NPK Complex Fertilizer Grades (14-35-14, 28-28-0)

14-35-14 and 28-28-0 are two of the most widely used Indian NPK complex grades, both marketed prominently by Coromandel International under the Gromor brand alongside the corresponding GSFC, IFFCO and Sakthi products. The two grades occupy distinct slots: 14-35-14 is a high-P-and-K basal for crops needing balanced P-K at sowing, while 28-28-0 is the highest-N Indian complex used where K is not required.

Composition

14-35-14 (Gromor 14-35-14):

Total nutrient content: 63% (N+P2O5+K2O), the highest among Indian complex grades
N form: entirely ammoniacal
Used on: paddy, cotton, groundnut, soya, chilli, sugarcane (but not on chloride-sensitive crops such as tobacco and grapes, because the K source is KCl)

28-28-0 (Gromor 28-28-0):

Nutrient content: 28% N + 28% P2O5
N split: 19% urea-form + 9% ammoniacal
P solubility: 25.2% of P in water-soluble form
Used on: pulses, chilli vegetative phase, oilseeds, sugarcane where K nutrition is met separately

Mode of action

Both grades release N, P (and K, in the case of 14-35-14) in the root zone. The amide fraction in 28-28-0 hydrolyses through urease activity, while the ammoniacal portion is taken up directly or nitrified. The relatively low water-solubility of P in 28-28-0 compared with Dap gives a slower P release suited to crops with a longer P uptake window.

Target use and dose

Basal application at sowing or transplanting at 50-100 kg per acre for most field crops, with the actual dose set by soil test and crop demand. 14-35-14 is a standard basal in cotton, chilli and paddy; 28-28-0 is used as a balanced N-P top-up in the early reproductive stages, particularly in chilli around 30-40 days after transplanting.

Subsidy and regulation

Both grades are FCO-notified complex fertilisers and fall under the Nutrient-Based Subsidy regime.

References

Coromandel Fertilizers Product Range. Coromandel International.
Gromor 14-35-14 Product Page. Coromandel International.