First time alfalfa grower needs help

In the spring of 2015 my family found ourselves in charge of my grandma's farm and have never done any farming. For example, I learned to drive a tractor this year. We had approximately 100 acres that needed planting, so we readied the fields that previously had alfalfa in them, but most of the alfalfa was dead and we were left with weeds. The fields were planted with approximately 25 pounds per acre of alfalfa and 20 pounds per acre of oats. We didn't know when we should cut out oats, so we let them get extremely long and then went about cutting them. Now that we are in the process of harvesting our fields, it seems that we have very little alfalfa among the oats. I am trying to determine what happened and what we can do to save our fields. My first thought is that the oats out competed the alfafa meaning that they sheilded the alfalfa from the sun causing the alfalfa to die.

 

Additionally, we are in the part of the country where the Gold King Mine spill prevented us from getting water for about 20 days. This obviously did not help our little plants.

 

My question is, what are your thoughts on reseeding the fields instead of tilling them and starting over again? Seeing as they really didn't have alfalfa to start with I do not think the toxic effect will be in play. There is a little new growth, but it is very thin. My thought is that I would like to reseed the fields using about 15 pounds per acre of alfalfa seed and drill the seed directly into the old growth. Will my plan work?

First time alfalfa grower needs help