My opinion
This article (in its current state) is weird. It looks like someone pushing an issue or their own advice or something. I can't explain it. Looks a little bit like an essay on agriculture in general. But the only information i think we need to keep from it which regards agricultural productivity is:

for economists: agricultural productivity is measuring production of an agricultural good + estimating its value on the market, which = an indication of its profit-making potential.

for farmers: the term agricultural productivity means first the ability (for themselves or their community) to survive on the agricultural goods they produce. [perhaps list here the agricultural products mentioned in the article which the community can use, e.g. food (crops, dairy & meat), hides, manure, etc]

the part about it being a better idea to produce a variety of products instead of just specialising in one product (eg crops) is interesting information, but i'm not sure it belongs here. Any ideas on how to incorporate it into this article, or perhaps another one?