Fertilizer and boron timing questions

[bpgreen]

I've got a couple of questions that are probably pretty basic. This may be the wrong forum. If so, feel free to move my post.

I know milorganite is sold around here, but I haven't found any recently. To be honest, I haven't looked hard, I'll look harder in the fall. Or even later this spring.

Is it ok to use the 10-10-10 fertilizer as a medium for the boron? I know the guide says to use milorganite, but I've got 10-10-10 and I don't have milorganite.

I haven't used synthetic fertilizer on my lawn for years (decades?), so bear with me.

The controller on my sprinkler died last year, and we're in extreme drought, so I decided not to fix or replace it and instead to go all in on natives and have even started favoring warm season grasses (mostly blue grama).

There's a chance of rain Monday, and also several other days in the next 10 days. If I apply the fertilizer on Sunday, and it doesn't rain Monday, do I need to water by hand? If not Monday, it's there a time when I do need to water by hand?

I spread spent grains every brew day, but I'm not concerned if those sit for months without water (and they often do). But I seem to recall that synthetic fertilizers need to be watered in.

[MorpheusPA]

It's actually OK if synthetics don't get watered in, but you may lose some of the nitrogen to the air as a pollutant. It usually self-limits to about 15%, absolute maximum, and that's in a damp, alkaline environment. Since you'll be mixing it with 20 Mule Team Borax (pH 9+), alkaline it'll be, at least a little. You're diluting that way down, though.

I wouldn't see any reason you can't use it as a boron carrier, though. Or you can use spent grains if you have enough to cover the entire area.

I'd water things in at some point if rainfall doesn't happen, but it doesn't have to be soon. That's mostly because there's still some dust. It irks my Puritan nature to waste.

[bpgreen]

Thanks. I brew 5 gallon batches, so I only cover a small chunk of the lawn each brew day. There's a chance of rain almost every day this week, so I'll get the fertilizer and boron down today