I discovered in a bean row this year a variety which expressed somewhat unusual leaf shape, more pointed than usual, and from a distance they looked almost a bit ruffled. So I've been working on finding a expert in my area to have a look at them. Turns out the individual in my area is on leave right now, but I did eventually find a bean agronomist/specialist who could help me out, as well as the team they work with. They are employed by the government to work in conjuction with commercial bean growers (some agriculture here is not free market as some crops are automatically 'sold' to government) in regards to plant diagnostics, and all manner of angles to increase bean yields and assess problems. Research and development is involved as well in what they do.
@Bluejay77 mentioned it might be helpful to share some of what I've learned from them, for anyone who may be interested. I am still sorting through all of information, but I picked out so far a few tidbits I thought were interesting to post here.
I have never fertilized my beans, mostly because my understanding was that beans are capable, for the most part, to fix their own nitrogen. And there is a strong sentiment in books etc. that it is easy to overfertilize beans and mess up your harvest. However, a recent study they shared with me showed that beans are able to fix anywhere from 11-75% of the nitrogen they require. Not nearly as much as many people think, myself included. Being such a wide range, they feel an application of nitrogen to bean crops is necessary. But it isn't a simple initial fertilization in that the when and where really matters.
So, for the first 30 days a growing bean plant will uptake less than 20% of all the nitrogen it will use in its life. But after 30 days the bean plants uptake increases really, really quickly. At the 45 to 50 day mark (from planting) the maximum daily uptake of nitrogen peaks. It's kind of amazing how they've literally got so fine a point on all this. An initial fertilization at an early stage wouldn't be very effective given it wouldn't really be used up for another month, if it didn't leach away with watering.
Another noteworthy point is that commercial bean growers turn in stems and foliage at seasons end back to the soil. I mention this because probably most of us compost the plants, or dispose of them one way or another, but we are removing them from our garden. They tell me this because if you look at their charts of how much various nutrients are returned back into the soil as a result of doing this it's quite surprising. 65% of the nitrogen is returned, among many others some of which return up to 80% of a given necessary nutrient. All the more reason to consider adding nutrients after several years of growing beans in an area where the plants are not turned under.
On the topic of crop rotation in a garden in regards to beans - not a good idea they say. Keep your beans in the same spot. Here's what they explained to me; the bean plant roots colonized by mycorrhizae (VAM) access a greater amount of soil, and this helps in extracting both water and greater nutrient levels. However, nutrient intake with regards to health and vigorous plant growth is most associated with P or Z uptake actually. When beans are planted where no beans have grown before, or other VAM fungi crops, the zinc uptake is lower. No matter how much Zn fertilizer is applied, the bean plants cannot take it up. So, in a garden better to plant beans in the same area if the beans are a priority crop for you.