Nitrogen Deficiency in Rice
Symptoms of nitrogen deficiency develop first in older leaves and move gradually up to the younger ones. Nitrogen deficient crops are generally stunted and discolored. Older leaves or whole plants become yellowish or light green and chlorotic at leaf tips. Except for young leaves, which are greener, leaves of nitrogen deficient plants are narrow, small, short, erect and discolored. Other symptoms are reduced tillering and reduced grain number. The visual symptoms of nitrogen deficiency can be confused with those of sulfur deficiency, which is however less common and tends to first affect younger leaves or all leaves on the plant. Mild nitrogen deficiency can be confused with iron deficiency, but the latter affects the emerging leaf first. Crops with suboptimal plant densities do not use fertilizer N efficiently.
High rates of nitrogen are important during the vegetative growth of the plant, for example during tillering or panicle initiation. In periods of favorable weather, it is important to provide the fast growing crops with a good nitrogen supply during these stages, so that they can reach their maximum vegetative and grain production potential. Soils particularly prone to nitrogen deficiency include sandy soils, acid sulfate or saline soils, phosphorus-deficient soils, poorly drained wetland soils, alkaline and calcareous soils with low soil organic matter status and a high potential for ammonia (NH3) volatilization losses. Frequent rainfalls, flooding or heavy irrigation wash down nitrogen into the soil and can also lead to deficiencies. Periods of drought stress hinder the absorption of water and nutrients, resulting in unbalanced nutrient supply. Finally, the soil pH also plays a role in the availability of nitrogen to the plant. Both low or high soil pH negatively affect the absorption of nitrogen by the plant.
High levels of organic matter in soils can enhance soil structure and improve the capacity of the soil to retain water and nutrients. 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.