Potato

Nutrient Management

Inputs required (for hectare)

Fertilizer management

• Potato is a heavy feeder and needs high doses of fertilizers for best yield of tubers.
• Role of organic manure is well established and according to organic matter content of the soil a dose of 10-15 tonnes/ha of well decomposed farm yard manure, leaf mould or compost gives better results.
• An application of 3 to 5 qt/ha of well powdered neem cake helps to control the insect/pest and it also supplies plant nutrients.
• These doses of manures should be supplemented with required quantities of fertilizer.
• Apart from major nutrients the crop needs micronutrients also which must be applied as the soil is losing them very fast.
• Potatoes are shallow and sparse rooted and 30 t crop removes 150 kg N, 50 kg P₂O₅, 350 kg K₂O, 90 kg CaO and 30 kg MgO. Tuberization and early bulking phase (65 to 85 DAP) are most critical for nutrient absorption.
• This crop responds well to Farm yard manure (FYM) and green manuring.
• This improves N use efficiency (1.82 to 1.92 q tuber per kg N) and yield potential.
• Application of FYM at 25 t/ha nearly meets P and K requirement and the yield potential is raised to - 2t/ha.
• Green manure crops like Dhancha has improved the potato tuber quality as evidenced from high dry matter, starch and ascorbic acid contents.
• However, sugar and protein contents remained unaffected.
• Nitrogen is the most limiting nutrient in all soils and stimulates crop emergence, leaf area, LAI, LAD, top growth and tuber growth by increasing their number, size and bulking period.
• Excessive N delays tuber initiation.
• Response to N is highest in alluvial soils and lowest in red soil and is highest in alluvial soils and lowest in red soil and rates range from 120 to 240 kg/ha (or over 300 kg in highly N deficient soil), depending on the variety and soil type. N produces larger grade tubers and longer duration cultivars are more responsive than shorter ones.
• The critical soil test for NO₃-N is 100 to 125 ppm, and alluvial soils are most deficient. Hence, the recommended N dose for Karnataka soils is 125 kg/ha.
• Application of P improves tuber number, size, help in rapid bulking, hastens maturity and counteracts the ill effects of excessive N.
• High response to applied P is observed in acid hill soils and lowest in black soils.
• Hence the application rate is 100 kg/ha in alluvial soils.
• This is applied in single dose at planting.
• The critical soils P (Olsen's or Bray's) is 10 to 20 PPM.
• Among the P sources water soluble SSP, DAP and pyrophosphates are better than rockphosphates or bone meal.
• Banding or point placement is better than broadcasting.
• It has been observed that Rockphosphate or SSP in the ratio of 1 : 3 is more effective than rockphosphate even in acid soils. Similarly, soaking mother tubers for 4 hrs in 1.5 per cent solution of SSP and 0.5 per cent urea before planting and dried under shade will greatly economize the fertilizers.
• By and large, hybrids are more responsive than Kufri Chandramukhi or K. Alankar. Potassium is a quality element and increases dry matter, starch content and better cooking quality.
• It improves tuber yield by increasing their size and helps in efficient utilization of N, Potassium offers resistance to water stress and disease.
• But the most important function it imparts resistance to frost damage.
• The critical soil test value is 100 to 120 PPM of NH₄OAC extractable K.
• Application rate varies from 100 to 125 kg K₂O/ha.
• K sources such as MOP, KCl and potassium scheonite are equally effective.
• Varietal differences exist and hybrids are more responsive to K dressing.
• The needs of secondary elements like Ca, Mg and S are met by the use of SSP, K₂SO₄ and ammonium sulphate.
• Liming may be useful in highly acidic soils.
• Nonetheless, application of Mg improves ascorbic acid content of tubers.
• In most soils, Zn deficiency was common.
• In black soils, Fe deficiency and in hill soils, Boron deficiency is frequently observed. Soil application of 25 kg ZnSO₄ or 25 kg FeSO₄ and 1 kg sodium borate would ameliorate this malady.
• But due to high seed rate (3 t/ha), seed treatment (soaking micronutrient solution of 0.05% for 3 hrs) seems most effective.
• Dipping seed tubers in 2 per cent ZnO suspension is equally effective.
• In highly acidic soils, toxicity of Zn and Cu was noticed which tend to accumulate in tubers.
• Sulphur is another nutrient being recognised as fourth major plant nutrient after nitrogen, phosphorus and potassium.
• A good response to sulphur application has been reported with respect to potato yields.
• But these responses have been found to vary widely due to differences in location, soil types, available sulphur status, source of sulphur, genotypes, growth conditions and crop management levels.
• Micro-nutrients play a specific role in the growth and development of a plant.
• The deficiency of Zn is most wide spread and ranges from 18-83 per cent of samples tested in seven stages of India followed by deficiency of Fe, Cu and Mn.
• Zinc deficiency occurs mainly in calcareous and high phosphorus containing soils, alkaline soils, heavy and peaky soils.
• Many a time, no foliar symptoms are seen in potato plant with the result that Zn deficiency often remains undetected.
• This results in reduced yields.
• Application of zinc sulphate by different methods (seed tuber treatment, soil application and foliar application) has shown a mean increase in tuber yield by 5.08 and 4.46 t ha-1 which accounted for an increase in tuber yield by 32.19 and 25.62 per cent over control.
• Application of sulphur in the form of sulphate of potash, gypsum and elemental sulphur at three levels 16, 32 and 48 kg sulphur ha-1 was found to influence the tuber yield significantly.
• Under the transitional tract of Dharwar under rainfed condition.
• Higher tuber yields (about 25% more) can be obtained by application of sulphur at 32 kg ha-1 in the form of gypsum (200 kg gypsum ha-1) and zinc sulphate either through seed tuber treatment (0.05%) or soil application (25 kg ha-1) or foliar application (0.2% at 45 DAP) on Typic chromosturt (black-clayey soils) of Northern transitional zone under rained conditions.
• In addition to the nutrient management, yield potential of any crop can be realised only when it is grown under optimum population level.
• The plant populations ranging from 56,000 to 1,48,000 ha-1 have been tried under different agro-climatic conditions.
• Under transitional tract of Dharwar a plant density of 98,766 (45 x 22.5 cm spacing) has been reported to give maximum yield in black soil under rainfed conditions.
• The paired row system of planting (with plant density of 1,01,010 plants ha-1) which facilitates for mechanical cultivation with bullocks can be adopted in place of recommended spacing of 45 x 22 cm (single row system of planting). Ammonium sulphate which gave 15-18 per cent high yield, may be preferred to urea as a source of nitrogen.

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Integrated Nutrient Management in potato

• The optimum doses of nitrogen, phosphorus and potassium vary greatly with the length of growing season, fertility status of the soil, soil type, cultivar, geographical location and the environmental factors.
• The use of chemical fertilizers involves non-renewable sources of energy.
• This calls for utilization of nutrients from renewable energy sources like farm yard manure (FYM).
• However, very little information is available for Karnataka state on effect of organic, inorganic and combination of both on the yield and yield parameters of potato and its economics.
• The research conducted in this respect in Karnataka have produced following results:
• Amongst the different fertility levels tested in the study, the economic optimum dosage was found to be 60 kg N + 50 kg P₂O₅ + 60 kg K₂O + 50 t FYM/ha by considering the cost benefit ratio with yield compared to the earlier recommended practices.

Use of growth retardant

• At present, Kufri Chandramukhi is a ruling variety in the Karnataka State and it produces excessive vegetative growth at the cost of tuber yield.
• In recent years efforts have been made to exploit yields in crop plants through use of many chemicals.
• In the light of the above fact, the effects of some growth retardant tested on potato have yielded following findings.
• It was evident that the spraying of mapiquat chloride at 100 to 150 PPM and CCC at 750 PPM at appropriate stage of growth (45 days after planting) of potato brings about favourable growth modification and help increasing in the yield of potatoes.
• As regards the quality of tubers, spraying of potato with growth retardant significantly increased the specific gravity of tubers, reducing sugars and non reducing sugar.
• From the above discussion, it emerges that the proper stage of application of any growth retardant to potato crop is 45 DAP.
• The foliar spray of new chemical mapiquat chloride was found very effective at the concentration of 100 to 150 PPM and was as effective as CCC at 750 PPM in bringing about desirable morphological/physiological changes to promote tumor yield.

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