Tuesday, December 22, 2015

What are the Benefits of Cover Crops?

Cover crops have grown in popularity over the last several years, and they will (undoubtedly) continue to grow in popularity. Why do people consider cover crops? What are the benefits?  A few key benefits come to mind when discussing the subject of cover crops.

Cover crops act as a green manure for crops. They assimilate nitrogen and other nutrients in the plant (such as phosphorus and potassium). This removes those nutrients from the soil environment where they might be subject to loss. For example, grass cover crops have been shown to reduce nitrate losses by 75 to 95%. This ability to sequester nutrients becomes particularly important for nitrogen and phosphorus which can move downstream into the Gulf of Mexico. Legume crops (vetch or crimson clover for instance) go a step further. While they assimilate nitrogen, they also take nitrogen from the air and fix it into a form the plant can use. The green manure properties of a cover crop have sometimes resulted in several to a couple dozen bushels of additional yield where corn follows a cover crop (depending upon the cover crop).

Cover crops also provide soil-related benefits. The root systems of cover crops physically hold soil particles in place during storm events. This reduces sheet, rill, and gulley erosion. Tilled cover crops may reduce soil erosion by as much as 50 percent with no-till cover crops sometimes reducing erosion by 90 percent. Decomposing cover crops also form organic compounds that promote granulated soil structure, improving soil silth. The resulting pore space provides an improved avenue for gas exchange, water storage, and root penetration, while taming down the likelihood of compaction. Cover crop material can also form a buffer that reduces evaporation thus conserv- ing soil moisture for the crop.

Cover crops can assist with weed control. The weed control properties of a cover crop primarily stem from cover crops shading the soil. This reduces seed germination which decreases weed competition for water, nutrients, light, and space. While shading plays a primary role in reduced weed pressure, some cover crops species produce allelopathic chemicals (chemicals that inhibit weed seeds from germinating, etc.). It should be noted that cover crops are not usually a standalone weed control option. They are best used along with a vigorous weed control program.

These benefits often eclipse the downside of using cover crops (trash-related planter issues, occasional yield penalties when corn is preceded by a grass cover crop, occasional issues with tied up nitrogen and herbicide resistance concerns). - Matt Montgomery, Burrus Sales Agronomist

Cover Crop Resource Guide http://crops.missouri.edu/covercrops/

Kevin Burrus, of Burrus Seed Farms shares his experience with cover crops.

Covers have been a nice fit for our seed corn rotation, due to early harvest of the seed corn, which allows for timing planting of the cover, we are realizing the full benefit of cover crops. Less residue with shorter stature inbred corn plants has been a challenge for soil tilth and erosion control, and covers have fixed both of those issues. The other benefits we have noticed are weed suppression and capturing residual nitrogen. All of these beneftis take management, and we have learned some of cover crop lessons the hard way. I feel like net, they have been a benefit, but understand they carry risks as well. - Kevin Burrus

Monday, December 14, 2015

What you should know about LibertyLink® Soybeans

We now know there are no new herbicides with different sites of action in the pipeline, so many growers await the approval of the introduction of soybean varieties with various herbicide traits.  For now, we are fortunate to have LibertyLink® soybeans.  In recent years, their sales have skyrocketed.  The Burrus/Hughes lineup of LibertyLink soybeans is:  Hughes 236LL, Hughes 266LL, Hughes 285LL, Hoblit 355LL, Hoblit 384LL, Hoblit 405LL, Hoblit 423LL, and Hoblit 456LL. The use of Liberty® or glufonsinate, a contact herbicide, along with the Burrus LibertyLink soybeans lineup, can be an effective tool to combat weeds like waterhemp, that can be resistant to other herbicide groups.  Burrus LibertyLink soybeans also offer yield. 

We continue to teach our growers how to achieve successful weed control with a LibertyLink system:

  • Before purchasing LibertyLink soybeans, check with your ag chemical supplier to make sure there will be an adequate supply of Liberty herbicide available.
  • Start weed free – Fall/spring burndown or tillage might be needed to rid fields of weeds before planting.  “Never plant into a stand of weeds, hoping for the best.”
  • The use of a full-rate of a preplant residual herbicide product will help to reduce weed populations, slow weed growth, and offer more flexibility on when the post application of Liberty can be applied.
  • Thorough weed coverage is key, when it comes to the application of Liberty because it is a contact herbicide.  Better coverage with Liberty can be accomplished by particular nozzles (flat fan or others) that provide medium spray droplets (250 to 350 microns), with higher pressures (40 to 60 psi), at slower application speeds (12 mph or less), with the addition of lots of water - 20 GPA), along with adjuvants such as 2.5 to 3 lbs AMS per acre.
  • Liberty is rainfast within 4 hours.  Be sure not spray Liberty at night or under adverse conditions (fog, heavy dew, rain or stress such as drought, cool temperatures, and extended periods of cloudiness). Spray Liberty after dawn and 2 hours before sunset to avoid the possibility of reduced weed control.
  • Apply the first post Liberty application (rate of 22-29 fl oz/A) 22 days after crop emergence or up to V3 soybean growth stage, before weeds reach a height above 3-4 inches.  The higher rate (up to 36 fl oz/acre) of Liberty might be needed if environmental conditions prevent timely application and weeds are 6- 10 inches tall.  However, an application of more than 22 oz. of Liberty is not recommended past V4 soybean growth stage.
  • A second post Liberty application (rate of 22 to 29 fl oz/acre) can be applied if needed, but keep in mind that your total use rate of Liberty cannot exceed 65 fl oz/acre.
  • The first and second applications of Liberty should be at least 5 days apart.
  • Use a full rate of a post residual herbicide with your post Liberty application if needed for harder to control weeds such as amaranths.