I grow corn directly on my blacktop driveway. I have what is an area surrounded by 6x6 landscape timbers about a foot deep. It's about 6ft x 8ft. When I cleaned my raised beds out, the poor/clay soil was deposited into this "corn bed" plus some left over straw, both on the bottom, maybe 3-4" worth (maybe an inch or so straw.) Over this I added about 8-10" of municipal compost that had a rating of around 1-1-1 or so (P & K were less than 1, N was around 1.1.) In this bed I used drip irrigation between rows. I started this bed about 2-3 years ago. I may have added some granular & some super triple phosphate back then. Everything grew great, corn was often 7+ feet for varieties that were listed as 6.5ft, and many were 2 ears for varieties that give 1 ear. At that time I started my corn in 3.5" deep pots indoors & transplanted them when they were about 4" tall.
Last year, I freshened the bed with about an inch of compost & planted crimson & kenland red clover a little late and decided to use it as a living mulch, planting right thru it. The clover had a head start on the corn and started getting vigorous and I pulled some making narrow rows N-S & E-W, thru the clover. I then used a bulb planter & made planting holes about 5" deep & filled with a mix of compost & Pro-mix & planted seeds for the corn instead of transplants. It was tough keeping clear spots in the clover as thunderstorms & wind blew the clover around often shading the corn sprouts. So some got devasted by leafhoppers & other pests living in the clover. BUT, I still had a decent crop, though not a full grid. Keep in mind I plant close & grow about 60-70 plants in this 6 x 8 area (it's not a perfect rectangle due to a large 20+ gallon container of beneficial/companion plants in one corner. I thinned most plants down to 1 plant from 2 or 3 seeds planted, and still had around 40+, even with the plants lost.
Last fall, in an attempt to freshen the beds, I started collecting coffee grounds from Starbucks to add to this bed plus a raised area of the same type compost I use to grow AG pumpkins. In the fall, I added a bunch of bags & raked it level, and wherever clover was left that stuck thru I pulled it & added it instead to a separate compost drum. The next raised bed over, the soil wasn't the best so I started adding layers of shredded leaves, coffee grounds, leaves, coffee grounds, etc, followed by a single layer of the filters spread out and another inch or so of grounds to hold the filters down. I had a lot of grounds, collecting them 3 or 4 times/week for a few months, including the other stuff they sell (capuccino?) I even partially covered a 2-3 yr old bee balm plant mound to where the stems were still visible thru the grounds.
In the spring, come April/May (I'm in Buffalo & there's still snow in April here) I started to fork the corn bed and add more grounds. Maybe after all said and done, another couple inches. I didn't have a way to keep track, as the bags of grounds often had other stuff in like plastic knives, cup lids, empty packets, filters, etc and the weight of the bags are pretty heavy so they only stick 4-5" of grounds in a doubled garbage bag. Also, the unused grounds were left in their bags over the winter, often covered by snow. They covered an area about 6ft by 3-4ft by as high as 3ft tall.
When it was warm enough to work the soil, I forked stuff in the best I could and somewhere around the beginning of May or so I started getting it ready for planting. When I forked near the very center of the bed, down deep hitting the clay base soilmix, & turning it over, it steamed on a rainy 50 degree day. I checked other spots but that was the only area, maybe there was more straw there and it was heating. I turned it a few times til the steam disspated and a few days later there was no more steam, and I tilled it the best I could with a Ryobi tiller attachment. I worried there was composting going on so used a thermometer that went down about 6" and I think the temp was around 60-65. I didn't have any compost yet this year so I cut holes with the bulb planter and filled with damp Pro-mix and pushed in 3 seeds in each "hole."
Backing up a bit, to last Fall, Parkseed had a Fall seed sale and I bought 4 or 5 varieties, mostly triplesweet & supersweet types to avoid cross pollination problems. I personally don't have any way to know how old the seeds are. The seeds were stored at room temp over the winter, and come spring when I opened them, I found some tiny bugs, maybe thrips or something, maybe 1/16th inch long & very narrow. I threw out any seeds that looked like they were "tunneled" and started putting them into plastic sealed bags. When planting time came, I only used seed that looked good with no damage. The seed was untreated. I planted Serendipity, How Sweet It Is, Honey Select, and Honey & Pearl.
I started planting on 5/8, and within a week or so many of the corn sprouted. I actually planted 1/2 the bed, waiting 4-5 days & planted the 2nd half with a different variety. The leaf/coffee grounds raised bed I did likewise on 5/16, again staggering planting & varieties.
The 2nd half of the 2nd bed NOTHING sprouted (Honey & Pearl, a 1988 AAS winner,) and on 5/23, I replanted the blank spots in the first bed. I replanted the 2nd bed's blank half with Butterfruit on 6/10. The Butterfruit sprouted within a week or so, about 15 of 20.
Going back to the bed on the driveway, I planted some onions started indoors as well as a couple types of beets around the edge. The other onions sat in cells for another week or so til I planted some in 5" pots. ALSO, on 5/12, I scattered some mesclun & lettuce mixes in the same bed, as well as arugula & a few other lettuces, and on 5/22 I cut more holes & filled with Pro-mix and planted 3 types of melons & 3 types of watermelons. I also planted 2 seeds of a 182 pound watermelon that won 1st place at IPGA weighoff, but directly into the bed without using any hole filled with Pro-mix.
The drip irrigation is set up with a line running between 2 rows of corn, but not between every row; in other words, 4 rows of corn have 2 drip lines instead of 3 lines. The lines have emitters built in every SIX inches.
SO HERE'S THE PROIBLEM(S):
Today, the corn in the driveway bed is from 6" tall to maybe 16" tall, depending on if originally planted or if reseeded. (Others in my area have corn 4ft tall.) The lower leaves are brownish golden-maroon, with maroon stems near the ground (on the Serendipity at least; How Sweet It Is is greener.) The tallest corn is around the edges. The clover grew back along one edge but is flowering PINK not red, and the few beets that did sprout are solid maroon and about 4" tall. (Many sprouted green but died off after the initial true leaves.) The corn in the 2nd bed (the bed with the leaves added) is about the same size but more uniform, maybe 12-16" though started 8 days later, and the half started 6/10 is anywhere from 6-12" tall.
The onions that were transplanted to the driveway bed are about 4" tall with brown dried tips; the ones planted in last year's reused soilmix in 5" pots are about 12-14" tall.
The lettuce mixes initially sprouted but died off. The only lettuces that are growing are the ones that ended up over the Pro-mix soilless mix. Some are 6-8" wide or tall.
The arugula sprouted but the seed leaves turned brown and died off.
The melons sprouted but are no bigger than a foot long vines or so. Likewise for the watermelons. And the seeds from the 182lb watermelon NEVER SPROUTED..
The Bee Balm, a perennial, never returned.
WHAT I CHECKED:
I checked the pH with a $30 meter and pH was 6.2. (I have 2 different meters & both were within 0.1 of each other.)
The moisture was about 3/4 scale on the meter, towards the wet, not dry. We've been getting rain regularly, or even more than regular amounts.
The fertility reading on the meter was 1/3 scale, on the border of "Too Little" and "Ideal" on the scale.
The texture of the soil was hard to describe but black, sticky/staining.
WHAT I DID:
Got compost. Added about an inch or so to the surface; took a fork & stuck it into the bed & repeated, making indentaion holes all the way down the row and across the rows between all the corn plants, tried sprinkling compost into all the holes & watered in.
Used water soluble 15-15-18 with minors; my drip system has a fertilizer injector and I water nearly every day and the fertilizer injects whenever the water runs thru, though at a very tiny amount, like 1/8 the rate. Also calcium nitrate (15-0-0) and Maxicrop seaweed 1-0-4 thru an Ortho hose end sprayer.
Called my local Extension Service. Got an old timer with a hearing problem, had to hold the phone away from my ear, that told me to buy some 10-10-10, and that 6.2 was too low a pH for corn. After getting into some of the details to him, he said don't add anymore coffee grounds or peat moss.
Coffee grounds can be used as a soil conditioner without composting first; the acidity of the grounds is usually washed away in the boiling water brewing process.
Obviously the problem has something to do with the coffee grounds but better results are in the 2nd bed, which I didn't till but was more lasagna style of grounds & maple leaves.
DID THE COMPOST RUN OUT of nutrients and is down to just woody matter? The N in the coffee grounds is composting the woody matter & any remaining straw? Why didn't the bed turn hot the last two years? The woody matter is tying up the N from the grounds and taking it away from the corn?
IS THE RAIN washing the N down to the straw & woody matter? Is the coffee absorbing all the water & not drying out enough, hence "overwatering?" Is the asphalt of the driveway reacting with the coffee grounds & giving off other chemicals?
What are the NPK of coffee grounds? (One edu site said the P was in the 30's I think & sounded too high) Can I flood the bed to leech off the coffee grounds' N? Does this look like an N or P deficiency? excess? Can I add more compost & water it in?
I could probably go on & on...
I already know a soil test is recommended but don't know if that will help at this time of the season.
ANY HELP IS GREATLY APPRECIATED; THANKS for any comments/help.