•Organic matter contribution

•Improved drainage

•Decreased salinity and leaching

•Better water use in following crops

The Rotational Benefits of Forages: Soil

Forage-based system

Continuous grain system

Forages contribute organic matter to soil and improve organic matter stability.

Soils with higher OM levels are better able to hold nutrients and are less erodable.

Changes in organic matter from 1964 to 1990 with and without forage in rotation.

Forages help to “de-water” very wet soils.

Water infiltration through soil is much higher after alfalfa.

Alfalfa roots may penetrate over 6 m deep. Channels made by forage roots improve water infiltration in soil and water use by other crops.

Alfalfa in rotation increased water use in following wheat crop by 5 cm (2 inches).

Even in establishment year alfalfa roots go deep

Deep rooted forages draw high water tables down. High water tables bring salts to the soil surface which causes salinity problems.

Kochia thrives in saline areas. Growing forages in rotation on this field can draw down the high water table and solve the salinity problem here.

Some forage grass species are very tolerant to saline conditions for those very saline areas. Examples include tall wheatgrass and tall fescue.

Rooting depth for annuals much less than for alfalfa

Rooting depth of Annual grain crops

Because forages root deeper than annuals, they are more effective at preventing nitrate leaching.

There is less risk of nitrate leaching with manure when spread on forage land.

Phosphate levels

Forages often use a lot of phosphorus so this nutrient will have to be replaced.

Method of forage termination influences benefits. When alfalfa is terminated with herbicide, N release is slower.

Tilling forages to remove them destroys valuable channels made by roots.

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“The Rotational Benefits of Forages”