Influence of Biochar on Soil Nutrients and Associated Rhizobacterial Communities of Mountainous Apple Trees in Northern Loess Plateau China

Rafiq Ahmad; Jianen Gao; Zhe Gao; Abdullah Khan; Izhar Ali; Shah Fahad

doi:10.3390/microorganisms10102078

Influence of Biochar on Soil Nutrients and Associated Rhizobacterial Communities of Mountainous Apple Trees in Northern Loess Plateau China

Microorganisms. 2022 Oct 20;10(10):2078. doi: 10.3390/microorganisms10102078.

Authors

Rafiq Ahmad^{1

2}, Jianen Gao^{1

2

3}, Zhe Gao³, Abdullah Khan⁴, Izhar Ali⁴, Shah Fahad⁵

Affiliations

¹ Institute of Soil and Water Conservation, Northwest A& F University, Yangling, Xianyang 712100, China.
² Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Xianyang 712100, China.
³ College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling, Xianyang 712100, China.
⁴ College of Agriculture, Guangxi University, Nanning 530004, China.
⁵ Department of Agronomy, Abdul Wali Khan University Mardan, Mardan 23200, KPK, Pakistan.

Abstract

Biochar application can enhance soil health and alter soil bacterial community structure. However, knowledge relating to biochar on soil nutrients of mountainous apple orchards and then assessing its effect on soil health, especially on soil microorganisms, is still scanty. Therefore, we evaluated the responses of six biochar treatments [Ck (0), T1 (2), T2 (4), T3 (6), T4 (8), and T5 (10) Mg hm^-2] with a basal dose of chemical fertilizer on the soil nutrients under potted apple trees across 3, 6, 9, and 12 months, and then investigated the responses of the rhizobacterial communities. Experimental findings demonstrated that: (i) Across the months, the biochar-applied treatment (T5) compared to the control significantly enhanced soil nutrients, including soil pH (2.12 to 2.29%), soil organic matter (35 to 40%), total nitrogen (59 to 65%), ammonium nitrogen (25 to 33%), nitrate nitrogen (163 to 169%), and the activities of urease (76 to 81%), alkaline phosphatase (30 to 33%), catalase (8.89 to 11.70%), and sucrase (23 to 29%). (ii) Compared to the control, the biochar-applied treatment (T5) had a more desirable relative abundance of the bacterial phylum Proteobacteria (35.47%), followed by Actinobacteria (8.59%), Firmicutes (5.74%), and Bacteroidota (2.77%). Similarly, the relative abundance of the bacterial genera in the T5 was Sphingomonas (8.23%) followed by RB41 (3.81%), Ellin6055 (3.42%), Lachnospiracea (1.61%), Bacillus (1.43%), Kineosporia (1.37%), Massilia (0.84%), and Odoribacter (0.34%) than the control. (iii) Among the alpha diversity, the biochar-applied treatment (T5) revealed the highest Chao1 (20%) and ACE (19.23%) indexes, while Shannon (1.63%) and Simpson (1.02%) had relatively lower indexes than the control. Furthermore, positive correlations were found between the soil nutrients and some of the abundant bacterial phyla. Overall, the findings of this research demonstrated that biochar application at 10 Mg hm^-2 (T5) along with the required chemical fertilizer is beneficial to improve soil health and pave the way for sustainable production in apple orchards of the northern loess plateau.

Keywords: apple trees; bacterial community structure; biochar; northern loess plateau; soil enzymes; soil nutrients.

Grants and funding

This research was funded by the National Key R&D Program of China (2021YFD190070402-4), National Natural Science Foundation of China (41877078), Key Research and Development Project of Shaanxi Province (2020ZDLSF06-03-01), National Key Research and Development Program of China (2017YFC0504703), Knowledge Innovation Program of the Chinese Academy of Sciences (A315021615).