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Core Ideas Mustard, oat, sudangrass, and buckwheat were the most productive cover crops. Excluding mustard from spring mixtures sometimes increased weed biomass. Excluding sudangrass from summer mixtures sometimes increased weed biomass. Forage radish was less productive, but suppressed weeds in monoculture and mixture. Cover crops can provide many ecosystem services and on‐farm adoption is increasing. Cover crop mixtures are popular, but little is known about the functional contributions of individual species in mixture. On‐farm field studies were conducted across 3 yr (2014–2016) and two locations (organic farms in central and northern Illinois) to assess the productivity and weed suppressive capacity of 12 cover crop species planted in monoculture and in mixture. Species were split into two equal (six species each) and seasonally appropriate groups (cool vs. warm season), planted in all possible monocultures and five‐way mixtures (divided proportionally to monoculture rates), and compared with a weedy control. Mustard [Brassica juncea (L.) Czern.] and oat (Avena sativa L.) were among the most productive (as much as 4.48 and 3.95 Mg ha−1, respectively) and weed suppressive spring cover crops. In 2 of 5 site‐years, excluding mustard from five‐way mixtures resulted in increased weed biomass. Sudangrass [Sorghum bicolor (L.) ssp. Drummondii] and buckwheat (Fagopyrum sagittatum Moench) were typically the most productive summer cover crops (as much as 8.78 and 7.11 Mg ha−1, respectively) and also reduced weed biomass. In 2 of 6 site‐years, excluding sudangrass from the mixture led to increased weed biomass. Forage radish (Raphanus sativus L.) had less aboveground biomass, but reduced weed biomass by 45 to 100%. Results are among the first to document species‐specific contributions to an ecosystem service in cover crop mixtures, and can be used to inform recipes for mixtures designed for greater productivity and weed suppression.

Sustainable practices are key to the improvement of soil fertility and quality in apple (Malus × domestica Borkh.) orchards. Rootstock genotype and fertilizer inputs can alter soil biology, as well as aboveground traits including nutrient acquisition. In this study, a factorial design was used to assess the interaction between two apple rootstocks, 'Geneva 41' ('G.41') and 'Malling 9' ('M.9') with four fertilizer treatments [chicken-litter compost, yardwaste compost, fertigation using Ca(NO 3 ) 2 , and an unamended control]. The bacterial community in the rhizosphere was assessed for its impact on both plant and soil properties for each rootstock × fertilizer treatment combination. The bacterial community was dominated by Acidobacteria, Proteobacteria, and Planctomycetes, but Verrucomicrobia and Chloroflexi were the most responsive to the fertilizer treatments. The chicken litter and yardwaste treatments had a greater effect on bacterial community structure than the control. Yardwaste, in particular, was associated with increased relative abundance of Chloroflexi, which was correlated with soil nutrient concentrations. Malling 9 had a greater bacterial diversity than G.41, but the rootstock treatment had no independent effect on the rhizosphere community structure. There was, however, a strong interaction between the rootstock and fertilizer treatments. Carbon cycling was the most prominent functional change associated with the soil bacterial community. These results suggest that compost amendments have a more positive effect on soil bacterial activity and nutrient availability than Ca(NO 3 ) 2 . Our work shows that waste-stream amendments can lead to multiple positive responses, such as increasing aboveground tree biomass, thus potentially improving orchard productivity.