Effect of planting density on leucaena leucocephala forage and Woody stems production under arid dry climate
Abstract
Lack of year round supply of forage for animal feed is common in most parts of dry lands. leucaenaleucocephala i s one of most widely used dry season tree legume forage. In this study, the effect of planting density on forage and woody stems production was investigated. Three different planting spacing corresponding to (40X40 cm, 60X60 cm and 80X80 cm) were applied t o tests its effects on tree growth and yield. Tree height and diameter were measured before every cutting harvest. In addition to that fresh and dry matter production of both stems and forage (tons/ha), stems, and leaves dry weight ratios over time were de termined. The study revealed that different planting densities were resulted in very high significant effect s on forage and stem production. Tree height was affected by planning density in most of the harvests, while diameter showed significant difference among the treatments in only one harvest. Planting trees at 40 cm distance produced higher forage yield with smaller woody stems sizes, whereas 60 and 80 cm spacing resulted in lesser forage yield, but with bigger stems size. This indicates that planting t rees at closer spacing produce higher wood and forage yield, but the wood with smaller sizes. There is also, observed seasonal variation in production in which hot weather lowered yield. The stems and leaves dry matter ratio revealed that leaves production is slightly higher than stem production and were not affected by planting density. The results conclude that planting leucaena in closer spacing in arid lands will supply a considerable amount of forage as supplementary feed in addition to wood that can b e used for different purposes.
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Introduction
Leucaena is fast growing multi-purpose drought resistance tree species (Yige et al., 2012). It is widely cultivated around the World for its highest wood production and wide ranges of uses (Arbonnier, 2004). Leucaenais classified among the most widely used forage tree legume (Shelton and Brewbaker, 1998). When pruned in a regular basis it can produce large quantities of palatable, digestible and nutritious foliage for ruminants. Under closer spacing and consecutive cuttings leucaena can yield forage of up to 40 tons dry matter/ ha (Wilkins, 2000). Supplementing animal fed with dried leucaena leaves will lead to higher weight gain (Rubanza et al., 2007). The leaves meal also, when combined with cassava base supplement enhanced feed intake, nutrient digestibility and rumen fermentation (Kang et al., 2012). It is believed that the presence of amino acid mimosine in the foliage may affect fodder quality (Ilham et al., 2015). However, ruminants rarely have problems with mimosine, because microbes in first stomach (rumen) alter mimosine to a 3,4-dihydroxy pyridine which is then broken down further into nontoxic compounds (Chaudhary and Al-Jowaid, 1999). Where the wood produced from leucaena have very high feasibility for many wood industrial products (Feria et al., 2011; hindi et al., 2010). The seeds are potential fermentable growth source for production of extracellular lipase enzyme (Singh et al., 2014). The seeds also, contain high properties galactomannan soluble polysaccharide (Nwokocha and Williams 2012). Further roles of the species as multiple purpose trees is a good candidate for sustainable animal farming system by increasing livestock live gain and in the same time reducing greenhouse gas emissions (Harrison et al., 2015).The tree was used as agroforestry tree in many countries, in windbreaks, shade and roadside (Debra and Justin, 2013; Elfeel et al., 2013).
Normally under dry land conditions, there is shortage of year round forage for livestock. Dried leucaena is used during the dry season as conserved hay for feeding dairy cows (Maasdorp et al., 1999). The objective of this study is to investigate the effect of planting density on forage and woody stem production. The aim is to determine best planting spacing that produce large amount of forage in the same time the remaining woody material can be used as fuel or other industrial purposes.
Conclusion
The current study highlights the importance of planting leucaena in closer spacing to provide a good quantity of forage and the remaining woody stems can be utilized for any other wood industrial purposes. Planting trees at 40X40 cm spacing produced higher forage and stem yield, however, the stems with smaller sizes. Whereas 60 spacing obtained lesser yie ld but the stems with bigger sizes. The leaves dry matter ratio is slightly higher than stems dry matter ratio and were not affected by planting density treatments.