Integrating manure management with winter rye for sustainable intensification of no-till corn silage systems for sequestering soil carbon.

Dairy producers often apply manure to meet the nitrogen (N) needs of a corn (Zea mays L.) crop (N-based management). This can increase soil carbon (C) but leads to overapplication of phosphorus (P) and potassium (K) which could result in increased soil test P (STP) and K (STK) over time. One stategy used in manure management to achieve N requirement of a corn crop while reducing STP and STK buildup and increasing soil C is to move from a N‐based applications of manure to a P‐based (crop‐removal) management with integrating winter cereal rye (Secale cereale L.; WCR) as double crop with corn silage and supplementing N need with inorganic fertilizer. A four-year trial was initiated in Breese, IL in 2019. The experimental design was a randomized complete block design with four replicates. Treatments were (1) corn silage with liquid UAN fertilizer; (2) P-based manure with no WRC; (3) N-based manure (liberal N credit) with no WCR; (4) N-based manure (conservative N credit) with no WCR; (5) P-based manure with WRC; (6) N-based manure (liberal N credit) with WCR; (7) N-based manure (conservative N credit) with WCR. We measured corn and rye yield, the N and P concentrations in the biomass, N and P removal and balances for the system, and soil test P. We also evaluated phospholipid fatty acids (PLFA), soil aggregate size distribution and stability, soil bulk density, soil β-glucosidase (BG) enzyme, soil organic C and labile C (POXC) over a 90 cm soil profile. Our results indicated that integrating WCR with P-based manure rates maintains STP over time. High rate of manure (conservative N credit) and WCR resulted in increased soil C which was supported by higher fungi:bacteria ratio in the soil.