A late-killed rye (Secale cereale L.) cover crop has many environmental benefits. However, rye can reduce following corn (Zea mays L.) yield and compromise pre-emergence herbicide activity. Our hypotheses were (i) rye reduces corn yields, especially if killed at late-boot stage; (ii) in-row tillage helps alleviate yield reductions; and (iii) postemergence weed control will be more effective than pre-emergence weed control in the presence of rye mulch. Corn was planted 7 to 10 d after rye was killed at early- and late-boot stage with no-till or zone-till. A no-rye control was included for comparison. Herbicide programs included half rate of pre-emergence herbicide, full rate of pre-emergence herbicide, and a postemergence herbicide. Rye biomass, soil bulk density, corn yield and population, and weed biomass were determined. Average rye biomass was 1480 kg ha-1 dry matter (DM) at early-boot stage and 4200 kg ha-1 DM at late-boot stage. In 2001, bulk density was reduced 0.08 Mg m-3 in the 0- to10-cm depth in the late-killed rye plots compared with no rye or early killed rye. Rye never reduced no-till corn yields. Allelopathic effects of rye on corn were absent, calling for a better understanding of its underlying principles. Zone-till did not improve corn yields. Good weed control resulted from all herbicide programs due to low weed severity. The results suggest that rye cover crops will not reduce corn yields if rye is killed 7 to 10 d before corn planting and if adequate N is applied.
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science