National Key Research and Development Program of China (No.2016YFD0300804)
为改善我国东北地区黑土亚耕层的土壤结构并解决当地玉米秸秆还田难问题，于2015—2018年开展切碎秸秆（QS）与秸秆颗粒（KL）2种秸秆形态下1倍（15 000 kg·hm-2）、3倍（45 000 kg·hm-2）与5倍（75 000 kg·hm-2）3种秸秆用量的一次性深埋（30～40 cm）还田试验，探究其对黑土亚耕层（20~40 cm）土壤容重、紧实度及土壤含水量的影响，并分析土壤团聚体变化对主要物理性状的调控效应。3年玉米成熟期的测试结果表明：（1）秸秆深还对亚耕层土壤容重、紧实度以及土壤含水量的改善程度高于耕层（0~20 cm），表现为随秸秆用量的增加而提高，随还田后的时间延长而降低，一次性秸秆高量深还改善土壤物理性状的效果可维持多年。（2）秸秆3倍、5倍量还田显著提高了亚耕层土壤> 0.25 mm与> 2 mm水稳性大团聚体的含量，降低了微团聚体含量；秸秆还田第1、2年为> 0.25 mm和> 2 mm水稳性团聚体的主要形成时期，其含量最高为CK的5倍和1.5倍（P< 0.05）。（3）亚耕层土壤0.25～0.053 mm微团聚体以及> 0.25 mm水稳性大团聚体含量均与土壤容重、紧实度以及采样时土壤含水量显著相关，其中0.25～0.053 mm、>2 mm和>0.25 mm粒径团聚体为2016与2017年驱动土壤物理性状变化的关键因子，1~0.5 mm粒径团聚体为2018年驱动土壤物理性状变化的关键因子。综上，切碎秸秆75 000 kg·hm-2还田是值得优先推荐的调控土壤团聚体分布、改善亚耕层土壤物理性状的良好措施，兼具改土培肥与秸秆资源化利用的双重优点，可为今后我国黑土区农田土壤改良提供理论依据与技术指导。
[Objective] In order to improve soil structure of the subsoil layer of black soil and solve the problem of how to return maize straw in Northeast China, a three-year (2015—2018) field experiment was carried out.[Method] The field experiment was designed to have three treatments in returning pattern, i.e. CK (no straw return), QS (returning of chopped straw) and KL (returning of pelletized straw), and three treatments in straw returning dosage, i.e. low dosage (15 000 kg·hm-2), medium dosage (45 000 kg·hm-2, 3 times as much as the low dosage) and high dosage (75000 kg·hm-2, 5 times as much as the low dosage), and all had the straw buried in the soil 30-40 cm depth. Effects of the treatments on soil bulk density, soil compactness and soil water content were explored, and effects of soil aggregate distribution regulating soil physical properties was analyzed.[Result] The tests of the soil samples collected at the maize maturity stage of the three year experiment show:1) The practice of deep straw returning reduced soil bulk density and soil compactness and increased soil water content, and the effects were more significant in the 20-40 cm layer than in the 0-20cm soil layer. Moreover, the effects become more significant with increasing of straw dosage, and less with the time going on, and the effects of straw returning once at a high rate might last for a few years. In the third year of the experiment, only QS5 reduced soil bulk density significantly or by 10.9% (P < 0.05), and QS5 and KL5 lowered soil compactness by 24.1% and 22.0% (P < 0.05), but raised soil water content by 8.9% and 7.4% (P < 0.05), respectively; 2) The treatments of medium and high in dosage significantly increased the content of macroaggregates and reduced the content of microaggregates in the subsoil, and the fractions of > 0.25 mm water stable aggregates and of the > 2 mm large aggregates increased significantly with rising straw dosage. What's more, the return of pelletized straw tended to promote the formation of macroaggregates than the return of chopped straw. The first and second years of straw returning were the main period for formation of macroaggregates, of which the highest content reached up to about 5 times and 1.5 times than that in CK, respectively; 3) Significant relationships were observed of 0.25-0.053 mm micro aggregate and > 0.25 mm water stable aggregate with soil bulk density, soil compactness and soil water content in the subsoil layer (P < 0.05), and the 0.25-0.053 mm, > 2 mm, and > 0.25 mm fractions of aggregates were the key factor driving changes in soil physical properties in 2016 and 2017, but the 1-0.5 mm fraction of aggregates was found to be the key factor driving the changes in soil physical properties in 2018.[Conclusion] Therefore, from the perspective of recycling maize straw in Northeast China, the return of chopped straw with a rate of 75 000 kg·hm-2 is a good management to regulate the distribution of soil aggregates and improve the physical properties of subsoil. The finding may provide a theoretical basis and technical guidance for improvement of soil structure of the black soil in China.
董建新,丛萍,刘娜,李玉义,王婧,逄焕成.秸秆深还对黑土亚耕层土壤物理性状及团聚体分布特征的影响[J].土壤学报,2021,58(4):921-934. DOI:10.11766/trxb202003180714 DONG Jianxin, CONG Ping, LIU Na, LI Yuyi, WANG Jing, PANG Huancheng. Effects of Deep Straw Incorporation on Subsoil Physical Properties and Aggregate Distribution in Black Soil[J]. Acta Pedologica Sinica,2021,58(4):921-934.复制