黑土夏玉米施用生物质炭最佳施用时期和最佳用量

生物质炭作为一种新型的土壤改良剂，不仅可以维持土壤肥力、改善土壤退化和污染，也可提升作物长势及生产效率。以松嫩平原黑土区为研究对象，设置了3种生物质炭施加水平C₅（5 t·hm-2），C₁₀（10 t·hm-2），C₁₅（15 t·hm-2）]，各水平设置下3种施加方案F₁（秋季施加），F₂（春秋两季各施加一半），F₃（春季施加）]，同时设置1组对照BL（无生物质炭施加）]，共计10种处理。比较分析了不同处理条件下夏玉米Zea mays植株根系特征、氮素空间分布状况、根系呼吸强度以及氮素利用效率等指标差异，构建生物质炭用量与氮素利用效率以及收获指数之间的关联函数，进而阐述生物质炭调控模式与作物生产效率之间的作用关系，为寻求生物质炭合理、高效利用的管理模式提供理论指导。结果表明:夏玉米根系长势受生物质炭调节的影响较大，其中C₅F₁，C₁₀F₁和C₁₅F₁处理条件下植株根系长度分别相对于BL处理增加了1 009.10，1 640.05和1 270.24 cm，C₁₀水平效果较为明显。同时，在F₂和F₃方案下，3种不同生物质炭用量处理表现出相同的规律；生物质炭的调控作用有效抑制了土壤氮素的无效流失，并且在C₁₀F₁处理条件下，土壤的固氮效果达到最优；生物质炭的保水性和保肥性提升了作物根系的呼吸强度，随着生物质炭的施入量增加，作物呼吸强度效果表现出先增加后减小的趋势，适宜地增加生物质炭的用量可以有效提升植株根系的代谢活动；生物质炭的调控作用在一定程度上促进了作物产量的积累，随着生物质炭施入量的增加以及施入方案的调整，C₁₀F₁处理条件下的作物产量、氮素利用效率以及收获指数最高。另外，生物质炭的施入量与作物产量、氮素利用效率等指标之间具有显著的二次函数关系，表明生物质炭供应与植株生产力之间存在最佳阈值。

Application period and dosage optimums for biochar additions in black soil with summer maize

As a new soil conditioner, biochar not only maintains soil fertility, improves soil degradation, and resolves pollution problems, also enhances crop growth and production efficiency. To promote a low-carbon economy for the world with biochar development, the Songnen Plain black soil area was selected as the research object. A total of ten treatments were set with three biochar application levels (C₅-5 t·hm-2, C₁₀-10 t·hm-2, and C₁₅-15 t·hm-2); three different application schemes (F₁-applied in autumn, F₂-half applied in spring and half in autumn. and F₃-applied in spring) for each application level; and one control group (BL-no biochar applied), and each test was processed in parallel. Combined with crop growth period, and regular artificial sampling. On this basis, the characteristics of the plant root system, nitrogen (N) spatial distribution, root respiration, and N-use efficiency for different treatment conditions were compared and analyzed. A correlation function of biochar amount and N-use efficiency versus the harvest index was constructed, and then the relationship between the biochar control mode and crop production efficiency was expounded. Results of the study showed that compared to the BL treatment, root length of plants with biochar treatments increased for C₅F₁(1 009.10 cm), for C₁₀F₁(1 640.05 cm), and for C₁₅F₁(1 270.24 cm) as did F₂ and F₃ for the three biochar application treatments and the results passed the significance test of P < 0.05. The control effect of biological carbon effectively inhibited the ineffective loss of soil N, and the N fixation effect of the soil reached the best level with the C₁₀F₁ treatment. Biochar's water retention and fertility enhanced the respiration rate of the plant roots; an increase in the biochar application rate first increased and then decreased the respiration rate(P < 0.05). Regulation of biochar additions promoted the accumulation of crop yield with an increase in the biochar application rate and adjustment of the application scheme; the C₁₀F₁ treatment had the best yield, N-use efficiency, and harvest index(P < 0.05). In addition, there was a quadratic function relationship between the biochar application rate and crop yield, N-use efficiency(P < 0.05), and other indicators meaning that there was an optimal threshold between biochar supply and plant productivity. Through the above studies, it can be seen that appropriate amount of biochar, with appropriate addition period, can effectively increase the growth and metabolism of crop lines, thereby increasing the yield and production efficiency of crops. Thus, this study provided theoretical guidance for seeking a reasonable and efficient management model with biochar, and showed that appropriately increasing the amount of biochar could effectively promote plant root metabolism.