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The effect of biochar and organic resource applications on lettuce cultivation was investigated. Treatment conditions of pot experiment were designed with CN (control), IF (inorganic fertilizer), BC400-1 (Rice husk biochar 400°C 1%), BC400-1+CP (Rice husk biochar 400°C 1%+compost), BC400-4 (Rice husk biochar 400°C 4%), BC400-4+CP (Rice husk biochar 400°C 4%+compost), BC600-1 (Rice husk biochar 600°C 1%), BC600-1+CP (Rice husk biochar 600°C 1%+compost), BC600-4 (Rice husk biochar 600°C 4%) and BC600-4+CP (Rice husk biochar 600°C 4%+compost). The lettuce fresh weight in IF, BC400, and BC600 treatments increased 185, 101-219, and 83-138%, respectively, over that in CN treatment. Total amount of nutrient uptake in lettuce increased in the order BC400-4+CP > IF ≒ BC600-4+CP ≧ BC400-4 ≧ BC400-1+ CP ≧ BC600-1+CP ≧ BC600-4 ≒ BC600-1 ≧ BC400-1 ≒ CN treatments. Considering the results of fresh weight, number of leaves, and nutrients of lettuce, the growth of lettuce was most effective in BC400-4+CP treatment, over that in the IF treatment. Application of combined biochar and compost significantly affected the chemical characteristics of field soil after lettuce harvest. In addition, the positive effects of biochar and compost in soil were related to improved nutrient availability-related parameters such pH and CEC. Therefore, proper application of biochar with compost is effective at improving lettuce cultivation and can benefit the soil environment.

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To improve the agricultural environment, utilization of biochar and organic materials from paddy fields gaining importance. This is because the long-term use of inorganic fertilizers aggravates the soil environment, and also because rice paddy is a major source of CH4 and N2O emissions during rice cultivation which involves continuous flooding. Recently, the application of organic materials and biochar to the soil has received increasing attention due to their potential benefits related to soil quality, crop growth, and greenhouse gas emission. This study examines the influence of biochar and straw treatments on rice growth, soil physicochemical properties, and global warming potential in the paddy field. Five treatments were applied for the study: control (Cn), inorganic fertilizer (IF), barley straw biochar (BC), barley straw (BS), and BC + BS. Soil quality after rice harvesting improved in the BC treated group. The yield components of rice were also improved in the BC + BS, compared to other treatments. These effects resulted in increased rice yield and uptake of nutrient contents in the BC + BS treatment. Total fluxes of CH4 and N2O relative to global warming significantly decreased by 37.3% and 65.2% in the BC + BS group than in the IF treatment, respectively. Consequentially, a cropping system with BC and BS is an effective strategy to improve rice productivity and soil quality and also reduce GHG emissions from paddy fields, thereby alleviating global warming.

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A field experiment was carried out to investigate crop productivity, emissions of carbon dioxide (CO2) and nitrous oxide (N2O), and soil quality of an upland field treated with compost and varying rates of biochar (BC) derived from soybean stalks during crop growing periods in a corn and Chinese cabbage rotation system. Compost was supplemented with BC derived from soybean stalks at varying rates of 5, 10, 15, and 20 t ha−1 (BC5, BC10, BC15, and BC20, respectively); the control (BC0) area was untreated. Our results reveal that crop productivity and emissions of CO2 and N2O varied significantly with the biochar application rate. Moreover, irrespective of the biochar application rate, crop productivity was improved after BC application as compared to the control treatment area, by 11.2–29.3% (average 17.0 ± 8.3%) for corn cultivation and 10.3–39.7% (average 27.8 ± 12.7%) for Chinese cabbage cultivation. Peak emissions of CO2 and N2O were mainly observed in the early period of crop cultivation, whereas low CO2 and N2O emissions were determined during the fallow period. Compared to the control area, significant differences were obtained for CO2 emissions produced by the different biochar application rates for both crops. During the two cropping periods, the overall N2O emission was significantly decreased with BC5, BC10, BC15, and BC20 applications as compared to the control, ranging from 11.1 to 13.6%, 8.7 to 15.4%, 23.1 to 26.0%, and 15.0 to 19.6%, respectively (average 16.9% decrease in the corn crop period and 16.3% in the Chinese cabbage crop period). Soil quality results after the final crop harvest show that bulk density, soil organic carbon (SOC), pH, and cation exchange capacity (CEC) were significantly improved by biochar application, as compared to the control. Taken together, our results indicate that compost application supplemented with biochar is potentially an appropriate strategy for achieving high crop productivity and improving soil quality in upland field conditions. In conclusion, appropriate application of biochar with compost has the concomitant advantages of enriching soil quality for long-term sustainable agriculture and reducing the use of inorganic fertilizers.

This study was conducted to evaluate the effect of application levels of inorganic fertilizer (IF) with corn waste biochar (BC) for corn cultivation in an upland field (34° 94ʹ 24ʺ N, 127° 56ʹ 55ʺ E). The IF (N-P-K 14.5-3.0-6.0 kg 10a -1 ) was applied at levels of 25%, 50%, 75%, and 100% of standard amount with BC (BC+IF25, BC+IF50, BC+IF75, and BC+IF100, respectively), and Cn (control), BC and IF treatments were added in this study. The BC was application of 500 kg 10a -1 at 20 days before corn sowing. The mean biomass productivity of corn plants, when grown under Cn, BC, IF, BC+IF25, BC+IF50, BC+75, and BC+IF100 treatment conditions, were 1.82, 2.21, 2.74, 2.40, 3.12, 3.73, and 4.05 kg m -2 , respectively. The corn length was 14.6-18.3 cm ear -1 in all treatments, and the total weight of corn increased in the order BC+IF100 ≒ BC+IF75 > BC+IF50 > IF > BC ≒ BC+IF25 > Cn treatments. The corn productivity was highest (3.97 kg m -2 ) in the BC+IF100 treatment. The corn grain yields in BC+IF50, BC+IF75, and BC+IF100 treatments increased by 145, 129, and 103% respectively, over that in the IF treatment. Based on our results, the minimum IF application level using biochar for corn cultivation was N of 7.25 kg 10a -1 , P of 1.5 kg 10a -1 , and K of 3.0 kg 10a -1 , respectively. Therefore, proper application of inorganic fertilizer with biochar is effective at improving corn cultivation and can benefit the soil environment.

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