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Carbon and nitrogen gains and losses of soybean biomass

Agriculture can contribute signifi cantly to climate change mitigation through biological carbon sequestration, i.e., the storage of atmospheric carbon in the plant pool through the process of photosynthesis. The objective of this study is to determine the carbon (C) and nitrogen (N) content in above- and below-ground biomass, as well as C and N balance of soybean biomass. Destructive harvest of aboveground (grain, stems, leaves, stubble) and belowground (root system) biomass of soybean (Glycine max L.) was conducted in Šašinovec, Croatia (45°50’ N ; 16°11’ E ; 120 m a.s.l.) in 2019. The C and N balance represents the diff erence between C and N gains (stems+leaves+stalks+root biomass) and losses (grain biomass) in the agroecosystem. The total dry matter yield is 16.53 t ha-1 and is composed of 23.7% grain, 48.6% stem, 20.8% leaf, 2.1% stubble and 4.9% root biomass. The average C and N content ranged from 25-55% and 0.5-7%, respectively. The total C balance is positive and is 3, 38 t ha-1, with total gains of 5, 52 t ha- 1 and total losses of 2, 14 t ha-1. The total N balance is negative and is -0.13 t ha-1, with total gains of 0.13 t ha-1 and total losses of 0.26 t ha-1. The negative N balance indicates that soybean biomass negatively aff ects soil quality and results in N losses from the agroecosystem, while the positive C balance indicates that soybean biomass can contribute to climate change mitigation through biological carbon sequestration under the studied agroecological conditions.

climate change mitigation, carbon balance, aboveground biomass, belowground biomass, soybean

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