Crop Dusting is a mod created by MrAmericanMike. It adds Poop and Fertile Dirt. Poop can be obtained by crouching when near crops and "venting", the default radius is a 4x4x3 area around the player in width, length, and height, respectively. Crop Dusting is also configurable to allow pigs to poop when near crops and named with a Name Tag name listed in the config. The default names are MrAmericanMike, M1Jordan, M1JordanAllen, Reuben, JonBams.
Technical details
Every 10 ticks by default, the mod checks a 4x4 square radius around the player for crops while they are crouch. This square is also checks one block above and one block below the player's Y-value, which is the position of their feet. Note that this check looks for actual crop blocks, not farmland. If a crop is found, including both vanilla and mod-created crops, it forces an extra block update for the crop. Normally, a block update for a block happens randomly based on the /gamerulerandomTickSpeed, which defaults to 3 for Java Edition. This number is used to select randomTickSpeed amount of blocks per subchunk, where each chunk has 16 subchunks, totaling 48 blocks selected per loaded chunk per tick. This forced update acts as a random block tick, and has a chance to increase the "age" of the crop. This chance is based on properties around the crop in its environment. The mod also has a random chance to spawn a particle of type EnumParticleTypes.EXPLOSION_NORMAL in a random location around a player while they are "venting," occurring every 10 ticks by default with a 3/10 chance. This property gives off the effect of crops growing by "venting"; however, it is a client-side effect that has no influence on the actual block updates.