Question

why is the growth rate in agriculture declining ?

Answer 1

Because when economic growth is characterised by a slow rise in the demand for food and rapid growth in farm relative to non-farm productivity, it is understandable that agriculture in a closed economy declines in relative terms as that economy develops. But why should agriculture decline in virtually all open growing economies as well, including those able to retain a comparative advantage in agricultural products? A key part of the answer is that the demand for non-tradable goods tends to be income elastic, so resources are diverted to their production even in open economies.