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Soil Biochemical and Greenhouse Gas Emission Dynamics Response to Nitrogen Application Rates Under Organic Rice Management
No full textRice (Oryza sativa) is a staple food that feeds over 50% of the world���s population. Maximizing rice production is critical to ensuring the global food security. However, inadequate nitrogen (N) management remains a key issue not only limiting rice production but also leading to the degradation of soil, water, and air quality. The implementation of organic management with rational use of N could be a promising strategy to achieve optimum rice production without sacrificing the sustainability of climate and environment.
However, managing nutrients, especially N management in organic rice could be more challenging compared to the conventional system. Thus, it is urgent to explore the effects of organic N management on soil health, greenhouse gas (GHG) emissions, and rice production. Parallel experiments were conducted employing greenhouse and field studies to examine the effects of N application rates of organic soil amendments on soil microbial biomass, physiology and agronomy of rice, nitrogen use efficiency (NUE), and GHG emissions.
Soil microbial biomass C and N at were significantly affected by N application rates of organic soil amendments. The use of NS at 150 kg N ha����� was observed to promote higher total microbial biomass C and N than any other application rate treatments. CO���, CH���, and N���O weekly fluxes were significantly influenced by different N rates of organic soil amendments at 44, 54, and 70 days after planting which was from the rice tillering to heading stages. Higher GWP was stimulated by highest N fertilization (150 kg N ha�����). A smallest GHGI was estimated in rice paddy receiving NS at 150 kg N ha�����. N application rates of organic soil amendments significantly enhance rice morpho-physiological and agronomic traits. The greatest tiller numbers, rice plant height, chlorophyll and N indexes, above-ground biomass, panicle number, rice yields, and NUE were associated with the application of NS at 150 kg N ha����� both in greenhouse and field tests. This study suggested that the use of NS at 150 kg N ha����� could be the optimal application to enhance soil health, promote rice growth and maintain high rice yield with less GHGI
