For calculating fertilizer requirements the nutrient removal of rice crop has to be considered. Field research in Asia has shown that for a yield increase of 1 t/ha and balanced N, P and K nutrition, rice consumes:
All macro- and micronutrients are essential for growth, however, nitrogen and potassium are the nutrients needed in greatest quantities in rice. Nitrogen affects all parameters contributing to yield (e.g. spikelet number per panicle, percentage of filled spikelets, grain protein content) und, thus, a sufficient N supply is necessary for achieving high yields. At the same time, N deficiency is the most commonly detected nutrient deficiency symptom in rice.
A balanced nutrient supply with split applications of (at least N) at a good timing is necessary to increase rice yield.
Phosphorus is particularly important in early growth stages (e.g. for tillering). P fertilizer is required when the rice plant‘s root system is not yet fully developed and the native soil P supply is small.
After heading, P uptake decreases and P is translocated from leaves to grain. However, a good long lasting P supply is vital for dry matter production, since the lack of P limits the photosynthetic rate.
Foliar P and Zn applied at heading is an efficient measure to boost yields on low P and Zn soils.