Yellowing soybeans

[RedDirtFarmer]

This is the first time I've ever grown soybeans, as there is no market in my area. Will need to haul them this fall quite a distance.

My pH is in the high 7's and the area is fully irrigated. We're capable of growing 275 bu. corn. The south 40 acres is a darker green, but the north 40 is considerably lighter in color, with a yellowish green tint to them. I'm thinking they're similar to corn as they get a little yellow when deprived of sunshine and the ground is holding moisture well.

We're getting some 90 degree weather now, so the next few days should help. I heard soybeans don't like "wet feet" so am thinking maybe I irrigated them too much, too early.

Any thoughts? Thanks in advance.

[Blacksandfarmer]

It sounds like you could have a manganese deficiency or possibly soybean cyst nematode. If it is a manganese deficiency you can add some manganese with your roundup and take care of the problem cheap and easy. If you have cyst nematodes you may want to consult your local agronomist for suggestions.

[Blacksandfarmer]

I must have missed the part about irrigating your beans already. We have many farmers in my area that have irrigated soybeans but they only irrigate this early if we are very dry. Typically guys with irrigated soybeans don't irrigate them until pod fill. If it were me I would give those beans a week to see if they come out of it.

[Pupdaddy]

Because it's your first year growing soybeans..I don't think you have any nematode problems yet. I would guess manganese deficiency..barring any explanation attributed to the irrigation. Manganese becomes harder for plants to absorb at pH's above 7...so yeah, you might be seeing it. I believe some soybean varieties absorb manganese easier than others...so that might account for one field looking greener than the other. A shot of chelated Mangenese can't hurt...and it's not very expensive. Some guys apply it along with their glyphosate....but if you've got "severe"  deficiency symptoms..you might want to do it several days after the glyphosate application.

[Nebrfarmr]

Unless the beans are actually showing signs of drought stress, it is best to wait to water them until the first blooms start turning to pods, and then again at early pod fill, and after that as needed.  If you irrigate too early, they seem to grow big and bushy, but don't seem to really yield any better.  Wet feet when young will cause yellow beans, as well.  If this is the case, a couple days of sunshine will take care of it.  If the innoculant didn't 'take', that also can cause them to be pale.  Around here, we don't have PH issues, or mag deficiencies, so I don't know much about that.

[Pupdaddy]

I forgot to mention another thing..all soybeans don't quite have the same color..some may be slightly greener than others. But Manganese deficiency is pretty easy to spot. With your pH...a yellowing between the veins of the leaf is probably the best indicator of it being Manganese. Some other deficiency's exhibit the same symptom...but with high 7 pH's...it's more than likely the Mn....