Research was conducted to evaluate the residual effect of burning and mechanical removal of sugarcane crop residue on weed control and sugarcane growth and yield. In one study, crop residue was removed in December or January within 3 wk after sugarcane harvest. Mechanical removal of residue from the row top and placement in the row middle using a Sunco Trash Tiger® was compared with burning and a no removal control. Superimposed on each residue removal treatment was tillage of row sides and middles in March and in May and a no-tillage program. Tillage efficiency in March when sugarcane was emerging from the winter dormant period was not negatively affected when residue was removed mechanically. Crop residue on the soil surface did not completely suppress winter weed emergence and growth. Based on sugarcane and sugar yield averaged across locations and tillage programs, mechanical removal of residue was as effective as burning. Sugar yield was reduced 7.9% when residue was not removed from the row top compared with burning or mechanical removal. In another study, crop residue of sugarcane harvested in early December was burned or removed mechanically from the row top 4 d after harvest and also mechanically in January, February, or March. Crop residue ground cover of 79% in March on the row top where residue was not removed provided some suppression of winter weeds. Sugarcane shoot population in April was reduced 16.1% when residue removal was delayed until March compared with December. Averaged across tillage and no-tillage treatments in March, sugarcane yield did not differ when residue was removed by burning in December compared with mechanical removal in December or January. Delaying mechanical removal of residue until February or March compared with residue removal in December decreased sugar yield an average of 13.1%.

Tillage is used in sugarcane to control weeds, eliminate ruts caused by harvest, destroy residue from the previous crop, and incorporate fertilizer. The effect of weed control and tillage programs on sugarcane growth and yield and on economics was evaluated over two growing seasons. In the first study, weeds were effectively controlled with a March application of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kg ai/ha either banded or broadcast. When tillage of row shoulders and middles in March was eliminated, soil temperature in the sugarcane drill early in the season was equal to that where March tillage was performed. Sugarcane early and late season stalk population and sugarcane and sugar yield were each equivalent for the full season tillage (tillage of row shoulders and middles in March and in May) and the no-till programs. Elimination of a single tillage operation reduced cost $16.28/ha, and herbicide applied as a band rather than broadcast reduced cost $30.49/ ha. For the no-till program, with herbicide banded in March, net return was increased $32.56/ha. In a subsequent study conducted at five locations, weed control was excellent when either pendimethalin at 2.77 kg ai/ha plus metribuzin at 1.26 kg ai/ha or hexazinone plus diuron at 0.59 kg/ha and 2.10 kg/ha was used. When the March tillage was eliminated, sugar yield was increased 8.6% (620 kg/ ha), and net return was increased $152.68/ha compared with March tillage. When the May tillage was eliminated sugar yield was increased 8% (580 kg/ha), and net return was increased $143.88/ha compared with May tillage. A reduction in tillage cost accounted for only $16.28 of the increase in net return per hectare, with the remainder due to increased yield with the elimination of the tillage operation.

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