Fertilizer Requirements of Sugarcane in China and High-Yield Fertilization Techniques and Timing

Fertilizer requirements of sugarcane in China and high-yield fertilization techniques and timing:Sugarcane has high yield and high fertilizer demand. According to measurements from various regions, for every 100 kg of millable cane produced, an average of 1.7-2.1 kg of nitrogen, 0.4-0.6 kg of phosphorus, and 2.0-2.7 kg of potassium is absorbed. Due to changes in the growth center at different growth stages of sugarcane, the amount and ratio of nutrient absorption also vary.

During the germination stage of sugarcane, the nutrients required mainly come from the nutrients stored in the seed cane itself, with no need to absorb nutrients from the outside. Until the seedling stage, as new roots and leaves continue to develop, it begins to absorb a small amount of nutrients from the soil, with the absorbed nitrogen, phosphorus, and potassium accounting for 3%, 1%, and 3% of the total absorption respectively. During the tillering stage, sugarcane continuously produces tillers, and nutrient absorption increases, with nitrogen, phosphorus, and potassium absorption accounting for 12%, 14%, and 17% of the total absorption respectively. Entering the growing stage, as the shoot tip, leaves, and root system proliferate and continuously renew, and the stem cane grows rapidly, the absorption of nitrogen, phosphorus, and potassium increases significantly, reaching 55%, 65%, and 65% of the total absorption respectively. The beginning of the growing stage is the period of maximum nutrient efficiency for sugarcane and also the critical period for fertilization. By the industrialmaturity stage, sugarcane growth gradually slows or stops, and fertilizer demand decreases, but nitrogen, phosphorus, and potassium absorption still accounts for 30%, 25%, and 15% of the total absorption respectively, to supply the metabolic needs of various plant parts and further accumulation of sucrose.

To meet the nutrient requirements of sugarcane, the fertilization measures that can be adopted are:

① Base fertilizer. Sugarcane not only has a high fertilizer demand but is also relatively tolerant of fertilizer. Sufficient base fertilizer can promote well-developed roots, rapid germination, and strong tillering, laying a good foundation for later growth. The base fertilizer rate is generally 2-3 tonnes of organic fertilizer, 3-5 kg of urea, 5-20 kg of superphosphate, and 5-8 kg of potassium fertilizer (potassium sulfate is preferable) per 667 sq m. If conditions permit, an additional 20-30 kg of oil cake can be applied. The base fertilizer should be applied in the planting furrow at planting time;

② Seedling fertilizer and tillering fertilizer. To promote early and rapid tillering of sugarcane, apply seedling-promoting fertilizer early and apply tillering fertilizer steadily. The seedling-promoting fertilizer is applied when seedlings are basically complete and have 3-4 leaves, with 3-4 kg of urea per 667 sq m, combined with 10 kg of phosphate fertilizer and 50-100 kg of plant ash. The amount and frequency of tillering fertilizer should be determined according to actual conditions. If the base fertilizer and seedling-promoting fertilizer are sufficient and the sugarcane seedlings are sturdy, it can be applied all at once at the peak tillering stage, and the rate should be reduced; conversely, if the seedlings are weak, the fertilizer rate should be increased and applied in two split applications. One application at the beginning of tillering to promote tillering is called tillering-promoting fertilizer; one application at the peak tillering stage to maintain strong tillers is called strong-tiller fertilizer. Generally, tillering fertilizer uses 1.5-2 tonnes of human and animal manure and 5-7 kg of urea per 667 sq m;

③ Stem-promoting fertilizer. When sugarcane enters the jointing and elongation stage, it is the period of fastest growth, largest growth volume, and highest fertilizer uptake in its entire life cycle, so it must be applied heavily. The stem-promoting fertilizer rate is about 2 tonnes of human and animal manure, 5-8 kg of urea, and 5 kg of potassium fertilizer per 667 sq m, applied in combination with intertillage and heavy earthing up; ④ Tail-strengthening fertilizer. In the late growth stage, sugarcane growth slows down, but insufficient fertilizer supply will affect sugar accumulation and is also detrimental to the development of lower cane buds. Therefore, a tail-strengthening fertilizer can be applied once. The tail-strengthening fertilizer is applied two months before maturity, with 2-3 kg of urea per 667 sq m, watered on, combined with heavy earthing up. The tail-strengthening fertilizer should not be applied too late or too much, to avoid excessive vegetative growth and delayed maturity.

It should be noted here that sugarcane is a crop with a relatively high silicon requirement, with silicon content in its leaves reaching as high as 4.5%. When soil available silicon is below 100 mg/kg, the effect of silicon application is significant. Silicon fertilizer is usually applied as a base fertilizer, with 450-650 kg of slag silicon fertilizer or 20 kg of high-efficiency silicon fertilizer (effective silicon dioxide greater than 50%) per 667 sq m, and the effect is even better when applied together with organic fertilizer.