1. Adequate soil application of K (40-60 kg ha-1).
2. Split application of applied K (2-3 times) is recommended for rice varieties/ hybrids / coarse textured sandy soils.
3. Rice straw containing 1.5 –2.5 % of water soluble K (being in ionic form) is a good source to maintain soil K status in intensely cultivated soils.

1. Owing to leaching losses in coarse textured soils with low CEC /high percolation.
2. Low soil pH (laterites/ acid sulphate soils with little or low base saturation).
3. Complete harvest /removal of straw.
4. High cropping intensity (soil mining).

1. K deficiency symptoms appear on old leaves. Chlorosis and necrosis begin in the margins and tips of leaves and extend downwards.
2. It often resembles Bacterial Leaf Blight (BLB) disease symptoms (K deficiency occurs uniformly while diseases occur in patches).
3. K deficient plants have poor lignifications and hence, easily lodge and become susceptible to fungal attack.
4. Occurrence of higher percentage of sterile spikelets.

1. K is not a constituent of any plant organ. Yet it is very important as it has myriad ionic roles.
2. K contributes to osmotic potential (balancing cation).
3. Being an activator for several enzymes (about 60), it is involved in polymerization of simple sugars into complex carbohydrates like cellulose/ starch/ lignin and amino acids into proteins.

1. Normally flooded soils are comfortable with available P due to favorable effects of flooding on P availability.
2. For better crop establishment, apply P @ 30-40 kg P2O5/ha in kharif and 60 – 80 kg P2O5/ha in rabi (low temperatures) as basal dose before transplanting.
3. For acid soils, use low cost phosphate rock or its 1: 1 mixture with SSP to economise P fertilizer. Mixing of SSP with cow dung (50% by fresh weight) is known to reduce P fixation in acid soils.

1. Low available soil P (course textured with low SOM).
2. High P fixation by Al and Fe (acidic soils) and Ca (calcareous / alkaline soils).
3. Insufficient flooding (in uplands/ aerobic condition /newly irrigated situations).

1. Being mobile, N deficiency symptoms are first observed in older leaves.
2. Growth of both roots and shoots is affected.
3. Affected plants show lower number of tillers.
4. P deficient plants have small leaves, erect leaves with dark green with red purple tint (accumulation of anthocyanin pigment).

1. P is present in plants as organic (DNA/ RNA – phospholipid in cell membranes ) and inorganic (ATP and pyrophosphate bonds) forms.
2. P is involved in export of starch from chloroplasts as triose phosphate to cells.
3. P occurs in storage compounds like phytin in grain which helps in formation of membrane and other cellular constituents during germination of seed.
4. Phytin has a high affinity for Zn and Fe and is considered more important in human nutrition.
5. P is involved in reproduction (DNA) and hastens maturity

1. The N requirement of rice plant varies according to the varieties, hybrids and soil.

2. Apply fertilizer N in 2-4 equal split doses depending on duration of the variety and soil type @ 40-80 kg N ha-1 during wet season (kharif) and 100-150 kg N ha-1 in dry season (rabi/boro) after draining the field.

1. Low N content of the soil (sandy /coarse textured soil with low SOM).
2. Low N fertilizer use efficiency (field to field irrigation / sodicity - voltalisation / high leaching / top dressing N in standing water causing denitrification).
3. Insufficient application of inorganic / organic manures.
4. Non inclusion of legumes in crop rotation (rice monoculture).

1. N deficiency in irrigated rice is rarely seen in field as adequate N fertilisation is applied all over. In fact, excess N application is more common.
2. N deficient plants look yellowish and are stunted with limited tillers.
3. Old leaves show symptoms as N is highly mobile.
4. They turn yellow is green and the accelerated senescence makes them brown and die young.
5. Rice tungro disease (RTD) symptoms/ insufficiency /cold injury also resemble N deficiency to some extent.

1. N being an important constituent of numerous organic structural /functional compounds likes amino acids/proteins/ nucleic acids/rubisco/enzymes etc. influences growth, development and yield of rice.
2. N strongly influences sink/source relationships mainly through source size /duration via leaf area index and leaf area duration which in turn determine supply of photosynthates to sink.
3. Imbalanced N in plant predisposes to the attack of several pest/diseases and increases spikelet sterility