Does anyone have any suggestions on how long we s hould wait before we disk in our sunhemp? We're developing 150ha of land for sugar cane, and the sunhemp is for the soil.

I was trying to find information about sunhemp for your nation of Zambia,
Ok, I am not a farmer so a lot of this means little to me, but here is some info
http://www.ifpri.org/events/conferences/2003/120103/papers/paper11.pdf

Also world Vision seems to sponsor a lot of these programs and could have more info
https://worldvision.org.nz/form_contact.asp?

This may be another group that offers support and advice
Services - Necofa (http://www.necofa.org/3.0.html)

It all depends on what you intend to achieve by growing the stuff. But to get max benefit from the nitrogen and or green manure aspect of sunhemp then one should fully incorp the sunhemp at aprox 10% flowering stage.Hope this helps.