for about of 16% in plant cane and 26% in ratoon. When trash is burned, the nitrogen is lost as nitrous oxide (No), Burned cane equals loss of soil N at an average of 44 kg N/ha/yr. Some of the P and K can also be lost through burning (Cook 1994). In trash farming, P uptake appears more efficient as the mulch protects the soil from desiccation and permits root proliferation in the soil surface where P levels are high. Mulching permits a ดgreater recycling of P from residues than burning, and Ball -Coelho et al (1993) suggest that lower P fertilization rates could be used to maintain productivity on sites where burning is practiced. Trash farming not only helps conserve organic matter in the soil during the in decomposition process but encourages N fixation in the sugarcane litter. Hill & Patriquin (1990) described a highly active system involving a microaerophilic Non fixing Azospirillum brasilense and a dematiaceous fungus Paecilomyces roseus. In Brazilian cane varieties, high yields
The effects of mulching on soil fertility have been studied in research stations and on-farm field trials in Vietnam (Mui et al 1997a, Mui ct al 1996). During a three year experiment, it was consistently shown that mulched fields had higher percentages of carbon, phosphorus,is even more evident in long term trash mulched fields with higher soil organic matter levels and a permanent surface mulch cover.
sin Northern Australia) N/ha are used in most non-trash farming cane producing countries such as Cuba, Peru, India and the United States (Boddey 1995) Soil properti Trash farming improves soil properties. Upon decomposition, sugarcane trash (as organic matter) is transformed into a stable product called humus, which is of agro-ecological importance (Tablc 2). Also, Hodge (1998) pointed to the importance of organic matter for long-term sustainability of agriculture. Conserved as mulch, sugarcane trash decomposes into humus improving soil tilth, and decreasing tillage required. By increasing water infiltration into the soil, water retention is improved, thereby decreasing the need for irrigation. Trash mulched canes can tolerate the normal dry season and El Nino events better than ratoon crops in burned cane fields, which have no trash mulch cover This effect
trash ratoon farming was done. Trash ratoon farming was found to be more financially beneficial than conventional ratoon farming (Table 3). ere trash farming was implemented, net returns increased by 43% in the first ratoon crop, with a net improvement in return over the years of p 7740. The trash farmed ratoon crop achieved the lowest cost (p 508/t). It was 31% below the cost of the conventional plant crop and l below the