Does stimulating ground arthropods enhance nutrient cycling in conventionally managed corn fields?

•Insect carcasses boost ground arthropod abundance on corn fields.•Insect carcasses and corn stover in combination increase predator abundance.•Insect carcasses increase nitrogen and phosphorus pools and microbial phosphorus.•Stimulating ground arthropods modestly enhanced nutrient cycling in corn fields. Exploring ways to reduce high-nutrient agricultural runoff is imperative, considering how such runoff reduces water quality and has the potential to cause harmful algal blooms. Ground arthropod communities, particularly detritivores (i.e. consume dead plant or animal tissue matter), are largely ignored as a possible avenue for reducing nutrient runoff. However, stimulating these organisms may help maintain nutrient availability with decreased fertilizer application rates, thereby increasing application efficiency while reducing nutrient runoff potential. With the aim of stimulating the detrital community and soil microbes to ultimately enhance nutrient availability, we added a labile substrate and nutrient source (carcasses of Hexagenia spp. (mayflies), as well as a recalcitrant substrate and nutrient source (Zea mays corn stover), both separately and in combination, to plots on four conventionally managed corn fields in northwest Ohio, U.S.A. Over the seven-week study period, we found that detritivores increased with mayfly additions with or without stover, but arthropods that prey on detritivores only increased with mayfly and corn additions in combination. Soil microbial biomass and enzyme activities did not respond to any treatments, but when mayflies were added microbial respiration increased. Respiration was positively correlated with arthropod abundance. Mayfly additions initially boosted water-soluble ammonium, and, in plots without stover, increased phosphate throughout the experiment. Overall, our results are consistent with other findings of generally low levels of biotic activity on conventional corn fields, making it difficult to stimulate further activity over short time-scales, like the seven-week one in this study. However, our results also indicate that additions of labile detritus enhance detritivores and nutrient availability. Adding labile detritus in combination with recalcitrant detritus, which promotes detritivore predators, may further enhance nutrient cycling rates. Thus, the potential for these amendments to stimulate soil biota to help maintain nutrient availability with decreased fertilizer application rates compels further stu