M. Zimková and J. Tomaskin
Grassland and Mountain Agriculture Research Institute
Mládeznícka 36, 974 21 Banská Bystrica, Slovakia
Introduction
Materials and methods
Results and discussion
Conclusions
References
In Slovakia, legume-based systems are regarded as being environmentally acceptable and in recent years also economically advantageous because of higher prices of N-fertilizers and other agricultural inputs. Thus, there is renewed interest and appraisal of grass/white clover mixtures in forage production systems.
The study of forage production during the growing season in comparison with root production was the aim of this research work, using pure-sown white clover and perennial ryegrass/clover swards.
The trial was established on 5 May 1992 at Banská Bystrica. The white clover and perennial ryegrass varieties listed in Table 1 were sown at the site Suchy vrch - Radvan (450 m a.s.l.; average annual temperature 6.3°C; annual rainfall 848 mm and during the growing period 451 mm).
After sowing at a seed rate 9 kg. ha-1 for the clovers and an additional 12 kg. ha-1 of ryegrass when sown in mixture, establishment, yield performance and weed infestation were investigated. Two cuts were made to control weeds and because of severe drought in summer '92, no yields could be measured except on the two ryegrass/white clover mixtures (Merganda + Merwi and Merlinda + Merwi). In 1993-94 three or four cuts were taken.
The soil was a rendzina with pH 6.8, 8.7 mg P. kg-1 and 107 mg K. Kg-1.
The plots were randomly established in four replicates with harvested area of 10 m2 in each plot; no fertilizers and no rhizobial inoculation were used.
The seasonal changes in root production were determined three times a year: at the beginning of the growing season, after the first cut and at the end of season. Root sampling was done by steel cylinder (15 cm3 volume) into a soil depth of 10-12 cm (10 replicates per plot). The increase in root growth was measured by means of small containers of metal net which were put into the soil profile at the beginning of the growing season to a depth of 10 cm.
At the end of the growing season containers were pulled out of the soil and the amount of roots which is intergrown in nets was measured. This measurement represents the annual growth increase of roots.
Sampled roots were washed in a stream of lukewarm water, dried at 60°C and weighed.
All white clover varieties and both mixtures germinated evenly. The dominant weeds were Chenopodium album and Stachys recta. After two weed control cuts (18 June and 17 July '92) all swards were well established but DM yields (0.99-1.38 t.ha-1) were only recordable from the mixtures.
The yields of pure white clover swards (Table 1) were lower than those from the ryegrass/white clover mixtures, though higher in 1994 in comparison with 1993.
Table 1. Herbage and root DM yields (t.ha-1) and root growth increase over the season (kg. m-2 per 10 cm depth)
|
Variety or mixture |
Country of origin |
Total DM yield |
Root DDM yield |
Root growth increase |
|||
|
1993 |
1994 |
1993 |
1994 |
1993 |
1994 |
||
|
Gwenda |
UK |
2.06 |
6.38 |
0.562 |
0.356 |
0.263 |
0.243 |
|
Menna |
UK |
1.72 |
6.07 |
0.444 |
0.434 |
0.235 |
0.168 |
|
Olwen |
UK |
2.32 |
6.93 |
0.512 |
0.265 |
0.323 |
0.145 |
|
S 184 |
UK |
1.62 |
5.77 |
0.436 |
0.408 |
0.233 |
0.202 |
|
Siwan |
UK |
3.49 |
5.88 |
0.628 |
0.372 |
0.193 |
0.129 |
|
Merganda + Merwi |
B |
7.38 |
9.56 |
0.835 |
0.403 |
0.349 |
0.202 |
|
Merlinda + Merwi |
B |
7.71 |
8.03 |
0.960 |
0.558 |
0.333 |
0.230 |
UK - United Kingdom; B - Belgium
The high productive potential of grass/white clover mixtures without N-fertilizer confirmed previous Slovak work by Kasper (1984) and Smajstrla (1985). The ryegrass/clover mixtures and pure-sown clovers gave the highest yields in 1994, since growing conditions were much better than in 1993 (Table 2).
Table 2. Average air temperatures (°C) and rainfall (mm) during growing season (April - September)
|
Year |
Air temperature |
Rainfall |
|
1992 |
15.8 |
287.0 |
|
1993 |
14.8 |
336.5 |
|
1994 |
16.0 |
564.7 |
It seems that 1994 was better for herbage yield and 1993 for root production to put more "energy" primarily into root growth (1993) and then in more favourable growth conditions into top growth (1994). The trial will be conducted also in 1995 to see the further development of root and forage yield.
On average over the two years, cvs Siwan and Olwen were the highest ranking clovers.
The root production and root growth increase were also greatest in mixtures, but in contrast to the herbage production, root production and root growth increase were greatest in 1993, possibly as a consequence of the drier conditions.
Our "root" results are in accordance with previous results of Jancovic (1985) and Fiala and Jakrlová (1987) under similar conditions.
Perennial ryegrass/white clover mixtures gave satisfactory amounts of forage and roots with nil external inputs. This suits well for animal production systems and for the storage for organic matter in the soil. Both these characteristics are advantageous for sustainable grassland farming without the need for high inputs.
FIAL, K. and JAKRLOVA J. (1987) Primární produkce lucních ekosystému aluvia jizní Moravy a oblasti Ceskomoravské vrchoviny. Teória a prax v odvetví lúkárstva, pasienkárstva a trávnych porastov. Kosice pp. 105-111
JANCOVIC J. (1985) Vplyv hnojenia na korenovú biomasu trávnych porastov. Agrochémia. 25, 2, pp. 43-45
KASPER J. (1984) Sledovania vytrvalosti niektorych druhov tráv a dateliny plazivej. Annual report of GRI Banská Bystrica, pp. 53-57
SMAJSTRLA V. (1985) Vyuzitie rôznych odrôd tráv a datelinovín. Annual report of GRI Banská Bystrica, pp. 15-17.
