Continuous corn (Zea mays L.) grown on sloping land and harvested for silage, returns few residues to the soil and leaves the soil unprotected against erosion for most of the year. Three field experiments were conducted on a Lima loam (a fine‐loamy, mixed, mesic Glossoboric Hapludalf) to determine the contributions from various intercrops and cover crops towards ground cover, dry matter, and N. In Exp. 1 and Exp. 2, the effects of intercrops and cover crops were measured by determining corn grain yields following the plow down of the various crops. Corn grain yields following the incorporation of various crops were compared to yields of corn where no cover crops had been incorporated but N rates of 0, 56 or 112 kg ha−1 had been applied. In Exp. 3, the effects of intercrops and cover crops on corn yields were measured over a 5‐yr period. First‐year corn grain yields were neither increased nor decreased as a result of seeding intercrops when the corn was 0.15 to 0.30 m high. All intercrop and cover crop treatments in Exp. 3 provided significantly more ground cover than the control treatment. Annual ryegrass (Lolium multiflorum Lam.), medium red clover (Trifolium pratense L.), and a combination of the two were the most effective in terms of ground cover and dry matter production.

Manure applied to cropland may serve as a source of weed introduction and dispersal. In 36 manure samples from 20 farms, apparently-viable seeds from 13 grasses and 35 broadleaf plants were found. Common lambsquarters was on more than half the farms, yellow foxtail on 35%, common chickweed and dandelion on 30%, and wild mustard, redroot pigweed, and barnyardgrass on 25%. Four farms had manure with no seeds at all; the remainder averaged 75 100 per 1000 kg manure. Twelve milking-cow and heifer barns on six farms with large velvetleaf infestations also were sampled with an average of 133 000 seeds per 1000 kg manure. Only one barn contained velvetleaf seeds. When compared to soil seedbank numbers, manure is not an important seed source for New York farms. However, problems may arise with imported feeds heavily infested with weed seed or which contain even small numbers of noxious weeds.

Six corn hybrids were studied in field experiments in 1989 and 1990 to identify hybrids and corn plant characteristics that may be valuable in systems using reduced levels of weed control. Four weed control treatments (no-control, cultivation-only, band herbicide-plus-cultivation, and broadcast herbicide) represented main plots and maize hybrids were subplots. Medium-season hybrids with differences in height, early-season vigor, and leafiness were used. There were significant differences among hybrids in leaf angle, leaf width, leaf number, plant height, leaf area index (LAI), plant dry matter (DM) and grain and stover yields. Lower yielding hybrids had grain yields that ranged from 87 to 91% of the highest yielding hybrid. Aboveground corn characteristics were not correlated with weed numbers, weed cover, or weed biomass. A significant interaction between hybrid and weed control for grain yields was observed in 1989, suggesting that some hybrids are more competitive when weed pressure is high.

Eight cultivation programs with several equipment combinations were compared with each other and with an atrazine plus pendimethalin herbicide program with and without supplemental cultivation from 1992 to 1994. In two of the three years, cultivation with a rotary hoe or tine weeder reduced weed seedling density by 39 to 74%. Tine weeding was more effective than rotary hoeing in 1992. Rotary hoeing or tine weeding reduced corn populations by an average of 6%. Weed control by different types of inter-row cultivators varied little, except that an in-row cultivator provided better control than a rolling cultivator in two years and better control than a shovel cultivator in one year. Weeds establishing from seeds were better controlled by herbicides in all three years, but weeds establishing from roots, rhizomes, and tubers were controlled as well or better by cultivation. Weed control was sometimes better using herbicides plus cultivation than with herbicides alone, but the combination damaged the crop in two of the three years. Cost of mechanical treatments which combined inter-row cultivation with rotary hoeing or tine weeding differed from that for the herbicide treatment by less than 2%. Yields of the best mechanical treatment and the herbicide treatment were nearly equal in all years, but the best mechanical regime varied between years. Consequently, mean net return was moderately higher for the herbicide treatment.

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