Influence of nitrogen on competition between cereals and their natural weed populations

Abstract

seed production and, hence, the seed pool and future weed population, suggesting that fertilize r usage can be exploited in an integrated programme of ciopiwecd management. A trend towards lower N fertilizer application owing lo concerns about the environment willlavour most of the weed spedes investigated in these experiments and change the composition of weed populations.The effects of nitrogen fertilizer on the growth and density of natural weed populations io spring barley (Hordeum vuigare L.) and winter wheat (Trlticum aestivum L.) were investigated in the absence of herbicide. An increased level of applied nitrogen did not enhance: weed germination, tended to decrease the total weed biomass and had a differential effect upon the biomass of individual weed spedes ia both wheat and barky. In competition with barley, Chenopodium album L. and Lamlum spp. had lower nitrogen optima ihan the crop, while Urtica wens L. had a higher nitrogen optimum. In competition with wheat, Stellaria media (L.) Vill., Lamium spp. and Veronica spp. had lower nitrogen optima than the crop. The systematic changes in nitrogen effect with time were analysed by fitting orthogonal polynomials to the growth and density curves. The methodology could be recommended for other studies in which time or other systematic factors are included, as it supplies information which a traditional analysis of variance cannot provide. Since seed production is positively correlated with biomass, so nitrogen level affects

Impact of Waste Materials and Organic Amendments on Soil Properties and Vegetative Performance

“…Several studies report increased weed growth in high nitrogen environments [43,44]. The opposite trend was observed in our study where, as Figure 6 clearly shows, an inverse relationship exists between available nitrogen and the invasion index.…”

Response of weed populations to tillage, reduced herbicide and fertilizer rates in wheat (Triticum aestivum) production

“…These results are in agreement with Valenti & Wicks (1992), who found that applying N to winter wheat decreased annual grass weed populations and weed yields, as well as with those obtained by Jørnsgård et al (1996). These authors found that above dry matter of Chenopodium album, Lamiun amplexicaule, Stellaria media and Veronica spp.…”

“…Conversely, in other studies, applications of N favored Setaria viridis (Peterson & Nalewaja, 1992) and Avena fatua (Carlson & Hill, 1986) over wheat. Jørnsgård et al (1996) found differences in the biomass of individual weed species in both wheat and barley crops with N fertilizer applications.…”

Long-Term Diverse Fertilizer Management on Weed Species and Communities in Winter Wheat Field

“…Fertilization affects not only the growth of crop but also on weed population [14] [15] [16]. Previous studies have been demonstrated that fertilization can significantly affect weed community composition, density and diversity [17] [18] [19].…”