Climate Changing: No-Till for Soil Health?

Like an intricate puzzle, soil health has so many different pieces it can be challenging to see what they are and how they fit together. One piece in rebuilding soil health is no-till farming. Also known as “direct seeding” in some circles, no-till farming involves keeping soil relatively undisturbed and protected with residue leftover from cover crops.  No-Till for Soil Health?

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“No-tillage management is a key component in improving the health of the soil,” said Jean Steiner, of the USDA-ARS Grazinglands Research Laboratory in El Reno, Oklahoma.

The problems with tilling can be summed up in two words: disturbance and compaction. Disturbing the soil releases carbon dioxide into the atmosphere, which contributes to the rise in global temperature (see Growing’s January 2016 issue). Soil compaction occurs on the surface whenever a vehicle drives across a field. Plowing and disk harrowing cause compaction lower in the soil profile by “smearing” the soil at the bottom of the tillage implement. After multiple years of tillage, a thin, dense layer of soil known as a “plowpan” develops that neither roots nor water can penetrate.

Although there are numerous benefits to no-till farming, some scientists fear no-till is being promoted as a silver bullet to mitigate climate change. In fact, no-till can be misapplied and thereby have no positive climatic effect. Matthew Ryan, of Ithaca, New York-based Cornell University’s School of Integrative Plant Sciences, warned that in certain soil types and environmental conditions, no-till can actually increase soil nitrous oxide emissions. For example, to offset productivity decreases that can occur with the transition to no-till management, one may be tempted to increase use of nitrogen fertilizer, which is made using large amounts of natural gas. The added nitrogen use cancels out fossil fuel reductions associated with on-farm fuel use.

Climate Changing: No-Till for Soil Health?

When properly applied, no-till management presents no disadvantages to climate health, according to Jerry Hatfield, co-author of the third National Climate Assessment. “Keeping the soil in place and preventing erosion is necessary to offset the more extreme precipitation events, which outweighs other potential detriments,” he said.

Benefits of no-till for mid- to large-scale growers

No-till and the associated maintenance of year-round vegetative soil cover offer many operational benefits:

• Protection from erosion and soil crusting
• Increased infiltration of rainfall
• Moderation of soil temperature
• Reducing evaporation rate to maintain a moister soil
• Improved soil structure that allows for more timely agronomic operations

In addition, adoption of no-till mitigates greenhouse gas emissions through reduced fuel usage. No-till also increases water and nutrient holding capacity, increases soil biology and allows for better nutrient cycling.

Financial benefits of no-till management include:
• Reduced input costs, such as less fuel and less fertilizer over time, with an improved soil biology and nutrient cycling
• Reduced labor costs as a result of fewer field operations and an ability to farm more area with less labor
• Increased stability of crop production, as untilled soils are more resilient to weather variation
• Increased overall land value, as it becomes more efficient in crop production

Evaluating no-till management for your operation

Exploring options with guidance from your local ag-extension service or USDA-NRCS agent will help you determine whether no-till management is right for you. Issues to consider include crop choice, growing region and adoption costs.

No-tillage management does not work well with all crops. As Tom Akin, a state resource conservationist with NRCS in Massachusetts explained, no-till is most successful with large-seeded crops, which store more energy than smaller seeds. Greater seed energy leads to greater chance of developing into a healthy seedling. Germinating seeds need to emerge from the soil, and seedlings need to develop leaves to capture solar energy. No-till soils can have varying amounts of plant residue that are not hospitable to the survival of small seeds, like carrots. Using pelleted seed (seed encased in an inert material to provide protection) is one adaptation that may allow growers of small seeded crops to successfully adopt no-till management. Another adaptation, trash whippers, moves residue away from the seed zone; planting into the narrow area ensures good seed-soil contact. Ryan said no-till works well for farmers in warm and dry environments, especially if they do not use irrigation.

“If no-till is not feasible, farmers should consider conservation or reduced tillage practices, such as strip till, which can work well even in cooler environments,” he noted. Yet some farmers as far north as Saskatchewan, Canada, have succeeded with no-till, according to Idaho state conservationist Curtis Elke.

As with any new farming method, you may experience a steep learning curve. You may require specialized no-till planters, no-till drills, or other equipment designed to make no-till feasible in a larger growing operation.

No-till planters differ from conventional planters in two major ways:

  1. A no-till planter usually has a leading “coulter” or interlocking finger-like row cleaners that cut through plant residue or “clean” and move the residue out of the seed row. No-till coulters usually can be added onto conventional planters.
  2.  No-till planters’ heavier implements have down-pressure springs that keep the planting units at a uniform depth relative to the heavy frame of the planter. Most conventional planters travel freely across the soil, with the planting units rising and falling with the microtopography of the soil’s surface.

Return on investment in no-till may be delayed by a few factors. Purchasing new equipment increases start-up costs. If soil is extremely diminished, it may take a few years for the soil biology to recover and respond to no-till. Adopting a new way of management means learning how the system responds to your unique operation. This involves time and may result in temporary loss of productivity associated with the learning curve. Changing to no-tillage may also require a change in the nutrient or pest management program.

Attending field days, talking to other producers who are succeeding at the systems being considered, and seeking support from Extension and USDA Conservation professionals can help you succeed.

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