Properties of Arrhenatherum elatius under arable land set aside Svobodová M., Šantrůček J., Brant V., Urbanec J. and Niňaj M. Czech University of Life Sciences Prague, Department of Forage Crops and Grassland Management, Prague, Czech Republic E-mail:
[email protected] Abstract The aim of the experiment was to evaluate the development of Arrhenatherum elatius cv. Median sward under extensive exploitation (cut once or three times, mulching once or twice per year) and its effect on the yield of a subsequent crop. The field plot experiment was established in Prague (Czech Republic) in 1996. After seven vegetation years the sward was treated with a total herbicide and reestablished with Lolium multiflorum cv Lolita. The dry mass yield (three cuts per year) and the botanical composition were measured during three years. The yield of only A. elatius under mulching twice per year was significantly higher by 57% in comparison with the plots that were cut three times per year. The yield of invading wild species was lowest under mulching twice per year – 28–31% of the total DMY. The total DMY of the following crop – L. multiflorum, was significantly highest on the plots where the forecrop was cut once per year (8.8 t ha–1), followed by those that had been mulched once per year (10% lower). The proportion of L. multiflorum in DMY was significantly highest on the plots where the forecrop was cut three times per year or mulched twice per year (92–96%). Keywords: Arrhenatherum, Lolium, set aside soil, mulching, cutting, forecrop value Introduction Changes in agricultural policy and actual conditions on the world market can cause, from time to time, a necessity of setting a part of arable land aside. Leaving it without any treatment causes various problems, especially with weed infestation and other aspects that influence soil fertility. To conserve the soil in good condition, grasses are the best species because of their good winter coverage, organic mass production, a good influence on the soil structure, protection of water against nitrate leaching, etc. (Novák, 1998; Svobodová and Šantrůček, 2005). According to the particular conditions, suitable grass species have to be chosen (Šantrůček et al., 2002). Grasses generally have a relatively high demand for rainfall. The optimum Lang’s rain factor (LRF) for forage grass cultivation is higher than 120, but the arable land in the Czech Republic is very often exposed to semiarid conditions (LRF = 40–50). Only a few grass species can produce enough phytomass under such conditions with Arrhenatherum elatius being one of the best adapted grasses. The aim of the experiment was to evaluate the development of Arrhenatherum elatius sward under extensive exploitation and its effects on the yield of a subsequent crop. Materials and methods The field plot experiment (3 × 10 m per plot) with Arrhenatherum elatius cv. Median was established in Prague (chernozem soil, altitude 281 m a.s.l., average annual precipitation 246
Grassland Science in Europe Vol 14
472 mm, average annual air temperature 9.3°C). The grass was sown as a monoculture without a companion crop in 1996: the sowing rate was 50 kg ha–1. The sward was cut once or three times or mulched once or twice per year. It was not fertilised. Dry mass yields and botanical composition were evaluated. After seven vegetation years the sward was treated with a total herbicide and reestablished with Lolium multiflorum cv. Lolita (sowing rate 60 kg ha–1) in late summer to evaluate the forecrop value of A. elatius. The dry mass yield (three cuts per year) and the botanical composition were analysed in the second and third vegetation years. The results were evaluated by analysis of variance ANOVA in Statgraphics programme version XV. Results and discussion
other species species
3C 2M 1M 1C
3C 2M 1M 1C
3C 2M 1M 1C
Arrhenatherumelatius Arrhenatherum
3C 2M 1M 1C
9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0
3C 2M 1M 1C
–1
(kg ha )
The average yield of the Arrhenatherum elatius sward (Figure 1) was 4,300–5,000 kg ha–1 in the third and fourth years, but in the fifth year the total yield was lower by 48% in comparison with the previous years. This represented the natural development of the sward under dry conditions (LRF 47-50). In the sixth and seventh year the yields of the sward increased because of higher precipitation (LRF 73 in both the years) especially under mulching twice per year. With this treatment nutrients are returned to the soil and used again if conditions are sufficiently moist. The yield of only A. elatius under mulching twice per year was significantly higher by 67% in the last two years in comparison with the plots cut three times per year (simulation of intensive forage exploitation) and by 57% during all the experiment (Dmin. α = 0.05 = 1,380 kg ha–1). It shows that two harvests are the optimum frequency for such climate conditions from the point of view of the sward yield (Šantrůček et al., 2002). The yield of invading wild species (Figure 1) increased under more humid conditions in the 6th and 7th year, and it was lowest under mulching twice per year – 28–31% of the total DMY in comparison with the plots harvested once per year (33–57%) and those cut three times per year (58–64%).
3rd year
4th year
5th year
6th year
7th year
Treatment/vegetation year
Figure 1. Sward composition of Arrhenatherum elatius (t.ha–1) (C – cut, M – mulching)
The average proportion of A. elatius in the total DMY calculated from all the experimental years was not significantly influenced by the sward treatment, because in the drier years (the first three ones) there were more weeds on the plots mulched twice per year (Figure 1, Table 1). This parameter was significantly influenced by the age of the sward – the average proportion of A. elatius (y) decreased linearly y = –11.4x + 107.4 (x = vegetation year – 2), R2 = 0.9854. Alternative functions of grasslands
247
Table 1. Proportion of Arrhenatherum elatius and other species in the DM yield (%) Treatment
3rd year
4th year
5th year
6th year
7th year
Average
Arrh. other Arrh. other Arrh. other Arrh. other Arrh. other Arrh. HG other
3 cuts
95
5
82
18
73
27
42
58
36
64
65
a
35
2 mulch
94
6
68
32
59
41
72
28
69
31
72
a
28
1 mulch
94
6
90
10
89
11
67
33
43
57
76
a
24
1 cut
99
1
97
3
86
14
60
40
51
49
78
a
22
Average
95
5
84
16
77
23
60
40
50
50
73
27
HG
d
cd
bc
ab
a
HG – homogenous groups (LSD, α = 0.05); Arrh. – Arhenatherum elatius
The other important aim of the experiment was to evaluate the influence of A. elatius swards used for setting arable land aside on the development and weed infestation of a following crop. The total DMY of the L. multiflorum sward was significantly the highest on the plots where the forecrop was cut once per year (8,800 kg ha–1), followed by those that had been mulched once per year (Table 2) – in both cases the average yields of the forecrop were lower than those with two or three harvests. The yields of only L. multiflorum (5,000–6,000 kg ha–1) were not influenced by the treatment of the forecrop, but its proportion in the total DMY was significantly the highest on the plots where the forecrop was harvested twice or three times per year (96 or 92%) and there was significantly more infestation with other species on the plots where the forecrop was harvested only once per year (Table 2). The total DM yield of L. multiflorum significantly decreased with the vegetation year and was highest for the first cut in the year. Table 2. Yield and composition of Lolium multiflorum swards Total DM yield (kg ha ) 3 cuts Treatment 2 mulch of forecrop 1 mulch
Cut
Year
DM yield of Lolium
Proportion of Lolium in DM
HG
(kg ha )
HG
(%)
HG
5,526
a
5,106
a
92.4
b
6,306
ab
6,039
a
95.8
b
–1
–1
7,995
ab
5,811
a
72.7
a
1 cut
8,811
b
5,790
a
65.7
a
1
st
4,140
c
3,581
c
86.5
b
2nd
2,015
b
1,546
b
76.7
b
3
rd
1,004
a
0,559
a
55.7
a
2nd
9,279
b
8,631
b
93.0
b
3rd
5,037
a
2,442
a
48.5
a
Conclusion The results show that weed infestation of a grass sward depends particularly on the persistency of the given grass species and the weed infestation of the following crop does not necessarily correlate with the weed infestation of the forecrop. It also depends on 248
Grassland Science in Europe Vol 14
the competitive capacity of the following crop, influenced by the nutrient pool, weather conditions etc. Acknowledgement: This research was supported by the Research Project No. MSM 6046070901 of the Ministry of Education, Youth and Sports of the Czech Republic.
References Novák J. (1998) Changes in grassland after additional sowing of grass mixture with dominance of valuable herbs. Rostlinná výroba, 44, 123–131. Śantrůček J., Svobodová M. and Brant V. (2002) Changes of botanical composition of grass stands under different ways of management. Rostlinná výroba, 48, 499–504. Svobodová M. and Šantrůček J. (2005) Setting arable land aside by temporary grassland. Savremena poljoprivreda (Contemporary Agriculture), 54, 561–565.
Alternative functions of grasslands
249
