It is actually a bad tool to achieve that and it is exactly what happened OTL. NEP failed to increase agricultural production substantially and its economic growth effect was basically limited to recovery of what damage Civil war did.
@Sam R. is very much correct here. NEP issue was that majority of the Soviet post-CIvil war peasantry got enough land to be subsistence farmers and nothing more, so they had very little ability to actually increase their production, as you need education in better agricultural practices, chemical fertilizers and mechanized labor for that. And subsistence farmer cannot afford anything from that list.
NEP allowed Soviet government to shift away (in a limited way) from the direct natural taxation of the peasantry to semi-regulated grain market on which peasants were selling their surplus to either state or private agents. But devil is, as usual, in the details. The effect of that semi-regulated market was that the grain price was at the lowest during and immediately after harvest season and slowly rose by and during winter season. So most of the sellers were incentivized to sell as late as possible. But to store grain (to sell it later) you need storage facilities which poor peasants were unable to afford.
As the result poorest peasants were forced to sell their harvests first at the lowest prices either to the state agents on the market or to private citizens (mostly other richer peasants who had infrastructure to store the grain or were in position to lease it) and because of that poor peasants had very little incentive to increase production as they were forced to sell cheap and also were unable to accumulate funds to expand their production or to lease/build grain storage to sell later next year.
Because of that NEP achieved basically nothing of what Soviet government wanted. Yeah, a small number of people became richer through being positioned as middle men in the grain trade, but overall economic effect of that was extremely limited and in the long term perspective would lead to slow dispossession of the poorest peasantry and rise of the new landowner class which was obviously unacceptable on ideological grounds. Because of that NEP was terminated.