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[Hans Lemurson]

The required grazing are per beast as listed in the wiki seems a little bit higher than what my in-game experience has suggested.

My understanding is that the Grazer Value is taken from the Raws and has a strong inverse correlation with Creature Size (Graze x Size = 60,000,000).  No objections there.  But how were the pasture sizes computed?

It seems that Pasture-Size * Grazing-Interval = about 20,000.  That 20,000 I assume represents the grass regrowth interval (inverse of growth speed), but where did THAT value come from?  How was it determined how quickly grass regrows?

I ask because I've been able to sustain a population of grazing animals (Yaks) on an area of grass that's considerably smaller than what the wiki suggests would be required.  Is grass growing faster than expected, or did I simply not wait long enough to witness my pasture stripped barren of all vegetation?

For that matter, how DOES grass regrowth work?  Is the "grass production rate" of a given area of ground constant, or does it vary based on the density of the grass per tile?  I would assume the production rate is zero on full-density grass, but do grass clumps appear at the same rate on bare earth as they do when thickening a sparse covering (this would be the "constant growth rate" model)?

So really my question all comes down to grass: How quick DOES it grow?  Does 20,000 mean that on average a dirt tile will grow a new clump of grass every 20,000 time units (~16 days)?  And if so, where does the 20,000 value come from?

[GreatWyrmGold]

Someone did experiments with goats and extrapolated.

[Sutremaine]

I've noticed that heavy grazers in a really large pasture eat their way through the pasture in a fan-shaped pattern from the top left outwards. As they do that, some of the grass in the stripped area regrows, and doesn't get trodden on. There's a smaller chance that a grazer in a large pasture will be stomping over any given square.

But any gains from that are unlikely to be significant, so it's likely that what you're seeing is the very slow stripping of the pasture. I've kept the wagon animals in an 11x11 pasture for the first year while everything else is set up, and it works out because the grass starts out at full growth. You couldn't keep them there permanently though, and you couldn't put more heavy grazers there immediately afterwards.

[Hans Lemurson]

Hmm...I think the fact that surface grass starts out fully filled-out may have given me the illusion that I could graze more on the land than I really could.  I was probably over-grazing, but the results wouldn't show for another year or so because I was starting at max grass.

I think the most proper test would be to have your pasture start off with freshly dug dirt, unless of course fresh grass growth is slower than the thickening of mature clumps.

[Hans Lemurson]

The Thread shudders and begins to move!
***
Ok, I've just been playing a Badlands map where I was doing a number of survival experiments, one of them involved penning my animals in channeled out pastures where grass will grow (pretending it's an oasis).

In addition to my wagon animals, a Yak and a One-Humped Camel, I brought two alpacas (for their long necks and resemblance to a miniature llama).  I initially had all 4 of them in a 121-tile (11x11) pasture and although this did stave off starvation, the dense clustering around each fresh spot of grass led to fighting which injured an alpaca.  I moved the Yak and Camel to a newly carved out pasture (roughly same size) with no grass in it at all, just to see how little they could survive on.

For the about a season, the Yak and Camel raced each other to each and every speck of grass, but after a while they were each able to have a grass patch to themselves, and then there started to be a bit of spare grass.  After 2 seasons, the pasture is now up to 26 tiles of grass; 19 Sparse, 7 normal.

According to the wiki, the Yak and Camel  should have pasture requirements of 256 and 169 tiles respectively, for an estimated total requirement of ~400 tiles of grazing land.  Despite requiring (in theory) 400 tiles of grazing land in order not to starve, the grass is growing faster than they eat it with just 116 tiles of fertile ground.

This leads me to one conclusion: the Pasture-Area values shown in the wiki are not correct.

And so after 16 months I must once again ask my original question:  Where did the pasture requirement values come from?  How were they calculated?  What method was used to compute the comparison with grass regrowth?  My cursory testing shows that the data on the wiki is off by a factor of 4.  What sorts of tests were performed to gather the data such that the values could be off by such a great degree?  GreatWyrmGold mentioned extrapolation from goats.  Could a large herd of goats have given erroneously low grass-growth values by trampling the grass as they nibbled and milled about?

[BlackFlyme]

This should probably be moved to the DF Wiki Discussion board.

Anyways, on the grazer page itself there is a disclaimer stating this:

Take the following numbers with a grain of salt; they ignore the differing abilities of various biomes to replenish grass and are instead based on a rule of thumb that 20000=Grazer*Required_tiles. Usually you can get along with way smaller pastures. Nevertheless, a fairly large herd can cause overgrazing fast, so keep an eye out for hungry animals and desolate grassless pastures.

I don't really know much on the subject of pastures though. Judging by the disclaimer, the chart may be aimed at raising livestock in biomes with little grass or slow grass growth.

[Hans Lemurson]

Oh wow, I can't believe I missed that disclaimer.  Disclaimer solves all problems!

If I was getting 4x better pasture yields than the wiki suggested it would be because the regions grass grows 4x as quickly as the value assumed.

I hadn't been sure where to put this thread when I first started it in 2012, 'wiki discussion' didn't seem quite right for debates on factual content, but I could be wrong.  For the sake of organization I put my new post in my old thread.

...Upon examination of the "Wiki Discussion" forum, I believe that that IS in fact the proper place for this thread.  Any chance it could be moved there?

[Larix]

As creator of the thread, you should have the "move thread" button in your context menu somewhere when looking at it; click it, choose a target board and finalise. Be careful to specify the correct board though - default is "administration", which is probably _not_ where you want it (when i tried to move a thread from here to wiki, i accidentally sent it there and couldn't get it back out. Quite embarrassing.).

The disclaimer in the wiki article has only been added in April 2013 (by user Old Ancient), after this thread was created.

It points at the issue, but doesn't describe the full extent of it - as you noticed, pasture sizes are probably overstated by a factor of three or four. I had a similar case: channelled down from the surface in badlands to make an 11x11 or so (might have been 10x10 only) pit and kept two horses and a sheep in there. Grass established itself in the pasture and the animals never grew hungry. An extra foal could not be kept in there for longer times.