With this spell, a
druid can increase the likelihood that
animals and plants will reproduce better.
Up to 12 HD of animals or a field of up to
10,000 square feet can be affected. Animals
(including humans and humanoids)
make their appropriate saving throws;
fields have a saving throw of 15 minus the
level of the druid. In the case of animals,
the likelihood of conception is increased
5% per level of the caster. If both animal
mates are included in the spell, the probabilities
are added together. In the case of
plants, the yield of the field is increased
5% per level of the caster over normal.
The reverse of this spell, sterilize, applies
the same percentages in reverse: thus, the
likelihood of conception in animals is
reduced 5% per level of the caster, and the
yield of plants is reduced 5% per level of
the caster, unless the saving throw is
made. In either case, large plants, such as
trees, must be treated individually:
orchards are not the same as crop fields.
Duration lasts until conception is successful
or until the growing season is over.

The Natural Order,
By Arthur Collins