Traditionally, sugarcane has been burned prior to harvest in order to eliminate leafy non-
sucrose containing material so that it does not have to be transported and milled. This burn,
while quick, efficient and relatively clean in terms of air quality effects, has caused concern
regarding the impact of smoke and ash on adjacent urban areas. In the past, harvesting
equipment was not very efficient in removing the leaves from the stalks and leaving this dry
mater in the field. Until recently green harvesting was not a practical alternative for South Texas
(Rozeff 1993). However, modern harvesters can separate trash from the millable cane much
more efficiently. Approximately 25% of the sugarcane crop in the Lower Rio Grande Valley of
Texas is currently harvested green. Now the challenge is how to manage the trash and what
impact this residue left in the field will have on the soil and on subsequent crops.
Retention of sugarcane residue in the field potentially has several effects both positive
and negative. Burning can be detrimental to soil structure and nutrient availability due to the
loss of soil organic matter. Retention of unburned residues can increase nutrient conservation,
reduce weed growth, and conserve soil moisture. Substantial losses of C and N due to sugarcane
residue burning have been reported (Ball-Coelho et al. 1993). However, the retained mulch
makes tillage operations more difficult, interferes with fertilizer and herbicide applications and
can immobilize N and P (Ng Kee Kwong et al. 1987). Extracts from sugarcane postharvest
residue were found to increase bud germination at low concentrations, but delayed early leaf
development at high concentrations on a subsequent sugarcane crop (Viator et al. 2006). Furrow
irrigation is more difficult when residues remain on the soil surface. Fire may play a role in
controlling insect populations and diseases.