The benefits of forages in the crop rotation have been observed for decades, however today few producers make the effort to capture them. Benefits include increased soil organic matter, improved soil physical properties, reduced soil erosion, suppression of weeds and disruption of plant disease cycles. At the 1997 annual conference, Martin Entz indicated that one of the most effective ways to realize the rotational benefits of forages is to cycle them through the rotation more quickly.
For those of us involved in soil conservation, these benefits match many of the same goals we are trying to attain. But one of the greatest fringe benefits from forages is increased yield of grain crops in subsequent years. In fact the rotational benefits of field peas on later wheat yields was greater where alfalfa had been previously included in the rotation. Increased yields are particularly evident in the black and gray soil zones. However, in the brown and dark brown soil zones the opposite often holds true. Generally the drying out of the soil profile is too great to overcome in these areas for the benefit of forages to be realized.
Weed suppression is another benefit of including forages in the rotation. Organic growers have been utilizing this favorable aspect of forages for years. Research has shown that weed suppression occurs even when the forage stand is only two to three years in duration.
Two of the main factors discouraging farmers from utilizing forages as part of the rotation are difficulty establishing and later difficulty in terminating perennial forage stands. Forage establishment may be improved through direct seeding. And substituting herbicides for tillage has proven to be effective in the termination of a forage stand.
Direct seeding forages rather than using conventional tillage methods, has proven to provide equal or better forage establishment. The superior plant establishment has been attributed to greater surface soil moisture observed in lower disturbance seeding systems. In the past forages have often been seeded with a companion or nurse crop. However a better approach may be to direct seed forages into an annual crop stubble.
In the past termination of forage stands has been expensive and not always successful (particularly in wet years) through intensive tillage. Alternatively, greater success may be realized by terminating the forage with a herbicide treatment and direct seeding an annual crop into the suppressed forage. When stands have been terminated in August/September of the previous year, there is no observed difference in yield between mechanically-killed vs chemically-killed trials. Lower wheat yields were observed if the herbicide treatment was done immediately prior to seeding. None-the-less, increased weed suppression has been observed where herbicides were used instead of tillage.
As you arrange the pieces of the rotation puzzle for your operation, take some time to consider if and where forages might play a role. It may be worth the time you $pend.