• It has been observed that tobacco cannot tolerate waterlogging at any stage of growth but at the same time the plants may not withstand drought also.
• Therefore, a compromising situation would be to give light and frequent irrigations to the crop. However, the interval and number of irrigations depends upon soil type, weather, cultivation and type of tobacco to be grown.
• The field should be irrigated when the soil moisture falls to about 20 per cent field capacity because higher soil moisture reduced the leaf quality.
• Hard water (saline) from wells must not have more than 50 ppm of chloride, otherwise the leaves have poor burning quality.

• During continuous dry spells one life saving irrigation can be given if water of good quality is available (with less than 50 ppm chlorides).

• The water from canals, tanks, wells and deep bore wells can be used but the chloride content should not exceed 50ppm. The total irrigation water required including rainfall is 200-250 mm/ha. to be applied in 6-8 irrigations.

Furrow irrigation

• Irrigation through all furrow system consumes more irrigation water and labour.
• The alternate/skip furrow method of irrigation is more economic and checks the wastage of irrigation water, electricity and time. It improves the leaf quality and gives 10-20% higher yield than all furrow irrigation.

Irrigation schedule

At the time of planting in plough furrow		15mm
1st irrigation	15-20th day after planting by surface irrigation, if needed	20mm
2nd irrigation	30-35th day after planting as surface irrigation	24mm
3rd irrigation	40-45th day after planting by furrow irrigation immediately after ridge formation	48mm
4th irrigation	50-55th day after planting by furrow irrigation	48mm
5th irrigation	65-70th day after planting by alternate skip furrow method	24mm
6th irrigation	80-85th day after planting by alternate skip furrow method	24mm
7th irrigation	95-100th day after planting by alternate skip furrow method	24mm
8th irrigation	115-120th day after planting by alternate skip furrow method	24mm

• In alternate / skip furrow method, in the subsequent irrigation avoid first irrigated furrows and irrigate the unirrigated furrows. Follow the same fashion in consecutive irrigations.
• Climatological approach of scheduling irrigation can also be followed if Agro-Met observatory is available in the vicinity of the crop area of standardised can evaporimeter is used

IW/CPE ratio	Cumulative pan evaporation	Crop growth stage (in days)
0.50	100 mm	Up to 45
1.00	50 mm	Up to 75
0.75	67 mm	Till final harvest

Sprinkler irrigation

• Irrigation through sprinkler system will economise the irrigation water and can be followed if cost is not a limiting factor with the farmer.

Just after planting	continously 3 days (3 times)	2 hours daily in the evening hours Will give100% establishment
After application of fertilizers	1-2 times	2 hours each time
Knee height to topping stage	3 times	5 hours each time
3 days before each harvest	1 time	1 hour

The cigar and cherrot tobacco grown in Tamil Nadu and Chewing tobacco in Bihar

• These tobaccos generally grown in irrigated conditions so about 15-18 irrigations are given

Bidi tobacco of Karnataka, Maharastra and Hookah and chewing tobaccos of West Bengal

• They are genarally grown as a rainfed crops, but under drought one or two irrigations are desrable for the production of better crop.

The hookah and chewing tobaccos grown in UP

• These are genrally grown under irrigated conditions and genaraaly 12-15 irrigations are given.

• A light irrigation at transplanting time will often improve establishment and early growth in light soils.
• Adequate moisture will promote faster growth and early maturity.
• Irrigation will reduce the amount of scalding of upper leaves and firing of lower leaves during dry weather.
• If tobacco is harvested during hot weather irrigation might improve curability of crop.
• If extended rainfall is received after an irrigation, there would be a damage from drowning, leaching of nutrients and lowering of yields under light soils.
• Analyse the irrigation water sample for chlorides. Adopt irrigation only with the water containing 50 ppm of chlorides and below.
• Irrigation is more efficient at night than during hot day time because of less evaporation.
• Moisture deficiencies are much more during grand growth phase of the crop (i.e.) after 40 days after planting.
• Soil moisture stress during early stages will improve deeper root development.
• An irrigation immediately after transplantation is most beneficial. a) help to settle the soil around the roots b) provides adequate moisture for faster root development c) cools the soil, increases humidity, reduce transpiration, reduces leaf scalding and parching and reduces transplanting shock. Keeps fertilizer injury to the minimum due to dilution.
• For good yield and quality, tobacco should not be subjected to severe drought conditions. Between establishment stage and knee-high stage of crop a little moisture stress is not harmful and it may improve yield and quality.
• Low soil moisture at this stage encourages deeper root development which is beneficial during grand growth period.
• Between knee-high stage to early bloom stage (Grand growth period) moisture is extremely important. Irrigate often to keep the soil moisture sufficiently high which ensures good leaf spread, rapid growth, high yield and quality.
• During the harvest period, occasionally, it may be desirable to irrigate tobacco. This should be done only during extreme drought.
• A slight moisture stress during harvest period reduces brown spot, slows down harvest rate which helps in improving yield and quality.
• It has been observed that tobacco leaf ripens faster (false ripening) after heavy rains or heavy irrigation. This faster ripening may be due to a) part of nitrogen being leached from root zone b) Excess water damage to the root system by cutting oxygen supply c) Physiological reaction within the leaf due to high moisture.
• If tobacco does not show any signs of wilting before 11.00 am, irrigation is not necessary.
• Changes in physical and chemical properties of leaf of irrigated tobacco is expected to be a) lighter in colour b) thinner, larger leaves, more leaves with less suckers c) lower in oil, nicotine and higher in sugars.