Wheat First Irrigation at CRI Stage and Urea Top-Dressing Timing: When, How Much and Before or After Water

The first irrigation in wheat is given at crown root initiation (CRI), the stage when permanent crown roots start to grow. Punjab Agricultural University advises a light first irrigation about three weeks after sowing for October-sown wheat and about four weeks for later sowing. Other sources differ by region: 21 to 25 days in the ICAR-IIWBR Karnal trial and 15 to 20 days at TNAU. PAU advises broadcasting urea before the first and second irrigation in its straw-management wheat package. In the Karnal trial, urea just before irrigation gave 2.70 to 5.21 quintal per hectare more grain than urea a week after, an average gain of 8.36 percent. Urea is 46 percent nitrogen, so 1 kg of nitrogen needs about 2.17 kg of urea. If water is short, one Indore trial found tillering the best single irrigation, so ask your KVK before skipping CRI.

CRI stands for crown root initiation. It is the early stage when a young wheat plant starts growing permanent crown roots from the base of the stem, after its first thin seed roots. It comes before heavy tillering, and Indian extension pages treat it as the most critical moment for the first irrigation.

A 2021 PLoS One paper on wheat roots describes the root system plainly: a plant typically has up to six seminal (seed) roots and about 10 to 15 crown roots, and the crown roots come out of the basal nodes of the main shoot and of each tiller. That detail explains the timing advice. Every new tiller builds its own crown roots, so the first irrigation sets up the roots that will feed the tillers that follow.

The TNAU Agritech Portal names crown root initiation and flowering as the two most critical stages for irrigation in wheat. Neither the paper nor the portal puts a yield-loss figure on skipping the CRI irrigation alone, so this guide does not either. What it can do is show the timing, the water and the urea plan that research stations actually tested.

Give the first irrigation about three weeks after sowing for October-sown wheat and about four weeks for later-sown wheat, and keep it light. This is the schedule in the Punjab Agricultural University package of practices. Other sources differ by region: the ICAR-IIWBR Karnal trial used 21 to 25 days and TNAU gives 15 to 20 days for Tamil Nadu.

The spread of 15 to 28 days is real, not a typing difference. Sowing date, soil, temperature and the crop duration of the region all move the stage. PAU itself shifts the date by soil: earlier on light soils and one week later on heavy paddy soils. If your state agriculture university publishes its own day count, use that over any single number here.

Because moisture at this stage decides how many crown roots and tillers form, and those set the yield base. A PAU drip study found fewer tillers and less dry matter as soil moisture deficit increased, and TNAU calls crown root initiation one of the two most critical stages in wheat irrigation.

The PAU drip-irrigation study at Ludhiana compared irrigating when 15, 25, 35 or 45 percent of the available soil water had been used up. The 15 percent plot had the highest number of tillers at 50 and 80 days after sowing, and the dry matter fell by 52 percent at 50 days when the crop was irrigated at 45 percent depletion instead of 15 percent. The authors link this to less moisture for cell expansion and tiller development.

That is a drip trial, so it does not say what happens if a flood-irrigated field misses one date. It does show the direction: early in the season, thirsty wheat grows fewer tillers and less leaf. Later stress costs yield in different ways. The ICAR-IIWBR note in Indian Farming states that stress at jointing means fewer heads per unit area and fewer seeds per head, while stress at heading and dough means less fertile spikes and lighter seed.

PAU says the first irrigation should be relatively light. Its irrigation time-table counts each irrigation as 7.5 cm of water for wheat on sandy loam or heavier soils, and it advises a heavy 10 cm pre-sowing irrigation. The papers opened give no separate depth for the CRI irrigation, so ask your KVK and use soil moisture as the guide.

Two useful numbers come from trials. In the CCS HAU Hisar study, the crop was irrigated at CRI and then whenever the ratio of irrigation water to cumulative pan evaporation reached a set value (0.90, 0.75 or 0.60). The wettest regime gave the highest grain yield, a mean of 5.12 t/ha in 2012-13, but the 0.75 regime gave the best water use efficiency (12.9 and 14.0 kg per hectare-mm in the two seasons). The same study found that sowing on raised beds cut consumptive water use by 9 to 12 percent compared with conventional tillage.

In the PAU drip trial, irrigating at 15 percent depletion saved 50 percent of the irrigation water compared with the conventional practice, and pooled grain yield was 10 percent higher than conventional. Drip is not available to every farmer, but it shows how much water flood irrigation can waste. If your groundwater is falling, the Atal Bhujal Yojana post explains the village water-budget scheme that ended in October 2025.

Spread it just before the irrigation. In the ICAR-IIWBR Karnal trial, urea top dressed just before irrigation gave 2.70 to 5.21 quintal per hectare more grain than the same dose spread about a week after irrigation, an average gain of 3.94 q/ha or 8.36 percent, at every nitrogen level tested.

The PAU package for wheat sown with rice-straw management also says to broadcast 45 kg urea per acre before the first and second irrigation; with a super seeder, it says urea can go on either before or after irrigation. The Karnal paper defines the two timings clearly. Before irrigation meant spreading urea just before the water went on. After irrigation meant waiting about a week, until the soil was firm enough to walk on. The authors also note that the early-timing plots earned more: an extra Rs 4,680 to Rs 9,043 per hectare (average Rs 6,843), calculated with the support price of the time, so treat the rupee figure as a ratio and not as today's gain.

The practical point is the gap. After a flood irrigation, wheat fields can stay too wet to enter for days, and urea gets delayed. Planning to spread urea before the water removes that delay. If your field is waterlogged after irrigation, see the diagnosis steps in wheat yellowing after first irrigation, which also explains when a field needs drainage before any more nitrogen.

It was a four-season trial at the ICAR-IIWBR research farm, Karnal, from 2010-11 to 2013-14, with 13 treatments: three nitrogen levels, two timings, two split plans and a no-nitrogen control. It is strong evidence for the north-western plains on sandy loam, and weaker for other soils and varieties.

Two limits matter. First, the soil was low in available nitrogen, so the response to nitrogen was large; a field with higher nitrogen supply may respond less. Second, the trial used one variety on one soil, and it does not compare heavy clay or saline fields. The paper does not test why the gain occurred.

PAU advises broadcasting 45 kg urea per acre with the first irrigation for timely-sown wheat, and 35 kg per acre for wheat sown after mid-December. Under the Karnal plan of 150 kg N per hectare in three equal splits, the first-irrigation share is 50 kg N, about 44 kg of urea per acre.

Urea is 46 percent nitrogen, as the PAU package also lists. So 1 kg of nitrogen needs 100 divided by 46, about 2.17 kg of urea. The table converts the Karnal split plan. It is arithmetic on the paper's nitrogen levels, not a new recommendation.

Remember that one-third of the nitrogen already went on as the basal dose at sowing in the Karnal plan. The PAU package works differently: it drills the full phosphorus dose (55 kg DAP per acre in medium-fertility soils) at sowing, needs no urea at sowing when DAP is the phosphorus source, and splits the urea between the first and second irrigation. For fields using single super phosphate, PAU adds 20 kg urea per acre at sowing.

Two bodies, two plans: Karnal tested three splits on sandy loam, PAU advises two urea doses with the first and second irrigation. Follow your own state university and your soil test. The zone-wise basal and top-dressing table is in the wheat sowing planner, and the way to read the nitrogen result on your card is in the soil health card guide, which rates available nitrogen as low below 280 kg per hectare. Buying rules and complaint steps for urea are in the DAP and urea shortage post.

Three equal splits beat four in the Karnal trial. A Punjab trial reached a different result with a different design, where nitrogen was spread over sowing, CRI, late jointing and flowering. Both are single-site trials, so treat the split count as a choice for your soil and variety, not a fixed law.

Why the apparent difference? The four-split plan in Karnal added a quarter at 60 to 65 days, a stage after most tillers are set. The Punjab plan used a quarter each at CRI, late jointing and flowering, so it was still a staged plan, but it was run in one season on one farm. The fair reading is that holding back some nitrogen for later stages did no harm in the Punjab trial, and that nitrogen on the surface through the whole season did no better in Karnal.

A note on the Punjab paper: its summary and its methods section describe one of its irrigation schedules (I3) differently, so only the clear findings are quoted here. For farmers, the safest approach is to keep the first top dressing tied to the first irrigation, which every plan above does, and to decide the later splits with your state advisory.

TNAU lists a minimum of five irrigations, with four to six depending on soil and rainfall. The Indore trial found four irrigations, at CRI, tillering, late jointing and flowering, gave the highest yield and economic return. Your own number depends on rainfall, soil and how much water you have.

The numbers rise with each added irrigation in the Punjab trial, but the trial was one season at one site, and more water is not always the better plan. The Hisar study above found that the wettest regime gave the highest yield while a middle regime gave the best water use efficiency. The right schedule balances yield against the water and diesel or electricity you have.

PAU also publishes a sowing-date timetable for wheat on sandy loam or heavier soils: for sowing up to 21 November, it spaces the second and third irrigations 5 to 6 weeks after the previous one and the fourth 4 weeks after, and the intervals shorten for later sowing. Day counts for later irrigations in the table are from different regions and are not a single national calendar. The sowing-date table later in this post turns the Karnal day counts into dates for you.

The Indore trial in central India recommends tillering for a single irrigation, tillering plus flowering for two, and CRI plus tillering plus flowering for three. This differs from the usual advice to protect CRI first, so ask your KVK before dropping the CRI irrigation in the north-western plains.

The ICAR-IARI Indore trial was run on Vertisols (black soils) for two rabi seasons, 2015-16 and 2016-17, with 15 treatments. Black soils hold a lot of water, which may be one reason a later single irrigation worked best there. The trial result should not be moved to sandy loam in Haryana without local advice.

For the north-western plains, the ICAR-IIWBR note on DBW 296 explains the problem plainly: parts of western Uttar Pradesh, Rajasthan, western Haryana and the sub-mountainous belt of Punjab face irrigation shortage and falling groundwater, and many farmers grow wheat varieties meant for full irrigation under restricted water. The note reports DBW 296 (Karan Aishwarya) at a mean yield of 56.1 q/ha under limited irrigation in timely-sown trials, with a potential of 83.3 q/ha. If you farm with restricted water, the variety choice is as important as the date.

The sources opened give no separate day count for light and heavy soils. The Karnal paper notes that a two-split nitrogen plan is understood to suit the heavier soils of eastern Haryana, and three splits the lighter soils of west and south-west Haryana. Use soil moisture and your state advisory for the exact date.

The Karnal trial soil was sandy loam with low organic carbon and low available nitrogen. The soil health card guide on this site shows how to read your own nitrogen and organic carbon values. For soil texture and water holding, the types of soil in India post says alluvial soil of the Indo-Gangetic plains is the main wheat region, that black soil holds the most water, and that red soil drains quickly.

Check the quality of your irrigation water as well. The soil salinity post covers wheat yield thresholds, the 4 dS/m limit for saline soil and why irrigation water should be tested for EC and SAR.

Add 21 to 28 days to your sowing date for the first irrigation, 40 to 45 days for the second and 60 to 65 days for a third. A crop sown on 5 November reaches the first window between 26 November and 3 December. The table is calendar arithmetic on these windows.

Later sowing costs yield, and that is the other reason to keep the calendar tight. In the PAU drip study, pooled grain yield fell by 9 percent when sowing moved from 25 October to 10 November, by 18 percent by 25 November and by 29 percent by 10 December. Sowing time, seed rate and varieties by zone are in the wheat sowing planner.

Sources do not agree on a corrected day count for very late sowing, so there is no adjusted window here. For wheat sown after mid-December, PAU lowers the urea to 35 kg per acre with each of the two irrigations.

The evidence points to four: spreading urea a week after the water, skipping the later irrigations, copying a dose from another region, and blaming every pale leaf on nitrogen. Each one has a source behind it, shown in the table.

More nitrogen is not the cure for every problem. The Karnal paper itself shows that timing and splitting raised nitrogen use efficiency at 90, 120 and 150 kg N, so a field short of yield may need better timing before it needs more bags.

Pale wheat after the first irrigation is not always nitrogen. Zinc, sulphur and manganese deficiency, waterlogging and yellow rust all look similar. The live yellowing guide separates them with field tests, and a sibling post on zinc deficiency in wheat symptoms and correction is planned in this series.

Read wheat yellowing after first irrigation before you add more urea to a pale field. It explains how to read the leaf, which leaves go yellow first and what to spray. For a soil that is short of both nitrogen and sulphur, a nitrogen-sulphur fertiliser such as ammonium sulphate is one option; the product page lists 21 percent nitrogen and 24 percent sulphur, and lists wheat among the cereals. It gives no wheat dose, so follow the label and your soil test.

For a wheat-focused set of inputs, the broader fertiliser range is on the fertilizers collection and the wheat crop products collection. Zinc deficiency in wheat has its own sibling post planned in this series.

Cold soil slows root growth and nutrient uptake, so winter yellowing is not always a urea shortage. Waterlogging pushes nitrogen out of the soil through denitrification. Frost matters mostly at heading for wheat. Three live posts on this site cover each case with sources.

• Cold soil: Cold weather and nutrient uptake explains how cold soil slows roots, why leaves turn yellow or purple, and why extra urea is not the answer. It notes that evidence on nitrogen uptake in cold soil is mixed.
• Waterlogging: the nitrogen deficiency guide says nitrogen is washed below the roots in light soils under heavy irrigation, and that poor drainage promotes denitrification.
• Frost: frost protection in crops rates wheat frost risk as low to moderate and recommends a light irrigation only at the heading stage when frost is forecast.

None of this changes the first-irrigation plan. It only means that the weeks after the water are a time to watch drainage and temperature, not a time to add urea by reflex.

Not on the evidence opened for this post. The Rajasthan nano urea post on this site reports a PAU study in which wheat yield fell 21.6 percent with nano urea sprays plus half the soil nitrogen. Keep the soil urea at the first irrigation, and check with your state university before replacing any of it.

The nano urea and nano DAP post gives general nano urea timing, a first spray at active tillering, about 30 to 35 days after germination, and notes that Punjab's high-input conditions may not carry over to other states. It does not give a wheat-specific spray schedule.

Count the days from sowing: plan the basal dose, give a light first irrigation at about 3 to 4 weeks with the first urea dose, watch colour for a week, then repeat the urea step with the second irrigation, around day 40 to 45 in the Karnal plan.

1. At sowing: apply the basal dose for your zone from the sowing planner (full phosphorus and potash and the first nitrogen share under the Karnal plan).
2. Around day 18 to 20: check soil moisture by hand and plan the water, so the first irrigation is not delayed past the window.
3. Day 21 to 28 (PAU: about 3 weeks for October sowing, about 4 weeks for later sowing): give a light first irrigation and broadcast the first top-dressing urea just before it. Keep to your zone dose and soil test.
4. Days 1 to 7 after the irrigation: look for waterlogging and for pale leaves. If the colour is off, work through the yellowing guide before adding more nitrogen.
5. Day 40 to 45: second irrigation and second urea share, again spread just before the water (Karnal plan); PAU also puts a urea dose with the second irrigation.
6. Later stages: plan irrigations for tillering, late jointing and flowering as water allows; if water is limited, follow your state advisory, and use the Indore trial result as a reference, not a rule.

Keep a small note of sowing date, irrigation dates and urea dates for each field. In a year when the crop looks pale or short, that record is the fastest way to see whether the cause was timing, water or nutrition.

Conclusion

The first irrigation at CRI, about three weeks after sowing for October-sown wheat and about four weeks for later sowing under the Punjab Agricultural University package, is the one date you can plan for and control. Spread the first top-dressing urea just before that water, because the ICAR-IIWBR Karnal trial found it out-yielded urea spread a week later by an average of 3.94 q/ha. Keep the split plan simple, tie each urea share to an irrigation, and check your state university for the exact split and day count. If water is short, treat the Indore trial as a reference only and ask your KVK before dropping the CRI irrigation. Do not use nitrogen to fix yellowing without checking zinc, sulphur, manganese and drainage first.