Nitorgen   Introduction One of the three major nutrients. Most limiting nutrient. Highly soluble and highly mobile. Rapid transformation into leachable forms. Losses may be as a gas ( volatalisation) when nitrate is exposed to anaerobic condition and leaching . Loss is very high in flooded soils. Role of N in Plant system Green color of plant (photosynthesis). Rapid vegetative growth (height , tillering , branching). Increased leaf size (more leaf area and high radiation use efficiency) Increased protein content of grain (% N x 6.25 = % Protein) Deficiency symptoms Stunted growth (less dry matter--less utilisation of inputs) Weak stem(Lodging of crop) Yellowing leaves(Less photosynthetic efficiency) Reduced grain yeild(Due to less source and sink development) Injury due to excess N Fertilizer   Leads other nutritional problems Increased pest and disease incidence Dark green Vegetation Lodging of crop due to excess growth Increased chaffy grains. N- Management in Rice Crop removal : 15 – 20 kg N / ton of rice Season Vs Utilisation of N Rainy season (Kharif): Smaller N requirement Reasons: Less sun shine Less yield potential (Lower source, sink development) Dry seasons (Rabi / summer): Higher N –Requirement Reasons: More sunshine Greater yield potential (More source, sink development) Critical stages of N Sufficient N at tillering (adequate no of tillers/unit area) Sufficient N just prior to and during P.I (to ensure adequate panicle size) Sufficient N at grain filling (to ensure sufficient photosynthate production to fill the grains) N - Management Use more splits for long duration varieties, for light textured soils and during dry season (Rabi or summer) Avoid large basal N application (Limited uptake since growth is slow during first three weeks after transplantation) Incorporate basal N into soil before planting / sowing Apply required N at tillering ( for more tillers i.e., source) Apply required N at P.I (for more panicles & grains i.e., Sink) Apply a late N dose (at flowering) only in dry season – long duration varieties – high yield potential . Create healthy reduced state by proper soil and water management. Healthy reduced zone helps in more absorption of ammonical – N on clay thus leaching and denitrification is reduced Iron and manganese availability is high H2S is not formed – even formed precipitated by Fe Prevails optimum pH (6.5 – 7.0) leads to availability of all major and minor nutrients. General Fertilizer recommendations for paddy for different regions of A.P. Region Season N P2O5(kg/ha) K 2O Srikakulam Vizianagaram Visakhapatnam (irrigated) Sarwa 60- 80 30 30 Rainfed Sarwa 60 30 30 Irrigated Dalwa 100-120 30 30 E. Godavari W. Godavari Krishna Sarwa Dalwa 40 80-100 30 40 30 40 Guntur Prakasam Nellore Sarwa 40-60 30 30 Rayalaseema Vanakaru 120-160 60 60 Telangana Sarwa 80-100 40 40 Steps for increasing N –use efficiency Apply right quantity at right time by right method. Root zone placement of N fertilizers Balanced fertilization. Supplementary use of organic manure's and bio fertilizers Correction of micro nutrient deficiency (especially zinc and Fe) Maintain adequate plant population (400-450 panicles / mt2) Proper water management practices. Effective weed control. The inorganic fertilizers Name of the fertilizer N % Remarks A) Urea 44.0 – 46.0 Urea, Ammonium sulphate nitrate, Calciumammonium nitrate and Calcium nitrate are generally used. Among which cost for 1 kg nitrogen is cheaper in urea. Ammonium sulphate should not be mixed with seed as germination of seed affected. Ammonium sulphate nitrate should not be mixed with lime and should not be applied along with the seed. Urea is an ideal fertilizer for foliar application also its contact with seed should be avoided. B) Ammonium Sulphate 19.9 – 20.0 C) Ammonium Sulphate Calcium Nitrate 26.0 D) Ammonium Nitrate 25.0 E) Ammonium Chloride 25.0 F) Calcium Nitrate 13.0 – 15.0 G) Sodium Nitrate 16.0 H) Calcium Cyanamid 21.0 I) Anhydrous Ammonium 82.0 J)AmmoniumNitrate 32.0 – 35.0   Compound Fertilizers Form N P2O5 K2O Companies A)Diammonium phosphate 18 46 0 GFCL, SPIC, PPL B)Urea Ammonium Phosphate (Gromor) 28 20 28 20 0 CFL, FACT, ZACL FACT C)Co(NH2)2(NH4) Hpo4 24 24 0 - NPK 10 26 26 IFFCO   17 17 17 MFL   15 15 15 RCF   19 19 19 ZACL   14 35 14 CFL, ZACL         Complex fertilizers are costlier than the straight fertilizers.

Top

Phosphorus Introduction One of the three major nutrients. Immobile Limiting nutrient – Limited availability Negligible / No loss Most of P fixed in soil. Role Of P In Plant System Stimulates growth and development of roots - More anchorage to plant - More uptake of nutrients. Promotes early flowering and ripening(Late planted crop comes to harvest in time) Encourage tillering Encounters adverse conditions in early stages of crop growth. Deficiency Symptoms Leaves turn to red from tip to margins Stunted growth Poor tillering Poor root growth Delayed flowering and maturity Injury Due To Excess P Application Fixed in soil – not available to plants Leads Zinc deficiency. In organic fertilizers Phosphatic fertilizers Super phosphate (Single) 16.0 – 20.0 Rock phosphate, Basic slag, Bone meal are insoluble phosphates and they are not usually recommended. Super Phosphate (Double) 30.0 – 35.0   Super Phosphate (Triple) 45.0 – 50.0   Basic slag 3.0 – 8.0   Mussori 23.0 – 24.0   Purulia 23.0   Compound Fertilizers Fertilizer N P K Companies A)Diammonium Phosphate 18 46 0 GFCL, SPIC, PPL B)Urea Ammonium Phosphate (Gromor) 18 46 0 CFL, FACT, ZACL ,FACT   24 24 0 -   28 20 28 20 0 0     10 26 26 IFFCO   17 17 17 MFL   15 15 15 RCF   19 19 19 ZACL   14 35 14 CFL, ZACL         Complex fertilizers are costlier than the straight fertilizers. Sources Of P Material Phosphate (P2O5) (per cent) Farm Yard Manure 0.4 – 0.8 Compost (Urban) 1.0 Compost (Rural) 0.3 – 0.6 Green Manures 0.1 – 0.2 Non-Edible Cakes   Castor cake 1.8 – 1.9 Cotton seedcake (undecorticated) 1.8 – 1.9 Mahua cake 0.8 – 0.9 Karanj cake 0.9 – 1.0 Neem cake 1.0 – 1.0 Safflower cake (undecorticated) 1.4 – 1.5 Deficiency Symptoms Leaves turn to red from tip to margins. Stunted growth. Poor tillering/branching. Poor root growth. Delayed flowering and maturity. P - Management In Rice 2-3 kg P is required for producing one tone of grain. P fertilizer requirement is smaller in rainy season (less sunshine smaller potential yield), larger in dry season (more sunshine, greater potential yield). P–Fertilizer should be applied before transplanting, since O is required in the initial stages of crop for root and tiller development. P is highly immobile, hence applied nearer to root zone before transplantation.

Top

Potassium Introduction One of the three major nutrients. Majority of soils are rich in potassium. Mobility is less than N and more than P Needs larger quantities by crop. K requirement is slightly smaller in rainy season over dry season. Excess quantities of hydrogen sulphide, organic acids, Carbondioxide and ferros iron retards potassium uptake. Excess Na and Ca in soil retards K absorption. Role in Plant system Involves in working of enzymes. Production and movement of photosynthates to sink Helps in proper uptake of other nutrients. Influences tillering or branching of plant Influences size and weight of grain. Induces tolerance in plant against stress (biotech and abiotech) Makes the plant tolerant to pests and diseases. Reduces adverse effects of unfavourable climatic conditions Inorganic Fertilizers Potassic fertilizers Fertilizer N P K Remarks Muriate of Potash(KCL) - - 50.0 – 60.0 The potassium chloride and potassium sulphate are not easily leached out. Potassium sulphate - - 48.0 – 52.0 --- Potassium phosphate - - 30.0 – 50.0 --- Complex Fertilizers Fertilizer N P K Companies NPK 10 26 26 IFFCO   17 17 17 MFL   15 15 15 RCF   19 19 19 ZACL   14 35 14 CFL, ZACL         Complex fertilizers are costlier than the straight fertilizers. Sources of K Organic Manures Material Potash (K2O) (per cent) Farm Yard Manure 0.5 – 1.9 Compost (Urban) 1.5 Compost (Rural) 0.7 – 1.0 Green Manures 0.6 – 0.8 Non-Edible Cakes Castor cake 1.0 – 1.1 Cotton seed cake (undecorticated) 1.6 – 1.7 Mahua cake 1.8 – 1.9 Karanj cake 1.3 – 1.4 Neem cake 1.4 – 1.5 Safflower cake (undecorticated) 1.2 – 1.3 K Management in Rice Potassium can be applied as basal dose along with phosphorus in the last puddling. For long duration varieties and high yielding varieties potassium can be applied in two splits i.e., as basal and at panicle initiation. Defficiency symptoms Brown yellow discoloration of old leaves, spreading inward from tip. Irregular necrotic spots on the leaves and panicle. Lodging of crop due to weakening of stem. More chaffy and shrivelled grains. Reduction in yield and crop quality. K deficiency is frequently accompanied by Helminthosporium leaf spots. Injury due to excess K application Leads to calcium, magnesium and iron deficiencies.

Top

Zinc Introduction Zinc importance in plant nutrition is recognised after the introduction of high yielding varieties. Zinc deficiency caused by intensive cropping. 80% of rice land deficient in zinc. After N and P zinc playing important role in rice. To get full benefits of N,.P,K, fertilizers zinc deficiency should be prevented. Role in Plant System Producing several enzymes Responsible for chlorophyll formation. Deficiency reduce photosynthetic activity. Playing a role in N – metabolism. Regulate auxin (harmone) production Promotes nucleic acid production for protein synthesis. Sources Zinc sulphate – Zn So4 7H2O (21%Zn) Zn So4 H2O (33% Zn) Chelate Zinc (12% Zn) Deficiency Symptoms Appearance of rusty brown spots and discoloration of older leaves starting from 2-3 weeks after planting. Uneven crop stand. Under acute conditions margins of older leaves dry up. Tillering and growth adversely affected (KHAIRA disease) Fresh leaves smaller in size. No uniform maturity of crop. Management of Zinc for Rice 50 kg of Zinc Sulphate /ha to soil in the final puddling in every Rabi season in double cropped wet lands. Once in 2-3 crops in single cropped areas. Give a gap of 4-5 days between application of phosphorus and Zinc since Zn has antogonistic effect with phosphorus. Zinc deficiency an standing crop can be corrected by spraying 0.2% zinc sulphate solution (2g/lt of water) about 500 liters of spray solution is required to cover one hectare. Spraying should be repeated 2-4 times at an interval of 5-10 days. Injury due to excess Fertilizer Excess zinc cause deficiency of Iron.

Top

Iron Introduction Iron deficiency in rice in now a days very common particularly under rainfed or irrigable dry conditions. Deficiency of Iron also seen where excess calcium is applied. In high pH soils Iron deficiency is common. Excess application of P, Mn, Cu, Zn leads to Iron deficiency. High temperatures cause some times Iron deficiency. Role in plant system Acts as a catalyst in chlorophyll formation. Necessary for almost all metabolisms of plant directly or indirectly. Sources Ferrous sulphate FeSo4 7H2O (19% Fe). Deficiency symptoms Intervienal chlorosis in stripes or streaks in young leaves. Drying starts inwards from tips and margins of leaves. Leaves become white in color and dried under severe conditions followed by shedding of leaves. Management of Nutrient Iron Ferrous ammonium sulphate or ferrous sulphate @ 20-30 g along with 2-3 g of citric acid per litre of water. 2-3 sprayings at 4-5 days intervals. Under high temperatures, spraying at low concentration of ferrous sulphate @ 5 g/lt is necessary. Deficiency symptoms Intervienal chlorosis in stripes or streaks in young leaves. Drying starts inwards from tips and margins of leaves. Leaves become white in color and dried under severe conditions followed by shedding of leaves.

Top

Sulphur Introduction It is one of the important plant nutrients after N,P & K. Due to non availability of fertilizers like ammonium sulphate and continuous use of nitrogenous fertilizers like urea sulphur deficiency is seen in some of the regions. Role in Plant System Neccessary for protein synthesis. Part of amino acid cysteine Important for chlorophyll formation. Sources Fertilizer S % Ammonium sulphate 23 Single super phosphate 11-15 Potassium sulphate 17-18 Gypsum (an hydrous) 23 Gypsum (usual) 18 Defeciency Symptoms Pale yellow or light green leaves. Retarded growth. Delayed maturity. Poor tillering. Injury due to excess fertilizer Necrosis of leaves Growth reduction. Dark color of leaves.

Top