Offset the hitch, plant down the field to the north, your rows will be 3.5 inches offset to the west.
Turn around at the end, come back in the same wheel tracks driving south, and now the rows will be offset 3.5 inches to the east.
This will give you a 7 inch spacing between the rows, centered on the normal 30 inch (or even 38 inch, whatever your planter is at) spacing.
If you have straight rows, it is pretty easy to duplicate the wheel tracks the 2nd pass and come out pretty good. But no, not always a perfect deal, I understand.
As of 5-6 years ago, the twin row planters were not indexed to each other, they did not stagger the seed drop in a zigzag. Great Plains rep said in tests it was not important, just the 7 inch spacing gave the corn roots more room. Actually if you understood what he was saying, they hadn't figured out a way to make the perfect stagger.
Any time you increase the spacing between corn plants - going from 40 to 30 to 20 to 15 inch rows - you can then increase the planting population a tad, and increase yields. Those increased yields need more fertilizer tho. Dad used to plant 18,000 population on 40 inch rows. I am trying 35,000 on 38 inch rows which is heavy; I understand those on 22/20 or 26 inch rows are near 40,000 population.
Anyhow, that is how it works here in normally water-rich southern MN.
Corn doesn't like shade when it is small, at that 4-5 leaf stage as it sits and builds it's root system. Weeds or other corn next to a plant of a taller height messes up that important growing period, the corn will abandon it's root building and try to grow taller, which makes for a poor corn plant the whole rest of the season.
This is why very accurate seeding depth, and good placement of one seed to the next will - in theory - help final yields. If one plant is shallow, another is deep, one comes up early and the later one to emerge will never amount to it's full potential, it will feel crowded and shaded by the older plant.
Likewise, corn planted in clumps with bigger gaps between them will struggle to dominate each other rather than focus on growing their best root system and reach best potential yield.
A corn planter with a good seed placement system - like a 7000, or a Case 900 or newer - will do a lot more for you as they can be set to do really good seed placement.
After that, if you can spread out the plants so they have more available area to draw nutrients from - as 15 or 20 inch or twin row setups do - then that too will increase yield.
I'd work on the better planter first I guiess, from what you say you have available. Better depth control on planting corn with a finger meter made a heck of a difference for me.
Twin row is interesting, but I don't think the results from a grain drill will be worth bothering with - seed depth and seed to seed placement will be more important than 'just getting any old planting system' to make twin rows 6-7 inches apart... You will lose more from the poor seed placement than you will gain from the twin rows.
Then of course we try for perfection, and monther nature messes us up with a flood or drought or both.
Ah, farming.
I like this discussion, and your thinking on twin rows. But I don't think there is a cheap way to do it well, and if it's not done well, it's probably not worth doing. Effort is better spent on getting the other things up to par to start with.
Again, what I see for my micro region 'here'. Other climates/ locations can be quite different, and what I do or see could fail miserably 'there'.
--->Paul
