Peanut straw application rate had a greater effect on decomposition and nitrogen, potassium and phosphorus release than irrigation

Aims: Peanut (Arachis hypogaea L.) straw decomposition and nutrient release (N, K, and P) processes were investigated using a 3-pool model (labile, intermediate, and resistant) to understand the determinant factors. Methods: A two-year field experiment was carried out with a split-plot design: the main plot contained two irrigation regimes, while the subplot contained three peanut straw incorporation rates. A total of 216 nylon-mesh bags consisting of peanut straw were buried at a depth of 20 cm, and were removed at 6 winter wheat growth stages (overwintering, double ridge, jointing, flowering, grain filling, and maturity), and the nutrient release (N, P and K) from the peanut straw was measured. Results: The decomposition dynamics of the labile and intermediate pools were similar in both years. The straw incorporation rate, rather than the irrigation regime, controlled the decomposition process, which increased with increased straw incorporation rates. At a high incorporation rate, the released N, P, and K from the peanut straw were approximately 39%, 30%, and 87% of the required regional fertilizer input for winter wheat, respectively. Furthermore, the N released from straw decomposition was strongly related to the released K as indicated by the stoichiometry ratio. The random forest model predicted that temperature, precipitation, and initial straw nutrients were the main drivers of peanut straw decomposition. Conclusions: We determined the nutrient stoichiometry and release characteristics of peanut straw decomposition, and found that in comparison to irrigation, the straw incorporation rate exhibits a more profound effect on the peanut straw decomposition process. Graphical abstract: [Figure not available: see fulltext.]