Combining low-input systems with conservation tillage may be feasible for field crops under northeastern conditions. This study compared the effects of herbicide-free (HF), organic (ORG), conventional (CONV), and herbicide-tolerant (GM) cropping systems applied to three 20 yr-old tillage treatments (MP, moldboard plow; CP, chisel plow; NT, no-till) on weed biomass and crop productivity in a 4-yr barley ( Hordeum vulgare L.)-red clover ( Trifolium pratense L.)-corn ( Zea mays L.)-soybean [ Glycine max (L.) Merr.] rotation. Barley yield (4.5 Mg ha -1), and red clover forage yield (two cuts: 5.3 Mg ha -1) were similar across treatments. With MP and CP tillage, silage corn yield for CONV and GM systems (15 Mg ha -1) was 25% greater than for HF and ORG (11 Mg ha -1), whereas HF-NT and ORG-NT systems produced no harvestable yield. Soybean yield for HF-MP and ORG-MP systems was similar to that for CONV and GM (2.4 Mg ha -1), whereas yield in for the HF and ORG systems with CP and NT was half or less than for other treatments. Some form of primary tillage (CP or MP) was needed in corn and soybean to achieve adequate weed control and yield in the ORG and HF systems. Midseason weed proportion of total biomass was greater in the HF and ORG systems with CP and NT, and provided good yield prediction in corn ( R2=0.74) and soybean ( R2=0.84). Nutrient availability appeared adequate in corn following N 2-fixing red clover but limiting in NT and CP for soybean following corn. Improving crop sequence, fertilization, and weed management will be key to the adoption of low-input systems using conservation tillage practices in cool, humid climates.
