I am asking for any recent studies exploring the agricultural terms of trade (prices of agricultural commodities compared with the price of farm inputs) particularly for small farms in the developing countries.
you could look at the work of b.arbara harriss and theo palaskas, journal of development studies. also theo palaskas "european journal of agricultural economics" and work of Alfred maizels, theo palaskas et. all in the article "Prebish - singer Hypothesis revisited" in the book Development Economics and Policy, D. Sapsford and J. Chen (eds Macmillan Press ltd, 1998)