Put sawdust or some other dry material (like newspaper) in after each 'dump'. Urine can be very smelly! Using separate areas for urine and feces can reduce the stench! Wash hands thoroughly after using...disease can spread easily. Locate the latrines some ways from camp and away from water sources.
Use a simple enclosure to provide privacy. The best method of reducing the normal unpleasantness is to have a bucket of wood ash and to put one scoop in after relieving yourself. This method assists in eliminating moisture and smell.
After the outhouse fills to within a foot of the ground level fill in the top of the pit and clearly mark the area so that no one accidentally falls in. The ground should be very firm due to the addition of the wood ash over time.
Spread the Waste - do it like they do on discovery channel
What is the reason, that makes human waste stink?! Think of a water toilet. The waste is flushed down into the ducts. Well, where you drop it, it won't stink - but think of the collected "broth" in the ducts....
What other toilets do you know of?! Well the outhouse...everybody loves it. The light, dampy smell... Especially when it is a public outhouse like the ones you find out there next to the trails - it will definitely stink.
But there still is an increase. The small plastic outhouses used on construction sites! A skunk is nothing compared to them - placed in the summer sun.
So far, so good. What is the problem of the toilets mentioned above?! What is the solution?!
Well, it is pretty simple. The above toilets use water, chemicals and cumulate the human waste. That produces a condition close to be perfect for putrefaction! The only thing to get rid of the stench is: keep it airy, dry and don't cumulate!
My way to achieve that is: create a nice and dry spot somewhere in the shrubs. Make a circle on the ground and call it "drop-off-ground". This is where your waste goes. After "dropping-off" take a wooden stick and roll the waste in the dust to cover it a bit. After that you go playing golf: spread the waste into the back of the shrub. Use your wooden stick as a golf club. Make sure you choose different directions. This way you creating compost. No bad smell at all! It smells like nice humus soil. If you use toilet paper, don't spread the paper. Separate it from the waste and dig a hole to put it in. For comfort and style lean a stick to a tree, so you can yourself lean back for a nice drop-off. This toilet works perfect for long-term use. If you use it for more than three people, use a second toilet and swap them regularly - so the environment has the chance to regenerate.
Don't forget to designate the back of the shrub to be a "no-go-area"!
So remember: keep it airy, dry and don't cumulate. No putrefaction, but compost.
I heard of someone that uses a sieve to strain the waste (don't cumulate), puts saw-dust on it and is airing it by a ventilator (keep it dry). He is also separating the fluids (urine) from the rest of the waste by using a bypass: a bottle and a hose. This composting-toilet is for indoor-use. It needs cleaning from time to time, power of course (for the ventilator) and that are the reasons I personally don't like it. :o) I like to watch the stars, the birds and other wildlife while pausing.