Dual-Purpose Rye, Wheat, and Triticale Cover Crops Offer Increased Forage Production and Nutrient Management but Demonstrate Nitrogen Immobilization Dynamics

Abstract

Dual-purpose cover crops (DPCCs) are gaining popularity for their potential to provide additional forage, while also providing significant ecosystem services. In the Northeastern United States, DPCCs can be incorporated into corn silage (Zea mays L.) production, increasing the environmental sustainability and economic resiliency of dairy systems. In a three-year field study, rye (Secale cereale L.), wheat (Triticum aestivum), and triticale (xTriticosecale) DPCCs provided an average of 4.1 Mg ha−1 of forage, without impacting subsequent corn silage yield. The relative feed values of triticale and wheat were 120 and 122, respectively, significantly greater than that of rye at 109. DPCCs removed 60 kg ha−1 of nitrogen (N) and 20 kg ha−1 of phosphorus (P) on average at harvest; this removal is important for nutrient management in manured systems with high P levels. The results of this experiment suggested that in addition to capturing nutrients from the fall manure application, DPCCs captured nutrients already present in the soil. The DPCC residue left in the field after harvest represented 46% of the total plant biomass, and returned 1.6 Mg ha−1 of carbon. Decomposition trends of DPCCs demonstrated nitrogen immobilization dynamics. Twenty percent of all the residual nitrogen was released in the first week after termination. The residual biomass continued to decompose, but the nitrogen decomposition was arrested. While, in this study, corn yields were not impeded, our findings demonstrated the potential to affect the fertility needs of corn in a multi-year rotation.