Increased loss rate of straw-derived nitrogen following the woody peat addition is more significant in saline than in non-saline paddy soil

Abstract

Elucidating the biological mechanisms underlying the loss of straw-derived N is crucial for developing eco-friendly and cost-effective methods for straw return to the field; however, research on this topic is lacking, particularly an integrated comparison of the conditions for woody peat-amended and non-amended in saline and non-saline soils. In this study, a pot experiment was conducted to monitor N loss from maize (Zea mays L.) straw labeled with ¹⁵N in saline (S) and non-saline (S0) soils with woody peat addition (W) or a control without woody peat addition (W0). Woody peat input tended to significantly increase the loss rate of straw-derived N (LSN) by 2.21 % in S0 soil and 10.02 % in S soil. In addition to the total N (TN), narG and nirK genes, a group of highly relevant bacterial taxa, greatly contributed to the LSN variations, although the bacterial taxa composition under W0 conditions was significantly different from that under W conditions. Furthermore, the composition of the bacterial community was determined and the taxa enriched and depleted following straw application were isolated. Under W conditions, the LSN was positively regulated by the recruited bacterial taxa and negatively regulated by the depleted bacterial taxa. However, the opposite was observed under W0 conditions. These highly relevant bacterial taxa contained different proportions of denitrifiers, further implicating their important role in mediating the loss of straw-derived N. Our results provide new insights into the driving factors of woody peat input to LSN in saline and non-saline soils, with implications for developing reasonable usage measures to control straw-N loss.