ABSTRACT

Changes in the bioavailability of nitrogen (N) and phosphorus (P) due to biochar have been frequently reported, raising concerns about the management and effectivity of biochar as soil amendment. We investigated the availability of N and P to maize plants cultivated in soil amended with 20 t ha⁻¹ and 30 t ha⁻¹ of biochar from sewage sludge (SSB₂₀, SSB₃₀) and coconut husk (CHB₂₀, CHB₃₀), in a greenhouse experiment. Plant biomass and concentration of N and P in plant tissue and in the rhizosphere and bulk soil were evaluated. All biochar treatments reduced the concentration of NH₄⁺-N by 22–88% in the soil. CHB₂₀, CHB₃₀ and SSB₂₀ increased NO₃^–N by 17–40% in the bulk soil and reduced it by 21–38% in the rhizosphere, whereas SSB₃₀ increased NO₃⁻ -N by 17–25% in both compartments, but decreased plant N and P uptake efficiency. Biochar increased shoot biomass and P availability by 12% and 12–50%, respectively, except the CHB₃₀, which reduced P availability and N and P uptake efficiency. Biochar improved plant growth during the first 60 days of cultivation in the Ultisol, being suitable as soil amendment at lower rate of application.

摘要

生物炭引起的氮 (N) 和磷 (P) 生物有效性的变化经常被报道，这引起了人们对生物炭作为土壤改良剂的管理和有效性的担忧。^{我们调查了用 20 t ha -1}和 30 t ha ^-1来自污水污泥（SSB ₂₀，SSB ₃₀）和椰子壳（CHB ₂₀，CHB ₃₀）的生物炭修正的土壤中种植的玉米植物的氮和磷的有效性，在温室实验中。对植物组织、根际和大块土壤中的植物生物量和 N 和 P 浓度进行了评估。_{所有生物炭处理都将土壤中 NH 4} ⁺ -N的浓度降低了22-88%。CHB ₂₀ , CHB₃₀和 SSB ₂₀在大块土壤中使NO ₃ ^- N 增加了 17-40%，在根际减少了 21-38%，而 SSB ₃₀在两个隔间中使NO ₃ ^- -N 增加了 17-25%，但减少了植物 N 和 P 的吸收效率。Biochar 分别增加了 12% 和 12-50% 的枝条生物量和 P 利用率，除了 CHB ₃₀降低了 P 利用率和 N 和 P 吸收效率。生物炭在 Ultisol 种植的前 60 天改善了植物生长，适合作为土壤改良剂，施用率较低。