But he knew that such tillage did increase his yield

But he knew that such tillage did increase his yield

Jethro Tull centered attention on the important fact that careful and thorough tillage increases the available plant food in the soil. He did not know why his crops were better when the ground was frequently and thoroughly tilled, but he knew that such tillage did increase his yield. He explained the fact by saying, "Tillage is manure." We have since learned the reason for the truth that Tull taught, and, while his explanation was incorrect, the practice that he was following was excellent. The stirring of the soil enables the air to circulate through it freely, and permits a breaking down of the compounds that contain the elements necessary to plant growth.

Fonte: Agriculture for Beginners