The application of biochar to agricultural soils to increase nutrient availability, crop production and carbon sequestration has gained increasing interest but data from field experiments on temperate, marginal soils are still under-represented. In the current study, biochar, produced from organic residues (digestates) from a biogas plant, was applied with and without digestates at low (3.4 t ha⁻¹) and intermediate (17.1 t ha⁻¹) rates to two acidic and sandy soils in northern Germany that are used for corn (Zea mays L.) production. Soil nutrient availability, crop yields, microbial biomass and carbon dioxide (CO₂) emissions from heterotrophic respiration were measured over two consecutive years. The effects of biochar application depended on the intrinsic properties of the two tested soils and the biochar application rates. Although the soils at the fallow site, with initially low nutrient concentrations, showed a significant increase in pH, soil nutrients and crop yield after low biochar application rates, a similar response was found at the cornfield site only after application of substantially larger amounts of biochar. The effect of a single dose of biochar at the beginning of the experiment diminished over time but was still detectable after 2 years. Whereas plant available nutrient concentrations increased after biochar application, the availability of potentially phytotoxic trace elements (Zn, Pb, Cd, Cr) decreased significantly, and although slight increases in microbial biomass carbon and heterotrophic CO₂ fluxes were observed after biochar application, they were mostly not significant. The results indicate that the application of relatively small amounts of biochar could have positive effects on plant available nutrients and crop yields of marginal arable soils and may decrease the need for mineral fertilizers while simultaneously increasing the sequestration of soil organic carbon.

中文翻译：

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生物炭对德国北部沙质土壤养分供应、作物产量和微生物呼吸的影响

将生物炭应用于农业土壤以增加养分可用性、作物产量和碳固存已引起越来越多的关注，但来自温带边缘土壤的田间试验数据仍然不足。在当前的研究中，由沼气厂的有机残留物（消化物）生产的生物炭以低（3.4 t ha ^-1）和中等（17.1 t ha ^-1）比率在两种酸性和沙质土壤中施用或不施用消化物在德国北部用于玉米 ( Zea mays L.) 生产。土壤养分有效性、作物产量、微生物生物量和二氧化碳（CO ₂) 连续两年测量来自异养呼吸的排放。生物炭施用的效果取决于两种测试土壤的内在特性和生物炭施用率。虽然休耕地的土壤，最初的养分浓度很低，在低生物炭施用率后显示出 pH、土壤养分和作物产量的显着增加，但只有在施用大量生物炭后，玉米地才发现类似的反应. 实验开始时单剂量 biochar 的影响随着时间的推移而减弱，但在 2 年后仍可检测到。施用生物炭后植物有效养分浓度增加，潜在植物毒性微量元素（Zn、Pb、Cd、Cr）的可用性显着降低，应用生物炭后观察到_{2 个}通量，它们大多不显着。结果表明，施用相对少量的生物炭可能对边缘可耕土壤的植物有效养分和作物产量产生积极影响，并可能减少对矿物肥料的需求，同时增加土壤有机碳的固存。