Decomposition and macronutrient release rates of cereal rye residue in a temperate agroecosystem

Abstract Cover crops provide important agroecosystem services that include reducing soil erosion and nutrient losses, improving soil structure, and enhancing nutrient cycling. While considerable research has investigated biomass decomposition and nitrogen (N) release from cover crop residues, significant knowledge gaps still exist, particularly related to the amounts and temporal release of other essential macronutrients such as phosphorus (P), potassium (K), and sulfur (S). This study aimed to determine, under field conditions, the release dynamics of carbon (C), N, P, K, and S from cereal rye (CR, Secale cereale L.) residue. Preliminary results showed important insights regarding the rate and timing of nutrient release following CR termination: (i) K exhibited the fastest release ( k = 0.0057), with ~ 68% (32.6 kg K ha −1 ) of the initial K content released within 16 days, followed by P ( k = 0.0051), with ~ 47% (3.1 kg P ha −1 ) released over the same period; (ii) S release rate ( k = 0.0014) followed a similar pattern to that of C ( k = 0.0014), with ~ 30% (1.0 kg S ha −1 ) released within 30 days; and (iii) C release was slightly faster than that of N ( k = 0.0010), consistent with previous findings in this region. These findings highlight that CR could release agronomically significant quantities of K during early decomposition, but not for P and S. Future research should evaluate how cover crop nutrient cycling influences soil nutrient availability and plant uptake, with the goal of informing more sustainable and site-specific fertilizer management strategies.