Nutrient management

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Nutrient management

Crop response:

At an optimum nitrogen applied the yield response is 0.5-1.2 t/ha per kg of N and sugar yield is 10-30kg.
Adequate presence of P2O5 in cane juice, about 300-400ppm, is necessary for proper clarification while processing. The yield response is 0.05-0.025 t/kg of applied P2O5.
Sugarcane is known as a devourer of K due to very heavy uptake by the crops with yield response 0.02-0.15 t/kg of applied K2O.

a. Nitrogen

It influences cane yield through its effect on leaf area, leaf area duration, leaf area index the improved yield attributes like number of millable canes, stalk length and girth.
Nitrogen requirement is greatest during tillering and early grand growth stage. Tillering phase requires N for tiller formation and growth.
No external N during germination required as use stored food material in the sett.
Very high amount of N uptake is around 30-45days i.e. beginning of tillering phase. The tillering phase commences around 30-45days sowing in field conditions.
Therefore, the first application should be at start of tillering phase. The first dose application in early maturing and short duration varieties is at 30DAS while in long duration varieties is at 45DAS.
Further N requirement is at beginning of grand growth phase or end of tillering phase. Therefore, the the second dose application is done at 90-120 days. Late application of N beyond 120 days in 12-month crop will have adverse effect on juice quality.
The recommended dose of nitrogen for irrigated and rainfed condition of Nepal is 150 and 120 kg/ha respectively in 2-3 splits at critical growth stages viz, tillering(45-60DAS), formative stage(60-75 DAS), and grand growth phase (75-100DAS).

Excess N results:

Prolongs vegetative growth.
Delay maturity and ripening.
Produce more dense stalk population but simultaneously causes mortalities of primaries and greater incidence of suckers.

N deficit results:

b. Phosphorus

Its requirement is relatively less ,however, plays a significant role in S/C production.
Necessary for protein formation and yield built up.
Plays an important role in cell divison and thus indispensable for crop and root growth.
If excess it is wasteful in most soils due to fixation problem.
If deficit it reduces tillering, affects stalk elongation, leaves grow close and leaf color appear green violet.
The recommended dose of P2O5 or irrigated and rainfed condition of Nepal is 60kg/ha.
Phosphorus application should be done before planting right below the setts in the root zone as P is highly immobile unlike N and K.

c. Potash

S/C is known as “devourer” of potash due to very heavy uptake by the crop, sometimes in excess of the requirement particularly under unlimited supply either due to excess application or due to greater native available K status.
K is required in carbon assimilation, of photosynthesis, translocation of carbohydrates.
Improves cane volume and girth.
Excess K leads to consumption known as “luxury consumption”.
The recommended dose of potash is 40kg K20/ha in irrigation and rainfed condition of Nepal.
Higher utilization of N by crops in presence of K, application of K is usually done along with N.
So, K applies along with N on 30-45DAS and 90-120DAS.
Since K is subjected to loss by fixation and leaching , it is advisable to apply potassium in split doses.

Micronutrients

Among the micronutrients the deficiency of Zn and Fe are frequently seen.
When S/C is grown after paddy the deficiency of Zn is commonly seen which is noticed by the stunted growth and patchy appearance.
In soils deficient in micronutrients like Fe ,Zn, Mn, Cu, Mo and B, in addition to major nutrients 25kg FeSO4, 20kg ZnSO4,10kg MnSO4,10kgCuSO4, 2.5 kg Sodium Molybdate and 5 kg Borax per hectare should be applied.
Also compost 10-15tonnes/ha and oil seed cake 5-10 tonnes/ha is done before 1 month of cane planting.