. Precisely the intersect pH was 3.6 for Haplic Acrisol and 4.5 for Rhodic Ferralsol, which was near the values of PZSE （soil point of zero salt effect） of these soils. The effects of ionic strength and pH on arsenate adsorption by these soils were interpreted by the adsorption model. The results of zeta potential suggested that the potential in adsorption plane becomes less negative with increasing ionic strength above soil PZSE and decreases with increasing ionic strength below soil PZSE. These results further supported the hypothesis of the adsorption model that the potential in the adsorption plane changes with ionic strength with an opposite trend to surface charge of the soils. Therefore, the change of the potential in the adsorption plane was mainly responsible for the change of arsenate adsorption induced by ionic strength on variable charge soils.
文摘Maize production in Kenya is constrained by weed infestation and nutrient deficiencies. Field studies were conducted during the 2008/2009 cropping seasons to investigate weeds in maize fields on three dominant soil types in Western Kenya. Weeds were inventoried and their composition was compared using Jaccard＇s index. The economic importance of weed species （potential to reduce yields and the difficulty to control them by manual weeding） was assessed through participatory surveys. Finally, field trials assessed the effects of management options （farmer＇s practice, clean weeding, green manure, zero-tillage ＋ cover crop and zero-tillage） on weed biomass and species composition. Across the three soil types, 55 weed species in 21 families were identified. Soil types influenced species composition as confirmed by Jaccard＇s similarity indices of 0.50, 0.58 and 0.62 for Nitisol vs. Acrisol, Ferralsol vs. Acrisol and Nitisol vs. Ferralsol, respectively. The economically important weeds were Commelina benghalensis, Cynodon nlemfuensis, Bidens pilosa, Galinsoga parviflora and Leonotis nepetifolia. Management options significantly （P 〈 0.05） reduced weed biomass, irrespective of soil type and seasons. Maize biomass response was highest （7-16 Mg ha1） in zero-tillage and zero-tillage ＋ cover crop and lowest （2-8 Mg ha1） in farmer＇s practice. Significantly negative relationships （P 〈 0.01, r2 = 0.37 - 0.51） were established between leaf area index of maize and weed biomass across the soils. Zero-tillage combined with the use of a cover crop had the lowest weed biomass （〈 30% of the farmer practice） and thus appears to be a promising strategy combining soil fertility improvement with weed suppression in smallholder maize farming systems of Western Kenya.
文摘Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar application is a promising approach to lower soil greenhouse gas emissions,particularly under high soil moisture conditions where denitrification is the primary N-transformation pathway.In a replicated field trial,we evaluated the effects of two contrasting biochars derived from poul-try litter and from hardwood on soil N_(2)O emissions,soil ammonium(NH4^(+))and nitrate(NO3^(−))status,pasture productivity and herbage nutrient content.A liming treatment to mimic the liming equivalence of the poultry litter biochar was used to separate any effects observed from changes in soil pH.To further separate the effects of biochars on soil N status,N_(2)O emissions and pasture N uptake,high and low N fertiliser doses(annual application of 672 kg N ha^(−1),336 kg N ha^(−1))were superimposed across all of the treatments.The N fertiliser dose had no significant impact on pasture yield.Application of poultry litter biochar resulted in significant increases in pasture productivity under both high and low N inputs.This was achieved by alleviating soil P,and possibly K nutritional constraints that are typical in Australian Ferralsols.Under the high N fertiliser dose,emissions of N_(2)O from the treatments and control were not significantly different(p>0.05)and ranged between 1.14 and 1.78 kg N_(2)O-N ha^(−1)across the 11-month study.The low N dose resulted in significantly lower emissions of N_(2)O of between 0.80 and 0.84 kg N_(2)O-N ha^(−1),but biochar had no significant effect on net emissions across the season.The lack of impact of biochar on N_(2)O emissions was attributed to the relatively dry conditions over the trial period resulting in nitrification being the most likely N-transformation pathway.During brief episodes of high soil moisture,peak emissions from the biochar plots were lower than from the control or lime treatment,but these differences did not impact on the emis-sion budget over the 11-month sampling campaign.
