ABSTRACT

Although biochar amendment could increase crop yield globally, it remains unclear how biochar improves grain yield. A two-year field experiment was conducted to investigate the role of plant roots in promoting crop growth under biochar amendment. The field experiment, started in 2015, was conducted in a rainfed region of North China. We hypothesized that biochar increases maize yield by promoting root growth. In the first year (2015), maize grain yield increased by 23.9% and 25.3% under biochar application rate of 20 and 40 t ha⁻¹, respectively. Biochar increased the biomass of maize stalk and root and their potassium uptake significantly. The root morphology of maize also improved significantly following biochar amendment. Yet, the double increase in biochar application rate did not lead to any additional grain yield increase. The grain yield was positively correlated with the maize ear size, the soil organic carbon content, the biomass of maize stalk and root and their K uptake. In the second year (2016), however, biochar had no effect on the root morphology and the grain yield was not affected. Here we show that biochar increases maize yield by increasing maize ear size directly and by promoting root growth and nutrient uptake indirectly.

摘要

尽管生物炭改良剂可以在全球范围内提高作物产量，但目前尚不清楚生物炭如何提高粮食产量。进行了为期两年的田间试验，以研究植物根系在生物炭改良剂下促进作物生长的作用。该田间试验于 2015 年开始，在华北雨养区进行。我们假设生物炭通过促进根系生长来增加玉米产量。第一年（2015 年），在生物炭施用量为 20 和 40 t ha ^{-1 的情况}下，玉米产量分别增加了 23.9% 和 25.3%， 分别。生物炭显着增加了玉米茎和根的生物量及其钾的吸收。生物炭改良后玉米的根系形态也得到了显着改善。然而，生物炭施用率的两倍增加并没有导致任何额外的谷物产量增加。籽粒产量与玉米穗大小、土壤有机碳含量、玉米茎和根生物量及其钾素吸收量呈正相关。然而，在第二年（2016 年），生物炭对根系形态没有影响，粮食产量也没有受到影响。在这里，我们表明生物炭通过直接增加玉米穗大小和间接促进根系生长和养分吸收来增加玉米产量。