Lentil Soil Requirements, Soil Preparation and Planting

Lentil (Lens culinaris) is a cool-season legume highly adaptable to semi-arid regions. Its successful cultivation depends on strategic planning, understanding its soil requirements, and suitable soil preparation before planting.

Soil Requirements for Lentils

Lentils thrive in well-drained, deep, loamy soils with a pH ranging from 6.0 to 8.0. However, they can tolerate slightly acidic soils down to a pH of 5.5 and even some alkaline soils up to pH 8.2. Lentils are sensitive to waterlogged conditions, which can quickly lead to root diseases, rots, and poor plant health. The tolerance of lentils to moderate salinity also makes them suitable for fields where some other crops might struggle (2). However, highly saline soils should still be avoided, as lentils do not perform well.

Regarding nutrients, lentils are light feeders but require certain elements to support and boost early growth and nitrogen fixation. They depend heavily on phosphorus (P) for root development and nitrogen-fixing nodules, with an average crop production of 180 lbs/ac (201.75 kg/ha), removing 1.7 to 2.0 lbs of phosphorus per acre (1.9 to 2.24 kg/ha). Potassium (K) is another essential nutrient, especially for supporting overall plant vigor. Although lentils are heavy users of potassium, most soils naturally supply sufficient quantities. Potassium deficiencies can occur on sandy soils, in which case side-banded applications are recommended to avoid germination damage.

Soil Preparation

Pre-Planting Considerations

Field selection is crucial in ensuring a good lentil crop. Ideally, lentils should follow cereals or crops like canola, peas, or fava beans in a rotation plan. Rotation with cereals helps reduce the incidence of diseases that affect cereals, as lentils are not a host for common cereal pathogens. However, farmers should be careful in fields where Sclerotinia stem rot or Ascochyta blight have been present, as these diseases can also affect lentils. Avoid fields with high herbicide residue, particularly from Groups 2 (ALS/AHAS inhibitors), 4 (growth regulators), 14 (protoporphyrinogen oxidase - PPO inhibitors), and 27 (4-Hydroxyphenylpyruvate dioxygenase - HPPD inhibitors), which can leave residual impacts on lentils.

Tillage and Bed Preparation

Preparing the soil begins with ensuring a firm, fine-textured seedbed, free from clods and debris. Lentils require a clean field with minimal competition from weeds, as they are poor competitors during early growth stages. Pre-plant tillage can help achieve this. However, excessive tillage should be avoided to prevent soil erosion and moisture loss (3). In no-till or reduced tillage systems, lentils benefit from sowing into crop residues, which helps conserve soil moisture, reduces evaporation, and improves crop establishment (1). Residues from the previous cereal crop also serve as a protective barrier, helping lentils grow more upright, thereby facilitating easier harvesting later.

Rolling after seeding is recommended to push down rocks and smooth the seedbed, which improves harvestability later in the season and reduces the risk of damaging equipment. Rolling should be done between seeding and the seventh-node stage to avoid damaging the crop's foliage.

Lentil Planting Practices

Planting Timing - When it is the Best Time to Plant Lentils

Timing is everything when planting lentils. Lentils are best to be sown in early spring when the soil temperature reaches at least 5°C (41°F), ensuring that the crop is well-established before the onset of hot summer weather. Seeding too early, however, may expose young plants to frost, although lentils are frost-tolerant to temperatures as low as -2°C (28°F). If the main shoot is frost-damaged, lentils can regrow from their scale nodes, though this may delay the crop's maturity. In regions with higher moisture, lentils can be sown later without significant yield loss, but in drier climates, early sowing is critical for maximizing water use (1).

Seeding Depth and Rate for Lentils

The ideal sowing depth is between 1 and 2 inches (2.5 to 5 cm), deep enough to help the seed access moisture without being too deep to delay emergence . Lentils planted at shallower depths may be prone to herbicide damage, while deeper seeding can result in slower germination and uneven stands. Seeding rates range from 40 to 70 lbs/ac (35 to 62.5 kg/ha), depending on the seed size and class. It is important to adjust the seeding rate based on the target plant density (3). For optimal growth, these seeding rates generally aim to establish 10 to 18 plants/ft2 (108 to 196 plants/m2). Proper calibration of seeding (e.g. sowing machines) equipment is crucial to achieve uniform seeding depth and plant growth.

Planting Distances for Lentils

Row spacing is relatively flexible for lentils, as they have an indeterminate growth habit. Row spacing should generally be between 6 and 12 inches (15 to 30.5 cm) (3). Narrower rows can promote quicker canopy closure, improving weed suppression, and reducing moisture loss. Dry sowing techniques can also be applied in areas with low rainfall, as lentils can be established well after rains if seeded into dry soil (1).

Dry Sowing

In low-rainfall areas, dry sowing can be practiced to take advantage of early moisture. Dry sown lentils often establish well once rainfall occurs, but herbicide programs should be carefully managed to prevent crop damage.