Effect of tillage systems, N, and cover crop on the composition of weed flora

Abstract

The adoption of conservation tillage systems has been challenged by concerns potential weed species shifts. A 9-yr study from 1988 to 1996 was conducted Delhi, Ontario, on a loamy sand soil to evaluate the effect of tillage systems (conventional [CT] and no-till [NT]), cover cropSecale cereale, and nitrogen (N) rate (0, 50, 100, 125, 150, and 200 kg N ha−1) on monocropZea maysL. (corn) yield and changes in the composition of the weed flora. CT consisted of spring moldboard plowing followed by cultivation with a tooth cultivator. Weed counts were taken in the last 3 yr of the study (1994, 1995, and 1996) prior to postemergence herbicide application and then again 2 to 3 wk after herbicide treatment. Composition or the weed flora was analyzed by canonical discriminant analysis (CDA). The relationship between weed density and tillage system was not consistent. Weed species composition differed between CT and NT systems.Chenopodium albumandAmaranthus retroflexuswere associated with CT andDigitaria sanguinaliswith NT. N rate and cover crop did not affect weed density or species composition. Proper management of weeds with herbicides appeared to minimize any long-term effect on the weed flora resulting from varying N rates.Zea maysyields did not differ between CT and NT systems but were greater in both systems with a cover crop at the higher N rates. Disturbance caused by tillage was more important than N rate and cover crop as a mechanism influencing composition of the weed flora.

Management of weed emergence and weed seed bank in response to different tillage, cropping systems and selected soil properties

“…Increases in diversity of species under NT have been predicted because the successional process of the weed community is allowed to proceed further than under conventional tillage (Swanton et al, 1999;Chauhan et al, 2012). In accordance with this postulate, the cumulative effects of conservation tillage techniques (NT and MT), in our study, increased the weed density and species diversity in soil persistent weed seed bank compared to conventional tillage technique, whereas the vertical seed distribution did not show significant differences.…”

Allelopathic Potential of Winter Cereals and Their Cover Crop Mulch Effect on Grass Weed Suppression and Corn Development

“…The corn yield increase in plots where barley cultivar Athinaida had incorporated is in agreement with findings of Shrestha et al (2002) who reported that soybean yield was increased by the presence of rye and corn used as cover crops. Also, Swanton et al (1999) found that corn yield was increased by a rye cover crop and Moore et al (1994) reported that soybean yield of the rye and triticale mulch treatments were 69 and 91% greater, respectively, than the bare soil treatment. The different effect of barley cultivar Athinaida on corn yield, compared with those of the other winter cereals tested, could be attributed to its stronger effect on grass weed emergence and growth.…”

Banded herbicide, rotary hoeing and cultivation effects on weed populations in ridge-tilled soybean

“…In 1990, rainfall was above normal in May and early June but was near normal after mid-June (Table 2). In general, the same weed species were found on a given farm in both years (Table 4) 15 , because of differences in selection regimes and growth conditions, but there are no unique problems presented by ridge-tillage in this respect, and the weed species recorded here are commonly found throughout the state.…”