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Figure 1.3 Two row alley farming on the contour near Trayning WA. Rainfall (considered in isolation) is not always a limiting factor in determining whether a site is suitable for mallees. Moisture availability, both surface and subsurface, which a mallee has access to over its lifespan to continue to survive and grow, is critical. As the mallee grows, its reliance upon surface moisture reduces as it accesses groundwater. In their natural environment, mallees occur in low to medium rainfall zones, generally 250 – 600mm. Mallees can be planted on a range of soil types, ranging from sandy clays through clay loams to heavy clays. The soil type identified will assist in the selecting the species to be planted on the site. Mallees will tolerate saline soil conditions up to 100 mS/m. Higher salinity levels (up to 200 mS/m) will have an effect on biomass production and the final commercial yield of a mallee crop. It is possible, however, that when growing mallees for environmental purposes, adequate growth rates will be achieved and sustained at these higher salinity levels. Sugar system Commercial cultivation of sugar cane is largely confined to the tropics. Outside the tropics the growth of the crop is limited by frost incidence; thus the southern limit of cane growing in Australia is the Clarence River in northern New South Wales. For good growth, sugar cane needs at least 1100 mm of rain (or irrigation) per year, warm sunny weather, freedom from frost and deep, well-drained soil. Fine, cool weather immediately before harvesting retards plant growth and increases the sugar content. Sugar cane is a versatile crop and will grow satisfactorily on a wide range of soils. Good drainage is essential. Surface levelling and underground drainage to eliminate waterlogging are recommended practices; research has demonstrated economic yield increases from improved drainage and reduced water-tables in sugar- growing areas. 9
1.1.4 Growth Cycle Mallee System Mallees have an initial phase of growth which may be described as a sapling stage, leading to the first harvest. From then on the crop can be repeatedly harvested as it regenerates readily from the lignotuber, which is a modified underground stem. In old mallee stands in Victoria and NSW, mallees have been harvested repeatedly on short cycles (typically one to two years) for many decades. In the industry model promoted in WA, where harvest intervals will be much longer (up to ten years) there will be some mortality but as there has not been any sustained harvesting of mallees in this system, it is not known how long a stand of mallees will persist, or how effectively the survivors will compensate for losses (by utilising the resources previously used by dead individuals) over several decades. The issue or mortality is covered further in section 1.1.5 below. The time between harvests varies mostly with available soil moisture and rainfall; growth on 19 widely dispersed trial sites in WA, measuring both unharvested mallee growth and growth of three and four year old coppice has recently been published by Peck et al (2011). Applying the estimation that harvesting efficiency demands at least 20 green tonnes of biomass per kilometre of row, the time to first harvest and between subsequent coppice harvests will range from four to ten years. Some poor sites may take longer and perhaps should be considered unsuitable for mallee cropping. Harvesting may also need to take into account the land use adjacent to the mallees at harvest, and it may be preferable to avoid harvesting the mallees at a time when high return annual crops in the adjacent alleys are in the latter half of their growing season. The complexity of harvest scheduling makes coordinated regional harvest planning essential to give markets certainty of consistent supply. However the mallees will not deteriorate in quality if left another season or two, provided the largest individual plants do not grow beyond the capacity of the harvester. Table 1.2 The changing harvest cycle length due to configuration and climatic conditions Sugar system The current sugar production system consists of the plant crop and three or more ratoons that are driven by the incidents of disease and weeds. The crops in the warmer growing regions (all of Qld) are harvested every year (weather permitting) with a greater proportion of standover crops predominating in the cooler areas of Northern NSW. A legume crop or other small crops may be grown in the fallow period between plough-out and replanting, or to break the monoculture. 10
- Page 1 and 2: Sustainable Biomass Supply Chain fo
- Page 3 and 4: Foreword This report provides an as
- Page 5 and 6: include business development (new p
- Page 7 and 8: Acknowledgments The authors would l
- Page 9 and 10: 4.1 Product Options and Supply Chai
- Page 11 and 12: Table 4.2 Assessment of current val
- Page 13 and 14: Figure 3.4 Tracked rigid self-prope
- Page 15 and 16: Executive Summary What the report i
- Page 17 and 18: • Biomass production potential of
- Page 19 and 20: • As the Industry expands, the mo
- Page 21 and 22: Harvesting, transport and storage s
- Page 23 and 24: Biomass processing, supply chain pl
- Page 25 and 26: Key barriers to biomass industries
- Page 27 and 28: Crop-Biomass Production Production
- Page 29 and 30: Figure 1.1 The cropping and pasture
- Page 31: Table 1.1 Mallee species used for p
- Page 35 and 36: northern New South Wales (where it
- Page 37 and 38: Almost 80% of the industry now cuts
- Page 39 and 40: Bark has relatively high ash but as
- Page 41 and 42: Carbon sinks Planting of mallees to
- Page 43 and 44: Table 1.5(a) State Land area devote
- Page 45 and 46: out the fluctuations in farm income
- Page 47 and 48: Mallee system Most of the mallee bi
- Page 49 and 50: inconclusive result may have been d
- Page 51 and 52: For a sustainable woody crop indust
- Page 53 and 54: changed significantly since they we
- Page 55 and 56: Figure 2.2 Biosystems Engineering p
- Page 57 and 58: Whole-of-crop harvesting represents
- Page 59 and 60: During the last decade the harvesti
- Page 61 and 62: single row, as this would improve t
- Page 63 and 64: 2.2.2.2 Weight Sugar System The Aus
- Page 65 and 66: Table 2.1 Harvester Comparison Tabl
- Page 67 and 68: The quality of cut may be less impo
- Page 69 and 70: ate than a 170 tonne/ha crop of sta
- Page 71 and 72: Dry Leaf 6.1 - 3.5 17.0 58.9 53.2 T
- Page 73 and 74: Bulk density will be a key consider
- Page 75 and 76: Table 2.4 EM levels in cane supply
- Page 77 and 78: L/T L/T 60 0.97 0.71 80 0.92 0.66 1
- Page 79 and 80: Total 7.5-26 16.5 Mallee System The
- Page 81 and 82: • waiting for mill delivery of em
Figure 1.3 Two row alley farming on the contour near Trayning WA.<br />
Rainfall (considered in isolation) is not always a limiting factor in determining whether a site is<br />
suitable for mallees. Moisture availability, both surface and subsurface, which a mallee has access to<br />
over its lifespan to continue to survive and grow, is critical. As the mallee grows, its reliance upon<br />
surface moisture reduces as it accesses groundwater. In their natural environment, mallees occur in<br />
low to medium rainfall zones, generally 250 – 600mm.<br />
Mallees can be planted on a range <strong>of</strong> soil types, ranging from sandy clays through clay loams to<br />
heavy clays. The soil type identified will assist in the selecting the species to be planted on the site.<br />
Mallees will tolerate saline soil conditions up to 100 mS/m. Higher salinity levels (up to 200 mS/m)<br />
will have an effect on biomass production and the final commercial yield <strong>of</strong> a mallee crop. It is<br />
possible, however, that when growing mallees for environmental purposes, adequate growth rates<br />
will be achieved and sustained at these higher salinity levels.<br />
Sugar system<br />
Commercial cultivation <strong>of</strong> sugar cane is largely confined to the tropics. Outside the tropics the<br />
growth <strong>of</strong> the crop is limited by frost incidence; thus the southern limit <strong>of</strong> cane growing in Australia<br />
is the Clarence River in northern New South Wales.<br />
For good growth, sugar cane needs at least 1100 mm <strong>of</strong> rain (or irrigation) per year, warm sunny<br />
weather, freedom from frost and deep, well-drained soil. Fine, cool weather immediately before<br />
harvesting retards plant growth and increases the sugar content.<br />
Sugar cane is a versatile crop and will grow satisfactorily on a wide range <strong>of</strong> soils. Good drainage is<br />
essential. Surface levelling and underground drainage to eliminate waterlogging are recommended<br />
practices; research has demonstrated economic yield increases from improved drainage and reduced<br />
water-tables in sugar- growing areas.<br />
9
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