A good understanding of the carbon cycles leads to an ability to spot the weaknesses in reporting about carbon emissions.

This article from Live Science Whatever happened to biodiesel? is an example.

The science in the article is generally accurate, but the way it is written is sloppy.

Are they saying planting trees will make up for burning fossil fuels?

Let's make some equations:

The overall process is:

seeds + fossil fuel used in cultivation + mined nitrate fertilizer + water + energy from the sun + CO2 = bio fuel + energy release + fossil CO2 + nitrate run off + oxygen

this breaks down into two separate equations

(1)  seeds + water + energy from the sun + CO2 = bio fuel from increase in seeds + oxygen + secondary biomass

   +

(2)  fossil fuel + mined nitrate fertilizer + oxygen = energy release + fossil carbon dioxide + nitrate run off.

Thus the question  becomes, can a field produce more energy than is required to till the ground, spread the fertilizer and harvest the product?

When it was a biological process it could:

seeds + horses fed on hay + fetilizer from the barn + energy from the sun + CO2 = bio fuel from increase in seeds + oxygen + secondary biomass + older horses

and here it is obvious that the secondary biomass on the right is the source of the hay on the left.

Looking at the problem like this, the solution starts to be obvious. Stop mining coal and oil, and live within the energy constraints of the sun and the soil and living plants with the current carbon cycle, and find a safe way to sequester the fossil carbon dioxide.