Farming is the management of complex biological systems, systems we do not fully understand. Agricultural science is the process of trying to understand those systems better, little by little. But there is much we still do not know. The most exciting science is when you have an interesting observation, and try to figure out what is behind it. The mystery of the missing smell Several years ago I was approached by a dairy farmer who had been applying extremely low rates of N fertiliser, yet achieving levels of production per hectare that were equivalent to high input conventional farms.