ABSTRACT
Three field experiments were conducted at the Teaching and Research Farm of the Department of Crop Science, Faculty of Agriculture, University of Nigeria, Nsukka. In the first experiment, the effects of fertilizer-N application and cutting management on establishment, growth and yield of guinea grass (Panicum maximum) were investigated. The experiment was a 4 x 4 factorial laid out in a randomized complete block design with three replications. Treatments comprised four levels of Nitrogen of 0, 150, 300, and 450 kg N ha-1 and four harvesting frequencies of 3-, 6-, 9- and 12-weekly intervals. A second experiment was conducted using guinea grass/verano stylo (Stylosanthes hamata) mixed swards. The experiment was a 3 x 3 x 2 factorial laid out in a randomized complete block design with three replications. Treatments comprised three swards types (pure grass, pure legume and grass-legume mixed swards), three harvesting frequencies of 4-, 8-, and 12-weekly intervals and two levels of nitrogen at 0, and 300 kg N ha-1. The third experiment was conducted to evaluate the effects of two cutting frequencies (4- and 8-weekly intervals) on the growth and yield of four legumes (Lablab purpureus, Stylosanthes hamata, Centrosema pascuorum and Stylosanthes guyanensis) and four grasses (Sorghum almum, Panicum maximum, Chloris gayana and Andropogon gayanus). Basal applications of muriate of potash (75 kg K ha-1) and single superphosphate (44 kg P ha-1) were also made by broadcasting in all the experiments. In the first experiment, tiller number per square metre, plant height and grass dry matter yield were increased by 44%, 6% and 53%, respectively, during the establishment year when fertilizer-N rate was increased from 0 to 450 kg N ha-1. Grass dry matter yield was increased by 41% and 149% when the interval between cuts was increased from 3- to 12-weekly intervals at the first and fourth harvest years, respectively. Plots cut at 3- or 6- weeks intervals exhibited much greater weed proportion than those cut 9-, or 12-weekly intervals. Increasing the interval between harvests from 3 to 12 weeks increased the proportion of stem relative to leaf blade in the grass swards. The proportion of inflorescence, plant height and dry matter percentages, were generally increased by increasing the interval between cuts. Tiller number decreased with increasing interval of cut. The total annual herbage dry matter yield was increased by 32% and 48% in 2001 and 2004, respectively, when fertilizer-N was increased from 0 to 450 kg N ha-1. Increasing the N rate from 0 to 450 kg N ha-1 increased the proportion of stem relative to the leaf blade in the grass swards. Plant height and tiller number were increased with increase in N application while the dry matter percentage was generally decreased with incremental application of nitrogen. A combination of 12-weekly interval of cut with 300 kg N ha-1 gave a significantly higher forage grass herbage dry matter yield compared with the values got from the 3- or 6-weekly interval combined with any N rate. Fertilizing at 300 or 450 kg N ha-1 when combined with cutting at 9 or 12-weekly interval between cuts was more effective in suppressing weed growth and weed dry matter as a proportion of the total herbage dry matter. The N % and crude protein contents in the leaf, stem and in total herbage dry matter decreased significantly with increasing interval between cuts. Yield of crude protein in the total herbage was significantly higher when cutting was done every 6 weeks compared with when done every 9 weeks. Nitrogen fertilizer x cutting frequency interaction effects on N %, crude protein contents and crude protein yields in the crop fractions and in total herbage dry matter were not statistically significant. On the average, the crude protein and mineral contents were higher in the leaf fraction than in the stem and inflorescence fractions. In the second experiment, herbage production was 16% and 69% higher on guinea grass/stylo swards in 2006 and 2007, respectively, compared with the yields for the pure guinea grass swards. Grass dry matter yield as a proportion of the total herbage dry matter was significantly increased from 45% to 61% in 2007 with 12-weekly cutting interval compared with 4-weekly interval. The weed proportion was significantly reduced from 28% to 19% with the infrequent cutting interval of 8-weeks compared with the 4-weeks in 2007. Cutting frequency did not influence the proportion of verano stylo in 2006 and 2007. However, the legume dry matter yield was generally increased with longer intervals between cuts. The effects of fertilizer-N rates on the proportions of grass, legume and weed in 2006 and 2007, were not statistically significant. The total herbage dry matter yield was significantly higher in guinea grass/stylo swards when cutting was done at 8-weekly interval compared with sole guinea grass or verano stylo at any interval between cuts. Crude protein yield of the guinea grass/stylo sward was higher than that of pure guinea grass sward by 8 %. In the third experiment, Stylosanthes guyanensishad the highest dry matter yield among the four legumes in 2007 when 8 weeks interval between cuts was employed. Among the four grasses, Chloris gayana produced significantly greater dry matter yield than Sorghum almum but had a similar yield value with Panicum maximum or with Andropogon gayanus in 2006. Andropogon gayanusyielded more than Chloris gayana but had a similar yield value withSorghum almum or with Panicum maximum in the first harvest year. Cutting interval did not influence the extent of legume cover. However, the extent of grass cover was increased by 30% when the interval between cuts was increased from 4 to 8 weeks. Weed cover in the legume plots was not influenced by cutting management. However, weed cover in the grass plots was significantly depressed by 21% with increased interval of cut from 4 to 8 weeks. The dry matter percentages among the grasses and the legumes were generally increased by increasing the interval between cuts. In 2006,Stylosanthes hamata had significantly higher dry matter content among the legumes than Lablab purpureus and Stylosanthes guyanensisbut did not differ with Centrosema pascuorum. In 2007, Lablab purpureum had significantly the least percentage dry matter compared with the other legumes. Stylosathes hamata had higher percentage dry matter than Centrosema pascuorum but did not differ with Stylosanthes guyanensis. Grass dry matter content did not vary among the grass species in 2006. In 2007, Sorghum almum had higher (P<0 .05="" content="" dry="" matter="" span="" than="">Chloris gayana but had similar value with Panicum maximum or with Andropogon gayanus.
TABLE OF CONTENTS
ABSTRACT
TABLE OF CONTENTS
LIST OF TABLES
CHAPTER ONE: INTRODUCTION
CHAPTER TWO: LITERATURE REVIEW
Guinea Grass (Panicum maximum Jacq.)
Verano Stylo (Stylosanthes hamata)
Lablab (Lablab purpureus)
Centrosema pascuorum
Stylsanthes guyanensis (Cook stylo)
Sorghum almum (Columbus grass)
Rhodes grass (Chloris gayana)
Gamba grass (Andropogon gayanus)
Potentials in the use of legumes for increasing
profitability and promoting sustainability in pasture production systems
Pasture grass response to defoliation management
Pasture legume response to defoliation management
Pasture grass response to fertilizer-N application
Pasture legume response to nitrogen fertilizer application
Pasture grass x legume response to nitrogen fertilizer Application
Pasture grass x legume response to cutting frequency
Pasture grass and legume response to cutting
management x nitrogen fertilizer interaction
CHAPTER THREE: MATERIALS AND METHODS
Experimental site
Experiment 1: Effects of nitrogen fertilizer application and cutting management on the establishment, growth and yield of guinea grass (Panicum maximum)
Land preparation
Planting and Treatment Allocation
Data Collection
Experiment 2: Effects of nitrogen fertilizer application and cutting management on the establishment, growth and yield of guinea grass-verano stylo mixed swards Land preparation
Planting and Treatment Allocation
Data collection
Experiment 3: Effect of cutting frequency on the growth and yield of four selected forage legumes and four forage grasses
Statistical Analysis
CHAPTER FOUR: RESULTS
Experiment 1: Effects of nitrogen fertilizer application and cutting management on the establishment, growth and yield of guinea grass (Panicum maximum)
Experiment 2: Effects of nitrogen fertilizer application and cutting management on the establishment, growth and yield of guinea grass-verano stylo mixed swards
Experiment 3: Effect of cutting frequency on the growth and yield of four selected forage legumes and four forage grasses
CHAPTER FIVE: DISCUSSION
CHAPTER SIX: SUMMARY AND CONCLUSION
RECOMMENDATION
REFERENCES
APPENDICES
INTRODUCTION
In Nigeria, feed deficits and low quality of the available feed, particularly during 5 to 7 months of the dry season are major constraints for optimum livestock production from the savanna rangelands (Omokanye, Kalla, Alawa and Otchere, 1998). Livestock production depends closely on the availability of animal feed of high quality. Availability of high quality feed is influenced by climatic conditions, plant species and stage of maturity, soil, the level of inputs and by management (Muhammad, Hena, Agishi and Olorunju, 2002; Enoh, Kijora, Peters and Yonkeu, 2005).
Smallholder producers of ruminants, particularly cattle, sheep and goats, in Nigeria rely on unimproved natural pasture as the main feed source, backed up with crop residues after harvest (Bamikole, Akinsoyinu, Ezenwa, Babayemi, Akinlade and Adewumi, 2004). The animals in consequence grow slowly, produce little milk and reproduce at long intervals. This problem of inadequate feeding stuff is further aggravated particularly in the dry season when grassland productivity is low (Oloyo and IIelaboye, 2002). The present poor production potential of pastures could be attributed to poor soil fertility and to poor management (Dev, 2001).
Most pastures in Nigeria lack proper management because of poor defoliation frequency and lack of proper fertilization. Pastures are often subjected to burning and extreme grazing which have been shown to result in serious deterioration of herbage (Dev, 2001). It has been noticed that economic factors make a viable commercial livestock industry imperative, needing the establishment of suitable sown pasture and feed lots to meet the higher nutritional needs of more productive animals (Bamikole et al., 2004). Increments in fodder production can be achieved by expansion of land areas under natural pastures or by increasing yields per unit land area. With the present trend of competitive land use, increasing forage production through expansion of land area of natural pasture is hardly feasible as a result of the demographic changes (Muhammad and Abubakar, 2004). In the emerging shift in animal management systems towards confinement because of the pressure on land, a strategic forage harvesting and management system suitable for confined ruminant livestock and which will guarantee a regular supply of high-quality forages to these livestock is required (Bamikole et al., 2004). Improvement of feed availability for the future requires development of sown pastures that are to be sustained under intensive systems of management. Intensive production system involves the use of
and Sorghum almum (Agishi, 1979). The legumes, which include;Stylosanthes guyanensis, Lablab purpureus, Stylosanthes hamata andCentrosema spp have proved very valuable (Onifade and Agishi, 1988).
In the tropics, supply of herbage for livestock during the dry months of the year declines substantially (Omaliko, 1983; Oloyo and IIelaboye, 2002). Enough herbage must be produced during the production period through intensive management techniques in order to make possible conservation for the lean season or off-season periods. Intensive management practices include the use of fertilizers, choice of forage species, cutting management, control of bushes and weeds and pasture establishment (Omaliko, 1983; Dev, 2001). Attempts at enhancing the nutritive quality of the forage, particularly nitrogen component have been through the use of nitrogen fertilizer or inclusion of legumes in mixtures (Bamikole, 2003) The use of adapted, improved and high yielding pasture legumes as sole crop or in mixture with grasses is one of the ways of achieving availability of good quality forage (Omokanye, Kalla, Alawa and Otchere, 1998). It is generally accepted that grasses normally have a competitive advantage over legumes (Wong and Wilson, 2005); however, pasture management techniques such as fertilization and defoliation management, are utilized in order to secure a desirable balance (Rhodes and Stern, 1978; Keftasa, 1996).
Intensive management practices require many inputs, which are not commonly used in natural grassland livestock production system. To be more readily adoptable and acceptable to the resource poor farmers, the system must not be capital intensive and must not require unduly sophisticated technology (Omaliko, 1983). The method of establishment of a pasture should be cost effective and with minimum soil working (Dev, 2001). Some knowledge of the effects of management, such as fertilization and cutting regimes on aspects of pasture establishment, growth and productivity could help to make many tropical pastures more productive and efficient for animal production.....
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