Nitrogen Nutrition in Groundnut

As with other crop plants, nitrogen plays an important role for good growth and development of groundnut.

Nitrogen is to a plant what petrol is to a car. Nitrogen drives plant growth which stops when plants run out of nitrogen. Nitrogen to some extent controls the efficient utilization of phosphorus and potassium. Nitrogen availability to plants is reflected in dark green color of stems and leaves, and vigorous growth.
Groundnut being a legume crop meets mostly its nitrogen requirement through fixation of nitrogen in the atmosphere. So, groundnut may not respond to large application of nitrogen fertilizers. Excess of nitrogen results in too much of vegetative growth at the expense of groundnut pod production. However, in early stages of plant growth nitrogen is very much in demand when the plants are in the initial stages of nitrogen fixation. A good strategy for nitrogen management in groundnut cultivation is to apply a starter dose of 15 to 20 kg N/ha, and encourage nitrogen fixation by Rhizobia inoculation to meet the nitrogen needs of plants.
The starter dose of nitrogen is side dressed along with phosphorus and potassium application just before sowing. This basal dose of nitrogen is applied preferably as ammonium sulfate as this fertilizer also contains sulfur (16%), an important nutrient for groundnut crop. Groundnut crop may not require any top dressing with nitrogen fertilizer. However, any requirement of top dressing of nitrogen need to be assessed by examining the nodules and nodulation for efficient biological nitrogen fixation by the crop. If the nodulation and nitrogen fixation is low or poor, then the crop need to be applied with 30 to 40 kg N/ha after 30 to 45 days of sowing. The top-dressing should be done at proper moisture level in soil followed by intercultivation or manual weeding.