Farm Talk

January 28, 2014

Cover crops boost yields in MU research

Mark Parker
CNHI

Parsons, Kansas — Cover crops can pack a powerful punch — improving soil health, water infiltration and potentially boosting yields, according to Tim Reinbott, superintendent of the University of Missouri’s Bradford Research Center.

Speaking at the recent Lawrence County Soils and Crops Conference, Reinbott said producers are still paying for a century of tillage.

That, he said, has resulted in a loss of top soil, soil organic matter, and soil microbes while reducing rooting depth.

Cover crops, Reinbott said, promote microbial activity while increasing the nutrient holding capacity of the soil as well as its ability to accept and retain moisture.

“Depending on the situation, you may get as much as 50 percent more water infiltration from using a cover crop,” he said.

Reinbott has also seen a positive yield response in crops following a cover crop planting.

In 2013 at the Bradford farm, several cover crop mixes topped the no-cover-crop plots in soybean yield. The covers were overseeded into corn the previous September. The control plot yielded 29 bushels per acre while beans following a cereal rye cover crop yielded 36. Crimson clover and rye also boosted soybean yields (by 5 bushels) while other combinations yielded at or near the control plots.

In corn following cover crops, crimson clover and rye ahead of the crop gave a 12-bushel advantage, hairy vetch was 24 bushels higher while most of the other covers yielded roughly the same as corn not following a cover crop.

Reinbott emphasized, however, that cover crop species have different attributes and characteristics. He urged growers to consider those factors when selecting a species or a mix.

Cost is another factor. Grasses, such as cereal rye, are fairly inexpensive — roughly $14 to $21 per acre. Some of the legumes, however, can cost about twice that amount, Reinbott said.

He also pointed out that corn growers especially will need to consider how cover crop er adication timing impacts planting. Some spec-ies, he said, may not get their maximum growth — and maximum nitrogen contribution — until late May which would interfere with corn planting.

Some of the cover crop species he described include:

•Hairy vetch — Big producer of biomass — as much as two to three tons per acre — with the potential to contribute a large amount of nitrogen to the soil. Planting window: August through mid-October. Drawback: produces hard seed and could interfere with a wheat rotation.

•Cereal rye — Very economical and winter hardy. High dry matter. Good weed suppression and deep rooting. Good in a mix with a legume.

•Crimson clover — Blooms early enough in the spring that it fits in well ahead of corn while getting enough growth ahead of eradication to contribute nitrogen. Plant August to September. Not as much biomass as hairy vetch.

•Tillage radishes — Tre-mendous roots that loosen the soil, reduce compaction and increase water infiltration. Winter kills, may suppress winter annuals and sequesters nitrogen.

•Austrian winter peas — Large biomass producer and can fix 80-120 lbs. of nitrogen per acre. Can be planted in fall or early spring. Not as winter hardy as some other legumes and may have seedling disease problems.

•Oats — Good companion crop with quick fall growth. Will winter kill.

•Triticale — Same hardiness of cereal rye with good forage potential but does not have the alleopathic potential of rye.

Although annual ryegrass offers many of the same beneficial characteristics as cereal rye, such as deep rooting and high biomass, it’s on Reinbott’s “Do Not Plant” list because it can quickly become a weed problem with potential herbicide resistance issues.

For the legumes, Reinbott cautioned that each species must be matched with a specific inoculum.

Regarding planting, he said his best results have been planting directly into the standing cover crop and then applying a burn-down herbicide prior to crop emergence.

Although cover crops are most often thought of as filling in the fall to spring gap, Reinbott noted that there are summer annual legumes  such as cowpeas, sesbania and sunn hemp that can be used to gain some nitrogen benefits between wheat harvest and frost.

He also said cover crops may be especially appealing to crop producers who can utilize them for grazing livestock, pointing out that they may offer very high quality grazing opportunities.