Important Crop Information: Seed To Soil Contact


Planting Tips And Crop Information: The Importance Of Seed To Soil Contact 


Almost all crop literature and crop information suggests that seed to soil contact is essential to a great harvest. It doesn't matter if it small seeded crop, like alfalfa, or a large-seeded crop, like soybeans, the way to begin a successful season is to make sure you have good seed to soil contact. Smaller seeds need less soil to germinate, but still benefit from good seed to soil contact. However, it's essential for larger seeds, like corn, to be planted in at least one inch of soil. The larger seeds need the cover and, because they're larger and more visible, they're often eaten by birds and insects. 


The Direction Of The Root Matters


Alfalfa seeds have a primary root that burrows downward to eventually form the taproot. This serves as a sort of anchor, so even if the alfalfa seed isn't covered as well, it's likely to germinate. Corn, however, the seminal root grows at a 45-degree angle, so corn seedlings need the cover of the soil to grow and the physical support of the soil around it. 


Pay Attention To The Quality Of Your Soil


Soil that sticks together in large clods is not good for seed-to soil contact and will need to be broken up. This may take significant time and energy, but it's well worth aerating and separating the clods to create a soil with better texture. Also, make sure that the soil beneath that first layer is permeable, because this is where your future plants will develop their root systems. Shallow root systems mean weaker plants. 


How Much Tillage Is Enough?


Unfortunately, there's no real hard and fast guide or crop information to determine how much tillage is enough. The amount of tillage depends on the crop, the topography, the field and weather conditions at the time of planting, and the soil type itself.


For example: Corn should be planted at least one in deep, two inches optimally. You can plant a bit shallower if this is an early crop and slightly deeper if you're planting late. You should also plant a bit deeper if the soil is dried out, or light textured. These variables in conjunction with seed to soil contact has a direct correlation with root strength.


Corn should be planted about 2 inches deep, slightly shallower with early planting, slightly deeper with late planting, especially into light-textured soils that have dried out. This depth of planting usually results in good seed-to-soil contact, which is why it’s almost never necessary to do any more soil firming than the press wheels on the corn planter do during planting.


Is "No-Till" A Misnomer?

Frankly, there's no such thing as "no-till", because even though a crop is "no-till" some of the soil is tilled before or after panting. Regardless, no-till corn planters still establish good seed to soil contact with fluted or ripple coulters.


If you decide to go the no-till/minimal-till route, just remember this helpful piece of crop information: Using no-till planters and equipment should not be a license to plant in overly watered, soggy soil. Especially if your soil has a high clay content that gets plastic or rubbery when wet. The coulter opens a slot to drop the seed in, but if the clay-heavy soil is wet, the slot won't be covered adequately and you may be faced with a poor yield. 


No till techniques do not do well in lighter soils, but do work well in sandy soils with a lot of drainage. And, even if you choose to go the no-till/minimal till route, in order to maintain good seed to soil contact, the land does need to be tilled every few years. 


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