>> Rick, there is a tree about 30 feet? away? and I have had to clear out some roots but the roots would be about 2 feetish down and very small so I don't know how much they'd be bothering them.
I agree with you that those tree roots don't seem likely to compete with pepper plants (at least not until they are fully mature). The "2 feet down" is more protection than "30 feet away"! If anything, the tree roots would help remove excess water! If you weren't irrigating so much, I would suspect tree roots of stealing needed water.
Maybe maybe (probably not) maybe, tree roots are drawing water down faster right there than elsewhere in the bed. If your N was mainly soluble, it MIGHT be leached out faster by frequent irrigation over thirsty tree roots. Probably not.
This site found that pepper roots in their experimental field didn't go below 2 feet until after 2-3 months old and into fruiting. Even then, most of the root systems was in the top 24" of soil.
http://www.soilandhealth.org/0...
"the bulk of absorption during the early life of the plant occurring in the surface foot of soil. When the flower buds appear, the root system thoroughly fills the soil 1.5 feet on all sides of the plant to a depth of 1 foot. Beneath the plant the second foot of soil is also quite thoroughly occupied. Mature plants have a lateral spread of 3 feet, the formerly horizontal laterals often turning downward into the second or third foot of soil. More oblique or vertical roots reach depths of 3 to 4 feet."
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"Hence only shallow tillage should be employed"
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Might you have hoed some weeds a little too deeply around the yellower plants?
>> The two I took out the root balls were very small actually, I was very surprised that they hadn't gone too far out of the planting pot size that they were originally.
My first guess was that the soil was too wet and not aerated enough for roots to spread easily, but I always suspect that. You should take that theory with a pinch of salt. I think I have an "overwatering feetish". ;-) The rest of the bed looked happy, so "waterlogged soil" seems unlikely.
P.S. Googling "pepper plant root system" brought up many images.
