ProCrop 1999

TILLAGE AND SEEDBED PREPARATION

Stand establishment is a critical crop yield factor for all crops, especially in saline soils. Salts affect germination and emergence in a manner similar to seedbed drying. Stand loss from poor emergence is directly proportional to soil salt concentrations beyond a relatively low threshold level. Many crops are much more sensitive to salt levels as a germinating seed and seedling than as an established plant (Table 1). Once a plant is established, it is normally more tolerant of higher salt levels.

Salt levels in a seedbed can often be managed to acceptable limits. Seeding of spring seeded crops on saline soils should be delayed as long as practical to take advantage of the leaching potential of spring rains. One inch of rainfall can reduce salt concentrations by 50 percent in the 1- to 2-inch seedbed required for most crops grown in North Dakota. Lowering the salt concentration in the seed planting zone can give a dramatic increase in seed germination and seedling survival.

No-till or reduced/minimum tillage systems which allow only shallow tillage are recommended for seed-bed preparation in saline soils. Salts leached away by winter snow melt and spring rains can be returned to the surface by deep spring tillage. Fall tillage should also be evaluated on the basis of spring seedbed preparation needs and relative salt levels in the tillage depth. Most deep tillage operations on saline land unnecessarily increase surface salt concentrations.

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