The Effects of Cane Trash on Yield and Nutrition from the Long-term Field Trial at Mount Edgecombe

This paper reports on the yield and nutritional trends over 61 years as affected by various treatments (trashed, burnt with tops either left or removed and all plots either fertilised or not fertilised) of the burning and trashing trial (BT1) at Mount Edgecombe. The overall mean residual yield benefit due to trashing was 9.3 tc/ha/an after 39 crops. The capacity of the Arcadia soil form (Vertisol) to sustain yields without fertiliser was 18 years or 8 crops. The fertilised trashed treatment produced 20 tons trash per hectare (variety N16), which contained about 150 kg N/ha, 20 kg P/ha and 260 kg K/ha. Trash from the green cane harvesting treatment with fertiliser was insufficient to prevent a decrease in soil organic matter. However, soil organic matter loss was greater for treatments where cane was burnt. The N and K released from cane trash contributed to the higher yields from the trashed treatments when compared with the burnt treatments. The fertilised treatments significantly increased soil acidification when compared with the non-fertilised treatments and trash from the green cane treatments also contributed to soil acidity. Only the fertilised treatments, whether trashed or burnt, showed a positive yield response to rainfall.