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Biochar is considered as a soil amendment for enhancing crop productivity. However, limited information is available on the residual effect of biochar application on rice grain yield and yield attributes. In this study, a fixed field experiment was conducted in a double rice-cropping system from 2017 to 2019. The dynamics of rice grain yield and yield attributes were monitored in the six growing seasons with 0, 20, and 40 t/ha biochar application. The re- sults showed that the averaged grain yields in the first four seasons were increased by 2.56-16.84% and 6.15-10.77% with 20 and 40 t/ha biochar application. The trend of increased grain yield in rice with biochar application during the first seasons was mainly attributable to an increase in total biomass, panicles per m2 and spikelets per panicle. Nonetheless, the grain yields in the sixth season were not influenced by biochar addition due to decreases in panicles per m2 and spikelets per panicle. Thus, it can be seen that the positive effects of biochar application on rice yield and yield attributes depend on the duration of biochar application. [ABSTRACT FROM AUTHOR]

Adopting the concept of the waste to wealth approach, agricultural waste from maize cob could be transformed into a renewable form of energy through thermo-chemical methods of treating the biomass. This method can be utilised for biochar production. The utilisation of biochar has several significant applications. These applications include the enhancement of the soil through amendment, stimulation of crop production by a variety nutrient inputs in the soil, etc. In this research work, a biochar was obtained through a slow pyrolysis process of maize cob waste. This experiment was carried out using a small-scale muffle furnace and subjecting the feedstock to heating at different temperatures (300, 400, 500 °C). The biochar was produced and characterised by a proximate analysis, scan electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, while the surface area was determined by Saer's method. The effect of the temperature on the yield of the biochar was investigated. The results show that the biochar yield decreases with an increasing temperature for the maize cob biochar at 300, 400 and 500 °C. The results of the physiochemical properties showed that the temperature has a great impact on the physicochemical properties of the biochar. The biochar produced at 300 °C has the highest fixed carbon content of 60.5%. The largest surface area was (281.8 m2·g-1) at 500 °C. [ABSTRACT FROM AUTHOR]

Pyrolysing agricultural crop residues and other biomass constitutes a newer method of transforming often difficult, waste materials into a novel type of soil amendment/additive. Simultaneously, this process also makes it possible to exploit part of the energy released in the agricultural production. Biochar, viewed as the solid product of biomass pyrolysis, is a remarkable, porous material, rich in carbon. Two agricultural crop residues, such as wheat and barley straw, were selected for the experimental studies. The results indicate that the practical temperature for the production of biochar from the two explored materials occurs in the vicinity of 600 °C. Starting at this temperature, the biochar produced complies safely with the principal European Biochar Certificate standards (EBC 2012). Thus, for the wheat straw and barley straw - originated char, the content of the carbon amounts to 67.2 and 67.0 mass %, the atomic ratio H : C is as large as 0.032 and 0.026, and the specific surface area amounts to 217 and 201 m²·g-1, respectively. [ABSTRACT FROM AUTHOR]

Soil microorganisms play a main role in the nutrient cycle and they also play an important role in soil health. This article studies the influence of three rates of biochar (0.5, 1 and 3%) in comparison with control (0 biochar) in two different soils (Valečov and Čistá) on soil microbiota activities. The biochar was prepared from 80% of digestate from Zea mays L. and 20% of cellulose fibres by pyrolysis (470°C, 17 min). The biochar ability to influence micro-bial processes in soil was determined by respiration and nitrification tests. There were no significant differences between basal respiration of control samples and biochar-amended samples. Basal respiration in the Valečov soil reached average amounts from 1.32 to 1.52 mg CO2/h/100 g. In the Čistá soil, basal respiration reached average amounts from 1.40 to 1.49 mg CO2/h/100 g. No significant differences were proved also in nitrification tests of both soils. Nitrifying potential was the highest in 3% rate of biochar amendment. There were no negative changes in the measured soil parameters. CO2 efflux was not higher in biochar-amended soil. [ABSTRACT FROM AUTHOR]

In this article, the effect of increasing dry matter content and reaction time of hydrothermal carbonization on mass yield of biochar was studied. Carbonization took place in batch experiments in a pressure vessel. Results have confirmed the assumption that the mass yield of biochar would increase with growing dry matter content in the initial solution and also with reaction time at reaction temperature of 200°C. It was found that components of the liquid product that remain in the biochar have a measurable impact on its mass yield. Mixing of the reactor proved to have a considerable effect on the mass yield as well. Biochar produced in absence of mixing had higher pore volume and higher yield. This was evident even after subtracting the equivalent liquid phase dry matter in the biochar after drying. [ABSTRACT FROM AUTHOR]