Yes, that's part of the reasons why your uncle produces as much grain as two thousand African farmers. The factors are

-Energy : contrast gas and men's muscles. If they could get some animal traction, it'd be nice.

-Ways to renew the fertility of the ground : your uncle uses various kind of chemicals (not all of which necessarily pollute), whereas the African farmer is probably using his excrement, or burnt wood in the southern parts of the continent where they are still doing Slash and Burn. But animal manure would increase productivity of the land, and works nicely with the preceding factor.

-Tools : Without energy, the plow is useless... And without capital, many tools are not accessible to the African farmer.

-Cultivated Varieties : one of the problem of developing world is that much work was put into selecting varieties adapted for industrial agriculture, of wheat, corn and rice, or for exportation, like coffee. Not as much work was put into variety selection of plants used in the South, such as manioc, millet, sweet potato, bananas, or to adapt varieties of grain for the techniques of non-industrial agriculture...

-Water : small parcel mean the investment in agriculture has to be done collectively ; and there are problems with state stability in Africa... The State practically appeared when irrigation became a necessity, in Egypt, Mesopotamia, India, or even with the Inca.

Un roi sans divertissement est un homme plein de misères