Response Patterns of Soil Nitrogen Cycling to Crop Residue Addition: A Review

The impact of adding crop residues to soil on nitrogen (N) cycling remains an area of ongoing research, as it is influenced by various mechanisms that differ across studies. Understanding the patterns of soil N cycling in response to crop residue addition and the underlying mechanisms is essential for optimizing crop residue management and sustaining agricultural production. The addition of crop residues can enhance crop N uptake by stimulating microbial N immobilization initially, followed by increased N mineralization and heterotrophic nitrification later in the season. However, it can also lead to increased N losses from the soil-plant system through processes like ammonia (NH3) volatilization, autotrophic nitrification, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA). On the other hand, crop residue addition can improve N retention in recalcitrant organic matter pools through abiotic N immobilization. The dominant mechanisms responsible for these effects can vary due to a combination of factors, resulting in a wide range of soil N cycling responses. Incorporating the simultaneous occurrence of various N processes with rate-based mechanisms may provide better predictions of soil N cycling response to crop residue addition. To validate these response patterns and quantify the influence of different factors, it is crucial to develop and refine rate-based N cycling models.