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Andrew Plant, Extension Agriculture Educator
Ellen Mallory, Sustainable Agriculture Specialist
Ellen Mallory, Sustainable Agriculture Specialist, University of Maine
It’d be a bit of an understatement to say that the weather this fall has not been so cooperative. Steady rain in late August and early September have hindered harvests and delayed planting of fall grains. Fall grains are winter annuals that are seeded in late summer and early fall and then harvested the following summer. Examples include winter wheat, winter rye, winter triticale, and winter spelt. Fall grains require mild temperatures to support adequate tillering, root growth, and crown development for winter survival. And while this is not an issue for this year, it is also possible to plant fall grains too early, which promotes too lush a growth and increases chances of winterkill and disease.
The recommended window for seeding fall grains in Maine is the first two weeks of September. Seeding in the third week September generally produces good results but after that yield potential declines. Of course, it depends on the year.
The table at the end of this article summarizes results from two years of planting date trials conducted near Orono, Maine. Four varieties of winter wheat were planted at three seeding dates in fall 2011 and five dates in fall 2012. Grain yields were measured and expressed as a percentage of the first seeding date. The fall and winter of 2011 were ideal for growing fall grains: relatively dry conditions facilitated timely seeding; above average temperatures supported growth into November; and a mild winter with good snow cover provided good winter survival. Arapahoe and Redeemer showed almost no yield penalty for seeding in October, and while Harvard and AC Morley yields were reduced to about 75% of the maximum, but that was still a respectable 3,800 to 4,400 pounds per acre.
The fall of 2012 was the extreme opposite. Excessive rain in September and October hindered fall growth. Over the winter, limited snow cover combined with low temperatures reduced winter survival. Yields from the September 15th planting were less than half those of the prior year. Yield reductions were also much more severe at the October 18th seeding date in 2012 than in 2011. However, even in 2012, the late September date produced relatively little reduction in yield.
We don’t know in advance what late fall and winter hold in store for us, so we have to give the crop the best chance to succeed under any conditions. If you are hoping to still get fall grains planted, here are a few things to consider.
Table. Effects of fall seeding date on winter wheat grain yields.
|Grain yield at September 15 planting date (lbs/acre)|
|Percentage of the maximum yield resulting from later planting dates (%)|
|Percentage of the maximum yield resulting from increased seeding rate (%)|
John Jemison, Soil and Water Quality Specialist, University of Maine
Reasons to plant late summer cover crops are many, but are sometimes unfortunately exceeded by the number of reasons why they are not done. I don’t think there is a Maine farmer today that would not ideally like to have a cover crop on fields to protect soil and water resources. What often interferes however is time, weather, resources, and possibly issues with subsequent crops.
For most organic farmers, cover crops are a very important weed management strategy. By densely planting a crop that you want to be there, you crowd out key broadleaf weeds, particularly winter annual weeds, as well as annual and perennial grasses. Planting oats at 100 lbs/ac provides a really nice cover crop that will protect the soil through the fall and will winterkill, allowing easy incorporation the following spring. This is my favorite cover crop strategy for my Orono community garden project, my home garden, and its my best recommendation for gardeners who don’t want to fight with rye that often overwinters and can be hard to kill in the spring without herbicides. A good substitution to the oat crop is to mix in peas at 25 – 30 lbs/acre while reducing the oats by a similar amount. The peas fix nitrogen (N) in the soil and help supply nitrogen the following spring when it’s incorporated. Oats are reasonably inexpensive (usually about $0.50/pound) and while the addition of peas adds to the cost, according to a USDA-ARS fact sheet, if you reduce the oat seeding rate, you can still keep the overall cost under $50/acre.
For some farmers, the continued growth of winter rye in the spring is a big advantage. The plant will pull water out of wet soils, and increasingly people are killing the rye with herbicides and no-till planting corn behind it. This conserves water, which while not a problem this year (ha!), could be in a drier year.
There can be other cover crops that have specific uses when planted before certain crops. We have been exploring the use of specific mustard crops because of their capacity to kill soil borne pathogens before planting potatoes. The thought is that the main mustard taproot can break up plow pans in the soil, and when you incorporate the leafy biomass into the soil, a natural gas is released which is toxic to specific soil pathogenic organisms. Peter Sexton found that potato yields were increased about 10% when following specific mustard cover crops – we call these high glucosinolate cover crops. We recently evaluated summer (season-long) high glucosinolate mustards (HGM) and found that most years HGM did lead to a reduced incidence of rhizoctonia and in some cases, also common scab in red potatoes. The problem with that approach is that farmers often don’t want to give up an entire season of crop production. That is why we have started to evaluate a late summer planted cover crops that we hope will have the same effect. My hope is that farmers harvesting early crops like peas or greens, could come in and plant HGM in late July or early August, produce a lot of biomass, and be able to incorporate that prior to planting potatoes. We are in the process of harvesting potatoes now; we look forward to seeing what the effect of these cover crops will have.
When we think about long-term soil productivity, it sure seems to me that cover crops are an excellent investment. Yes, it takes time to plant and incorporate cover crops, but it is an investment in preserving the soil for generations to come. It seems like we are having wetter fall and spring seasons, and as such I think we have an obligation to cover our soils to protect soil productivity and water quality for the long run.
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