Major and Micro Nutrients

Nitrogen

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

General Fertilizer recommendations for paddy for different regions of A.P.

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

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

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.

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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 Ferrous 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

Complex fertilizers

Sources of K

Organic Manures

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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.

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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 - 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 antagonistic 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.

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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.

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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

Deficiency 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.

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Organic Manures

Introduction

• Organic Manures obtained either from cattle or plants.
• Use of organic manures by farmers is an age-old practice in agriculture.
• Organic manure's - maintains better structure of soil
  • improves water holding capacity of light soils
  • improves aeration in heavy soils.
  • Food materials for millions of microbes
  • Microbes essential for mineralization process
  • Improves availability of nutrients from fertilizer sources.

Organic Manures

Bulky Organic Manures

FYM, Poultry manure, Municipal wastes, sheep & goat Manures, vermiculture etc.,

Concentrated Organic Manures

Oil cakes (edible and non-edible)

Nutrient composition

Organic Sources

Biofertilizers

Introduction

Bio fertilizers are

• microbial products containing living cells of different types of micro organisms possess the innate ability either to fix or mobilize important nutrient elements from non-usable forms through biological process.
• needed to be applied to soil to enhance microbial activity in the rhizosphere playing a significant role in integrated plant nutrient systems (IPNS)

Types of Bio Fertilizers

1. 1. Nitrogen fixers
2. 2. Phosphate solubilisers

Nitrogen fixers

• Among N-fixers azospirillum is widely recommended because of its easy adaptability and limited host specificity.
• A micro aerophilic bacterium
• Associative symbiotic
• Lives inside the cortical cells and xylem vessels of plant roots.
• Also known to secrete growth promoting substances like gibberellic acid and IAA which enhance root proliferation and growth of crop plants.
• Having ability to fix 25-40 kg N/ha/year.

Phosphate solubilisers

• Phosphorus in soil is in insoluble form due to fixation. In this context the release of soluble phosphorus from fixed and insoluble forms in the soil aided by micro organisms assumes significance.
• Belonging to the genera bacillus and pseudomonas.
• Posses the ability to solubilize insoluble forms of phosphorus and make it available to plants.
• Solubilization affected by the secretion of organic acids and enzymes which facilitate the crop to assimilate phosphorus easily.
• Known to produce amino acids and growth promoting substances which help in better growth of plants.
• Solublize and made available about 30 kg P/ha/annum.

Applications

Soil application

• Mix Azospirillum and phosphobacteria required for 1 ha (2 kg each) and add this mixture to 10 lit of water.
• Sprinkle the suspension on 100 kg FYM and mix uniformly.
• Apply the mixture near the root zone along the planting rows and cover with soil.
• Azospirillum and phosphobacteria each at 2 kg/ha are to be mixed with 50 kg of well powdered decomposed FYM/compost.
• Apply the mixture of biofertilizers to the rice before transplanting.

Seed treatment

• Prepare a slurry of Azospirillum 600 g +phosphobacteria 600 g with one litre rice gruel and mixed with 25 kg of rice seeds and ensure uniform seed coating.
• Dry in shade and sow the seeds within an hour of treatment. Advantages of Biofertilizers harnesses atmospheric nitrogen and makes it available directly to the plants.
• increases phosphorus uptake by solubilising and releasing unavailable phosphorus.
• enhances root proliferation due to release of growth promoting hormones.
• increases the crop yields by 10 - 25 %.
• improves soil properties and sustain soil fertility.
• are cost effective and environment friendly.
• benefit to cost ratio of biofertilizers is fairly high.

Precautions to be taken while application of Biofertilizers

• Do not mix biofertilizers with fertilizers, insecticide and herbicides.
• Treat the seed with bio fertilizer with a gap of 24 hrs if seeds are to be treated with other types of dressing chemicals(fungicides, herbicides etc.,)
• Store biofertilizer packets away from sunlight or heat.
• Use biofertilizer before the expiry date indicated on the packet.
• Irrigation has to be given after biofertilizer application.

Foliar Fertilizers

Introduction

• In recent years soluble fertilizers otherwise known as foliar fertilizers were introduced in A.P in the names of Polyfeed and Multi K
• Polyfeed contains 19 : 19 : 19 NPK with 6 micro-nutrients like iron, manganese, boron, zinc, copper and molybdenum, while multi K contains 13 : 0: 46 NPK.
• These fertilizers provide nutrients to the plant by foliar application as these fertilizers are completely soluble in water.
• These fertilizers have no other impurities like sodium and chloride and they are 100 % nutrients and these nutrients are easily absorbed through the leaves.
• In certain occasions like prolonged drought, there is no scope to apply fertilizers to the soil for want of moisture. Like wise in flooded conditions due to continuous rains fertilizers could not be applied to the soil.
• In such special circumstances these soluble fertilizers are must to protect the crop against hunger and this forms a compulsory act of crisis management.
• And the foliar application of Speciality fertilizers play an important role in supplying the nutrients at critical stages of flowering and fruit development.
• The experiments conducted in different countries indicated that these soluble fertilizers as supplement to soil application of fertilizers enhances the production per unit area ranging from15-25%.
• The trials conducted in Andhra Pradesh and Tamilnadu also indicated that the use of Speciality fertilizers enhance the yields in several crops like Paddy by 10%, Pulses, Chillies, Cotton, Groundnut by 20% and Cashew and mango by 20%

Types of Fertilizers

1) Multi - K 13% Nitrogen and 46% K
2) Polyfeed 19:19:19 N: P:K and 6 micronutrients

• These Speciality fertilizers are to be applied at the recommended concentrations. These fertilizers are compatable with insecticides and fungicides except sulphur

Application

• Application is suggested at different critical plant stages as nutritional foliar spray and fertilization. Eg: Before reproductive stage and after grain setting @1% spray of multi K.

Results

• The experiments conducted at NARDI indicated that foliar spray of 1 % either polyfeed or Multi K at 45, 60 and 75 days after planting increased the rice yield by about 10 % over unsprayed control. Observation trials conducted by KVK (NFCL) indicated that foliar application of Multi K at 1 % at the time of maximum tillering and prior to panicle initiation resulted in increased yield of 16.8 % over untreated control.

Fertilizer recovery

• Recovery of top dressed fertilizer varies throughout the life cycle (mainly as a function of root growth)
• In terms of N recovered from fertilizer N applied (%)
  • Basal 15-30
  • At midtillering 30-50
  • At panicle initiation 45-75
  • At flowering 35-60

Phosphorous and Potassium

• P and K are typically applied as basal application , although application at 10 DAS in direct sown crops may improve the recovery efficiency of P applied from 20-35%.
• K can also be splitted and the splitted 50% K at basal and 50% at PI but this is mainly to improve pest resistance.

Nutrient conversion factors

Quantities of Fertilizers required to provide a particular quantity of nutrient

Benifits of Polyfeed

1. 1. Readily taken up by plants, correct deficiencies of both macro and micro nutrients.
2. 2. Immediately increases grain size.
3. 3. Improved protein content in grains.
4. 4. Efficient utilization of all nutrients.

Multi - K

1. 1. Efficient utilization of nutrient in the plant.
2. 2. Induces panicle initiation.
3. 3. Induces resistance from pests and diseases.
4. 4. Imparts drought and lodging resistance
5. 5. Improved protein content in grains.
6. 6. Improves crop quality.
   

Area wise Nutrient Recommendations

Krishna Godavari Zone

North Coastal Zone

Southern Zone

Scarce Rainfall Zone