Effects of Nitrogen Fertilizer and Plant Spacing on Two Pasture Grasses (Brachiaria Decumbens and Digitaria Decumbens )
CHAPTER ONE
OBJECTIVES OF THE STUDY
For the aforementioned reasons, it is necessary to evaluate pasture grasses under humid environmental conditions in order to deduce an appropriate agronomic system for their management. The objectives of the study were:
- To evaluate the influence of NPK fertilizer on the growth and herbage yield of two pasture grasses(Brachiaria decumbens and Digitaria decumbens)
- To evaluate the effect of spacing on the growth and herbage yield of two pasture grasses(Brachiaria decumbens and Digitaria decumbens).
CHAPTER TWO
LITERATURE REVIEW
Description of Test Crops
Brachiaria decumbens
Brachiaria decumbens also known as signal grass is a pasture grass belonging to the family poaceae. It is native to tropical and subtropical regions, of Africa. (Miles et al.,2004), There are about 100 species (Utsunomiya et al., 2005) that include decumbens, ruziziensis fusiformis, erusiformis, mutica, ramose, nigropedata etc. (Mendis-Bonata et al.,2006). Brachiaria decumbens is a vigorous stoloniferous perennial grass that can be established either by seed or by cutting (Gil et al., 1991). They have an erect stem arising from a stoloniferous base and their roots develop from the lower node producing a dense sward. The leaves are lanceolate and 8 – 10 mm wide. The flowers with 2 – 5 recemes are 2 – 5 cm long. They have broad ciliate rachis and 4mm long spikelets. They grow within latitude 27oN and S and from sea level to 1750 m above sea level. Brachiaria requires a temperature of 30 – 35oC for optimal growth (Ndikumana and de Leew 1996). It prefers an annual rainfall of 1500 mm or more, however, it has a good drought tolerance and is adapted to a dry season of 4-5 months. Once established, it tolerates waterlogged soil although it grows better on well drained soils. Brachiaria decumbens can tolerate up to 6 months of drought (CIAT, 1998). It is a short day plant (Hopkison et al., 1996) that is adapted to a wide range of soils but performs better on acidic soils than other grasses. They also perform well on moderately fertile to very fertile soils (Rao et al.,1996) because they are tolerant of high Al, low P and low Ca concentrations (Wenzl et al.,2002). They are highly susceptible to spittle bug but tolerate leaf- eating insects.
Digitaria decumbens
Digitaria decumbens also known as pangola grass belongs to the family gramineae (poaceae). Pangola grass is thought to have originated in the Pangola River in the eastern Transvaal or in the adjacent Zululand districts of Southern Africa. It is now cultivated in the majority of subtropical, tropical and warm temperate countries (Bogdan, 1977). Pangola grass is a stoloniferous perennial with stems that are up to 120 cm high. The leaves are linear-lanceolate to linear, 10-25 cm long and 2 -7 mm wide. The inflorescence has one to two whorls with 5 to 10 spikes that are up to 13 cm long with many spikelets of 2.7 – 3.0 mm long. Roots grow best at soil temperatures of 27 – 30°C. It requires an annual rainfall range of 500 to 900 mm and with a well-pronounced dry season .They grow best under humid conditions, and can withstand drought and tolerate slight waterlogging but not sustained flooding. They respond well to NPK and micronutrient fertilization (especially Cu). Digitaria tolerates a broad pH range from 4.5 to 8.0 and grows on a wide range of soils. It tolerates high soil Al (Bogdan, 1977), has a fair shade tolerance and is also tolerant of small to moderate amounts of Na or NaCl in the soil. It is resistant to root knot nematode, but does not produce viable seeds thus it is propagated vegetatively.
CHAPTER THREE
MATERIALS AND METHOD
Experimental Site
The field experiment was conducted at the Research farm of the Faculty of Agriculture, University of Benin, Benin City, Edo State, Nigeria. The area is located within latitude 60 14’S and 7034’ N and longitude 50 43’ S and 60 43’ E. The site is at an elevation of 500 m above sea level. Mean annual rainfall is 2000 mm and mean temperature range is 25-280 C
Collection of Planting Propagules and Fertilizer
The propagules and fertilizer used were obtained from the Department of Crop Science, Faculty of Agriculture, University of Benin, Benin city.
Treatments and Experimental Design
Twelve factorial treatments were composed from 2 grasses (Brachiaria decumbens and Digitaria decumbens), 3 fertilizer application rates (0, 120, 240 kg NPK ha-1) and 2 plant spacing (30 x 30 cm and 30 x 40 cm). The 12 treatments were fitted into a Randomized Complete Block Design (RCBD) and replicated three times. The plots were 3 m x 4 m in size and each plot was separated from the next one by 50 cm whereas each replication was boarded from the next one by 1m.
CHAPTER FOUR
RESULT
Fresh Herbage Yield
Table 1 shows the effect of grass, plant spacing, fertilizer application and their interactions on fresh herbage yield. The effect of grass was significant at 12 weeks after transplanting (WAT) and highly significant at 18 WAT. In both cases, Brachiaria decumbens produced significantly higher fresh herbage yield than Digitaria decumbens. The difference between the grasses was 11.8 % and 36.6 % at 12 and18 WAT, respectively in favour of Brachiaria decumbens. The effect of spacing was not significant at any interval of sampling. Fertilizer application exerted a highly significant effect on fresh herbage yield at 12 and 18 WAT. In both cases, the effect of fertilizer on fresh herbage yield was linear; increasing significantly with fertilizer application. The 240 kg NPK ha-1 application rate produced significantly higher fresh herbage than the 120 kg NPK ha-1 application rate which also furnished significantly greater fresh herbage yield than the 0 kg NPK ha-1 treatment. The interactions were not significant.
CHAPTER FIVE
DISCUSSION
Effect of Grass Genotype
The study clearly revealed that Brachiaria decumbens is superior to Digitaria decumbens in terms of growth and fresh herbage yield. This is because the former grass was significantly better than the latter grass in virtually all the variables measured. This difference may be ascribed to the genetic variation between the grasses and the environmental influence upon the genotype. Genotype x environment interactions influence the phenotypic expression of most forage crops (Bogdan, 1977). Although both grasses posses a decumbent growth habit, Brachiaria has a more erect structure than Digitaria. This factor may have contributed to a higher sward height recorded by Brachiaria. Furthermore, the greater tillering ability of Brachiaria compared to Digitaria may have contributed to the higher fresh herbage yield of Brachiaria since tillering increases dry matter yield (Humphreys, 1999). This implies that Brachiaria can supply substantial quantities of good quality forage for ruminant livestock in the humid forest zone of Nigeria. However, it is noteworthy that wild grass grasscutters who foraged on the grasses during the period of experimentation, exhibited a preference for Digitaria. This is quite relevant because several domestic grasscutter farms that have sprung up in the humid rainforest region may find Digitaria to be an important component of their fodder bank.
CHAPTER SIX
CONCLUSION AND RECOMMENDATION
Conclusion
Brachiaria decumbens exhibited better growth and higher herbage yield than Digitaria decumbens. The widely spaced plants produced significantly (p< 0.01) more tillers than the narrowly spaced plants. Fertilizer application exhibited a linear response on all the measured variables.
Recommendation
Brachiaria decumbens and Digitaria decumbens produced impressive fresh herbage yields of 5.4 t ha-1 and 3.9 t ha-1, respectively in the first year of establishment. Based on their impressive performance, both grasses deserve to be further evaluated in the humid forest zone of Nigeria.
REFERENCES
- Agishi, E.C. 1971. Use of legumes for livestock production in Nigeria. Samaru Agric. News1. 13: 115-119
- Akinola, J.O. (1982). Effect of plant spacing and fertilizer nitrogen on herbage production of elephant grass. Nigerian journal of animal production 9(1): 21-26.
- Bahar, S.N.G. and A.B. Korkut, ( 1998). Research on effect of planting densities on the yield of corm and cormel in some gladiolus cultivars. Turkish J. Agric. Forest. 22 (1): 51-58
- Bogdan, A.V. (1961) Tropical Pasture and fodder plants.Trop.ric. ser., Longman Inc. New York, pp: 77 86. Rhodes grass still a major sown pasture .Queens land. Agric. J., 93: 528-536
- Bogdan, A.V.(1977). Tropical pasture and fodder plants. Tropical Agricultre series, Longman London. 472 pp.
- CIAT, Tropical Grasses and Legumes: Optimizing Genetic Diversity for Multipurpose Use, Annual report 1998, Centro International de Agricultura Tropical, Cali Colombia, 1998.
- Ezenwa, I. and Aken’ova, M.E. 1998. Performance of mixtures of selected grasses And adapted herbaceous legumes in south-west Nigeria. Tropical Grasslands, 32: 131-138.
- Federal ministry of Agriculture and water Reserve (FMAWR) (2008).Federal Republic of Nigeria. Draft National security programme. 107 pp.
- Frederiksen, J.H and Kategile, J.A (1980). The effect of Nitrogen fertilization and time of cutting in first growth in Brachiaria brizantha on yield, crusde protein content and in vitro digestibility. Tropical Animal Production 5: 136-143
- Gil, E., Alvarez E; and Maldonado, 1991. Distancia distribution establishment de tree species de Brachiaria asciadas con leguminosas pastures Tropicale. 13(3): 11- 14