Soil temperature in a sugar-cane crop as a function of the management system

Air and soil temperatures are, by far, the most important state variables o f agroecosystems. In the case of sugar-cane (Saccharum officinarum L.) they affect plant development, maturation and a series of biological and physic al-chemical soil processes. This paper presents a comparative study of thre e management practices, applied to the first ratoon of a sugar-cane crop es tablished on a Rhodic Kandiudox (Terra Roxa Estruturada) of Piracicaba, SP, Brazil. The management practices are: (i) interrow with bare soil; (ii) tr ash mulching, maintaining harvest residues (straw+tips) on the soil; (iii) soil with residues from burning the prior crop. Soil temperature was measur ed with digital stick thermometers driven into the soil down to the depths of 0.03, 0.06 and 0.09 m, meter by meter, close to the crop row, along an 8 4-point transect that covered all treatments and borders. The measurements were performed from November 1998 (right after the first harvest of the pla nted cane) to June 1999. The effects of the treatments on soil temperature were, evidently, more prominent in the period November/February when the pl ants had a smaller height, not closing interrows. Data that were collected on typical days, chosen along the development cycle of the crop, always fro m 11:00 to 12:00 a.m., show significant differences, mainly between mulched and non mulched treatments, reaching values as high as 7 degreesC for the average of the three depths. A comparative analysis is made between treatme nts and their effects are discussed in relation to the sugar-cane crop.