442 Earth Sciences Building, Department of Renewable Resources, University of Alberta, Edmonton T6G 2E3, Canada.
Sci Total Environ. 2019 Apr 1;659:463-472. doi: 10.1016/j.scitotenv.2018.12.380. Epub 2018 Dec 27.
Application of biochars produced by pyrolyzing organic residues to cropland has been proposed to be an effective approach to better use of organic residues, decrease soil greenhouse gas emission and increase soil fertility. However, the effect of biochar application on processes occurring in the bulk soil vs that in the rhizosphere is poorly understood. This study investigated the effects of manure pellet and woodchip biochars, as compared to that of unpyrolyzed (raw) manure pellet and woodchip, on plant grain yield, and soil respiration in the bulk and rhizosphere soils in a greenhouse experiment using the rhizobox technique. The raw manure pellet and woodchip and their biochars were applied to the soil at the rate of 57 t ha and spring wheat (Triticum aestivum L. var. GP168) was grown in the rhizosphere compartment of the rhizobox. Soil amendment with raw manure pellet and its biochar significantly increased plant grain yield by 36.3 and 16.1%, as compared to the control (without amendment), while raw woodchip and its biochar applications significantly decreased plant grain yield. Manure pellet and woodchip biochars significantly reduced soil respiration from the rhizosphere by 24.6 and 29.7%, respectively, relative to the control, but not that from the bulk soil (P > 0.05). Relativized cumulative CO emission was significantly reduced by both manure pellet and woodchip biochars from rhizosphere and bulk soils. Dissolved organic carbon and nitrogen were increased (P < 0.01) in all soil amendment treatments in both bulk and rhizosphere soils, but microbial biomass carbon and nitrogen in the rhizosphere soil were reduced by manure pellet biochar application. We conclude that biochars produced from organic residues have differential impacts on processes in bulk and rhizosphere soils, and thus measurements based on bulk soil alone may result in erroneous conclusions about the effect of biochars on soil CO emission.
应用热解有机残渣制成的生物炭来改良农田被认为是一种有效利用有机残渣、减少土壤温室气体排放和提高土壤肥力的方法。然而，生物炭的应用对原状土壤和根际土壤中发生的过程的影响仍知之甚少。本研究采用根盒技术，在温室条件下，通过大田试验，研究了与未热解（原状）有机肥球和木片相比，有机肥球和木片生物炭对根际和非根际土壤中植物籽粒产量和土壤呼吸的影响。将原状有机肥球和木片及其生物炭以 57 t ha 的用量施用于土壤，在根盒的根际室种植春小麦（Triticum aestivum L. var. GP168）。与对照（不施肥）相比，原状有机肥球及其生物炭的施用显著增加了 36.3%和 16.1%的植物籽粒产量，而原状木片及其生物炭的施用则显著降低了植物籽粒产量。与对照相比，有机肥球和木片生物炭分别显著降低了根际土壤呼吸 24.6%和 29.7%，但对原状土壤呼吸没有影响（P>0.05）。相对于对照，根际和原状土壤的相对累积 CO 排放均显著降低。在原状土壤和根际土壤中，所有土壤处理均增加了溶解性有机碳和氮（P<0.01），但有机肥球生物炭的应用降低了根际土壤微生物生物量碳和氮。综上所述，有机残渣制成的生物炭对原状土壤和根际土壤中的过程有不同的影响，因此仅基于原状土壤的测量可能会导致对生物炭对土壤 CO 排放影响的错误结论。
