부산대학교 도서관

Background and aims Crop residues and soil types play an important role in soil C and N storage. The objectives of this study were to quantify the effects of crop residue quality and interactions with soil type on soil C and N, in the short- and medium-term, and to determine the responses related to the priming effect (PE). Methods Residues of vetch (Vicia sativa L.), pea (Pisum sativum L.) and wheat (Triticum aestivum L.) crops with different chemical compositions and labelled with ¹³C and ¹⁵N were left to decompose on the surface of either a sandy-loam soil or a clay soil incubated under laboratory conditions at 25 °C for 360 days. We measured the total CO₂-C and CO₂-¹³C emitted during decomposition, the soil mineral N content and the amounts of ¹³C and ¹⁵N remaining in both the surface residue particles and the bulk soil. Results Over the short-term, the vetch residues decomposed faster than those of wheat and pea on the soil surface due to their more favourable chemical composition for biodegradation; after one year, however, this difference disappeared. We observed extra soil C mineralization in all cases, i.e., the PE was positive for all treatments and was directly related to the water-soluble (vetch > pea > wheat) and soil C contents (clay soil > sandy-loam soil). Conversely, the fete of the added ¹⁵N and net N mineralization differed considerably between the three residues and was strongly related to the initial N content of the residue. Conclusions Crop residue quality and soil type affected the soil PE and soil C balance but not the fate of crop residue-C after one year. Net soil N mineralization was observed in all crop residues, with large early differences (vetch > pea > wheat), which were maintained on a medium-term basis. Our results emphasize the need to jointly consider C and N dynamics as well as short-and medium-term effects to manage agricultural and environmental services provided by the recycling of crop residues to agricultural soils.