Shen Ying, Zhang Tingting, Cui Jichao, Chen Siyu, Han Huifang, Ning Tangyuan
College of Agronomy, Shandong Agricultural University, Tai'an, Shandong Province, P.R. China.
PeerJ. 2021 Mar 24;9:e11099. doi: 10.7717/peerj.11099. eCollection 2021.
Soil degradation is one of the main problems in agricultural production and leads to decreases in soil quality and productivity. Improper farming practices speed this process and are therefore not conducive to food security. The North China Plain (NCP) is a key agricultural area that greatly influences food security in China. To explore the effects of different tillage measures on aggregate-associated organic carbon (AOC), the accumulation and transport of dry matter, and maize yield, and to identify the most suitable tillage method for use on the NCP, a field experiment was conducted at Shandong Agricultural University from 2016-2017 using plots that have been farmed using conservation tillage since 2002.
In this study, Zhengdan 958 summer maize was used as the test material and undisturbed soil and plant samples were obtained under four tillage methods-no-tillage (NT, tillage depth: 0 cm); rotary tillage (RT, tillage depth: 10 cm); conventional tillage (CT, tillage depth: 20 cm); subsoiling (SS, tillage depth: 40 cm)-which were used to determine the AOC and dry matter contents, as well as the yields of two summer maize growing seasons. Each sample was replicated three times and the AOC content was determined via potassium dichromate oxidation colorimetry. Potassium dichromate oxidized organic carbon in organic matter was employed to reduce hexadecent chromium into green trivalent chromium. Colorimetry was then used to determine the amount of reduced trivalent chromium and calculate the organic matter content.
The resulting data were statistically analyzed and the results showed that, compared with CT, the AOC contents with NT and SS increased by 5.65% and 9.73%, respectively, while that with RT decreased by 0.12%. Conventional tillage resulted in the highest mean dry matter weight when the maize reached maturity, which was 19.19%, 9.83%, and 3.38% higher than those achieved using NT, RT, and SS, respectively. No significant difference was found between CT and SS treatments, both of which tended to increase the accumulation of dry matter as well as its contribution of assimilates to grain yield post-anthesis. Compared with CT, the mean yield increased at a rate of 0.18% with SS, while yields declined at rates of 17.17% and 11.15 with NT and RT, respectively. The yield with NT was the lowest, though the harvest indices with NT and SS were higher than those with RT and CT. Overall, SS increased the accumulation of dry matter and its contribution of assimilates to grain yields post-anthesis, as well as the AOC content and yields, making it the ideal tillage method for the NCP.
土壤退化是农业生产中的主要问题之一，会导致土壤质量和生产力下降。不当的耕作方式会加速这一过程，因此不利于粮食安全。华北平原是对中国粮食安全有重大影响的关键农业区。为探究不同耕作措施对团聚体有机碳（AOC）、干物质积累与转运以及玉米产量的影响，并确定华北平原最适宜的耕作方式，2016 - 2017年在山东农业大学进行了田间试验，试验地块自2002年以来一直采用保护性耕作。
本研究以郑单958夏玉米为试验材料，在四种耕作方式下获取原状土壤和植株样本，包括免耕（NT，耕作深度：0厘米）；旋耕（RT，耕作深度：10厘米）；传统耕作（CT，耕作深度：20厘米）；深松（SS，耕作深度：40厘米），用于测定两个夏玉米生长季的AOC和干物质含量以及产量。每个样本重复三次，采用重铬酸钾氧化比色法测定AOC含量。利用重铬酸钾氧化有机质中的有机碳，将十六价铬还原为绿色三价铬，然后用比色法测定还原的三价铬量并计算有机质含量。
对所得数据进行统计分析，结果表明，与CT相比，NT和SS的AOC含量分别增加了5.65%和9.73%，而RT的AOC含量下降了0.12%。玉米成熟时，传统耕作的平均干物质重量最高，分别比NT、RT和SS高19.19%、9.83%和3.38%。CT和SS处理之间未发现显著差异，二者均倾向于增加干物质积累及其在花后对籽粒产量的同化物贡献。与CT相比，SS的平均产量提高了0.18%，而NT和RT的产量分别下降了17.17%和11.15%。NT的产量最低，不过NT和SS的收获指数高于RT和CT。总体而言，深松增加了干物质积累及其在花后对籽粒产量的同化物贡献，以及AOC含量和产量，使其成为华北平原理想的耕作方式。
