Are polycultures for silage pragmatic medleys or gallimaufries?: Silage polyculture data 2016 to 2018

This dataset and accompanying supplemental materials are companion pieces to the journal article “Are polycultures for silage pragmatic medleys or gallimaufries?” published in Agronomy Journal in 2021 by Burton et al. Maize silage is a particularly important dairy crop in Pennsylvania and across the US, but abiotic stress stemming from climate change can cause yearly variation in yield. Polycultures are mixtures of species that are grown together in the same field at the same time; their use may help stabilize yield across years. Silage is a good candidate to test polyculture use in a modern row crop system due to the technique of harvesting the plant whole, chopping, and mixing. We tested four monocultures (two maize, one soy, and one sorghum) and three polycultures (maize + sorghum, maize + soy, and maize + sorghum + soy + sunflower) and assessed biomass yield, residual soil nitrogen, and nitrogen, phosphorus, and potassium content of the harvested material. Plots were randomized in five blocks for three years (2016-2018) in Rock Springs, Pennsylvania (40°42'58.3" N, 77°56'05.3" W; elevation 330 m above sea level). Key findings were that maize + sorghum polycultures can retain yields similar to maize monocultures and increase potassium content. Maize + soy polycultures may decrease yield compared to maize monocultures, but increase nitrogen, phosphorus, and potassium content. Additionally, soy-containing treatments tended to leave more residual nitrogen in the ground compared to sorghum-containing treatments.