Organic grain producers are interested in reducing tillage to conserve soil and decrease labor and fuel costs. We examined agronomic and economic tradeoffs associated with alternative strategies for reducing tillage frequency and intensity in a cover crop–soybean (Glycine max L. Merr.) sequence within a corn (Zea mays L.)–soybean–spelt (Triticum spelta L.) organic cropping system experiment in Pennsylvania. Tillage-based soybean production preceded by a cover crop mixture of annual ryegrass (Lolium perenne L. ssp. multiflorum), orchardgrass (Dactylis glomerata L.) and forage radish (Raphanus sativus L.) interseeded into corn grain (Z. mays L.) was compared with reduced-tillage soybean production preceded by roller-crimped cereal rye (Secale cereale L.) that was sown after corn silage. Total aboveground weed biomass did not differ between soybean production strategies. Each strategy, however, was characterized by high inter-annual variability in weed abundance. Tillage-based soybean production marginally increased grain yield by 0.28 Mg ha−1 compared with reduced-tillage soybean. A path model of soybean yield indicated that soybean stand establishment and weed biomass were primary drivers of yield, but soybean production strategy had a measurable effect on yields due to factors other than within-season weed–crop competition. Cumulative tillage frequency and intensity were quantified for each cover crop—sequence using the Soil Tillage Intensity Rating (STIR) index. The reduced-tillage soybean sequence resulted in 50% less soil disturbance compared to tillage-based soybean sequence across study years. Finally, enterprise budget comparisons showed that the reduced-tillage soybean sequence resulted in lower input costs than the tillage-based soybean sequence but was approximately $114 ha−1 less profitable because of lower average yields.

Reducing the intensity and frequency of tillage in organic grain production systems is likely to produce several agronomic, economic, and environmental tradeoffs. We evaluated four organic corn (Zea mays L.) sequences in a 3‐yr, full‐entry organic cropping systems experiment. Two sequences included a hairy vetch (Vicia villosa Roth)/triticale (Triticale hexaploide Lart.) mixture sown after spelt harvest that differed in tillage practices (no‐till [NT], conventional) before corn and corn harvest management (silage, grain). Two sequences included a red clover (Trifolium pretense L.)/timothy (Phleum pretense L.) mixture frost‐seeded into spelt in late winter followed by conventional tillage preceding corn and either silage or grain harvest. Our results showed that late‐season weed biomass did not differ across alternative sequences, although both tillage and NT corn production resulted in high in‐row weed pressure in different years. Cover crop management prior to tillage‐based corn production did not affect grain yields, but NT silage production resulted in lower yields compared with the tilled sequence. Corn silage yields were positively correlated with corn populations in both tilled and NT systems. The NT sequence lowered tillage frequency and intensity by 39 and 52%, respectively, compared with tillage‐based corn production as measured using established metrics, including the soil disturbance rating, but did not significantly influence labile carbon pools. Sequences using underseeded red clover resulted in higher net returns compared with hairy vetch sequences due to additional income from fall forage harvests.

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