Management of rice production systems to increase productivity

Crops have high nitrogen requirements and often respond with
dramatic growth and yield increase to the addition of nitrogen. Some consider
it the most important nutrient. Certainly, the magic of plant growth cannot
properly take place without phosphorus and potassium, the other major
nutrients, and essential secondary and micro‐nutrients found in rice grain are
shown in Table 4. It is clear that only in combination can nitrogen do its best.
Table 4. Average Nutrient Concentrations in Kilogram per Ton Rice Grain
at 14% Moisture
N P K S Mg Ca Cu Fe Mn Na Zn
10 2.5 3.1 0.8 1.0 0.2 0.004 0.025 0.096 0.071 0.018
35
RIRDC, 2002
From an investigation conducted by Batten (2002), it is evident that
accumulation of N in the vegetative body is high during the initial growth
stages and declines with age during the later growth stages (Table 5).
Table 5. Nitrogen Concentration in Rice Straw at Different Growth Stages
Growth Stage N %
Mid‐Tillering 3.43 – 3.85
Panicle Initiation 2.03 – 2.56
Harvest 0.62 – 0.69
Batten, 2002