18th Congress of the European Society for Agronomy

Weed response to long-term cultivation practices

Not scheduled

15m

Les Dortoirs (1st floor) (The Couvent des Jacobins)

Poster Synergies between short- and long-term goals Poster session #1

Speaker

Jan Winkler (Department of Plant Biology, Faculty of AgriSciences, Mendel University in Brno (Czech Republic))

Description

1. Introduction
   Long-term field trials are a unique scientific tool that can be used to study changes in the weed species spectrum under different management practices over time.
2. Materials, methods
   The long-term field trial was located at the Žabčice Experimental Station (South Moravia Region, Czech Republic). The field trial was established in 1970 and was designed as a long-term monoculture of spring barley with different management practices. Two variants of basic tillage and three variants of straw management were used in the experiment. The tillage variants were (i) traditional tillage: basal tillage is done by plowing to a depth of 0.22 m, pre-sowing preparation and seeding, (ii) minimization tillage: basal tillage is done by disk tillage to a depth of 0.12 m, pre-sowing preparation and seeding. Straw management options: (a) straw is harvested and transported after harvest, (b) straw is left in place and incorporated into the soil after harvest, (c) straw is burned after harvest.
   The weed assessment was carried out using the counting method. Monitoring was carried out between 2001 and 2018. The time of evaluation was always the same stage of spring barley and before herbicide application. Statistical processing of the data was done by correspondence analysis (CCA).
3. Results
   A total of 49 weed species were found during the monitoring period. Based on the weed response, the agricultural practices can be divided into three groups. The first group is traditional practices involving plowing (traditional tillage), harvesting and straw removal, which are technologies that have been used for a long time. The first group is more suitable for typical, less damaging weed species (e.g. Amaranthus spp., Anagallis arvensis, Echinochloa crus-galli, Lamium purpureum, Microrrhinum minus, Papaver rhoeas, Persicaria lapathifolia, Persicaria maculosa, Polygonum aviculare, Silene noctiflora, Veronica persica, Veronica polita nebo Viola arvensis).
   The second group consists of minimum tillage practices and straw incorporation. These practices have been newly applied in recent decades. Each of these groups of management practices induces a different weed response. The second group creates more favorable conditions for the occurrence of difficult to control and atypical weed species (e.g. Avena fatua, Consolida orientalis, Convolvulus arvensis, Datura stramonium, Elytrigia repens, Fallopia convolvulus a Galium aparine).
   The third group consists of the straw burning variant, which is purely experimental and cannot be applied in practice on large areas for legal reasons. The third group, represented by straw burning, seems to be the most effective method of weed control. Higher abundance of e.g. Cirsium arvense, Fumaria officinalis, Lamium amplexicaule, Sinapis arvensis a Stellaria media.
4. Discussion
   Several studies have shown that management practices can be combined and work synergistically to reduce weeds. Using a combination of management practices to control weeds provides some protection against potential herbicide failure. This makes control more effective under changing environmental conditions. Straw management and tillage affect the soil environment (nutrient dynamics, C:N ratio, physical properties, light conditions, etc.), which also affects weeds. Straw and post-harvest residues can have an allelopathic effect on the germination of some weed species.
   In the future, we can expect a change in the species composition of weeds even in spring barley stands. The occurrence of typical species such as Avena fatua, Fallopia convolvulus will probably decrease and, on the contrary, the occurrence of invasive species (Echinochloa crus-galli or Amaranthus spp.) will increase. The established weed community in spring barley monocultures consists mainly of native and domesticated species (apophytes and archaeophytes). Barley stands, regardless of the cultivation methods used, do not allow the spread of new invasive weeds. However, even here there are changes in the species composition of weeds caused, among other things, by climate change.