In dry years, intensive tillage-based cropping creates a tremendous risk for soil erosion and crop failure. Before the adoption of reduced tillage cropping systems, there were significant nutrient inefficiencies due to soil moisture loss at the time of seeding. When it’s dry, seeding of any sort will always be a concern for slow germination and poor emergence. Fear of the unknown persists. When will it rain and how much?

 

An early spring thaw poses a significant risk when fields are left bare for an extended period before seeding starts. Direct seeding retains a protective mulch of crop residue to maintain seedbed moisture. Any pre-seed tillage may allow desiccating winds to displace fertile organic matter and draw down the soil moisture, leaving exposed topsoil hardened and subject to deep cracking and further moisture loss - a major hit against profitable crop production!

 

Generally, germination occurs under minimal soil moisture with good seed to soil contact. Without rain and residue cover, soil tends to dry down to the depth of previous disturbance. Extremely dry fields may require a departure from normal direct seeding. Placing seed into moisture is best, even when it’s dry 2 or 3 inches down. However, too much packed soil on top (deep seeding) may hamper seedling emergence. Thus, adequate seeding depth is all about the amount of packed soil on top of the seed rather than actual depth of furrow. The drier the topsoil, the more difficult it becomes to seal in precious moisture and still pack shallow. Normally, a depth of 1 inch or less is sufficient for direct seeding most crops. A slower seeding speed may be required as soil dries down.

 

The main goal of direct seeding is to minimize stubble knock down and soil moisture loss, and is best achieved with narrow openers on wide row spacing to optimize field efficiencies for precision-placement of fertilizer. A single field pass to seed and fertilize the crop is possible. Less aggressive implements for single-shoot direct seeding can work provided that safe seed-placed fertilizer guidelines are met. In dry soils, regardless of texture, the less disturbance the better. Double-shoot drills are seldom a disadvantage, however, under extreme moisture deficit, reducing crop nutrients may be wise.

 

How dry is too dry? Available field moisture can be easily assessed with a soil probe. A formula for adjusting seeding rates and crop fertility plans is not quite as simple. Crop establishment and optimal plant density are subject to these decisions, and the weather. Generally most cereal, pulse, and oilseed crops we grow tend to yield-compensate as moisture becomes the limiting factor. No body knows how soon the rains will come!

 

Unusually dry conditions at seeding time can impact weed control and crop rotation strategies. A drought-proofing approach may be required to survive. Experience with a crop-free fallow sequence, or growing different crops like peas or winter wheat can be extremely helpful. Direct seeding of short-season forage crops can be delayed until rains come. Tillage can almost always be avoided, and soil moisture conserved with effective use of herbicide for weeds.

 

Reduced tillage and direct seeding are the best solutions to manage dry soil. In fact, many of the problems and challenges of seeding into wet soils are also best managed with less tillage and direct seeding. There appears to be no better way to stabilize crop establishment, enhance nutrient uptake, and improve yield potential. The equipment and skill required to do so are not necessarily acquired “at the drop of a hat”.

 

Tips for direct seeding into dry soil 

 Hints for crop rotation & weeds when it’s dry

 Crop-available Soil Nutrients

It is important to understand how soil texture, organic matter, and moisture interact with fertilizer rates. Long-term direct seeding studies indicate that changes in soil nutrient cycling occur when tillage is reduced and crop rotations are diversified. Some crops use less water than others and/or access soil moisture better in their roots. High quality soils tend to hold more water and cycle nutrients well, therefore growing high-yielding crops. The balance between fertility inputs and nutrient export (harvest) should ultimately establish a sustainable equilibrium where soil nutrient supply plus fertilizer meet crop demand. A good soil-testing program is fundamental as a decision-making tool, inspired by the dynamics of crop rotation, and coupled with a commitment to reducing tillage.