WBC-VIII-Vol.4 – Resources – Forestry, Plantations and ... - BambuSC

Shoot harvests represent a smaller nutrient sink than culm harvests. For example, nutrients removed in fresh
shoots (on average 16 t/ha/year yield; 5-10% dry weight; 4.0, 0.6, and 4.0% N, P, and K) average at 49, 7, and
49 kg N, P, and K/ha/year. In stands managed for optimal shoot production a significant amount of biomass and
nutrients are removed in shoot and culm harvests – about 85, 16, and 112 kg N, P and K/ha/year are removed
when bamboo is grown for average shoot and timber yields Kleinhenz and Midmore 2001). Shoot yields
reported to reach 40 t/ha per year (Pan 1986) would considerably increase the demand for nutrients.
A series of field experiments have been conducted in Australia and the Philippines (Midmore et al. 1998;
Midmore and Kleinhenz 2000; Kleinhenz and Midmore 2001, 2002) and more recently (Midmore 2009a). In the
latter, best practice was imposed as a ‘control’ treatment, and then in other treatments omitting one or other
practice (for example, omit fertiliser and/or irrigation, omit the thinning regime) to study the impacts upon shoot
and culm (pole) production. The following section draws heavily on the outcomes of the series of experiments
conducted under project activities funded by the Australian Centre for International Agricultural Research, and
published recently by Midmore (2009a).
Appropriate management practices for sustainable shoot production
Although a group of species with a long association with Asian cultures, bamboo in Australia was originally
planted starting in the 1990s with a view to producing bamboo shoots to offset the importation of canned
produce (Midmore 1998), and later to expand into rewarding export markets identified in Asia (Collins and
Keiler 2005). In contrast, in the Philippines, bamboo is harvested mainly as a timber substitute, with only
localised cultivation and use of shoots as a vegetable—indeed local ordinances often prohibit shoot harvests
(Virtucio and Roxas 2003). In other Asian countries it is valued not only for timber, but also for fresh shoots
especially in the hot summer monsoon season when other vegetable species are in short supply.
Management factors that influence shoot production (Kleinhenz and Midmore 2001 and many of the >200 cited
references contained therein) fall mainly under irrigation, fertiliser, mulch and thinning regimes. Species has an
overriding effect on shoot size, number and timing of production and some tentative conclusions are drawn from
the experimental data published by Midmore (2009a).
Irrigation and rainfall
Supply of water to bamboo just before and during the shoot season has been recognised as an enhancing factor
for the onset and continued production of shoots from running (monopodial, e.g. Physostachys pubescens)
species of bamboo (Kleinhenz et al. 2003), and data from more recently reported experiments (Zhu et al. 2009;
Malab et al. 2009) and others (e.g., Thanarak 1996) confirm this for clumping (sympodial) bamboo species.
For example, in the Philippines, at the two sites where irrigation was an experimental factor (Ilocos Norte and
Capiz), irrigation increased the number of emerged shoots,; the effect was greatest if combined with fertiliser
application (Malab et al. 2009; Marquez 2009). In an Australian site in Queensland (Zhu et al. 2009), a
treatment of withholding irrigation was confounded by a complete absence of clump management and the
combined effect of which was to significantly reduce the number and size of shoots that emerged. However, the
VIII World Bamboo Congress Proceedings Vol 4-72