not really any extra nitrogen, but my soil ratio is 2 part potting mix, 1 part perlite, 1 part wiggle worm castings. so that probably helps some... the pictures you saw were about a week from harvest, and there was no yellowing of any leaves except for a few way under the canopy. those leaves would yellow and fall off in a matter of twelve hours.. the plant dropped the leaf very quickly. the amazing thing about there being no yellowing is that i stopped all nuts at week 5 of flowering, then used a half strength Gravity Flower Hardener solution for two waterings then just distilled water till the end and had no yellowing of any bud or top leaves. these were the healthiest plants i have ever had... my last harvest did have some yellowing a week or two following up o harvesting.. heres some pics of that