Rice (Oryza sativa)
Organic manuring
Apply organic manure in the form of farmyard manure or compost or green leaf @ 5 t/ha and incorporate into the soil while ploughing. vermicompost or coirpith compost @2.5 t/ha can be substituted for 5 t/ha FYM in Onattukara region. The entire quantity of phosphatic fertilizers may be applied along with the organic manures.
Green Crop Manuring
Cowpea may be raised as an intercrop in dry seeded low land (semi-dry) rice by sowing 12.5 kg seed/ha along with rice to serve as a source of green manure. When the rice field gets submerged with the onset of southwest monsoon, cowpea at the age of about six weeks and at active vegetative stage decays and gets self-incorporated in the soil adding substantial quantity of green manure. Such a system of concurrent growing of cowpea also reduces weed pressure in semi-dry rice.
Concurrent growing of cowpea/daincha
When there is an undue delay in the onset of monsoon, concurrently grown cowpea in rice fields can be incorporated by spraying 2,4 –D @ 1.0 kg/ha at 30-40 days after sowing without affecting the yield with a substantial reduction on weed incidence
In wet seeded rice, daincha can be raised as an intercrop by sowing 20 kg seed of daincha/ha along with rice (seed rate 60 kg/ha) to serve as a source of green manure. Daincha can be incorporated by spraying 2, 4–D @ 1.0 kg/ha at 30 days after sowing thereby adding substantial quantity of green manure. System of concurrent growing of daincha can also reduce the weed pressure in wet seeded rice.
Fertilizer Application (kg/ha)
| Kind of land/region | Variety | N | P2O5 | K2O |
|---|---|---|---|---|
| Uplands (modan) | Upland local varieties | 40 | 20 | 30 |
| Uplands (modan) | High yielding short duration varieties | 60 | 30 | 30 |
| Wet lands (All regions) | ||||
| High yielding short duration varieties | 70 | 35 | 35 | |
| High yielding medium duration varieties | 90 | 45 | 45 | |
| Local varieties | 40 | 20 | 20 | |
| H4 | 70 | 45 | 45 | |
| Mahsuri | 50 | 25 | 25 | |
| Kole Lands | ||||
| *Short duration varieties | 90 | 35 | 45 | |
| *Medium duration high yielding varieties | 110 | 45 | 45 | |
| Kattukampal and Ponnani kole lands | *Medium duration high yielding varieties | 110 | 45 | 55 |
| Wetland (Kuttanad)** | Medium duration HYV | 90 | 45 | 15 |
| Onattukara | Dhanya | 60 | 30 | 30 |
| Koottumundakan | ||||
| Photo insensitive varieties for first crop | 40 | 20 | 20 | |
| Photo sensitive varieties for second crop | 20 | 10 | 10 |
*Location specific recommendations. Strict surveillance of pests and diseases is a must under such situations.
**Wherever the soil K status is medium to high based on soil test data and also where incorporation of straw is a practice and tidal contribution of the nutrient is significant.
Stages of Fertilizer Application
| Kind of land/region | Variety | Straight fertilizers (g/plant) | Remarks | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N | P | K | |||||||||
| BA | AT | API | BA | AT | API | BA | AT | API | **For direct seeded crop, one week after sowing | ||
| Uplands | PTB 28,29,30 | 1/3 | 1/3 | 1/3 | Full | 1/2* | 1/2 | * Full dose as basal is also recommended | |||
| HY short duration | 1/3 | 1/3 | 1/3 | Full | 1/2* | 1/2 | * Full dose as basal is also duration recommended | ||||
| Wet land, direct seeded | General | 1/3* | 1/3 | 1/3 | Full | 1/2* | 1/2 | *For wet seeded, the first dose to be given 1 week after sowing. For dry seeded, first application to be given after establishment of the seedlings | |||
| Mahsuri | 1/3 | 1/3* | 1/3** | Full | 1/2 | 1/2** | *45 DAS, **85 DAS | ||||
| Wet land, transplanted | |||||||||||
| HY short duration | 2/3 | 1/3* | Full | 1/2 | 1/2 | *5-7 days before PI | |||||
| HY medium duration | 1/2 | 1/2* | Full | 1/2 | 1/2* | *5-7 days before PI | |||||
| Mahsuri | 1/2 | 1/4* | 1/4** | Full | 1/2 | 1/2** | *40 DAP, ** 60 DAP | ||||
| Onattukara Wayanad and hilly region | General | 1/2 | 1/4 | 1/4 | Full | 1/2 | 1/2 | In very coarse soils, N & K may be given in five equal splits | |||
| Long duration transplanted | 1/2 | 1/3 | Full* | 1/2 | 1/2 | *Along with first application of N & K | |||||
| Koottumundakan | Direct seeded | 1/2 | 1/3 | Full** | 1/2* | 1/2 | *45 days after seeding, **With first application of N & K |
||||
| First crop Second crop |
1/2 Full* | 1/2 | Full Full* | 1/2 Full* | 1/2 | *Entire quantity as single dose immediately after the harvest of first crop | |||||
BA = Basal application; AT = At tillering; API = At panicle initiation; HY = High yielding;
DAP = Days after planting; DAS = Days after seeding
Fertilizer application
For modan cultivation (upland crop) and direct seeded crop in wet lands, apply nitrogen in three equal split doses, first as basal dressing, second at tillering stage (three weeks after seeding) and the third at panicle initiation stage (about thirty days before flowering). Apply the full dose of phosphorus at the time of land preparation as basal dressing. Apply potash either in a single dose as basal or in two split doses half as basal and half at the panicle initiation stage.
In Kuttanad region, wherever wet broadcasting (direct seeding) is adopted, give the first basal application of the nitrogen at the time of letting in water after drying the field. Water-soluble phosphorus can be recommended for application in two split doses in Kuttanad region, as basal and at maximum tillering stage.
The general principle to be followed is that in light soils as well as in soils with high leaching, nitrogen may be applied in three or four split doses according to the duration of the variety.
For typical Onattukara region, where soil is sandy loam and with iron toxicity problem, apply 5 tonnes of organic matter or vermicompost 2.5 t and 67.5 kg K2O ha-1 (Potassium Oxide).
During the first crop season, when basal application of nitrogen is not possible due to incessant rains, basal dose can be shifted to 15 days after transplanting.
In coarse sandy loam soils with high percolation as in Onattukara region, nitrogen and potash fertilizers may be applied in five equal splits at planting, 15th, 38th, 53rd and 70th day for medium duration varieties which coincide with the stages of early tillering, neck node differentiation, early reduction division and heading stages respectively in the case of medium duration varieties.
For Thiruvananthapuram and Malappuram districts, phosphorus application is essential for increasing rice yields. Rock phosphate may be substituted for superphosphate.
Basal dose of nitrogen may be postponed to initial tillering phase of rice crop, especially during the rainy season. Split application of potash @ 50% basal, 25% at tillering and 25per cent at panicle initiation stage is recommended for this region.
In sequential cropping of rice, application of 50% of the nutrient requirement (on nitrogen equivalent basis) as organics (FYM, rice straw, green manure) and 50% as fertilizers during kharif season and the entire dose of nutrients as fertilizers in rabi season enhances the grain and straw yield. The organics may be incorporated 3 weeks before transplanting.
Application of 25% of the nutrient requirement as organics and 75% as fertilizers during kharif season and reducing the fertilizer dose of rabi by 25% gives comparable yield with full POP recommendation during both seasons.
Specific dose of fertilizer for Koottumundakan system
A fertilizer dose of (N:P2O5:K2O) 20:10:10 kg ha-1 for the first crop and 30:15:15 kg ha-1 for the second crop is recommended for high yield in Koottumundakan system. N and K2O may be applied in two equal parts for the first crop, one as basal and other at panicle initiation stage. P2O5 may be applied fully as basal. The fertilizer for second crop may be applied as a single dose immediately after the harvest of the first crop (ad hoc recommendation).
Fertilizers (N:P2O5:K2O) @ 40:20:20 kg ha-1 for virippu and 20:10:10 kg ha-1 for the photosensitive mundakan crop are recommended as economic dose for the northern region under Koottumundakan practice
Methods of fertilizer application
For pre-planting application, apply the fertilizers at the final ploughing. In areas where availability of water is assured, temporarily draining the field one day prior to application and re-flooding after 12 hours is recommended for top dressing of fertilizer.
For increasing the efficiency of urea for top dressing, mix urea with six times its weight of slightly moist soil and apply to the field 24 - 28 hours after mixing. Oil seed cakes such as punna and neem cakes can also be mixed with urea (1 part of oil cake + 5 parts of urea by weight) for increasing fertilizer use efficiency. This method is particularly useful for basal application of nitrogen. Under special conditions of drought and water-logging, apply nitrogen as foliar spray. Urea may be applied as a low volume spray at 15% concentration using power sprayer or at 5% concentration using a high volume sprayer, the quantity applied in one application being limited to 15 kg ha-1 .
When zinc deficiency is noticed, apply zinc sulphate @ 20 kg ha-1 . Early stages of zinc deficiency are evidenced by interveinal chlorosis, bleaching of midribs and light yellow colouration of the leaf. Older leaves develop brown rusty spots and are extremely brittle. Zinc sulphate and potash should not be applied on the same day.
In Kari soils of Kuttanad, apply Dolomite @ 450 Kg/ha as two splits, half at the time of initial ploughing and half as top dressing one week prior to the application of fertilizers at the Panicle Initiation stage.
The effect of zinc application can persist upto five years depending on the soil and cropping pattern. Hence soil application is not required for every season. Soil zinc status should be monitored before application to avoid accumulating toxic concentration of zinc.
Split application of water-soluble phosphatic fertilizers in two equal splits as basal and at maximum tillering stage is effective in giving higher grain and straw yield than the full dose as basal dressing under certain situations.
When the soil has less than 10 ppm of calcium chloride extractable sulphur or 15 ppm of phosphate extractable sulphur, substitute urea with ammonium phosphate sulphate to correct sulphur deficiency. For medium duration rice grown in brown hydromorphic soils ammonium phosphate sulphate may be used to supply 25 kg sulphur per hectare to protect the crop from sulphur deficiency (ad hoc recommendations).
Potassium (K) status of soil is maintained by straw incorporation. After straw incorporation, if soil analysis prior to cropping season indicates low potassium status, potassium should be applied @ 15 kg K2O (Potassium Oxide) ha -1 .
Application of magnesium as basal dose in the form of magnesium sulphate (16% MgO) or magnesite (40% MgO) or dolomite (10% MgO) @ 20 kg MgO/ha is effective in giving a significant increase in grain and straw yield of rice in magnesium deficient soils. In non-deficient soils, a marginal increase in grain and straw yield is also obtained. On per unit MgO basis, magnesite is more concentrated and cheaper than magnesium sulphate.
In iron toxic laterite soils of Kerala, application of 120 kg potash ha-1 + lime 150 kg ha-1 + silica 100 kg ha-1 (as sodium silicate 250 kg ha-1 or fine silica 100 kg ha-1 or rice husk ash 500 kg ha-1 ) is recommended for higher yields.
Liming
In general, addition of lime is absolutely necessary when the pH is lower than 5.5 and it is advisable when pH varies between 5.5 and 6.5.
Apply lime @ 600 kg/ha in two split doses, the first dose of 350 kg/ha as basal dressing at the time of first ploughing and the second dose of 250 kg/ha as top dressing about one month after sowing.
A time lag of 1 week should be given between application of lime and fertilizers. For top dressing, lime may be applied one week prior to the application of fertilizers.
