Components of Harvested Crop Dry Weight

This week in my Crop and Weed Sciences capstone class, Cropping Systems: An Integrated Approach, we were asked the question, what actually compromises the finished dry weight of the crops we harvest?

This led our class to venture guesses on what would contribute to that final weight.

Some groups guessed the initial seed, water and nutrients from the soil, photosynthesis, etcetera.

What our instructor told us at the end is that the elemental components of dry weight by percentage are about 45% carbon, 45% oxygen, 5% hydrogen, 2-3% nitrogen, and less than one percent phosphorus.

Looking closer at those yield components, 45% of grain dry weight is carbon. Plants get their carbon from the atmosphere in the form of CO₂. They have the same access to carbon dioxide that we do as humans from the atmosphere and yet, plants being the amazing factories they are, are able to break down that carbon dioxide and compress it into 45% of its seeds' dry weight. That's amazing if you ask me.