Soil Temperatures - March 30, 2023 - Amy Timmerman, Extension Educator
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- [0:01] This is Amy Timmerman with this week’s extension update.
- [0:03] A fall-planted cereal rye, wheat, or triticale cover crop can have both
- [0:08] positive and negative impacts, for example by tying up nitrogen,
- [0:13] reducing soil moisture prior to planting, increasing insect pressure,
- [0:17] reducing weed pressure, reducing soil erosion and allelopathy.
- [0:22] Each year we receive questions on termination timing of cereal covers.
- [0:26] This question occurs as farmers consider trade-offs between a positive return on
- [0:30] investment from the cover crop, by allowing more biomass growth with
- [0:34] the potential for yield loss if termination is delayed too long.
- [0:37] Information being shared can be confusing, with one source saying to terminate
- [0:41] pre-plant but other sources say to plant green into the cover.
- [0:45] What’s the “right” answer? We don’t know if there is one.
- [0:49] That’s because farmers’ goals and level of risk vary.
- [0:52] In general, there are less risks to planting green with soybean than corn.
- [0:56] Today I am going to share items to consider when planting green.
- [1:01] When planting green consider starting with number 1 -
- [1:05] Apply nitrogen as a starter with corn when planting green;
- [1:08] nitrogen tie-up is perhaps a bigger issue than any potential allelopathy.
- [1:13] 2. Wait for the corn or soybean seed to begin germination before
- [1:17] terminating the cover crop (which may be a few days).
- [1:21] 3. Waiting to terminate a few days after planting also allows the rye
- [1:25] that’s been run over by the planter to regrow and kill better.
- [1:30] 4. If irrigation is available, have the nitrogen system ready to
- [1:34] go prior to planting in the event you need to add some moisture into a dry seedbed.
- [1:40] 5. Upon planting the field, scout for insect pressure,
- [1:44] particularly observing if any adult wheat stem maggot flies are present.
- [1:50] 6. For those who wanted the greatest amount of
- [1:53] biomass for weed suppression in soybean,
- [1:56] termination of rye occurred closer to heading.
- [1:59] For those who plan to roller-crimp rye for weed control,
- [2:02] termination occurs at boot stage to heading.
- [2:06] 6. When terminating a rye cover crop, if the cover is 12 inches or more
- [2:10] and you’re planning on a residual herbicide,
- [2:13] consider waiting on the residual as a second pass
- [2:16] over the rye after it starts dying.
- [2:19] We realize no one wants an additional pass or expense.
- [2:23] Observation and research show that less residual gets
- [2:26] down to the soil when cover crops are 12 inches or taller.
- [2:29] How long one waits for the second pass for rye to start dying will depend
- [2:34] on the environmental conditions each year.
- [2:36] The other option if one chooses to add residual when terminating
- [2:40] is to plan on an irrigation or rainfall event shortly after application
- [2:44] to help move the residual herbicide down into the soil.
- [2:48] And finally, Risk Management Agency Guidelines allow for planting green
- [2:53] and are based on “best management practices”
- [2:56] for different zones and for irrigated or non-irrigated ground.
- [3:00] You can read more about this at USDA’s Cover Crops site.
- [3:05] This is for crops with a contract change date of June 30, 2019, or later, beginning
- [3:10] with the 2020 crop year and including successive crop years.
- [3:15] If you have additional questions about terminating cover crops
- [3:19] prior to planting please reach out to your local extension educator.
- [3:22] This has been Amy Timmerman with Nebraska Extension