Occurrence of couch grass [Elytrigia repens (L.) Desv. ex Nevski] under different grassland management

STÝBNAROVA MARIE, MICOVA PAVLINA, KARABCOVA HANA, SVOZILOVA MARIE: Occurrence of couch grass [Elytrigia repens (L.) Desv. ex Nevski] under diff erent grassland management. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 5, pp. 1399–1404 The objective of this research was to investigate occurrence of common couch grass (Elytrigia repens (L.) Desv. ex Nevski) under diff erent grassland management by means of a small-plot trial. The trial was managed during 2003–2011 with four levels of utilisation: intensive (4 cuts per year, 1st cut on 15 May), medium intensive (3 cuts per year, 1st cut on 30 May), low intensive (2 cuts per year, 1st cut on 15 June), and extensive (2 cuts per year, 1st cut on 30 June). Four rates of fertilisation were applied for each utilisation treatment: nil-fertilisation, P30K60, N90P30K60, and N180P30K60 (pure nutrients). The intensively utilised treatments without N fertilisation showed the lowest mean percentage cover of couch (3.0 %, and 2.8 %, respectively). Further, we found a signifi cant increase in couch grass cover (up to about 30 %) as a response to nitrogen fertilisation and it was most signifi cant in grasslands utilised with two cuts per year. It can be concluded that grassland utilisation in three cuts per year and the dose 90 kg.ha−1 of nitrogen led to the maintenance of the occurrence of couch at the reasonable level up to 10–15 %. permanent grasslands, couch grass, N fertilisation, cutting frequency Common couch grass (also called quackgrass: Elytrigia repens (L.) Desv. ex Nevski) is considered a primary noxious highly invasive weed (Westra and Wyse, 1981). As Sheaff er et al. (2004) mentioned couch grass is noted for aggressive spreading by rhizomes and persistence. It is frequently concentrated in the hedge bottoms and fi eld margins and it rapidly spreads out from the fi eld margins into cultivated fi elds. As couch grass is adaptable to a range of environments and management regimes, it o en becomes the predominant grass in hay fi elds, pastures, and set-aside fi elds. Knowledge about the response of couch grass to the diff erent management practices is necessary to improve animal production. The occurrence of couch grass is one of the main factors reducing both grass yield and quality in cultivated meadows and pastures (Carrere et al., 2010). Subsequently, the animal performance could be negatively aff ected. A percentage cover of over 15 % is not generally desirable with respect to the poorer forage value of this species. Beside its negative impact on the forage quality in natural grasslands, couch grass is able to outcompete and exclude native vegetation, resulting in an overall loss of biodiversity. Considering the negative eff ects of the weeds occurred in farmland areas they are o en commonly controlled by herbicides (Hasan, 1994; Davis and Ballingal, 2009). Chemical methods of couch grass control are, however, expensive and may have negative eff ects on the environment (Bergkvist et al., 2010). The chemicals usage is entirely prohibited in organic farming. Little information is available on how occurrence of couch changes in response to diff erent grassland management treatments. Ðileika (2001) reported the advised management of new grassland by its renovation. As author mentions if some weeds still remain a problem chemical weed control may be necessary. Gaisler et al. (2008) recommended mulching performed at least twice a year as suitable way for non-chemical restriction of undesirable 1400 Marie Stýbnarova, Pavlina Micova, Hana Karabcova, Marie Svozilova weeds such as Cirsium arvense, Urtica dioica or Elytrigia repens. The percentage cover of Elytrigia repens was especially promoted by no management. Dostalek and Frantik (2008) came to the similar conclusion that the cover of Elytrigia repens increased a er grassland abandonment. The biology and non-chemical control of common couch was further documented by Bond et al. (2007). Brandsaeter et al. (2010) mentioned that the success of weed management aimed at depleting the regenerative structures of perennial weeds depends largely on the sprouting activity of rhizome and root buds. Authors results implied that E. repens are more likely to be controlled by mechanical measures in autumn. Growth characteristics of Elytrigia repens in autumn were described also by Torrensen et al. (2010). It is still an open question whether good grassland management can improve botanical composition without radical restoration or herbicides usage. This paper contains information about changes of couch grass dominance in permanent grasslands by diff erent management practices obtained on the basis of the long-term small-plot trial investigation. The objective of this study was to determine the eff ects of diff erent doses of N fertilizer (ammonium salt with limestone) and diff erent intensities of grassland utilisation (cutting regime) on the occurrence of couch in permanent grasslands under the conditions of the Czech Republic. Recommendations regarding the ways of the couch grass regulation are in compliance with the organic farming principles. They could be applied in wide range of conditions without the risk of the soil or ground water contamination with undesirable chemicals. MATERIALS AND METHODS Permanent grassland vegetation relating to the alliance Arrhenatherion has been studied in terms of a long-term small-plot trial. The experiment was established in 2003 in the locality of Rapotin (altitude 400 m a.s.l.; 49°58’N, 17°0’E; annual rainfall 693 mm; mean annual temperature 7.2 °C). The locality is situated in an upland region with mild climate conditions. Meteorological data during the monitored period are given in Fig. 1. The whole area belongs to the geomorphological unit called the Hrubý Jesenik. The soil is sandy-loam, type modal cambisol (horizons Ao–Bv-B/Cc–Cc). Before the experiment setup, the grassland had been used as cattle pasture. The experimental design was a randomised complete block with four replicates and a plot size of 12.5 m2. Four levels of intensity of utilisation were used: treatment 1 = intensive (1st cut on 15 May, 4 cuts per year – cuts at 45-day intervals); treatment 2 = medium intensive (1st cut on 31 May, 3 cuts per year at 60-day intervals); treatment 3 = low intensive (1st cut on 15 June, 2 cuts per year at 90-day intervals) and treatment 4 = extensive (1st cut on 30 June, 1 or 2 cuts per year, 2nd cut a er 90 days). Each utilisation treatment was divided into four levels of fertilisation: treatment A = nil-fertilisation, treatment B = P30K60, treatment C = N90P30K60, treatment D = N180P30K60 (pure nutrients). Phosphorus was applied as superphosphate and potassium as potassium salt once in the spring. Calcium ammonium nitrate was used as a nitrogen fertilizer. Dosing of nitrogen (total dose 90 kg.ha−1 or 180 kg.ha−1) for particular treatments was: • intensive utilisation – 30 kg.ha−1 or 60 kg.ha−1 at spring; 30 kg.ha−1 or 60 kg.ha−1 a er the fi rst cut; 30 kg.ha−1 or 60 kg.ha−1 a er the second cut; • medium intensive utilisation – 30 kg.ha−1 or 60 kg. ha−1 at spring; 30 kg.ha−1 or 60 kg.ha−1 a er the fi rst cut; 30 kg.ha−1 or 60 kg.ha−1 a er the second cut; • low intensive utilisation – 45 kg.ha−1 or 90 kg.ha−1 at spring; 45 kg.ha−1 or 90 kg.ha−1 a er the fi rst cut; • extensive utilisation – 45 kg.ha−1 or 90 kg.ha−1 at spring; 45 kg.ha−1 or 90 kg.ha−1 a er the fi rst cut. The botanical composition of swards was estimated during 2003–2011 by means of the projective dominance method (in %). To avoid the subjectivity of personal estimation, sequent classifi cation of total dominance into morphologically diff erent fl oristic groups and particular species was used. A two-way ANOVA (eff ects of intensity of utilisation, fertilisation and their interactions) followed by post hoc comparison using Tukey’s HSD test at the 0.05 level of signifi cance was used to evaluate the data using the so ware Statistica v. 10.