While Sachs’ interests lie primarily in studying plant processes while establishing botanical knowledge, Knop could be rightfully called the true father of water culture. His experiments laid the foundation for what we now know today called hydroponics.
In his early experiments, Knop sprouted seeds in sand and fibre netting before transplanting the seedlings into cork stoppers with drilled holes, securing them with cotton wadding, and then suspending them in glass containers filled with solution. By doing so, Knop inadvertently established the technique most widely used for future laboratory experiments.
Using this method, Knop was the first to realise that plants gain a large amount of weight simply from the food stored in their seeds and that seeds provide nourishment to the parts of the plant that form first. In addition, by this time, it had been established that soil nutrients must be in a soluble form for plants and that the number of soluble nutrients in soil was minuscule compared to those that were insoluble. These two pieces of information would form the basis for Knop’s future scientific experimentation.
What wasn’t available then were specific ways to measure these properties, such as osmotic pressure, nor did researchers of the day know what those properties might be. And while Knop deduced that nutrient solutions that were too concentrated might do more harm than good, he had no idea why.
Despite this lack of understanding, in 1860, Knop successfully grew plants without soil, weighing many times more than their seeds and containing a larger quantity of nutrients. In 1868, other scientists using Knop’s methods grew buckwheat plants weighing 4,786 times more than their original seed and oats weighing 2,359 times more. These experiments firmly established that plants can be grown successfully and productively without soil.