MY 2 cents(30+ yrs of planting food plots for wildlife and longer doing farming )
1.) When is the best time to plant turnips in the northeast (WV, PA)?
best advice here is to learn what the growth rate of the seed your planning to plant is(as in is ita 45 day seed 50-70-90? and so on, all seeds have a date of when there growth is)
THEN once you know this info, look at when frosts are typically in YOUR AREA, and have seeds planted so they mature before the frost frosts are expected !
2.) How long should you wait after spraying (killing grass/weeds) until you start planting?
Typically I suggest waiting at least 24 hours, some CLAIM less is OK< but more time IMO is better than less, as what happens when you spray burn down chemical , the plant has to adsorb the chemical and get it all the way into the roots to be 100% effective
so for me I wauit at least 24 hours 48 even better IMO!
3.) Can you lime before tilling?
you can lime about any time you want, BUT< Lime takes a LOT of time to do anything, and the ONLY way lime works is to have a partial of lime meet/touch/mix with a partial of dirt
which is why the BEST way to add lime is to disc the lime or some other way of turning the soil over to MIX IN the lime with the soil/dirt!
when you simply dump lime on top of a NON disturbed soil/ground
it takes even longer for the lime to leak into the ground thru vegetation and HARD top layer and from there the compacted soil will always have weaker spots , so when rains come the lime will pour into the softer spots leaving a LOT of area to NOT get any benefit from the lime at all
typically the BEST time to TOP dress(dump lime on TOP of a plot) is in winter time, so the lime has more time to leak into the ground and the freezing thawing of the ground will actually help suck in down and then allows time to get some of the benefits of the lime!
lime can take YRS to work, to lower PH to a level one wants, and it typically is NEVER done in one application!
SO< if your soil PH is off, the best time to add lime is as FAST as you can , as it will again take time to adjust PH
so longer its in the ground the sooner it will start to work!
BUT top dressing is only really good for MINOR adjusting of PH!
if you need to alter lime a bunch, , mixing it into the soil will be the WAY better way to add lime to see results in a timely manor!
(and FYI< typically the cheapest way to lime is in bulk lime spreading, many places offer it, but you tend to need to know WHO does it, but the price difference and easy of having it bulk spread is way worth the effort to find who does it in your area, asking any local farmers or contacting your local soil conservation office might get you a number to the service, and again the difference in costs is HUGE!
4.) Can you fertilize your crop after planting seed?
YES< you can add fertilizer about any time you want, however, at certian times and pending amounts and type of fertilizer being used, you can BURT new growth
the best time to add fertilizer typically is when plating the seed! this way as the fertilizer breaks down and gets absorbed the seed can use it to grow stronger and faster , to increase odds of it making it!
you can also, add more fertilizer after things are growing, but its preferred to do so when things are planted
pending crop being planted some actually benefit from adding nitrogen AFTER they have reached a certian stage in growth!
another draw back to adding fertilizer AFTER things have started to grow is, when you spread it, you will be running over young growth , and that can stress the growing plant out to the point it won't recover! or can lower the growth rate allowing weds and other things to over take them! as weeds typically are extremely hardy plants and will also benefit from the added boost fertilizer adds!(and don't forget that ALL bags of seeds contain an amount of WEED seeds(also called unknown seeds)
read the label and you will see this!
and this is why even planting after burning down a site, you still get weeds growing up in plots! as you actually planted then at time of seeding your other crop!