Combined application of biochar and nitrogen fertilizer improves rice yield, microbial activity and N-metabolism in a pot experiment

Izhar Ali; Saif Ullah; Liang He; Quan Zhao; Anas Iqbal; Shangqing Wei; Tariq Shah; Niyaz Ali; Yan Bo; Muhammad Adnan; Amanullah; Ligeng Jiang

doi:10.7717/peerj.10311

Combined application of biochar and nitrogen fertilizer improves rice yield, microbial activity and N-metabolism in a pot experiment

PeerJ. 2020 Nov 13:8:e10311. doi: 10.7717/peerj.10311. eCollection 2020.

Authors

Izhar Ali^#¹, Saif Ullah^#¹, Liang He¹, Quan Zhao¹, Anas Iqbal¹, Shangqing Wei¹, Tariq Shah², Niyaz Ali³, Yan Bo¹, Muhammad Adnan¹, Amanullah², Ligeng Jiang¹

Affiliations

¹ Key Laboratory of Crop Cultivation and Farming System, College of Agriculture, Guangxi University, Nanning, Guangxi, China.
² Department of Agronomy, Faculty of Crop Production Sciences, University of Agriculture, Peshawar, Pakistan.
³ State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China.

^# Contributed equally.

Abstract

The excessive use of synthetic nitrogen (N) fertilizers in rice (Oryza sativa L.) has resulted in high N loss, soil degradation, and environmental pollution in a changing climate. Soil biochar amendment is proposed as a climate change mitigation tool that supports carbon sequestration and reduces N losses and greenhouse gas (GHG) emissions from the soil. The current study evaluated the impact of four different rates of biochar (B) (C/B₀-0 t ha^-1, B₁-20 t ha^-1, B₂-40 t ha^-1, and B₃-60 t ha^-1) and two N levels (N₁; low (270 kg N ha^-1) and N₂; high (360 kg N ha^-1)), on rice (cultivar Zhenguiai) grown in pots. Significant increases in the average soil microbial biomass N (SMBN) (88%) and carbon (87%) were recorded at the highest rate of 60-ton ha^-1B and 360 kg N ha^-1 compared to the control (N₁C) during both seasons (S1 and S2). The photochemical efficiency (Fv/Fm), quantum yield of the photosystem (PS) II (ΦPS II), electron transport rate (ETR), and photochemical quenching (qP) were enhanced at low rates of biochar applications (20 to 40 t B ha^-1) for high and low N rates across the seasons. Nitrate reductase (NR), glutamine synthetase (GS), and glutamine 2-oxoglutarate aminotransferase (GOGAT) activity were, on average, 39%, 55%, and 63% higher in the N₁B₃, N₂B₂, and N₂B₃ treatments, respectively than the N₁C. The grain quality was higher in the N1B₃ treatment than the N₁C, i.e., the protein content (PC), amylose content (AC), percent brown rice (BRP), and percent milled rice (MRP) were, on average, 16%, 28%, 4.6%, and 5% higher, respectively in both seasons. The results of this study indicated that biochar addition to the soil in combination with N fertilizers increased the dry matter (DM) content, N uptake, and grain yield of rice by 24%, 27%, and 64%, respectively, compared to the N₁C.

Keywords: Biochar; Chlorophyll fluorescence; Grain quality; N accumulation; N metabolism activities; Soil microbial biomass; Soil physicochemical properties.

Grants and funding

This research was financially supported by the National Key Research and Development Project of China (2016YFD030050902). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.