Green cane trash blanket
Australia - Trash blanket
left: Harvesting of green sugar cane and simultaneous spreading of the separated residues, leaving a dense mulch cover, the so called green cane trash blanket. (Photo: Hanspeter Liniger)
right: A ‘ratoon’: a re-growing sugar cane sprouts through the trash blanket after harvest. (Photo: Hanspeter Liniger)


Elimination of burning as a pre-harvest treatment of sugar cane, and managing the resultant trash as a protective blanket to give multiple on and off-site benefits.

Under conventional production systems, sugar cane is burnt before being harvested. This reduces the volume of trash - comprising green leaves, dead leaves and top growth - making harvesting of the cane simpler, and subsequent cultivation of the soil easier. In the humid tropics of North Queensland, harvesting of cane used to be carried out by hand - as it still is in many parts of the developing tropics. Burning was necessary to make harvesting possible in a dense stand (and to reduce the danger of snakes). However, with the advent of mechanical harvesters in the 1960s, burning continued to be practiced through habit. A new system then brought fundamental changes in soil management: The ‘green cane trash blanket’ (GCTB) technology refers to the practice of harvesting non-burnt cane, and trash blown out behind in rows by the sugar cane harvester. This trash forms a more or less complete blanket over the field. The harvested lines of cane re-grow (‘ratoon’) through this surface cover, and the next year the cycle is repeated: the cane is once again harvested and more trash accumulates in the inter-rows. Generally the basic cropping cycle is the same, whether cane is burnt or not. This involves planting of new cane stock (cuttings or ‘billets’) in the first year, harvesting this ‘plant crop’ in the second year, and then in years three, four, five and six taking successive ‘ratoon’ harvests. In year six, after harvest, it is still common, even under the GCTB system, to burn the residual trash so that the old cane stools can be more easily ploughed out, and the ground ‘worked up’ (cultivated) ready for replanting. A minority of planters, however, are doing away with burning altogether, and ploughing in the residual trash before replanting. A further variation is not to plough out and replant after the harvest in year six, but to spray the old cane stock with glysophate (a broad spectrum non-selective systemic herbicide) to kill it, then to plant a legume (typically soy bean) as a green manure crop, and only replant the subsequent year after ploughing-in the legume. Under this latter system, one year of harvest is lost, but there are added benefits to the structure and nutrient content of the soil. Whatever variation of GCTB is used, there are advantages in terms of increased organic matter, improved soil structure, more biodiversity (especially below ground) and a marked reduction in surface erosion - from over 50 t/ha to around 5 t/ha on average. Less erosion is good for the growers - but is also of crucial importance off-site, as sediment lost from the coastal sugar cane strip is washed out to sea, and damages the growing coral of the Great Barrier Reef.
Location: North Queensland, Australia
Region: Ingham
Technology area: 800 km2
Conservation measure: agronomic
Stage of intervention: mitigation / reduction of land degradation
Origin: Developed through land user`s initiative,
Land use type:
Cropland: Perennial (non-woody) cropping
Climate: humid, tropics
WOCAT database reference: T_AUS003en
Related approach: The ‘triple bottom line’ (AUS03)
Compiled by: Anthony J. Webster, CSIRO
Date: 2005-09-01



Classification
Land use problems:
- Conventional burning of sugar cane before harvest can lead to compaction of top soil and reduced organic matter. There is also, despite the low slopes, a serious problem of sheet/rill erosion that has a negative impact both on the fields, and also off-site on the coral reef. (expert's point of view)
- soil erosion, weeds, flooding (land user's point of view)


Land useClimateDegradationConservation measure
Land use Humid
Perennial (non-woody) cropping
rainfed
humid
Soil erosion by water: loss of topsoil / surface erosion, offsite degradation effects, Chemical soil deterioration: fertility decline and reduced organic matter content
Agronomic
Stage of interventionOriginLevel of technical knowledge
   Prevention
   Mitigation / Reduction
   Rehabilitation
   Land users initiative
   Experiments / Research
   Externally introduced
   Agricultural advisor
   Land user
Main causes of land degradation:
Main technical functions:
- control of raindrop splash
- improvement of ground cover
- improvement of soil structure
- control of dispersed runoff
Secondary technical functions:
- increase in organic matter
- increase of infiltration
- increase in soil fertility
- increase in surface roughness

Environment
Natural Environment
Average annual rainfall (mm)Altitude (m a.s.l.)    LandformSlope (%)
> 4000 mm
3000-4000 mm
2000-3000 mm
1500-2000 mm
1000-1500 mm
750-1000 mm
500-750 mm
250-500 mm
< 250 mm

> 4000   
3000-4000   
2500-3000   
2000-2500   
1500-2000   
1000-1500   
500-1000   
100-500   
<100   

    plateau / plains
    ridges
    mountain slopes
    hill slopes
    footslopes
    valley floors

flat
gentle
moderate
rolling
hilly
steep
very steep

Soil depth (cm)

0-20
20-50
50-80
80-120
>120
Growing season(s): 300 days (Aug - May)
Soil texture: medium (loam)
Soil fertility: high, medium
Topsoil organic matter: low (<1%)
Soil drainage/infiltration: good

Human Environment
Cropland per household (ha)

<0.5
0.5-1
1-2
2-5
5-15
15-50
50-100
100-500
500-1,000
1,000-10,000
>10,000
Land ownership: individual, titled
Land use rights: individual
Relative level of wealth: average

Importance of off-farm income: 10-50% of all income: various off-farm enterprises undertaken to supplement income during years of poor sugar prices
Market orientation: commercial / market
Mechanization:
Livestock grazing on cropland:


blob_id=381Technical drawing

Harvester harvesting cane and depositing trash on surface (Anthony J.Webster)

Implementation activities, inputs and costs
Establishment activities

Maintenance/recurrent activitiesMaintenance/recurrent inputs and costs per ha per year
- mulching of inter-rows with trash [previously: burn cane with associated trash and then harvest]
- fertilize cane
- spray with Amicide (very efficient herbicide, systemic and non-selective)
- spray with Amicide
InputsCosts (US$)% met by land user
Agricultural  
  - fertilizer 120.00 100%
  - herbicides 33.00 100%
Other  
  - Contract harvesting 390.00 100%
TOTAL 543.00 100.00%

Remarks:

The year budgeted above is a non-planting year, the costs therefore refer to an established crop which grows throughout the year and is harvested in August. The assumption is a cane yield of 80 t/ha. Each of the three categories of costing groups machinery, labour (at US$12 per hour) and inputs together. The comparative costs for a burnt cane crop system with the same yield are (a) contract harvesting = US$ 378 (b) fertilizer = US$ 120 (c) herbicide = US$ 56, plus (d) cultivation = US$ 30. Note that under the burnt cane system, soil cultivation/tillage is required, but the cost of harvesting is a little cheaper. The total for the burnt crop system is US$ 584 compared with US$ 543 for the GCTB crop, representing a saving of approx. US$ 40 (around 7%) per hectare per year.

Assessment
Impacts of the Technology
Production and socio-economic benefitsProduction and socio-economic disadvantages
   increased farm income
Socio-cultural benefitsSocio-cultural disadvantages
   improved conservation / erosion knowledge
   enhanced reputation of sugar cane growers as 'environmentally friendly'
Ecological benefitsEcological disadvantages
   reduced surface runoff
   improved soil cover
   reduced soil loss
   increased soil organic matter / below ground C
   loss of nutrients reduced, inproved soil structure
   biodiversity enhancement (above and below ground)
   increased soil moisture
   improved excess water drainage
   increase in soil fertility
Off-site benefitsOff-site disadvantages
   reduced downstream siltation
   reduced wind transported sediments
   reduced downstream flooding
   reduced groundwater river pollution
Contribution to human well-being / livelihoods

Benefits /costs according to land user
Benefits compared with costsshort-term:long-term:
Establishmentnot specifiednot specified
Maintenance / recurrentslightly positivepositive

Acceptance / adoption:

95% of land user families have implemented the technology voluntary.
There is little trend towards (growing) spontaneous adoption of the technology. It is possible that the few growers who persist in burning will eventually adopt the GCTB system through social and environmental pressure.

Concluding statements

Strengths and how to sustain/improveWeaknesses and how to overcome
GCTB systems offer multiple on-farm environmental benefits Continue to refine the system, by encouraging (a) non burning of trash in the
Increases overall farm income by maintaining yields of sugar cane while Continue to refine the system.
GCTB systems provide protection to the coral reef, through substantially reducing the sediment yield that reaches the lagoon and thence the Great Barrier Reef Give recognition to the growers for their overall environmental contribution.
Some burning still continues through (a) the few farmers who have not yet adopted GCTB and (b) the common practice of burning trash before replanting Continue to encourage non-burning for multiple reasons.


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