USDA, Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, 9611 South Riverbend Avenue, Parlier, CA 93648-9757, United States of America.
USDA, Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, 9611 South Riverbend Avenue, Parlier, CA 93648-9757, United States of America.
Sci Total Environ. 2023 Aug 20;887:164146. doi: 10.1016/j.scitotenv.2023.164146. Epub 2023 May 13.
Application of inorganic nitrogen (N) fertilizers in agriculture can increase emissions of nitrous oxide, a potent greenhouse gas, leaching of nitrate (NO), a groundwater contaminant hazardous to human health, and soil acidification. Soil amendment with biochar potentially mitigates these losses and undesirable outcomes. However, there have been considerable inconsistencies in reported impacts, likely owing to variable physiochemical characteristics of the biochar materials and/or the soil environment. This study methodically evaluated the impact of biochar soil incorporation on N transformation and underlying microbial processes using soils with varying biochar types, soil texture, soil moisture, and manure compost co- amendments. Laboratory incubations were conducted to monitor the fate of urea fertilizer N spiked in biochar amended and unamended soils by assaying soil ammonium (NH), nitrite (NO), and NO concentrations, pH, and abundances of soil nitrifiers; ammonia oxidizing bacteria and archaea (AOB and AOA) and Nitrospira with the capacity to perform complete ammonia oxidation (comammox). Soil moisture was a critical factor affecting N transformation processes, more so than biochar, but biochar did result in significantly different concentrations of N species in response to urea application. Biochar enhanced nitrification, more significantly in drier conditions and in sandy soil. Biochar offered some buffering potential in the neutral-alkaline, unsaturated soils, preventing >1 unit drop in pH compared to unamended soils. Co-application of biochar with manure composts enhanced nitrification slightly, which was evidenced by higher abundances of some soil nitrifiers at 4 weeks, although increases in nitrification rates were not statistically significant. Soil nitrifier populations tended to increase in response to a pinewood biochar, but trends differed for saturated soil, in soils of differing textures, or when different biochar materials were evaluated. Thus, when evaluating implications of biochar on the fate of mineral N fertilizer, soil moisture and other environment conditions should be considered.
农业中无机氮肥（N）的应用会增加一氧化二氮（N2O）的排放，一氧化二氮是一种强效温室气体，还会导致硝酸盐（NO）的淋失，硝酸盐是一种对人类健康有害的地下水污染物，并会导致土壤酸化。生物炭土壤改良剂可能会减轻这些损失和不良后果。然而，报告的影响存在相当大的不一致，这可能是由于生物炭材料和/或土壤环境的物理化学特性不同。本研究系统地评估了使用具有不同生物炭类型、土壤质地、土壤湿度和粪肥堆肥共添加的土壤，将生物炭掺入土壤对 N 转化和潜在微生物过程的影响。通过测定土壤中添加和未添加生物炭的土壤中尿素肥料 N 的命运，进行了实验室孵化实验，检测土壤中的铵（NH）、亚硝酸盐（NO）和硝酸盐（NO）浓度、pH 值以及具有完全氨氧化能力的土壤硝化菌；氨氧化细菌和古菌（AOB 和 AOA）和硝化螺旋菌的丰度。土壤湿度是影响 N 转化过程的关键因素，比生物炭更重要，但生物炭确实会导致在施加尿素后，N 物质的浓度显著不同。生物炭增强了硝化作用，在干燥条件下和沙质土壤中更为显著。生物炭在中性-碱性、不饱和土壤中具有一定的缓冲能力，与未添加生物炭的土壤相比，可防止 pH 值下降超过 1 个单位。生物炭与粪肥堆肥的共添加略微增强了硝化作用，这在 4 周时一些土壤硝化菌的丰度更高时得到了证明，尽管硝化作用速率的增加没有统计学意义。土壤硝化菌种群倾向于对松木生物炭做出反应而增加，但在饱和土壤、不同质地的土壤或评估不同生物炭材料时，趋势不同。因此，在评估生物炭对矿物 N 肥料命运的影响时，应考虑土壤湿度和其他环境条件。
