Fertilizer Requirement

Introduction Nursery and Transplantation Stage Non-bearing Stage Bearing Stage Foliar Stage Nutritional Disorders Flower Inducing Property of Potassium Nitrate


  • The life cycle of mango may be divided into five stages: the nursery, the establishment in the field, the non-bearing period, the bearing period, and the aging trees.
  • The nutritional requirements in each of these periods differ.
  • Speedy growth of root-stock seedlings and proper establishment of grafts are the chief objectives in nursery.
  • At the time of establishment in the field, it is necessary to ensure least mortality.
  • The main requirements in the pre-bearing age are rapid growth of the tree and the development of a sound and strong framework.
  • During the bearing period, good cropping, regular bearing and high quality of fruit are expected.
  • When the trees are aged, rejuvenation or reinvigoration is desired.
  • These objectives have to be met by different prescriptions.

Manuring Schedules for Mango Suggested by Various Workers


Recommendations (All doses are in kg, if not otherwise stated


(a) Nursery stage


Liquid manure @ 225 g plant-1 at fortnightly intervals starting 3 months after planting stones.

Cheema et al., 1954


Grower mixture (4-7-5 or 4-9-3 with 25-30% organically derived N @ of 3.5 to 7.0 g tree-1

Singh, 1960


AS or CAN at the rate of 22 to 27 kg N ha-1 once or twice

Singh, 1967

(b) Pit manuring


50 FYM + 2.5 BM + 4.0 WA should be mixed with soil of the pit while filling.

Burns and Prayag, 1921


Lower 60 cm of the pit 15 to 20 FYM + 3.0 BM Upper 30 cm of the pit 5.0 FYM + 1.0 to 1.5 B.M. + 1 kg NOC

Allan, 1935


5-10 FYM, 6 to 12 months before planting

Naik, 1949


12.5 FYM + 0.75 BM + 1.25 WA

Chemma et al., 1954

(c) Non-bearing stage


10 FYM + 2.5 BM + 5.0 WA (5 FYM + 0.5 BM + 1.0 WA)

Burns and Prayag, 1921


2.5 to 5.0 FYM + 1.5 NOC + 1.5 SP/BM + 0.38 K2SO4

Allan, 1935


18.7 FYM + 2.4 MB/SP + 0.3 AS + 0.5 lime + 0.5 WA/K2SO4 (3.7 FYM, 0.5 BM + 0.3 AS + 0.3 lime 0.9 WA or 0.3 K2SO4)

Roy, 1953


75 g N + 110 g P2O5 + 55 g K2O; 40 to 80% of N should be organically derived

Singh, 1967


12.5 FYM + 2.5 BM + 5.0 WA (5.0 FYM + 0.5 BM + 1.0 WA)

Mari Gowda, 1974


9.0 FYM + 3.00 BM + 5.0 WA (5.0 FYM + 0.5 BM + 0.91 WA)

Singh, 1969


4.7 to 18.7 FYM + 0.3 to 0.5 AS

Singh and Jawanda, 1961

(d) Bearing stage
4 to 6 year old


18.7 to 37.4 FYM + 0.5 to 1.0 AS

Singh and Jawanda, 1961


22.5 to 50.0 FYM + 1.0 - 1.38 AS

Singh, et al., 1962

3. 60 - 100 FYM + 2.0 - 4.00 AS + 2 - 3 SP + 0.25 - 1.00 MOP Parsai, 1974

5th year onward


10-20 FYM + 0.72 N + 0.28 P2O5 + 0.60 K2O

Mari-Gowda, 1974

6 to 9 year old
5. 2.5 to 3.25 AS + 2.50 SP + 1.5 SOP Singh, 1967
7 to 9 year old

65 to 87 FYM + 1.5 - 2.0 AS

Singh et al., 1962
7 to 11 year old
7. 37 to 55 FYM + 1.0 to 2.0 AS Singh and Jawanda, 1961
10 year onwards


50 FYM + 7.5 BM + 15 WA

Burns and Prayag, 1920


25 FYM +7.5 BM + 2.5 AS

Waggle, 1931


20 to 22.5 FYM + 2.0 NOC + 6 mixture of BM/SP with SOP

Allan, 1935


730 g N 180 g P2O5 + 680 g K2O

Roy et al., 1951


750 g N 185 g P2O5 + 680 g K2O

Mallik and De, 1951


100 - 200 FYM + 2.25 - 4.00 AS

Singh et al., 1962


50 FYM + 7.5 BM + 15 WA

Bhandari & chinnapa, 1963


50 FYM + 7.5 BM + 15 WA + 2 - 3 AS

Ditto, 1966

(e) Other basis


37.5 FYM + 10 BM + 3.00 AS

Waggle, 1931


80 g N 120 g P2O5 + 80 g K2O year-1 age

Prasad % Saran, 1969-71


  1. General manuring @ 10 cart loads of FYM every year
  2. Heavy fruiting year - 50 FYM + 7.5 BM + 15 WA

Gandhi, 1955


20 NPK and Mg mixture in the proportion of 6:3:10:3 to compensate for the loss due to removal of 1000 kg of fruit

Singh, 1962

  • AS = Ammonium sulphate, BM = Bone Meal, MOP = Muriate of Potash, NOC = Neem Oil Cake, SOP = Sulphate of Potash, SP = Super Phosphate, WA = Wood Ash.


Nursery and Transplantation Stage

Nursery Stage

  • It is usual to keep the nursery fields rich in humus for improving their water-holding capacity and promoting root growth.
  • Normally, 25-40 tonnes of farmyard manure is applied to a hectare where mango stones are sown or the grafts are planted after severance from the trees.
  • When pots are used, they are generally filled with a mixture of leaf mould, top-soil and sand in the ratio of 8:8:1.
  • For improving the growth of seedlings, light doses of inorganic fertilizers, viz., ammonium sulphate and calcium ammonium nitrate, at the rate of 22 to 27 kg. of N or 247 to 309 kg. of fertilizer per hectare are applied either once or twice at an interval of about 20 days.
  • Where the application of farmyard manure attracts white ants and causes damage, it is advisable to apply Eldrin or Gammexane in suitable doses.

Transplation Stage

  • It is generally advisable not to apply any manure at the time of planting. Almost all soils selected for planting mangoes have enough nutrients available to support growth of the trees at least for a year.
  • If the soils are too poor to sustain them even over such a short period, they are best not utilized for mango cultivation.
  • Further, the application of manure at the time of transplantation can prove harmful.
  • It may attract white ants.


Non-Bearing Stage

  • This stage extends from the time the plant gets established in the field.
  • In this period the need for calcium, nitrogen and phosphorus is high.
  • Potassium is also required in reasonable amounts.
  • In soils with a high calcium content and pH ranging from 7.0 to 8.0, surface application of calcium may not be necessary but in soils where pH is low, 5.5 to 6.5, it may be necessary to add calcium in the form of dolomitic lime.
  • The quantities required to be applied would depend upon the soil reaction and, in certain cases, may run as high as 2,200 to 3,300 kg. Per hectare.
  • During the non-bearing period nitrogen is particularly required in sufficient amounts to induce vigorous growth.
  • It would be better if some part of N is derived from organic matter so that soil texture, moisture-holding capacity and ultimately the growth and development of roots improve.
  • Phosphorus would be required to cope with high respiration rates and for translocation of carbohydrates.
  • Potassium would also be required to meet the need of photosynthesis but its need during non-bearing period would be comparatively less than that during the bearing period when it is required for sugar and starch synthesis in greater quantities.
  • These needs will be met roughly in N, P and K are applied at the rate of 75, 110 and 55 gm. Of N, P2O5 and K2O for each year of age of the tree with 40 to 80 per cent N derived from an organic source.


Bearing Stage

  • The mango is a terminal bearer.
  • The fruit-bud differentiation takes place about four to five months before flowering.
  • In the year of heavy flowering and fruiting the vegetative growth is limited which, in turn, affects the next crop, because the shoots from the earlier flushes in spring are the ones to flower in the next spring.
  • If the early flush of vegetative shoots is not put out be the tree owing to heavy flowering and fruiting, there would be very few mature shoots available at the time of bud differentiation or formation of floral buds; hence, there would be no flowering in the next spring.
  • The manuring of the bearing tree is thus faced with certain complex problems which the grower must keep in mind in order to adjust his practices fruitfully.
  • In heavy crop years, thus, the objectives should be:
  1. securing sufficient vegetative growth early in the season for the next year's cropping,
  2. maintenance of tree vigour, and
  3. Improving the quality of fruit.

These can be partially achieved in one of the two ways:

  1. by application of a heavier dose of nitrogen a little earlier than flowering in the 'on' year to initiate vegetative growth, and
  2. The suppression of bud differentiation in the 'off' year so that the cropping in the 'on' year is reduced and the production of vegetative shoots is promoted.
  3. Deeping these problems in view, the manurial needs of bearing trees have been experimented with at several places in India.
  4. Based on the results of such investigations the following schedule of manuring for a bearing mango tree is recommended.


Foliar Feeding

  • Foliar sprays of macronutrients have been used to supplement their soil applications to obtain quick response and to correct deficiencies.


  • Urea has been sprayed singly or in combination with superphosphate and/or potash or growth regulators.
  • The recommended spray of 4 per cent urea which resulted in increased length of terminal shoots, number of leaves per shoot, leaf area per shoot, leaf N and water content in Langra snd Chausa cultivars and did not cause any injury.
  • 2 to 4 per cent urea shortened the p of flowering by 5 to 7 days and improved yield, and flower bud formation was depressed by 2 per cent urea.
  • The reduction in duration of flowering and increase in number of flowers, fruit set and fruit retention by urea spray.
  • The higher fruit yield is obtained by two sprays of 4 per cent urea at full bloom and observed leaf scorching by 6, 8 and 10 per cent concentrations.
  • In both these studies, 6 per cent concentration was suggested as the critical limit when leaf injury was noticed.
  • The mechanism of injury either through ammonia toxicity or due to biuret has not been established.
  • The vegetative growth increased in the three cultivars, Langra, Deshehari and Totapari as the concentration of urea spray was increased from 2 to 6 per cent.
  • Fruit weight was maximum by 4 per cent urea in Deshehari and Totapari whereas it was the highest by 6 per cent concentration in Langra.
  • Fruits from urea sprayed trees remained darker green than in the control.
  • Concentrations of 8 to 10 per cent urea delayed maturity by 10 to 15 days.
  • Results of effect on fruit weight have not been consistent.
  • 4 percent urea resulted in the highest TSS, total sugars and ascorbic acid in fruits whereas acidity increased concentration of urea from 2 to 6 per cent.
  • Use of combined spray of N and P has been found to be more beneficial presumably because of increased recovery of P in the presence of N as observed with 0.5 per cent orthophosphoric acid combined with 2 per cent urea spray, especially in March.
  • 2 and 4 per cent urea increased panicle length, number of secondarybranches per panicle, duration of flowering, number of male and hermaphrodite flowers, fruit set and fruit yield per panicle.
  • Double superphosphate sprays also increased panicle length, duration of flowering and number of male and hermaphrodite flowers.
  • Combined spray of N and P increased length of terminal shoots and size of leaves, advanced panicle emergence, caused a moderate increase in flowering and fruiting characters and increased fruit yield, TSS, reducing and non-reducing sugars, ascorbic acid and acidity.
  • Similar increase in fruit quality was obtained in Langra also.
  • Fruits of good size and quality by three combined sprays of 3 per cent potassium nitrate and 0.6 per cent sodium hydrogen orthophosphate after panicle emergence.
  • A combined spray of 1 per cent urea and 1.35 per cent of muriate of potash gave marked increase in fruit yield.
  • An increase in the levels of N, P and K in the leaves with an increase in the concentration of their sprays but the highest yield (60.5 kg per tree) was obtained from the lowest (1 per cent) concentration.
  • Foliar sprays of urea in combination with growth regulators had significant effect on growth characters.
  • Sex ratio was narrowed down by urea and growth regulator sprays.
  • At pea stage, spray of 4 per cent urea and 40 ppm NAA retained maximum number of fruits per panicle but, at later stage, 40 ppm of 2, 4-D in combination with 4 per cent urea retained the highest number. Fruit weight, sugars, TSS, ascorbic acid.
  • TSS/acid ratio were improved and acidity was reduced.
  • The maximum retention of fruits is obtained by combined spray of 6 per cent urea and 150 ppm NAA and 4 per cent urea with 120 ppm NAA.


  • Studies on the effect of micronutrient sprays on growth, flowering, fruiting, yield and quality of mango are inadequate, foliar spray of 1 per cent zinc sulphate with 500 or 1000 ppm CCC significantly increased number of panicles per shoot and fruit set and improved fruit quality.
  • The improvement in fruit quality is attained by zinc sulphate spray.
  • Progressive increase in the length of terminal shoot, number of leaves and leaf area, length of floral panicle, number of male and hermaphrodite flowers and yield with an increase in the concentration of zinc sulphate from 0.2 to 0.8 per cent was also observed.
  • Significant effect of boron on the growth, flowering, fruiting and fruit quality of Langra by 0.8 per cent boric acid spray was observed an increase in fruit size.
  • Weight, TSS, ascorbic acid, acidity and sugar content by the spray of boric acid and zinc sulphate.
  • An increase in the status of N, P, K, Ca and Mg in leaves following the spray of b -naphthoxy acetic acid and Ga.
  • More flowering also occurred in the flowing 'off' year.


Nutritional Disorders


Scorched leaf margins


  • Scorching of leaf margins is the characteristic symptom of potassium deficiency.
  • Scorching starts from tip downwards.
  • Fruit quality is reduced.
  • Trees with potassium deficiency are easily prone to pests and diseases attack.


  • Application of 1 kg muriate of potash or sulphate of potash along with 2-kg urea and 6 kg superphosphate during July-August in the basin and incorporation could rectify potassium deficiency.
  • Dropped leaves should also be incorporated along with manures to enrich the soil health and fertility.



Interveinal chlorosis

Small, narow, rosette leaves

  • Due to zinc deficiency the leaves become small and narrow with leaf margins bent upward or downward.
  • Internodal length is reduced drastically and the twig with crowded leaves gives rosette appearance.
  • Pale intervenial areas and green veins are typical of zinc deficient leaves.
  • The tree with zinc hunger does not grow well and the yield, size and quality of the fruit are reduced.
  • Small plants with severe zinc deficiency may die.
  • Zinc deficiency is conspicuously seen in alkaline and saline soils.


  • Zinc deficiency can be rectified by spraying zinc sulphate 5 g + 10 g urea /litre water twice at 15 days interval.


Bleached mango leaves


  • The leaves lose green colour and turn white and is called "Bleaching".
  • The size of the leaf is reduced.
  • In severe cases of iron deficiency, the leaves dry from tip downwards.
  • The deficiency is common in soils with high calcium content.
  • Hence, the effect is known as "calcium induced iron chlorosis".
  • The growth of the tree is restricted; yield and quality of the fruit are reduced.
  • Small plants may die due to acute iron deficiency.


  • Two sprays at fifteen days interval with ferrous sulphate 2.5 g or Annabedi 5 g + 1 g citric acid per litre of water effectively check iron deficiency.


Fruit Cracking

Brown areas in Fruit pulp



  • Cracking of fruit is the characteristic symptom of boron deficiency.
  • Lusterless leathery leaves with thickened veins are the other associated symptoms.
  • Brown areas in yellow fruit pulp is conspicuous.


  • Application of 100 g borax or boric acid per tree incorporated with recommended dose of manures during July-August can rectify boron deficiency.

Salt Injury

Scorching of leaves

Tip drying


  • The leaves are scorched due to excess salt in soil or irrigation water.
  • The leaves lose their natural colour and turn to bronze colour.
  • Tip burning is also seen in severe cases of salt injury.


  • Raise Diancha (Sesbania) as green manure crop with onset of monsoon in the inter-spaces of the orchard during tree bearing years and remove Diancha plants with roots at flower bud stage and incorporate in soil of the tree basin.
  • Farm yard manure and compost should be applied adequately every year.
  • Gypsum filled gunny bag if kept in flowing irrigation water will reduce salt effect.

Critical Leaf Nutrient Standards


Kumar and Nauriyal (1977)

Bhargava and Chadha (1988)

Biswas et al., (1987)

N (%)




P (%)




K (%)




Ca (%)




Mg (%)




S (%)




Fe (m g/g)




MN (m g/g)




Zn (m g/g)




Cu (m g/g)





Flower Inducing Property of Potassium Nitrate Spray

  • Mango trees are known to bear normal crops only in alternate years.
  • The problem lies in the inability of once-fruited shoots to develop flower buds once again for the next year's crop.
  • The normal habit of a mango tree is that the once-fruited shoots have to develop new fruiting wood terminally which can develop next year's flowers and in this process one season of flowering and fruiting is skipped over causing 'off' phase in trees leading to bienniality in bearing.
  • Potassium nitrate is one of the chemicals which has shown some potential in promotion of flowering in off phase mango trees.
  • The speciality of KNO3 is that it seem to have the capacity for breaking dormancy in buds and especially if the bud is a differentiated one, the flowering becomes obvious.

Mode of Action

  • A sharp increase in nitrate reductase activity of mango leaves occurs 24 hours after KNO3 spraying.
  • This is a normal response of many species to nitrate.
  • The reduction of nitrate to ammonia (nitrate -- nitrite -- ammonia), a fundamental biochemical process, is thought to be the first step in the mechanism of action of KNO3.
  • Ammonia is used in the nitrogen metabolism of plants to form amino acids one of which may be Methionine.
  • The Methionine could bring about mango flowering in India, although not quite consistently so. Methionine is a precursor of ethylene has the flower-inducing property.
  • If indeed KNO3 acts via ethylene the level of this gas should increase shortly after spraying the nitrate salt.
  • Flowering is observed in shoots treated with KNO3.
  • The effect of KNO3 is an inductive process, i.e., it transformed shoots from vegetative to reproductive phase.
  • Direct application of ethylene should result in faster and better flowering than KNO3, assuming the gas is the basic causal agent.
  • Test materials should have the same initial physiological condition, e.g., both have no preformed dormant axillary protrusions.
  • No experiment of this nature has been done.
  • What is known today is that the manifestation at the shoot apex of the effect of ethylene is first noticed on the 20th day.
  • With KNO3 the earliest changes took place on the fourth day but this involved buds with axillary protrusions.
  • With KNO3, the axillary protrusions enlarged and thickened 4 d after spraying.
  • Floral activity was firmly established on the sixth day with the appearance of much grown, finger-like, axillary protrusions.
  • Distinct floral parts and elongated main axis can be seen on the eighth day.

Cultivar Response

  • The Philippine mangoes 'Carabao', 'Pahutan' and 'Pico' are very responsive to KNO3 under defined or undefined physiological conditions of trees and shoots.
  • A recent addition to the list of responsive cultivars is the so-called "Digos", inappropriately referred to in Mindanao as Carabao mango.
  • 'Manila', a cultivar of the 'Carabao' race introduced to Mexico, flowered at least 30 days ahead of the control after spraying 20 g/l KNO3.
  • 'Nam Doc Mai', a Thai mango is a foreign cultivar which allegedly responds positively to KNO3 in its home origin (Hira 1984, personal communication).
  • Along with cvs. Luzon (not recognized in the Philippines), Florigon, Mulgoa, Harmonams (most likely Arumanis), Neeluddin, Cambodiana (and local?), Sabre Rouge, Sabre Blanc and Rough, 'Nam Doc Mai' has also been reported to flower in Australia after two spraying of 40 g/l KNO3.
  • Other cultivars showed a marked flowering response only after the third spraying.
  • Except Digos, all other mangoes responsive to KNO3 in the Philippines is polyembryonic.
  • No data on embryony of Digos mango is available.
  • The unresponsive cultivars, on the other hand, are mostly monoembryonic.
  • Whether embryony is important or not has not been established yet.
  • A trial in India (Central Mango Research Stateion 1978) where mangoes are practically all monoembryonic, was unsuccessful.
  • 'Kachamitha', a cultivar of Indian origin grown in the Philippines since 1911 has not been reported to flower with KNO3.


Common name

Flowering (%)


M. indica ("Carabao")



Barba (1974)

M. altissima


70 to 100

Bondad et al. (1979b)

M. odorata



Calvo (1983)

Comparison with other Materials

  • KNO3 is the most effective salt of nitrate followed by NaNO3 then NH4NO3.
  • The least effective was Ca(NO3)2.
  • Potassium nitrate was also more effective than ethephon or benzyladenine but the latter two chemicals have synergistic effect with the former.
  • The most compatible combination consisted of a mixture of the three substances.
  • Limited trials indicate that KNO3 is incompatible with ascorbic acid.
  • The latter is ineffective on 'Carabao' but promoted flowering of mangoes in India.
  • Ammonium sulfate and urea are antagonistic with KNO3.

Comparision with Smudging

  • Potassium nitrate spraying results in more intense flowering than smudging.
  • Because of uniform flowering, sprayed trees become completely covered with panicles and this is very evident at full bloom.
  • Previous works on smudging reported no quantitative estimate of the canopy area covered by flowers.
  • Smudging may eventually result in a high percentage flowering but could not completely cover the canopy with fully-opened panicles because floral emergence is greatly protracted.
  • The flowering and fruiting of 'Carabao' mango are quicker with KNO3 than smudging.
  • All developmental stages of flowers and fruits are attained earlier and their rates of growth faster with KNO3.
  • Intense flowering leads to significantly smaller fruits, only about 124.3 g for KNO3 compared to 175.7 g for smudging.

Year-Round Flowering

  • The period from July to February is well outside the fruiting season and forcing trees from March to October to fruit during the former months is of considerable practical value.
  • With KNO3 'Carabao' mango can be forced to flower from August to February.

Toxicity, Long-Term Effects and Corrective Measures

  • The concentration of KNO3 required for flowering is about 10 g/l of a high grade (99%), commercially-available material.
  • This is lower than that used in other fruit crops like citrus which is sprayed with 36 g/l. potassium nitrate is also a commonly used foliar fertilizer in the production of ornamental and vegetable crops.
  • It is therefore surprising to encounter reports on leaf burning resulting from KNO3 spraying.
  • There is experimental evidence that up to 20 g/l, KNO3 does not cause leaf burning of healthy young and old 'Carabao' mango shoots.
  • A mixture of 3.0 per cent solution of potassium nitrate and 0.6 per cent solution of sodium dihydrogen orthophosphate was found most effective in increasing the size and quality of fruits.
  • Spraying of higher concentration of these chemicals had adverse effects on fruit quality and size.
  • At the treatment combination of 5 per cent potassium nitrate and 1 per cent sodium dihydrogen orthophosphate, toxic effect on the foliage of mango crop was observed.
  • It was noted that the fruits of good size and quality can be obtained by three sprayings of 3.0 per cent solution of potassium nitrate and 0.6 per cent solution of sodium dihydrogen orthophosphate in combination at frequent intervals of one week on mango crop after panicle emergence.
  • Application of 3 or 4 sprays, of 1 or 2 per cent of potassium nitrate to the trees during the period of fruit bud differentiation following the harvest of normal load of crop in 'On' year crop either alone or in combination with certain growth regulators like TIBA or Ethrel has resulted in promoting flowering directly on fruited shoots to the extent of 30-40 per cent which otherwise would have been unfruitful.


Andhra Pradesh