First, citrus trees have surface roots, so they do not have to watered deeply. Their roots are out at the drip line, the area where the outermost leaves are. So you may want to adjust your watering.

Second, yellowing leaves are usually a sign of iron deficiency which citrus tend to have. You can add iron (Ironite) as a granule or foliar spray.

Third, you want to fertilize your citrus three times every other month (if you're using chemical fertilizer) starting around Feb/March depending on where in SD you are. I prefer an organic fertilizer which can be used at any time. I would stay away from Miracle Grow especially.

Fourth, last year was a strange weather year. My mandarin and navel trees were particularly off. So, it may just have been the weather that caused your lack of fruit.

Lastly, you can prune the trees however and whenever you want. Some people say that fruit trees should only be as tall as your arms can reach.

Hope this helps and good luck!

My Grandpa read that if a tree thinks it is dying, it will produce. He had a Meyer Lemon that didn't bear fruit. So, he took a knife and cut a semi circle of bark off that trunk. Amazing!! It still produces to this day! Grandpa is dead now, but his production theory has stuck in my brain! This tree is in La Crescenta, CA.

bud/bloom drop is usually due to temperature changes (ex. a really hot week in spring that changes back to colder temperatures) or uneven watering.
My Grapefruit is particularly sensitive to the rapid temp. changes in spring.

wanda

Be sure you are using "citrus" fertilizer. They need very specific trace minerals to flower, fruit and ripen.

Fertilizing is definitely very important! My mom purchased a lemon tree a while back, and never once got fruit from it. The nursery suggested we fertilize it, and shortly after I did so, it blossomed and is now setting fruit!

Be sure to get citrus fertilizer.

Your soil you say is rock hard and on a hill. Rock hard soil is usually also compacted and lacking the air the roots require to take up water and nutrients. Right now I would mulch with finished compost from an inch or two from the trunk out beyond the drip line. Three or four inches of compost with the winter rains would add nutrients and earth worms and help relieve the compacted soil. I also agree with the other posters that you need a regular fertilizing schedule. Al

Good advice from Al and others regarding watering, mulching and fertilizing, and keeping soil moisture consistent and not letting it go too dry helps with getting good, juicy fruit. As to pruning, I would suggest that you do it in stages if you want to reduce the height of trees over all. I'd suggest that it is safest to only remove a third or less of foliage at any one time. You might also consider thinning out the center of the tree to make it easier to climb into it to pick ripe fruit. Be aware that exposed citrus branches that were formerly densely shaded can sunburn badly and damage the bark, so any heavy thinning is probably best in cooler months so the trees have a chance to acclimate without getting damaged by hot sun.

Adding a deep organic mulch and perhaps drip soaker lines in a spiral pattern below the mulch is a good way to give them more water without wasting it.

This is my citrus problem ! Since the ground has always been copmpact and my luck all rocks except for the large planting hole I've always sprayed the leaves before the direct sun with various products including Kelp and Ironrite.
My question being was that I used Supersoil compost, coffee grounds and worm castings along with bone meal mixed into my garden soil where the flowers are but now that ground too is rock hard with a brown root or mossy covering which must have come from the compost but it is amazingly hard to even shovel and I wouldn't want to harm the rose roots. Is mulch a good thing this time of the year before the wet season. I'm sure all the nutrients must be sitting on top of this compacted whatever. debbysunshine@hotmail.com

Debbie, our ground is also rock hard and full of rocks as well. (I've hauled about 5 buckets of rocks/concrete/roof tiles out of the areas I've been working on amending and I still have most of our property to go!)

Even just adding compost and organic matter on top (but not too close to the trunk) will improve the soil (and help retain moisture). Adding it during fall is the ideal time, since we actually get some rain and things break down faster. Eventually, the worms will come and start mixing everything up for you, it just takes a little time!

We used to have no worms around. We took out some large trees out front a little while ago, ground them up, and put that material on top of our soil. The top few inches are now a deep rich black, and very crumbly, and we have quite a few worms out front now. The same thing will happen to your mulch :)