Pennsylvania Cover Crops: Is This the Year to Plant Green?

Planting green into cereal rye. Photo: Heidi Reed, Pennsylvania State University

Farmers focused on getting the best establishment and maximum benefits from their cover crops chase the combine with a drill in a normal year, seeding cover crops as soon as possible after harvest. However, the priority shifted to just getting main crops off the field between raindrops last fall.

The plan to use cover crops was abandoned for many fields due to uncooperative weather, but some were still planted when time and field conditions allowed. Nonetheless, the opportunity to plant was postponed until later than recommended on most acres. For instance, cereal rye, our most winter-hardy cover crop, should be planted between September and November 1, according to the Penn State Agronomy Guide. Personal communication with growers disclosed that wheat or rye planted after Thanksgiving and into December was not uncommon.

Windshield scouting by agronomy educators around the state has thus revealed a disheartening, if expected, trend—less green than usual, and a lot of mud. Those cover crops that did survive the winter despite late planting are more sparse and smaller than usual. Some will fill out, providing essential protection for soil this spring. However, getting substantial ground cover before burn-down time will depend on good growing conditions through April.

One spring cover crop management option for those who want more out of their measly covers is planting green. Planting green is when the main crop is planted into a living green cover crop, as opposed to the more common practice of preplant-burndown a week or more before main crop planting. Planting green allows additional time for cover crop growth in the spring, when cover crops are growing most vigorously, and could be a way to compensate for poor establishment tied to late cover crop planting dates last fall.

Planting green is gaining popularity but has not been extensively researched. Researchers at Penn State recognized the need to provide growers with data to inform their management, so they studied the practice for 12 site-years with corn and 14 site-years with soybean from 2015-2017.

Results showed several benefits of planting green, including significant cover crop growth and biomass accumulation; drier soil at planting; soil moisture conservation later in the growing season; and no difference in soybean yield compared to the preplant-killed cover crop treatment. This could translate into improved soil conservation; better planting conditions in a wet year; and enough soilwater to help a crop through in the event of a summer dry spell.

If we get a wet spring like last year, planting green may be a good way to adapt to make the most out of a challenging situation. There are some management changes that growers should be aware of when planting green, and we recommend reading the full research summary linked below for more information.

For details on planting green with corn and soybeans in Pennsylvania, see Planting Green 101: Penn State Research Summary, summarizing 3 years of Penn State research.

Then, to help us improve our programming, take our 6-question, anonymous survey on planting green.

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