Lentils Water Requirements and Irrigation Systems

Lentils are typically grown in arid conditions but can also be cultivated under irrigation with careful water management. Due to their shallow root system, lentils have specific water requirements, making them particularly vulnerable to waterlogging and over-irrigation. These can lead to crop failure or significantly reduced yields. Understanding the balance between sufficient water and preventing water accumulation is essential for optimizing lentil production.

Water Requirements of Lentils

Lentils need moderate moisture for optimum growth, especially during critical stages such as flowering and pod formation. The total water requirement for lentil crops, including rainfall and irrigation, typically ranges between a minimum of 10 inches to a maximum of 18 inches (250 and 450 mm) (1,2). They also require a stable dry period in spring to ensure ripening. However, the crop is relatively drought-tolerant and can withstand moderate water stress, especially in dryland environments. This adaptability allows lentils to grow successfully in regions with limited water availability.

Studies conducted by the Canada Saskatchewan Irrigation Diversification Centre (CSIDC) revealed that lentil responses to irrigation are highly variable. Over-irrigation (or excess amount of water from rainfalls), especially before flowering, can significantly reduce yields. Research shows that allowing the soil to dry between irrigation events improves crop resilience and health. Lentil plants, although shallow-rooted, can access moisture within the topsoil, but too much moisture can cause them to die quickly, especially if flooded (4).

Excess water can result in several issues, including increased disease pressure, delayed crop maturity, and lower yields. To avoid these problems, choosing fields with light-textured, well-drained soils is essential. Lentils are highly susceptible to waterlogging, and excess moisture in the soil can lead to root rot and diseases such as sclerotinia, anthracnose, and botrytis. Therefore, balancing water application while maintaining an open, well-ventilated canopy is critical to preventing disease outbreaks and promoting optimal plant health.

Irrigation Systems for Lentil Cultivation

When irrigating lentils, choosing the right irrigation system is critical to ensuring that the crop receives the necessary water without causing waterlogging or excess moisture, which could harm the crop. Based on the information available, the following irrigation systems can be applied:

Drip Irrigation: Drip irrigation is one of the most efficient systems for lentils, delivering water directly to the plant's root zone. It minimizes water wastage due to evaporation and runoff, which is crucial since lentils have a shallow root system. Drip irrigation helps maintain an optimal soil moisture level while preventing the excessive wetting of foliage, reducing the risk of fungal diseases like sclerotinia.
Sprinkler Irrigation: Sprinkler systems can be used during the early stages of lentil growth when uniform moisture distribution is essential. However, care should be taken to avoid excessive moisture on the foliage, which can increase disease risks. Sprinkler irrigation is most useful during early growth, but its use may be limited later in the season to prevent waterlogging or over-wetting of the soil.
Furrow irrigation: Furrow irrigation is a traditional technique where water is distributed to the field through small channels, or furrows, between crop rows. This approach can work well for lentils, particularly in regions with sufficient water supply. However, proper land leveling and well-designed furrows are essential to avoid water pooling and waterlogging and ensure even distribution.

Rainwater Harvesting and Supplemental Irrigation: In regions with unpredictable rainfall, integrating rainwater harvesting with supplemental irrigation can help ensure that lentil crops receive sufficient water. This method reduces the dependency on groundwater or surface water sources and allows water to be applied during critical growth stages, such as flowering and pod development.

Irrigation Guidelines and Water Requirements per Growth Stage

Irrigation management must be carefully planned for each growth stage to ensure optimal soil moisture without causing water accumulation.

Here are key points for effective irrigation of lentil crops in each growing stage:

Early Irrigation (Post-Seeding): After seeding, you shall ensure the soil is brought to field capacity within the upper 23 inches (60 cm) to encourage germination and early root development. This initial moisture is crucial for establishing a strong plant base (3).
Mid-Growth Stage: During early June, apply around 0.8 to 1.2 inches (2. to 3 cm) of water if drought symptoms appear. Lentils can be particularly sensitive to water stress at this stage, leading to stunted growth and reduced yield potential (4).
Flowering and Pod Formation: Although irrigation is generally avoided in mid-to-late June, a slight moisture stress can encourage a better seed set. To help with pod filling, supplemental irrigation of about 0.5 inches (1.27 cm) may be needed just before canopy closure (4).
Late Season: It is essential to allow a moderate moisture deficit to encourage crop maturity, especially after pod filling. Over-irrigation at this stage can delay maturity and affect harvest quality.

Note

Fungicide Considerations: If fungicides are used, irrigation should be delayed by at least two weeks to prevent leaching into the lentil root zone, which could damage the crop.

Best Practices for Water Management

Careful water management is essential for optimizing lentil yields under irrigation. Several factors affect the water needs of lentil crops:

Soil Moisture Monitoring: Regularly monitoring soil moisture helps to apply water only when necessary. Over-irrigation can lead to waterlogging and diseases like root rot.
Drip Irrigation: This method is highly efficient, supplying water directly to the root zone and minimizing wastage. It allows precise control of soil moisture levels, which is particularly important for shallow-rooted crops like lentils.
Avoiding Waterlogging: Lentils are highly susceptible to standing water and cannot tolerate waterlogged soils for long. Thus, drainage systems and proper field preparation are crucial when growing lentils under irrigation.
Disease Management: Excess moisture promotes the spread of diseases such as sclerotinia and anthracnose. Growers are advised to apply fungicides during critical stages, such as early flowering, to protect the crop from these diseases.
Monitoring: By using tools like soil moisture sensors, tensiometers, or evapotranspiration calculators, farmers can more accurately gauge the crop's water needs based on the local climate and soil conditions