There's little difference between 2:1:2 and 3:1:3 when your focus is to limit the amount of N you're supplying. If you just reduce the amount of 3:1:2 ratio fertilizer you're supplying in order to induce a mild N deficiency, you're going to get a K deficiency to go right along with it. The extra K included when you cut back on the dosage of N prevents that likely K deficiency. When the ratio is 3:1:3, you just do a little more limiting. ;-) Instead of looking for a 2:1:2 ratio fertilizer that won't be easy to find, you can utilize the added versatility that an extra shot of K adds to your 3:1:2 ratio fertilizer, but you're still the guy in charge of the N supply, not the fertilizer's ratio. People lose sight of that all the time. They might say I use a 1:1:1 ratio fertilizer because I don't like all that N in a 3:1:3 ratio fertilizer, but they promptly feed the plant enough N to make it happy. They end up giving the plant the same amount of N either way - it's just that with the 1:1:1 ratio fertilizers it's impossible to give a plant enough N without OVER-supplying both P and K, but especially P.
I'm off on an adventure in the morning. A visit with my daughter & family, then on to Chicago for some fun at the Midwest Bonsai Show. I'll see you guys on Sunday.
Al
Q