Both vegetative growth and fruit production are severely restricted when nitrogen supply is inadequate. Symptoms of nitrogen deficiency develop first in older leaves and move gradually up to the younger ones. In mild cases, the mature leaves turn pale green uniformly and plants appear dull and spindly. If the lack of nitrogen is severe, new leaves grow small but remain green, whereas the oldest leaves turn yellow and gradually shrivel and die. If the problem is not corrected, the yellowing spreads up the shoot to younger leaves and plant growth is stunted. Fruits are no longer marketable as they are pale, short and thick and yields are greatly reduced.
Deficiencies may occur because of low reserves of nitrogen in the soil or limited availability to the plant. They can be observed in soils with too low or too high pH, or in sandy or light soils with little organic content that are prone to nutrient leaching and drought. Heavy irrigation and high rainfall wash the nutrients from the root zone and can lead to deficiency. Drought conditions, in turn, block the transport of water and nutrients to the plants. Most plants need nitrogen in large amounts and deficiencies often limit plant growth. A shortage of nitrogen reduces the plants capacity to trap energy through photosynthesis. As a consequence crop yields are highly dependent on nitrogen availability. Nitrogen deficiency may render the plant more sensitive to salinity. Foliar or soil analyses can be helpful to confirm visual diagnosis of nitrogen deficiency.
Apply substances containing nitrogen such as ammonia, guano, horn meal, nitrolime, as well as animal manure. High levels of organic matter can enhance soil structure and improve the capacity of the soil to retain water and nutrients.
Use a balanced fertilizer program appropriate to the soil and to the crop. Amendments can be done using products based on urea, ammonium or nitrate. Nitrogen is often provided as part of base fertilization products containing different rates of this nutrient together with phosphorus and potassium (the so-called N-P-K base trio). The form in which nitrogen is supplied is of major importance because of the possible pH variations for example. Take care of the specified amounts and right utilization. To prevent possible salt burn to leaves when applying any foliar spray, spray late in the afternoon or during cloudy weather.
Excessive or unbalanced use of fertilizers may result in some micronutrients becoming unavailable to the plant.,Check the pH of the soil and lime if necessary to get the optimal range.,Add organic matter to the soil in form of manure or plant mulch.,Provide fields with good drainage and do not overwater.,Make sure to water plants regularly during periods of drought.