Fertility Requirements

AMOUNT REQUIRED

• Fertility requirements for chickpeas are not well-defined. Based on limited data, the requirements for phosphorus, potassium, and sulphur are similar to peas or lentils. 

Nitrogen (N)

• Chickpea has the ability to fix nitrogen from the air. The process works like this:
  • The chickpea forms a symbiotic relationship with specific bacteria, which live in association with plant roots.
  • The bacteria (Rhizobium) infect the plant roots inducing nodule formation.
  • The bacteria use nutrients from the plant and provide nitrogen to the plant in return.
• For this reason, most of the nitrogen required by chickpea can be provided from the soil and fixation. This can greatly reduce and often eliminate the need to add N fertilizer. Inoculation with the proper strain of rhizobium bacteria is essential to ensure fixation.
• A well-inoculated crop should not require nitrogen fertilizer, provided the appropriate Rhizobium inoculants are used and nitrogen fixation is optimized.
• Well-nodulated chickpea plants can derive 50% to 80% of their nitrogen requirement through fixation under favourable growing conditions.
• If nitrogen fixation is not optimized due to unfavourable growing conditions (e.g. relatively dry seedbed), chickpeas may benefit from low rates of starter nitrogen in some years.
• Nitrogen fertilization management can be used to manage maturity.

Phosphorus (P2O5)

• Chickpeas have a relatively high requirement for phosphorus.
• Phosphorus promotes the development of extensive root systems and vigorous seedlings. Encouraging vigorous root growth is an important step in promoting good nodule development, nitrogen fixation, and early more uniform maturity.
• Chickpeas remove approximately 0.36 lb P205 per bushel of seed harvested.
• The maximum safe rate of actual seed placed phosphate is 20 lb/ac.
• Chickpeas grown on soils testing low in available phosphorus may respond to phosphate fertilizer even though dramatic yield responses are not always achieved.
• Even though seed yield may not be increased every year in response to phosphorus fertilizer, the crop may still benefit from earlier maturity.
• Phosphorus moves poorly in soil, so it should be placed near the seed. On the other hand, germination and emergence can be reduced if too much phosphate is placed with the seed.
• Research has also shown that although phosphorus is a limiting factor in many Alberta soils, build-up of soil phosphorus tends to raise available soil phosphorus levels and phosphorus fertilizer responses are often not dramatic.
• Rates of seed-placed phosphate should be reduced if the seedbed has less than ideal moisture conditions. Higher rates of phosphate fertilizer placed in the seed row with narrow openers like discs or knives can damage the emerging seedling and reduce the stand.
• If higher phosphate rates are required, banding the fertilizer away from the seed (sideband or to the side and below) should be considered. If sidebanding, sideband all the phosphate fertilizer, especially when using narrow openers.

Potassium

(K2O)

• Potassium is usually not required as a fertilizer supplement in most soils where chickpeas are grown.
• When soil test levels are very low, a small amount should be seed-placed. However, seed-placing potassium may cause seedling damage. The maximum safe rate of potassium and phosphorus is 20 lb/ac (22 kg/ha).

Sulphur (S)

• Some soils are deficient in plant-available sulphur in the topsoil but have enough sulphur in the subsoil to meet crop requirements.
• In wetter, cooler conditions, plants may suffer from a lack of sulphur before plant roots grow down into the subsoil containing sulphur.
• Sulphur deficiencies are frequently a problem in the Black and Grey Wooded soil areas of Alberta and occasionally a problem in the Brown and Dark Brown soil areas.
• For testing purposes, soil samples should be taken from the 0–6 inch, 6–12 inch and 12–24 inch depths to determine the amounts of sulphur at each depth.
• Soils testing low in available sulphur should have this deficiency corrected by side-banding, mid-row banding, or broadcasting ammonium sulphate, which contains sulphur in a plant-available form.
• If sulphur is required, apply a sulphate containing fertilizer such as ammonium sulphate (21-0-0-24).
• Elemental sulphur fertilizer won’t be available to the plant in the year it is applied – elemental sulphur is best used in a longer term program to build soil sulphur levels.

Micronutrients

• Micronutrient deficiencies for chickpea production have not been identified as a widespread problem through chickpea growing areas of Western Canada.
• If a micronutrient deficiency is suspected, it is advisable to analyze soil and plant samples within the suspect area and compare the analysis to soil and plant samples collected from a non-affected area of the same field.
• If the analysis confirms a micronutrient deficiency at a relatively early growth stage, a foliar application of the appropriate micronutrient fertilizer may correct the problem.
• For more information, recommended soil micronutrient levels are included in the fact sheet: Minerals for Plants, Animals and Man, Agdex 531-3 and Micronutrient Requirements of Crops, Agdex 531-1.