Ag PhD this week, organic matter. Farmers like to talk about organic matter because it does matter!
Each one percent of soil organic matter allows it to hold 4% more water. That was critical in this year's drought. This is what farmer's call "good land" or better land because it yields more. Each one percent also holds 20-30 pounds of nitrogen so a 5% organic matter soil can provide 100-150 pounds of nitrogen to the crop produced on it.
Each percent also holds a few pounds of phosphorous and a little less sulfur, all valuable nutrients to produce a crop. All those tons of plant material on top of the soil may turn into a tiny bit of humus, or soil organic matter over time. It all depends what you do to it.
A main benefit of notilling is to slowly increase organic matter content of soil over time. This is why I feel soil should never be tilled unless you just have to or don't know any better!
Organic matter is a reservoir of nutrients that can be released to the soil. Each percent of organic matter in the soil releases 20 to 30 pounds of nitrogen, 4.5 to 6.6 pounds of P2O5, and 2 to 3 pounds of sulfur per year. The nutrient release occurs predominantly in the spring and summer, so summer crops benefit more from organic-matter mineralization than winter crops.
Organic matter behaves somewhat like a sponge, with the ability to absorb and hold up to 90 percent of its weight in water. A great advantage of the water-holding capacity of organic matter is that the matter will release most of the water that it absorbs to plants. In contrast, clay holds great quantities of water, but much of it is unavailable to plants.
•Soil Structure Aggregation
Organic matter causes soil to clump and form soil aggregates, which improves soil structure. With better soil structure, permeability (infiltration of water through the soil) improves, in turn improving the soil's ability to take up and hold water.
This property of organic matter is not widely known. Data used in the universal soil loss equation indicate that increasing soil organic matter from 1 to 3 percent can reduce erosion 20 to 33 percent because of increased water infiltration and stable soil aggregate formation caused by organic matter."
This is about as simple as I can show you, don't till! I have to watch myself driving down the road and see some poor soul fall plowing. I have uttered the ugly words, "damned tillers!"
Tilling releases that precious carbon in organic matter to the atmosphere.
Lord knows we don't need any more carbon in our air.
Whether or not you're a row crop farmer, plant trees so we can breathe!