QUESTION #15 

What is an ideal seedbed for alfalfa? 

EXPLANATION: To ensure good soil-to-seed contact, clods should be less than 1/4 inch in diameter. This is often accomplished by a disking followed by spring-tooth and spike-tooth harrowing to further break clods and to help smooth the field. The final operation may be a corrugated roller or cultipacker to crush the remaining clods and finish firming. 

Seedbed preparation should be done when there is sufficient moisture in the soil so that it crumbles when worked. There is usually a short time after each rain when soil moisture is just right. 

It is important to have moist soil 1 to 3 inches below the surface at planting; however, it is not essential to have moisture at the surface. Most successful alfalfa plantings are made when the seed is planted into dry surface soil. Moisture required for germination and initial seedling growth comes from rain or irrigation after planting. If the soil is dry to a depth of 4 to 6 inches, it is difficult to prepare a good seedbed and may take over an inch of rain to wet the soil enough for germination of the alfalfa. 

A good seedbed shows boot prints or the bars of a tractor tire. If the soil is too hard, no imprint is made. If the soil is too fluffy, no detail remains of boot prints or tractor tire bars.

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QUESTION #16 

When should seedbed preparation begin? 

EXPLANATION: Seedbed preparation starts with good planning. This includes site selection and correcting drainage problems at least a year before planting alfalfa. Beginning at least one year in advance of alfalfa planting, soil should be tested and necessary adjustments should begin to correct soil pH and fertility. 

Weed control in the crop preceding alfalfa decreases weed seed production and helps reduce weeds in new stands. This is critical if a moldboard plow is not used as the primary tillage in preparing the alfalfa seedbed. 

After removing the previous crop, there are many possible combinations of tillage implements used to prepare the seedbed. Generally, typical steps include primary tillage (often immediately following the removal of the previous crop), disking, leveling, and smoothing. To conserve soil moisture prior to planting in September, all but final leveling and smoothing should be done before mid August.

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QUESTION #17 

Do I have to moldboard plow before planting alfalfa? 

EXPLANATION: Many alfalfa producers believe that plowing at least 8" deep is essential to bury crop residue and control weeds by burying growing plants and nongerminated seeds. In soils that develop hardpans, a chisel plow is commonly used to rip through existing hardpan layers. However, OSU researchers have found that deep disking can be used as a substitute for moldboard or chisel plowing. Compared to other primary tillage, moldboard plowing is more expensive and time consuming. In some soils, moldboard plowing also increases the potential for wind erosion. 

Another factor to consider in stand establishment is the smoothness of the field. Moldboard plowing, followed by secondary tillage such as shallow disking, leveling, and harrowing, normally creates a much smoother seedbed than systems using chisel plowing or deep disking as the primary tillage method.

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