Corn yield and nitrogen recovery following rye (Secale cereale L.) in monoculture and polyculture service crops

Planting service crops (SC) with late summer manure applications has been promoted as an agronomic practice to capture manure nitrogen (N) and release it to the following season’s cash crop, thereby reducing fertilizer N requirements. The present study explored this hypothesis using a cereal rye (Secale cereale L.) monoculture SC, along with two polyculture SCs (four species and 12 species) both containing rye, planted after winter wheat (Triticum aestivum L.) harvest, in systems with and without liquid hog manure. The following spring, SC regrowth was chemically terminated one week prior to corn (Zea mays L.) planting, and a sidedress N application was made at the six-eight leaf stage to half of the plots. Corn N accumulation and final grain yield were reduced up to 20% following the rye monoculture in both years, even though SCs did not reduce soil mineral N nor partial plant-available N over the corn growing season. Additionally, the sidedress N application could not overcome the yield loss associated with rye. Thus, this study did not observe N release by SCs to the following cash crop and demonstrates that yield loss can occur when corn follows rye SCs irrespective of changes in plant available N. This research reinforces the importance of selecting appropriate species and their proportions in polycultures, to mitigate negative impacts of SCs, especially those of rye on corn.