So, What are Brassicas?
Brassica – what a strange word. It is the common term used to describe the wide variety of plants that are members of the Brassicaceae family. When referring to the cover crop and forage member of this category they can be generalized as flowering broadleaf plants with some form of taproot. There is a lot going on throughout these various types of brassicas. From radishes to rapeseed to kale, let’s see what they are all about.
Above Ground Action
The above sample was taken in September and analyzes the top growth on a radish that was sown in late summer. Things like the moisture content, nitrogen, and trace mineral results show us that this will break down quickly when it dies and release all that good stuff to our soil to feed the soil biology. The information like crude protein, NDF, and TDN tell us that it is going to be highly palatable and digestible to cattle providing a lot of energy in their diet.
The forage quality and soil enhancing quality of this radish top can be carried across many of the brassicas used for forages and cover crops. Many brassicas have been improved for forage quality of their above ground growth. These improved varieties include T-Raptor hybrid brassica, Bayou Kale, Graza forage radish, Barsica rape, Pick-Axe radish, Winfred rape, Hunter forage turnip, and Barkant turnip. All of these have varying specifics for timing of planting and some niche uses but can be categorized as forage brassicas.
Below Ground Action
The analysis of the same radish’s tuber is an excellent example of how brassica roots provide more than physical benefits to the soil. They also pull up and store nutrients such as calcium, phosphorus, potassium and sulfur. As the below ground portion of brassicas decay and break down, they will smell bad, but soil biology doesn’t mind. Your underground livestock are happy to receive the decaying material and will ensure these nutrients are available for any crops following the brassicas.
The physical benefits of brassicas, like the radish, are what is most commonly known about the family. Once radishes began being used as a cover crop to break up compaction, the news spread like wildfire. And it is true: the taproots and tubers on many brassicas will create physical channels through the soil to reduce compaction and create pathways for air, water, and soil life. However, it is not only radishes that will achieve this! Turnips, rapes, and radishes all have varying sizes and depth of taproots that can work to condition your soil. Some of our favorites to recommend are Pick-Axe radish, Barkant tankard turnip, and Barsica rape. Based on a full look at your resource concern and planting time, some or all three of these can be recommended to achieve correction of physical soil ailments.
Many of the above-mentioned brassicas have been bred for specific uses and are improved varieties in the Brassicaceae family. Common varieties of brassicas do exist that can serve as an economical way for you to add diversity of root systems or foliage to your blends. Things like Dwarf Essex rape and Purple Top turnips can fit this role, but keep in mind, these may not be as productive above or below ground as the improved varieties.
Overall, brassicas are a great way to add diversity to a cover crop mix to improve soils physically and through nutrient uptake and release. Many of these improved varieties can also take your grazing to the next level and extend your season. Now that you know all about brassicas, consider where they could benefit your operation!