You might consider looking at companies that help agro firms become competitive:

http://www.agsquared.com/

http://www.adapt-n.com/

I think that uncertainty is always present  for agricultural firms. For example, in a form of weather.

What do you mean by competitiveness? If this is microeconomic formulation, then firm with identical conditions (equal capital, equal labor endowment) are always competitive in the sense that in microeconomic equilibrium they will sell at the same price and get zero expected profit. There are many  microeoconmic models about competition in the environment of uncertainty.

If you are talking about survival of real firms in this environment, then asymmetric access to credit or bad luck can give advantage to some firms and ruin the others. This happens when financial markets are not perfect and in real situation this is often the case.