5.2 Materials and methods
5.2.4 On-farm establishment of Brachiaria grasses
Improved Brachiaria grass seeds were supplied by CIAT after receiving an importation permit from the Rwandan Ministry of Agriculture and Animal Resources (MINAGRI).
The different species of Brachiaria were multiplied by seed in the nursery at Karama Research Station of Rwandan Agricultural Research Institute (ISAR). From the plants, established vegetative material was taken to the different sites. Apart from these grass species, Brachiaria decumbens (native grass) and Cenchrus ciliaris (Buffel grass) were used as control species in the on-farm trials in both Bugesera and Nyamagabe districts.
Cenchrus ciliaris (Buffel grass) has been tested under different agro-ecological zones of Rwanda and showed good adaptation in the Bugesera district (Myambi 2006). Currently, buffel grass is naturalised and used by farmers as forage in different areas of Rwanda.
The on-farm trial was carried out on three cells in the low rainfall (Bugesera district) and three in the aluminium toxicity acidic soil (Nyamagabe district). The distances between the three cells in each district are shown (Figure 5.1). In each cell, four farmers were selected and hence 12 farmers for each district. The distances were calculated using the global positioning system (GPS) waypoint option. The Bugesera district is a lowland area where selected farmers were close to one another (<2,894 m) whereas in the Nyamagabe district this was not always possible due to the steep slopes in the area (<6,575 m). The distance between the two districts by road is about 223 km from southeast to southwest of the country. Within a cell the distance from one farmer to another varied according to the district (Table 5.2) and the distance between cells within the district varied according to target farmers (Figure 5.1A and 5.1B).
Table 5. 2 The distance between selected farmers within a cell per district
Cells Distance between farmers within a cell
The Bugesera district Murama Varying from 50 m to 200 m Musenyi 2894 m
Mareba 2154 m
The Nyamagabe district Ngiryi Varying from 3459 m to 4505 m Kigeme Varying from 2376 m to 6575 m Murambi Varying from 2681 m to 4073 m
Figure 5. 1 Location of study sites in Rwanda
During on-farm establishment, a total of three Brachiaria varieties and five hybrids with two local control grasses were established at the Karama research station of ISAR. These were used for vegetative material for on-farm participatory trials. The experimental design (Figure 5.2) comprised 10 plots (2 m x 3 m) which included five hybrids of Brachiaria, three cultivars of Brachiaria and two local forage controls Brachiaria
B A
decumbens (indigenous grass) and naturalized Cenchrus ciliaris. Although many farmers use Napier grass (Pennisetum purpureum) as fodder, it was not used as a control grass because of its tall growth habit and different cutting height from Brachiaria grass. The indigenous Brachiaria and the naturalised buffel grass (Cenchrus ciliaris) were considered as suitable controls in this trial since farmers, even those who use Napier grass, rely on the „cut-and carry‟ of indigenous Brachiaria from the roadside. The distribution of treatments (forage grasses) within plots was different from one farm to another.
3 m 2m 1m
1 m
Figure 5. 2 Experimental design of on-farm trial
Before trial establishment, soil samples from four selected farms within each cell in the Bugesera and Nyamagabe districts were analyzed for pH, Al3+ and available phosphorus following the recommendations of Anderson and Ingram (1993) for tropical soils standard methods of analysis. The plot size was 2 m x 3 m and the spacing between plots was 1 m. All grasses were established without fertilizer application.
5. 2.5 Evaluation of forage 5.2.5.1 Quantity and quality
Forage yield evaluation took place six times a year at approximately two monthly intervals with cutting at 10 cm height. For the creeping species, especially Brachiaria decumbens and Cenchrus ciliaris, cutting at 10 cm height was recommended by Tudsri et al. (2002). For erect species, cutting at 10 cm height increases the yield (Tarawali et
Brachiaria hybrid Bro2/1485
B. brizantha cv. Marandu
C. ciliaris (control) Brachiaria
hybrid Bro2/0465
B. decumbens cv. Basilisk
B.
decumbens Local grass (control) Brachiaria
hybrid cv.
Mulato II
Brachiaria hybrid cv.
Mulato
B. brizantha cv. Toledo
Brachiaria hybrid Bro2/1452
al. 1995). Biomass was harvested in a 1 m2 quadrat randomly placed within each 2 m x 3 m plot at each of the following harvest time:
- during peak of first rainy season (November 2007) - during beginning of first dry season (January 2008) - during the second rainy season (March 2008) - during the end of second rainy season (May 2008) - during the dry season (July 2008)
- during the rainy season (September 2008)
After collecting samples from 1 m2 quadrat, the whole plot was cut to allow the homogenous regrowth for the next cut.
Biomass subsamples from 1 m2 quadrat were oven dried at 105oC to constant mass to give dry matter production estimates during the study period (Griggs et al. 2007, Ibáñez and Alomar 2008). The dry matter was calculated as indicated by Tarawali et al. (1995), Pieper (1978) cited by Kidunda (1996):
Dry matter (DM) yield kg ha-1= (Tot FW x ( DW ss/FW ss)) x 10 where:
Tot FW= Total fresh weight from 1 m2 quadrat in grams DW ss= Dry weight of the subsample in grams
FW ss= Fresh weight of the subsample in grams
All samples were taken to the laboratory of animal feed analysis at Rubona Research Station of the Rwandan Agriculture Research Institute (ISAR) and at High Institute of Agriculture and Animal Husbandry of Busogo (ISAE Busogo) for nutritive value analysis. Samples taken from dried grasses were chemically analysed according to the recommendations of AOAC (1990) (once in the wet season and once in the dry season) for crude protein, phosphorus and calcium.
5.2.5.2 Participatory variety selection
Participatory variety selection (PVS) is used in many on-farm research trials to allow the farmers to judge and select the best crop varieties and/or hybrids established on their
farms (Walker 2007, Misiko et al. 2008, Vial et al. 2008). The PVS approach fosters adoption and dissemination of new technologies in suitable niches for high production of the new options (Joshi et al. 1997, Gowda et al. 2000). It also helps to empower farmers with knowledge of the new technology (Pandit et al. 2007a, Jun et al. 2009). At the end of the trial, a PVS was done in order to know which varieties and/or hybrids of Brachiaria were selected and preferred by farmers according to their criteria. All farmers that had Brachiaria grass on their farm participated in this variety selection. Farmers met on one plot of grass treatments in each area. Based on identified criteria, they gave negative and positive feedback on each variety and hybrid used in the experiment. From the criteria given, the farmers ranked all the forage plants. Forage that possessed many positive criteria were likely to get a high rank.