Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of...Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended soil.However, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro-and macro-structural stability, and resilience of two differently textured soils,fine sand(FS) and sandy loam(SL). Test substrates were prepared by adding 50 or 100 g kg^(-1) biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.展开更多
Remotely sensed air temperature data from NASA POWER are widely used in regions with scarce climatic observations,particularly for agricultural applications such as calculating crop water requirements.This study emplo...Remotely sensed air temperature data from NASA POWER are widely used in regions with scarce climatic observations,particularly for agricultural applications such as calculating crop water requirements.This study employed a suite of machine learning(ML)algorithms to correct biases in NASA POWER air temperature outputs,including multiple support vector regression(svR)variants—Linear SVR,Quadratic SVR,Cubic SVR,Fine Gaussian SVR,Medium Gaussian SVR,Coarse Gaussian SVR—and ensemble decision tree models:bagged trees(BGT)and boosted trees(BT).The objective of this study was to assess the ability of different ML algorithms to reduce biases in NASA POWER air temperature data,with the broader goal of identifying the most suitable ML method for air temperature bias correction in Nigeria.For this analysis,we used daily air temperature records from seven meteorological stations across diverse regions of Nigeria.The performance of NASA POWER minimum and maximum air temperature datasets was evaluated using standard error metrics.Subsequent application of ML algorithms significantly improved data accuracy:the normalized root mean square error(NRMSE)of the corrected outputs was mostly below 10%,indicating excellent predictive performance when ML was integrated.Among the SVR variants tested,Fine Gaussian SVR consistently yielded the best prediction results.This finding suggests that Fine Gaussian SVR is a robust tool for enhancingthe reliability of air temperature data—critical for improving the accuracy of crop water requirement calculations in regions where in-situ air temperature observations are limited.展开更多
The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,t...The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,the strength of their individual and combined effects on crop productivity has been scarcely reported.In addition,few studies have assessed their individual and co-application effects on economic returns.Therefore,a 2-year field experiment which consisted of factorial combination of irrigation(I)[100%full irrigation(FI),80%FI and 60%FI],biochar(0 and 20 t/ha)and fertiliser(0 and 300 kg/ha)was conducted.According to the results,irrigation was the dominant factor that influences maize grain yield,followed by inorganic fertiliser and biochar,and they were all significant in their main effects.The strength of interaction effects among,I,F and B on maize grain yield follow the sequence F×I>B×F>B×I.The economic analysis showed that the ternary combination of B,F and I was more economical than the binary combination of B plus I,and F plus I(in that order),when compared with the standalone application of I at maximum production in the field experiment.In addition,combined applications of biochar and fertiliser improved soil nutrients,nutrient uptake in all irrigation treatments,compared to the standalone applications of biochar or fertiliser.Further research is,therefore,recommended for long-term evaluation of the economic viability of integrating biochar with fertiliser under irrigation.展开更多
基金the George Foster Research Fellowship provided by Alexander yon Humboldt Fellowship of Germany.
文摘Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended soil.However, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro-and macro-structural stability, and resilience of two differently textured soils,fine sand(FS) and sandy loam(SL). Test substrates were prepared by adding 50 or 100 g kg^(-1) biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.
基金funded by a grant(RE-KRIS/FF66/43)from King Mongkut's Institute of Technology Ladkrabang(KMITL)and the National Science,Research and Innovation Fund(NSRF)。
文摘Remotely sensed air temperature data from NASA POWER are widely used in regions with scarce climatic observations,particularly for agricultural applications such as calculating crop water requirements.This study employed a suite of machine learning(ML)algorithms to correct biases in NASA POWER air temperature outputs,including multiple support vector regression(svR)variants—Linear SVR,Quadratic SVR,Cubic SVR,Fine Gaussian SVR,Medium Gaussian SVR,Coarse Gaussian SVR—and ensemble decision tree models:bagged trees(BGT)and boosted trees(BT).The objective of this study was to assess the ability of different ML algorithms to reduce biases in NASA POWER air temperature data,with the broader goal of identifying the most suitable ML method for air temperature bias correction in Nigeria.For this analysis,we used daily air temperature records from seven meteorological stations across diverse regions of Nigeria.The performance of NASA POWER minimum and maximum air temperature datasets was evaluated using standard error metrics.Subsequent application of ML algorithms significantly improved data accuracy:the normalized root mean square error(NRMSE)of the corrected outputs was mostly below 10%,indicating excellent predictive performance when ML was integrated.Among the SVR variants tested,Fine Gaussian SVR consistently yielded the best prediction results.This finding suggests that Fine Gaussian SVR is a robust tool for enhancingthe reliability of air temperature data—critical for improving the accuracy of crop water requirement calculations in regions where in-situ air temperature observations are limited.
基金We appreciate the research grant from the Tertiary Education Trust Fund(TETFUND)Nigeria,which was used to fund part of this research.
文摘The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,the strength of their individual and combined effects on crop productivity has been scarcely reported.In addition,few studies have assessed their individual and co-application effects on economic returns.Therefore,a 2-year field experiment which consisted of factorial combination of irrigation(I)[100%full irrigation(FI),80%FI and 60%FI],biochar(0 and 20 t/ha)and fertiliser(0 and 300 kg/ha)was conducted.According to the results,irrigation was the dominant factor that influences maize grain yield,followed by inorganic fertiliser and biochar,and they were all significant in their main effects.The strength of interaction effects among,I,F and B on maize grain yield follow the sequence F×I>B×F>B×I.The economic analysis showed that the ternary combination of B,F and I was more economical than the binary combination of B plus I,and F plus I(in that order),when compared with the standalone application of I at maximum production in the field experiment.In addition,combined applications of biochar and fertiliser improved soil nutrients,nutrient uptake in all irrigation treatments,compared to the standalone applications of biochar or fertiliser.Further research is,therefore,recommended for long-term evaluation of the economic viability of integrating biochar with fertiliser under irrigation.
