My lawn is a mix of Kikuyu, clover and grasses mostly. I use Roundup to spray around the edges of the lawn. I am atan age where handweeding is not likely to get done. The spraying leaves a band of about 1ft of bare soil around the lawn. In which I grow my vegetables. And they grow wonderfully. I have always put it down to the good volcanic soil. I never knew that Roundup left some nitrogen. Certainly there is no ill effect on the vege plantsthat I can see. To a large extent this is all anecdotal. Ina. Ina Crossley Auckland New Zealand Zone 10 On 2/04/2013 10:38 p.m., Christian Lachaud wrote: > 2) Nitrogen : Roundup breaks down into nitrogen, which causes some > fertilizing effect.