Adopt appropriate nutrient management to improve yield and quality of vegetables  Vegetables have become an integral part of cropping systems in India. The country is currently the second largest producer of vegetables in the world. The suitability of vegetables to fit into different cropping systems, better economic returns as well as its strong export potential, has ensured major focus in this sector from all concerned namely, farmers, government and the fertilizer industry. At present, nearly 6.2 million hectares (2.8% of the net cultivable area) are under vegetable cultivation, producing 98.5 million tones of vegetables, nearly 14% of the world share. Fresh and processed vegetables account for a large share of export from this country and there is considerable scope of increasing the exportable quantity and earning of foreign exchange. However, the productivity of vegetables is quite low in India (15.52 t/ha) as compared to the developed countries, and the per capita consumption of vegetables, 140g/day/person, is also low. Inadequate and imbalanced supply of nutrients is one of the most important factors responsible for low productivity of vegetables in this country. Nutrient demands of vegetables are generally high and inadequate nutrient application renders the soil deficient in macro, secondary and the micronutrients. It is perhaps the most important factor to reckon that if the nutrients removed from the field are not replaced by external nutrient inputs then the sustainability of production is jeopardized due to decline in soil fertility. Vegetables may be categorized into the following four groups based on their nutrient removal characteristics: Very high removal: Cabbage, cauliflower, knolkhol, celery, sweet potato, etc.; High removal: Potato, brinjal, carrot, beet, etc.; Moderate removal: Onion, garlic, tomato, beans, spinach, peas, radish, etc.; Low removal: Okra, cucumber, pumpkin, lettuce, etc. Some ideas about the nutrient requirement of vegetable can be obtained from the following table:
Nutrient removal by some vegetables (kg/ha)
Crop | Yield (t/ha) | N | P2O5 | K20 | MgO | S |
Potato | 40 | 175 | 80 | 310 | 40 | 20 |
Cabbage | 70 | 370 | 85 | 480 | 60 | 80 |
Carrot | 30 | 125 | 55 | 200 | 30 | NA |
Cauliflower | 50 | 250 | 100 | 350 | 30 | NA |
Cucumber | 40 | 70 | 50 | 120 | 60 | NA |
Brinjal | 60 | 175 | 40 | 300 | 30 | 10 |
Okra | 20 | 60 | 25 | 90 | 35 | 10 |
Onion & Garlic | 35 | 120 | 50 | 160 | 15 | 20 |
Pumpkin | 50 | 90 | 70 | 160 | 40 | NA |
Radish | 20 | 120 | 60 | 120 | 30 | NA |
Spinach | 25 | 120 | 45 | 200 | 35 | NA |
Tomato | 50 | 140 | 65 | 190 | 25 | 30 |
Source: Dr. H. L. S. Tandon (2000) Fertilizer Recommendation for Horticultural Crops
 The nutrient application rates for a particular vegetable will depend, among other things, on the nature of the soil, type and variety of the crop and past cropping and fertilization history of the field. Available diagnostic techniques, including identification of deficiency symptoms as well as soil and plant tests are helpful in determining what additions are needed. Visual nutrient deficiency symptoms are generally manifested in the leaves. It is a quick technique, but one needs to be an expert to recognize the deficiency symptoms which often can be quite confusing, and allows salvaging the crop with a foliar or soil application of the appropriate nutrient. However, it should be recognized clearly that productivity potential of a particular crop is seriously hampered by the limiting nutrient even before the deficiency symptoms are visible on the crop. On the contrary, soil tests can help us plan a proper nutrient management. When soil tests are employed to determine which nutrients are deficient and by how much, nutrient balances in the soil can be achieved by appropriate nutrient application rates , which helps in better economics of production and ensures environmental safety. Plant tissue analysis is another option available to optimize nutrient application in vegetables. The basic principle behind this technique is that the nutrient concentration on plant tissues is related to the amount of nutrient element available in soil. If the nutrient level in the tissues falls below the critical concentration, the soil may be deficient in that element for optimum plant growth and would require application of the concerned nutrient. General range of nutrient content in fully developed leaves of vegetable crops is given in the following table: Nutrient level in leaf tissue of vegetables
Nutrient | Unit | Per cent or ppm of dry weight of leaf |
 | | Sufficient | Critical |
Nitrogen | % | 1.5-4.00 | 1.00-1.50 |
Phosphorus | % | 0.25-0.80 | 0.20-0.25 |
Potassium | % | 2.00-9.00 | 1.50-2.00 |
Calcium | % | 0.35-2.00 | 0.35-0.80 |
Magnesium | % | 0.25-1.00 | 0.20-0.25 |
Sulphur | % | 0.16-0.50 | 0.10-0.16 |
Manganese | ppm | 30-200 | 30-50 |
Iron | ppm | 50-250 | 50-80 |
Zinc | ppm | 30-100 | 20-30 |
Boron | ppm | 30-60 | 20-30 |
Copper | ppm | 8-20 | 4-8 |
Molybdenum | ppm | 0.5-5.0 | 0.2-0.5 |
Source: Dr. T. K. Maity & Dr. D. Sanyal (2004), PPIC-IP workshop on "Review & Refinement of Fertilizer Recommendation for Major crops of West Bengal"
It is, however, critical to know that one can not just pick any leaf or other plant part and send it for analysis of nutrient content and correlate it back to nutrient requirement of the crop. Since relatively more importance is attached to plant tissue analysis than soil analysis in fruit and vegetable crops, sampling of plant parts assumes great importance, much like the collection of a representative soil sample.
Guideline for plant sampling
Crop | Plant parts to be sampled | Stage of Growth |
Tomato | 4th to 6th leaf from growing tip | Early bloom |
Chilli | Young matured leaves | Early fruit set |
Cauliflower | Young matured outside leaves | Button stage of curd |
Cabbage | First matured leaf from central whorl | Prior to heading |
Broccoli | Young matured leaves | First bud formation stage |
Brussels sprouts | Young matured leaves | Mid growth |
Melons & Pumpkin | Matured leaf near the base portion of plant on main stem | Early growth prior to fruit set |
Beans | 2-3 fully developed leaves at top of the plant | Initial flowering |
Pea | Leaves from 3rd node down from top | Initial flowering |
Root crops | Young matured leaves from central rings | Prior to root enlargement |
Bulb crops | Young matured leaves from center | Prior to bulbing |
Leafy greens | Youngest mature leaf | Mid growth |
Potato | 4th to 6th leaf from growing tip | Early growth (30-40 DAT) |
Source: Dr. T. K. Maity & Dr. D. Sanyal (2004), PPIC-IP workshop on "Review & Refinement of Fertilizer Recommendation for Major crops of West Bengal"
As stated in the previous sections, applying nutrients after assessing the requirement through soil and/or plant analysis ensures adequate and balanced application of all required nutrients, ensuring better efficiency and economics of fertilizer application. However, the existing soil and plant analysis infrastructure in the zone is inadequate to provide individual recommendations to farmers. Under such situations one can use the following table as a guide for nutrient application. This is the modified state fertilizer recommendation for vegetables for West Bengal, released recently by the State Agriculture Department of West Benga,l and the modifications are done on the basis of a PPIC-IP workshop on "Review & Refinement of Fertilizer Recommendation for Major crops of West Bengal". In the absence of accurate soil/plant analysis, this table will provide a standard nutrient dose, based on field experimental results in different parts of the State, to ensure better yield and quality of crops.
Nutrient recommendation for vegetable crops in West Bengal
Source: Department of Agriculture, Govt. of West Bengal (2005)
Crop | N (kg/ha) | P2O5 (kg/ha) | K2O (kg/ha) |
Summer Brinjal | 120 | 60 | 60 |
Winter Brinjal | 150 | 100 | 100 |
Onion | 150 | 100 | 150 |
Local Tomato | 100 | 50 | 50 |
Hybrid Tomato | 180 | 90 | 90 |
Chilli | 90 | 60 | 60 |
Cabbage | 200 | 100 | 100 |
Cauliflower | 150 | 100 | 100 |
Ginger, Turmeric | 120 | 60 | 80 |
Beans | 50 | 60 | 80 |
Radish | 60 | 60 | 60 |
Garlic, Turnip, Carrot, Beet | 80 | 60 | 60 |
Lady's finger (Bhindi) | 100 | 50 | 50 |
Gourds, Pumpkin, Cucumber | 140 | 70 | 70 |
Capsicum | 100 | 80 | 80 |
Arum | 150 | 100 | 150 |
Spinach | 80 | 60 | 60 |
Elephant foot yam | 200 | 100 | 150 |
Sweet potato | 80 | 50 | 100 |
Local Watermelon | 90 | 60 | 60 |
Hybrid Watermelon | 150 | 100 | 100 |
Palwal | 120 | 60 | 60 |
* Apply sulfur @ 10-15 kg/ha
* Apply Zn as Zinc sulphate @ 25 kg/ha, B as Borax @ 10 kg/ha and Mo as Ammonium molybdate @ 0.5 kg/ha at the time of land preparation if deficiency is apparent in soil test report or in previous crop.
* Apply FYM @ 10 t/ha
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