Hi
I have grown alfalfa in my field and faced a issue of a weed called Cuscutta.
This weed is present in the seed itself as it gets transfered from the mother plant.
Once this come into the field, it is impossible to get rid of and you have to start again.
I suggest you should purchase seeds which are free from this weed.
Its difficult to understand as you will not be aware where the seeds come from. Best option is to use a sample in small area. You will come to know in only 3 weeks. Then go for larger plantation. I lost about 1/2 acre of lucerne and have decided not to grow it anymore. My way of looking at this is feed some more quantity of concentrates as it is easy to handle and cost is marginally higher. With lucerene, you need to feed at least 5 kg per cow.
Further caution, it requires some amount of maintenance, like weeding, watering etc. Only if you have some labour to take care of it, I suggest you go for it.
If you go ahead, then I sugegst you do it with bed system and use microsprinklers, it works nicely. I found this on the tnau website.
Best of luck.
Nikhil
