AUTHOR=Ferdous J. , Mumu N. J. , Hossain M. B. , Hoque M. A. , Zaman M. , Müller C. , Jahiruddin M. , Bell R. W. , Jahangir M. M. R. 

TITLE=Co-application of biochar and compost with decreased N fertilizer reduced annual ammonia emissions in wetland rice

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=6

YEAR=2023

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2022.1067112

DOI=10.3389/fsufs.2022.1067112

ISSN=2571-581X

ABSTRACT=<p>Ammonia (NH<sub>3</sub>) emission from rice fields is a dominant nitrogen (N) loss pathway causing negative impacts on farm profitability and the environment. Reducing N fertilizer application to compensate for N inputs in organic amendments was evaluated for effects on N loss <italic>via</italic> volatilization, rice yields and post-harvest soil properties in an annual irrigated rice (Boro) – pre-monsoon rice (Aus) – monsoon (Aman) rice sequence. That experiment was conducted using the integrated plant nutrition system (IPNS; nutrient contents in organic amendments were subtracted from the full recommended fertilizer dose i.e., RD of chemical fertilizers) where six treatments with four replications were applied in each season: (T<sub>1</sub>) no fertilizer (control), (T<sub>2</sub>) RD, (T<sub>3</sub>) poultry manure biochar (3 t ha<sup>−1</sup>; pyrolyzed at 450°C) + decreased dose of recommended fertilizer (DRD), (T<sub>4</sub>) rice husk ash (3 t ha<sup>−1</sup>) + DRD, (T<sub>5</sub>) compost (3 t ha<sup>−1</sup>) + DRD, and (T<sub>6</sub>) compost (1.5 t ha<sup>−1</sup>)+ biochar (1.5 t ha<sup>−1</sup>) + DRD. The N loss <italic>via</italic> volatilization varied twofold among seasons being 16% in irrigated rice and 29% in the pre-monsoon rice crop. In irrigated rice, T<sub>6</sub> had significantly lower NH<sub>3</sub> emissions than all other treatments, except the control while in pre-monsoon and monsoon seasons, T<sub>6</sub> and T<sub>3</sub> were alike. Pooling the three seasons together, biochar (T<sub>3</sub>) or biochar plus compost (T<sub>6</sub>) reduced NH<sub>3</sub> loss <italic>via</italic> volatilization by 36-37% while compost alone (T<sub>5</sub>) reduced NH<sub>3</sub> loss by 23% relative to RD. Biochar (T<sub>3</sub>) and biochar plus compost mixture (T<sub>6</sub>) reduced yield-scaled NH<sub>3</sub> emissions by 40 and 47% relative to the RD of chemical fertilizer (T<sub>2</sub>). The organic amendments with IPNS reduced the quantity of N fertilizer application by 65, 7, 24, and 45% in T<sub>3</sub>, T<sub>4</sub>, T<sub>5</sub>, and T<sub>6</sub> treatments, respectively, while rice yields and soil chemical properties in all seasons were similar to the RD. This study suggests that incorporation of biochar alone or co-applied with compost and decrease of N fertilizer on an IPNS basis in rice-based cropping systems can reduce N application rates and NH<sub>3</sub> emissions without harming yield or soil quality.</p>