What is the difference between de facto and de jure segregation? which does the policy of bussing attempt to solve?

A de facto segregaton is the actual segreation and the jure is legal segregation ( the second is no longer found in the US, but the first one is). The policy of busing (children to schools) is trying to solve the de facto segregation.

In general, the large-scale industrialisation of agriculture in North and South America, Australia and Europe and the “Green Revolution” in Asia have led to a clear and detailed description of the problems small-scale farmers frequently face in terms of productivity and efficiency, as well as the practices they use.

hope this helps :)