Soil Types and Crop Yield

Several times a year I travel the western USA to inspect our seed production fields. I see beautiful country, meet new people, and reinforce my deep appreciate for farmers and producers. I learn news things every time I hit the road. Sometimes I have deep existential moments, sometimes the driving is torture. Other times I have really cool AH-HA! moments that I want to share. I recently had one of those AH-HA! moments inspecting fields in Idaho. I got a birds-eye view of a challenge many folks see manifest in their seeding efforts.

By a stroke of fate and “I know a guy” circumstance, our grower arranged for us to inspect fields from a HELICOPTER!! How cool is THAT!? We flew for hours over hundreds of pivots of grain, alfalfa, corn and dozens of other crops and we inspected our own seed production fields. As we flew over the Snake River and two tributaries, I got a birds eye view of the dramatic effect of soil type on production.

Spread out before me for miles in every direction were winding, mosaic patterns in grain and hay fields. The ancient horseshoe bends, goosenecks, meanders and embankments of the Snake river were all there as clear as if the river were there yesterday. In each one of those ancient river features were evidence of dozens of different soil strata – sand bars, gravel beds, clay banks and heavy soil deposits. It looked the swirls in ice cream.

Every soil type has an effect on the plants that grown in it. Mineral deposits, pH levels and microbes all contribute to – or detract from – healthy seed development and plant growth. The ability of soil to retain water is called field capacity, and different field capacities have a direct effect on crops. In sandy soils and gravel bars the water drains straight through with very little retention. The result is plants that grow in fits and spurts that correspond with available water. They often head out prematurely due to stress and “mixed signals” from the water – a feast-or-famine scenario.  In heavy clay soils or compacted soils the water wont penetrate the surface. Seedlings often germinate but soon die from underdeveloped roots and poor access to water that never penetrates the soil. In others the soil is boggy and holds water, drowning roots, causing rot and suffocating plants. “Good soil” for crop production is somewhere in the middle with just the right blend of ingredients.

Eons of geologic development have carved America into different geologic areas of different soil types. The great plains and midwest enjoy fertile soil with mostly neutral pH deposited from the expansion and retraction of ancient ice fields. The coasts have more acidic soils that support hardwood forests and conifers. The Rocky Mountains and Great Basin have mostly high mountain valleys with variable soils high in pH. As rivers flow from high mountains and deposit soils in the floodplains, different soils settle in different areas of the alluvia fan.

The enclosed pictures show how the different soil strata have an effect on the life cycle of a plant, and how the difference can very literally be drawn as a line in the sand. So the next time you are puzzled by the way your plants are growing in your field, check your soils. You may in fact have a distinct strata line effecting your outcome.

This map shows the varied soil types of the USA. The same varied soils that occur on a nation-wide macro level also happen on a regional and site-specific sale. Dramatic differences in soil type can be inches apart and change multiple times in the same field based on elevation and ancient soil deposits.

The fields in this picture were all water with the same sprinkler lines and same water schedule. The difference in outcome is a result of different soil strata. Different minerals, pH and how the soil retains or sheds the water have a dramatic effect on crop production. Ancient water ways are clearly visible in the fields.

This photo shows the dramatic effect that soil type can have on crop and forage production. Old river ways are visible in the grain fields, manifest in varied maturity levels. Different alluvial fans and soil strata have different mineral, pH and microbe levels, and each hold and drain water at different rates. This can have a profound effect on seedling success, plant development and forage production. The current Snake River is seen in the upper left hand corner of the photo.