A diet that includes some meat is actually a more efficient use of land.
I read the article you link to and see it is very location specific indeed. In any case it doesn't have any real statistics and contradicts much of the data in the UN Food and Agriculture Report, at least when generalised to a pan-American or Europe-wide geography (where I live).
Simply put, grass fed cow parts are nutritionally ideal but take much longer to raise (more water and resources over a lifetime) and consume larger amounts of space overall due to the comparative inefficiencies of grain vs grass.
At current rates of meat consumption we'd need to raze a hell of a lot more forest to support this ideal form of producing edible animal pieces, even if we did turn those monocrops to grass.
To reiterate, already at today's rates of consumption -continuing with ~80% grain-supplemented feed for the majority of animals eaten- conservative estimates place 50% of all tenable land on earth will be dedicated to chicken, pig and cow parts by 2050. One (luxury) food stuff with a ~54:1 protein inefficiency ratio!
Again, the world agricultural authority, comprised of highly respected scientists, The FAO, says that agriculture is at the heart of both every environmental stress on the planet, floods, acid rain, erosion, pollution of water ways, deforestation..
In the absense of meat-trees (which I fully support) there's only one thing to do to ensure future generations of humans have a breathable, bareable, biologically diverse world to live in: eat less, ideally no, meat. It's not working and solely eating grass fed animals are the inverse of a solution to this effect. Sometimes we have to make sacrifices, disciplining our hedonism and dietary vanities to look after the big picture. Many traditions prove to be stupid when shifted into a contemporary context, meat eating in the 21st century is one of them and will be remembered as such, along-with human slavery, inequality to women and lead pipes. A very smart thing to do to reduce environmental impact of this selfish diet is to raise your kids vegetarian. Kids I've known raised vegetarian think meat is a bizarre hedonism, right into adulthood!
I'm curious, what do you eat if you don't eat meat and don't eat monocrops? Do you grow all of your own food?
I live in a city with very cheap and high quality markets, Eating out is also easy. I don't have a garden, though I'd love one. I try to eat an entirely raw, dairy-free meal at least once a day, not out of dietary convention but simply because I am a faster thinker and feel physically stronger if I do.
A typical day might start with brown sunflower-seed bread with olive oil, rock salt and a thin slice of Queso de Manchego or porridge and chopped banana with a little soy milk and brown sugar. I'll often have a soy-milk latte or black espresso, made at home. Lunch may include a fresh chopped celery and bulgar salad with walnuts, volcanic salt and olive-oil/honey dressing. I live in an area with excellent turkish food, so if I'm out I might have a falafel with pickles or haloumi and oven baked potato wedges thrown in. Maybe I'll grab some lebanese or whip together a fresh mozzarella ball, cherry tomato and basil salad. For dinner I might have a green curry with coconut milk, sweet courgette, green sprouts and button mushrooms, tempeh or seitan on a bed of black rice; oven baked Parmigiani Aubergine or Setas de la Plancha with white wine marinade. To K.I.S.S I may just put together a whole grain pasta, with chopped almonds, paprika sauce and a little rocket salad on the side. Glass of wine or wheat beer follows.