Do You Know the Right NPK Ratio for Different Crops?

- Dr. Yatin Kumar Mehta

A ratio is a comparison of two or more things in relation to each other. When we talk about nutrients like NPK, it shows the relative quantity of these three elements. Under normal conditions, for crops like wheat, maize, rice, and other cereals, the ratio is 4 : 2 : 1. That means if there are four parts nitrogen, then there will be two parts phosphorus and one part potash.

The important point here is that simply applying fertilizer in the field is not enough; for proper growth and yield, the right NPK ratio is essential. Each crop has different nutrient requirements. That is why crop categories have been made and a ratio is prescribed for them, which gives a general guideline so that you are not over-applying any particular nutrient.

What is the NPK Ratio for Major Crops?

1. Cereal Crops (Wheat, Rice, Maize, Barley, Jowar, etc.):
The ratio is 4 : 2 : 1 because these crops need rapid growth of leaves and stems. Therefore, nitrogen is given in higher proportion, and the total yield is also the highest.

2. Pulses (Chickpea, Pigeon pea, Green gram, Black gram, Lentil, Groundnut, Soybean):
The ratio is 1 : 2 : 1 because these crops fix their own nitrogen with the help of Rhizobium in their roots. They require more phosphorus for strong roots and good grain formation.

3. Oilseeds (Mustard, Sunflower, Sesame, Linseed):
The average ratio is 2 or 3 : 1 : 1. Balanced nitrogen, phosphorus, and potash are essential for oil formation.

4. Vegetables (Tomato, Okra, Chilli, Cabbage, etc.):
The ratio is 2 : 1 : 2. These crops need both foliage and fruits, hence nitrogen and potash are equally important.

5. Vine Crops (Pumpkin, Bottle gourd, Watermelon, Bitter gourd, Cucumber, etc.):
The ratio is 2 : 1 : 2. These crops bear fruits for a long time, so potash is required in higher amounts.

6. Tuber Crops (Potato, Onion, Carrot, Radish, Ginger, Turmeric, etc.):
The ratio varies with the crop, ranging from 1:1:2, 2:1:2, to even 1:1:1 according to different research studies.

In general, scientific recommendations are based on these ratios, but farmers often do not follow them. In crops like wheat and rice, nitrogen is overused while potash is neglected. Similarly, applying urea in standing soybean crops or excessive phosphorus in garlic and onion reduces the availability of other nutrients. In reality, this is where the saying “both money and yield are lost” fits well—farmers spend money but do not get higher production.

Note: By linking fertilizer use with soil testing, farmers can get good yields at lower costs. If required, nutrients can also be supplied through foliar sprays in standing crops.

Author is Project Director at ‘ATMA’, District Neemuch, Madhya Pradesh.
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