Sure. Dry yeast you can sanitize package, cut with sanitized sizzors, use 1/2, fold and refrigerate for a short period in a sanitized ziplock, and you might be fine (not that a new brewer should try this). The number of cells in a dry yeast package (11, 11.5 grams) is more than needed for a 5 gallon batch. It is easy to pour the contents onto a sanitary surface on a scale (coffee filter) and measure out half. This would only be for a packet designed for 5 gallons, used in a 2 or 2.5 gallon batch.
Liquid yeast pouches need to be shared and kneaded to make it humongous, then sanitized, then poured into the wort. Measuring out half of the contents, assuming they are mixed correctly for an equal distribution of cells (unless you have a microscope), then saving half in a sanitary environment, is not advised. Harvesting the yeast cake can of course be done, but not by a novice brewer. And that's not using half the packet.
That's why I said a half pouch of liquid yeast should not be saved.
Just when it seemed that @Creeps McLane was ready to give up on competitions, he takes Tucson by storm with his saison! So to commemorate the day, I put together a quick (but inspired) recipe -- a traditional saison fermented with the 'shirt off my back' Safale BE-134 yeast. Additionally, to thank @JoshR and @MRB Tim for making the MUG comp. happen, I've included a Mr. Beer BrewMax Golden LME in the recipe for good measure.🍻
Saison de Frais
Weyermann Pilsner, 3 lb.
Weyermann Vienna, 1 lb.
Torrified Wheat, 0.13 lb.
Flaked Rye, 0.13 lb.
Simpsons Aromatic malt, 0.25 lb.
BrewMax Golden LME, 0.55 lb.
Summit (16.7% AA), 0.2 oz., 60 min.
Styrian Golding (2.6 AA), 0.5 oz., 20 min.
Styrian Golding, 0.5 oz., 10 min.
French Strisselspalt (1.2% AA), 0.5 oz., 5 min.
Fermentis SafAle BE-134
Mash grains for 60 min. at 150-152 F.
Mash-out at 168 F for 10 min.
Sparge with hot tap water.
Boil 90 min, hopping as noted.
Chill wort to 70 F, aerate, and pitch BE-134.
Hope for a Packer win.
Ferment for 2-3 weeks.
Thanks for the beers Creeps and good luck on your future brews!