Bob mixes have their niche, but often have much bigger problems. Some of it boils down to matching the with planting techniques and methods. I don't use BOB mixes but that is largely driven by the huge cost differential when you are working at scale. I mix my own. Yes, there are times when I really want a very even seed distribution on a small field. In that case, I broadcast the seed by hand from a chest mount (solo) spreader where I can control the amount with fine granularity. Because walk and crank speeds vary, I always set it low, make a first pass, and then open it more and make a second. I broadcast each seed component individually. It takes a lot of time and is only practical for tiny fields.
When I planting larger fields (1 acre plus), I don't have the time or energy to do this. For mixes, I use a broadcast spreader behind my tractor. Most mixes I use have a cereal grain (usually WR) component. It acts as a carrier for small seed like clover or brassica. The settings on a tractor mount broadcast spreader are usually too coarse for low rates of small seed. Here is how I mix:
My broadcast spreader will handle around 100+ lbs of WR easily. I first measure out the small seed for the field and put it in a bucket. I will then put 1/2 a bag of WR into the broadcast spreader and I'll put about 1/4 of the bucket of small seed on top. I'll then add the rest of the bag of WR and follow it with the next 1/4 of the bucket of small seed. I'll then use my arms to reach in and mix that seed well. Don't mix too much or as 4Wandering says, the small seed will go to the bottom. I then add another 1/2 bag of WR, the next 1/4 bucket of small seed, the rest of the WR, and the rest of the small seed. I then reach in and mix that top half of seed.
I set the opening to give me under broadcast 100 lbs/ac of winter rye. It took me a couple tries when I first started to get this setting based on tractor speed. This lets me make one pass and have some leftover seed. I then just run randomly across the field to spread what is left in the spreader. A broadcast spreader has an agitator. If you spread seed at too low of a rate (opening too small or tractor too slow), the agitator operates much more over an acre. This over-agitation can cause small seed to go to the bottom. However with the tractor moving faster and the opening wider, there really isn't time for this to happen.
In most cases, I'm happy with the results of this technique and it saves a lot of time. The key is to start with the seed well mixed and use a high rate cereal component a the carrier.
Most of the seeds we plant for fall don't require depth. They can be surface broadcast just fine as long as they get good seed/soil contact and rain. This is much better for your soil than traditional tillage and dragging to cover. If any of your seed is planted to deep you have tilled much deeper than needed. At most, we need only to scratch the surface a bit for most fall seed.
Google "Ray the soil guy" and watch some of his videos regarding the impact tillage has on soil health and then read some of Crimson and Camo's throw and mow threads for techniques for small equipment plotters. Minimize tillage. Most fall seed does not need to be covered. if you are going to till to scratch the surface, broadcast the seed first and then lightly till (top inch or less). This will give the seed sufficient seed soil contact. Broadcasting through a standing crop and then mowing it requires no tillage. The seed falls to the bare ground under the standing crop (with good initial weed control) and then the crop is mowed to form a mulch on top of the seed. For some crops like soybeans, you can leave them standing. If you get the timing right, you broadcast seed as the leaves yellow and it falls to the ground. The leaves then fall forming the mulch and you have a fall cover crop growing under the standing bean stalks with pods attached. The best of all worlds as the dying beans release N for the fall crop.
You can't throw and mow through things that form turf like fescue, but it is a great technique that promotes soil health and nutrient cycling.
Many large seeded warm season annuals (beans, corn, sunflowers, etc.) that are planted in the spring are a different story . They don't surface broadcast well. They do need some amount of depth to germinate. The best option for these is a no-till drill. It preserves soil health while providing sufficient planting depth.
As for seed predation, we have great turkey populations and I have not found that to be an issue when sufficient much is present after mowing in the fall. Turkey move as the feed and while they will eat some of the larger seed, you can easily compensate for this by upping the seeding rate for WR in the mix. Most of the smaller seed is not an issue with this technique. I have had turkey dig up drilled soybeans in the spring but again, when working at scale, it is not enough to impact my results significantly. The biggest seed predation issue I've seen is when trying to frost seed on top of snow. In the winter small birds are short on food sources and clover seed sitting highly visible on snow can be predated.
Thanks,
Jack
