| The main factors that have adverse impact on cane yield and nutrients use efficiency in sugarcane-planting areas of China are excessive fertilizer application and lack of appropriate fertilization control at the middle and late growth stages. To address these issues, a series of field experiments, which included evaluation of different sugarcane genotypes,"3414’experiment of NPK, formula fertilizer, nutrient regulation for high yield and high efficiency, and application of slow release fertilizer were conducted in Guangdong province. The dry matter and NPK accumulation characteristics of different genotypes were identified. A nutrient application system for sugarcane areas in western Guangdong province was set up. Formula fertilizer designed exclusively for sugarcane was tested in the field. The cultivation techniques for high nutrients efficiency were further optimized and demonstrated.The main results were concluded as follows:1. The dry matter and nutrient accumulation were significantly different among genotypes at various stages. A larger proportion of dry matter was accumulated at the elongation stage. The percentages of dry matter were7.5%,15.5%,29.7%and47.3%at the germination stage, tillering stage, early elongation stage and late elongation stage, respectively. Accumulation of N/P/K increased with the advance of growth, even at a faster pace since the tillering stage with the percentage surpassing50%at the elongation stage. Sugarcane cultivation for high yield required1.72kg of N,0.42kg of P and4.09kg of K on average for producing one ton of millable cane.2.’3414’ experiments at52locations were conducted under different soil fertility levels in western Guangdong province, and appropriate N/P/K rates were recommended accordingly. In another word, the soil alkaline hydrolysis nitrogen, available phosphorus and available potassium were classified into five ratings (the lowest, lower, medium, higher, the highest) with75%,85%,90%and95%of the relative yield as a critical value.200～390kg/ha of N,80～280kg/ha of P2O5and100～380kg/ha of K2O were recommended in this region, while minor adjustments were needed according to different levels of soil fertility, relative yield and target yield.3. Formula of fertilizer specifically for sugarcane was designed according to sugarcane nutrient absorption characteristic, soil conditions and target yield, i.e., formulas for both the base and the top-dressing fertilizer were12-20-13and25-10-16. Furthermore, the elements of silicon, magnesium and sulfur were necessarily added and the formula was optimized.345kg/ha of N,195kg/ha of P2O5and240kg/ha of K2O were required for producing100t/ha of cane yield. The field experiments indicated that application of formula fertilizer was more favorable for the dry matter accumulation of sugarcane than farmer habitual fertilization. The cane yield under optimized fertilizer application was11.5%higher, cost of fertilizers19.2%lower and profit11.5%higher, compared to farmers.4. Potential of high yield and high efficiency could be further exploited through sowing more seedcanes, plastic film mulching and irrigating. The experiment results showed that the cane yields with treatments of "high-yield and high-efficiency’ and ’further high-yield and high-efficiency’, compared to farmers, were10.0%and16.1%higher,12.9%and16.5%of sucrose content were higher and10.0%and16.1%of profit were higher, respectively.5. Application of slow release fertilizer could make it possible to reduce nitrogen and simplify fertilization. The experiment results showed that the cane yield with application of an equal amount of slow release fertilizer increased11%compared to the traditional fertilizer treatment. The similar cane yield was obtained from both the traditional fertilizer treatment and the reducing20%nutrients with slow release fertilizer. Also labor could be saved due to one less fertilizer application. What’s more, nitrogen use efficiency was enhanced from31.4%to40.4%. |
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