Evaluation on the fertilization of sugarcane in the main ecological areas of Yunnan Province

Objectives Yunnan Province is the second largest production base for sugarcane and sugar in China. Investigation of current nutrient inputs and problems in different sugarcane production regions is of great significance for increasing sugarcane yield and quality, generating farmers’ income and promoting sustainable development of sugarcane industry in Yunnan.

Methods About 1350 households (samples) in 24 counties were interviewed from 2013 to 2014. The sugarcane yields, fertilization habits, types and applying methods were acquired through the questionnaire survey. Nutrient inputs were calculated from the actual fertilizer inputs and the labeled nutrient contents on the product packages.

Results From the literature, the recommended fertilizer amounts should be N 285–350 kg/hm², P₂O₅ 200–250 kg/hm² and K₂O 175–225 kg/hm², with a reasonable N∶P₂O₅∶K₂O ratio of 1∶0.7∶0.6 when the yields of sugarcane were in the range of 85.00–90.00 t/hm². The actual surveys showed that the average sugarcane yields varied significantly among the production areas, the highest level of 81.40 t/hm² was in the South subtropical humid regions (SSHR), and the media level of 81.73 t/hm² was in the middle subtropical humid regions (MSHR) and lowest yield level of 75.44 t/hm² in the north tropic semi-humid region (NTSHR). About 99.71% of sugarcane farmers applied base fertilizers in SSHR, while 94.17% and 93.94% sugarcane farmers in MSHR and NTSHR applied both basal and top-dressing fertilizers. The mainly used chemical fertilizers were urea, ordinary superphosphate and compound fertilizers. Compound fertilizers were so popular that 94.13% of the farmers choose to use. The organic fertilizers was not commonly applied and the mainly organic nutrient sources were merely from filtrated mud, alcoholic waste water and the returning of sugarcane-leaves. Fertilizer inputs of N, P₂O₅ and K₂O were 193.67 kg/hm², 116.79 kg/hm² and 95.86 kg/hm². The highest fertilizer nutrient input in all the surveyed regions in Yunnan was nitrogen, and then was phosphous and potassium. For the application of fertilizers once basal application and twice application of basal plus topdressing are the two mine ways. The fertilizers were mainly applied in drills and holes. However, the top dressed fertilizers were rarely covered with earth, as high as 82.53% of investigated sugarcane farmer did like this in the SSHR.

Conclusions Phenomenon of taking to additional fertilizers, despises to base fertilizers; taking to chemical fertilizers, despises to organic fertilizers and taking to nitrogenous fertilizers, despises to potash fertilizers was ubiquity in different ecological conditions in Yunnan. Fertilizers were used without earthing in most of sugarcane regions. Extension work should be strengthened in the basal plus topdressing of fertilizers and the appropriate organic fertilizer input. The nitrogen and phosphorous input ratio should be balanced in some regions, and the potassium input should be increased in all the regions. Top-dressing of fertilizer in deep should become compulsive to improve efficiencies of fertilizer usage.