Principles of Soil Health
|
|
Douglas Landblom
DREC Beef Cattle and Integrated Systems Specialist
Dickinson Research Extension Center
Office: 701-456-1109; Mobil: 701-690-8245
|
|
How best to create and maintain high quality soils varies across different landscapes; however, there are soil health principles that apply to all soils with the underlying purpose to increase and maintain soil organic matter. Without adherence to practices that reduce soil quality degradation, soils can become severely degraded making them more subject to erosion and low productivity. Principles of soil health include 1) minimizing or eliminating tillage, 2) growing a diverse mix of crops, 3) maintaining live roots in soil as long as possible, 4) keeping soil covered with cover crops and/or crop residue, and 5) utilizing livestock grazing whenever possible.
Why minimize or eliminate tillage? Since tillage is a common and ancient seedbed preparation practice, it is difficult to imagine not using tillage to prepare a seedbed. Tillage is actually very destructive for soils for several reasons. Tilled fields are more subject to erosion due to more rapid organic matter depletion resulting from soil aeration, which increases microbial decomposition of organic matter. This increase in soil organic matter depletion reduces macro and micro nutrients resulting from microbial activity as well as soil carbon. Many continuously tilled soils are degraded and require large amounts of fertilizer, which over time contributes to declining soil pH.
Crop diversification is an important key to stabilizing soil structure, reducing soil erosion, increasing productivity, reducing weed infestation, and reducing or eliminating the use of commercial fertilizers. Crop rotations used in the semi-arid region of the northern Great Plains, where typical annual precipitation ranges from 12-16 inches per year, are different than those grown in regions of higher precipitation. Due to unpredictable precipitation levels, crop considerations for rotation in the semi-arid region include identifying crops that have low water use characteristics that can be grown preceding high water use crops. For example, growing field pea or soybean ahead of corn or sunflower in the cropping sequence provides a habitat that facilitates microbial decomposition of soil organic matter [sda1] and provides a supply of mineralized N for the subsequent crop. Crop rotation management includes balancing the type and number of crops grown in a manner in which soil organic matter increases over time. Setting a holistic goal for production without the use of commercial fertilizer or at least very minimal amounts (starter in cold early spring soils) is attainable. North Dakota is ideally situated in the northern Great Plains where high dollar value cool- and warm-season crops will flourish in complex crop rotations and coincide with farm program requirements. Complex crop rotations that include high residue crops with extensive root systems need to be incorporated often to provide a continuous supply of soil organic matter for microbial driven nutrient cycling of N and all other macro- and micro-nutrients.
Maintaining living roots in the soil is important to extend the summer growing period. Summer annual crops are not as effective as cover crops that include a variety of plant species known to continue growing late into fall and some species are frost tolerant. Cover crops can be grown in a dual cropping sequence in which a winter crop is planted in the fall following a small grain summer annual and harvested the next spring as hay or grazed prior to being reseeded to a multi-specie cover crop for fall utilization. Production from the two crops combined will yield 4.5 to 5.0 tons of forage per acre. A problem with this dual cover crop system is that seed germination after seeding in late June or early July can be problematic and seed may lay in dry soil for 3-5 weeks before significant precipitation is received that will facilitate germination. This delay in germination significantly reduces above- and below-ground biomass. Results from long-term dual cover crop measurements has shown that there is approximately a 60% probability that a cover crop seeded in late June will produce a cover crop with desirable biomass. However, even in seasons when moisture is limited and grazing or hay harvest are also limited, a dual cover crop is still beneficial for erosion control, aggregation, and overall soil health. And another alternative is growing a full season cover crop although the tonnage will be less that the combined tonnage from a dual cover crop procedure.
Manure from livestock grazing adds to soil organic matter and is very economically beneficial to the system. On farms where there are livestock cover crops are a very valuable feed resource compared to feeding harvested forage in drylot. Extending the grazing season with cover crops reduces daily feed cost per cow, which will fluctuate according to the price of hay in any given year.
In my next update, I will present information relative to the attributes of various cover crop species and when a given crop type would be included in a cover crop mix for either cool- or warm-season utilization.
|
|
The NDSU Extension does not endorse commercial products or companies even though reference may be made to tradenames, trademarks or service names. NDSU encourages you to use and share this content, but please do so under the conditions of our Creative Commons license. You may copy, distribute, transmit and adapt this work as long as you give full attribution, don’t use the work for commercial purposes and share your resulting work similarly. For more information, visit www.ag.ndsu.edu/agcomm/creative-commons.
County commissions, North Dakota State University and U.S. Department of Agriculture cooperating. NDSU does not discriminate in its programs and activities on the basis of age, color, gender expression/identity, genetic information, marital status, national origin, participation in lawful off-campus activity, physical or mental disability, pregnancy, public assistance status, race, religion, sex, sexual orientation, spousal relationship to current employee, or veteran status, as applicable. Direct inquiries to Vice Provost for Title IX/ADA Coordinator, Old Main 201, NDSU Main Campus, 701-231-7708, ndsu.eoaa@ndsu.edu. This publication will be made available in alternative formats for people with disabilities upon request, 701-231-7881.
|
|
|
|
|
|
|
