Now is the time to plant cereal rye as a winter cover crop. Cereal rye is a winter annual grass, surviving the winter in all of Pennsylvania and north into USDA hardiness zone 3.

It fits into many crop rotations and has been the most widely used cover crop species in Pennsylvania, as it can be established in the fall after corn or soybean harvest.

It germinates at temperatures as low as 34 degrees and does best on well-drained soil with a pH between 6 and 7, say Extension agronomists Heidi Reed and
Sjoerd Duiker.

When seeded early in the recommended September to Nov. 1 window for Pennsylvania, rye establishes quickly and tillers in the fall, but stays vegetative until spring.

When paired with ample fertility, it has explosive spring growth and can reach 6 feet tall and up to 10,000 pounds per acre of dry matter, especially when termination is delayed.

Dry matter production can still reach greater than 2,000 pounds per acre if rye is seeded late in the window, or even after the recommended window in southeastern Pennsylvania, but only if termination is delayed in the spring.

Rye aggressively competes with weeds and can provide effective weed suppression, especially of winter annual species.

Rye produces secondary chemicals that can be toxic to other plant species, but recent research shows this effect is short-lived (it subsides within about a week of rye termination), and likely plays only a small role in weed suppression.

Rye mulch protects soil from erosion while reducing water evaporation, especially when roller-crimped at termination.

Additionally, rye takes up free nitrogen from the soil, which reduces nitrate leaching to groundwater.

Its large root system helps resist and alleviate soil compaction that can be caused by heavy equipment.

Its abundance of above- and belowground biomass makes it an effective tool to help increase soil organic matter too.

One disadvantage of rye is its high carbon-to-nitrogen ratio when mature (the rye straw ratio is 80), which may cause N deficiency in the next crop.

Further, its aggressive growth in the spring can make it difficult to control at a farmer’s preferred growth stage during rainy weather when fields are inaccessible.

It also consumes large quantities of soil moisture in the spring, which can cause moisture stress during establishment of the following crop in a drought year.

Cereal rye is the earliest maturing of all the small grain species, though there is variability among varieties of cereal rye.

Variety not stated, or VNS, rye is the most affordable option and is widely planted but lacks predictable characteristics of specific varieties.

The optimal seeding dates are from September to late October, but cereal rye can be planted as late as December or January in southern parts of the state.

In the latter case, only spring benefits will be seen as there will be no cover in the fall.

Seeding depth should be 1 to 1.5 inches. If soil conditions are dry, increase seeding depth to 2 inches.

If you are broadcasting after main crop harvest, you can improve stand establishment by following up with a cultipacker or shallow cultivation pass.

The recommended rye seeding rate is usually given as 30 to 120 pounds per acre.

Because there are on average 18,000 rye seeds per pound, you should plant 500,000 to 2 million seeds per acre.

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