Soil acidity management of long-term no-till fields in Montana to prevent crop failure

View the project final report

Commodities

• Agronomic: barley, canola, peas (field, cowpeas), wheat

Practices

• Crop Production: cover crops, cropping systems, fertilizers, no-till, nutrient management, lime applications
• Farm Business Management: budgets/cost and returns
• Production Systems: dryland farming
• Soil Management: soil analysis, soil quality/health
• Sustainable Communities: local and regional food systems

Soil acidity has become a problem for many dryland producers in Montana, impacting
production and land sustainability. Without remediation, cereal grains, pulses, and other crops
can no longer be grown in some areas. This problem can be traced to a rise in fertilizer N
consumption and no-till cropping systems which have become the norm in the major small grain
producing counties. Although the benefits of no-till are well recognized (erosion control,
moisture conservation, greater soil organic matter, lower energy and labor costs), there are
drawbacks including acidification of surface soil layers leading to crop aluminum toxicity. This
project proposes to address the emerging problem of soil acidification by engaging with growers
in northern and central Montana who are currently experiencing lost production and
sustainability, and who are now experimenting with remediation strategies, including lime
applications, crop diversification, and intensification with cover crops. On-farm field-scale trials
are planned to evaluate the efficacy of these remediation strategies. In addition, replicated smallplot
trials are planned to identify crop species and cultivars with resistance to aluminum, and the
impact of N fertilizer sources on soil acidification. Lab studies are planned to define the best
protocols for estimating lime requirements. This project will identify effective mitigation and
prevention strategies that can be adopted by growers in regions experiencing soil acidification.
Education and outreach activities include field day presentations, workshop presentations by
researchers, podcasts, a soil acidification webpage, short summaries in grain grower newsletters
and magazines, and an Extension Bulletin on acidification and its prevention. Farmer surveys are
planned to quantify the impact of this study on knowledge of soil acidity remediation, soil
quality, and crop sustainability. The potential significance of this project is tremendous as
surveys of soil samples indicate a downward trend in pH, which is likely to continue unless this
problem is addressed.

1) To develop and execute an on-farm soil acidity remediation and prevention program in
central and northern Montana (April 2017-October 2019).
2) Identify soil buffer test methods that provide the best estimate of lime requirements for soils
in central and northern Montana (July 2017- October 2019).
3) Identify canola, pea, barley, and wheat cultivars along with crop species grown in cover crop
polycultures or cocktails that are best adapted to low pH environments (July 2017-April
2020).
4). Provide agricultural stakeholders with the research results they need to make informed
decisions on acid soil mitigation and prevention with both direct engagement, through Field
Days, workshops, one-on-one, and indirect contacts including press releases, webpage, radio
interviews, and a video, and evaluate the impact of this outreach and engagement effort. Our
goal is to reach >500 people directly and have another >5,000 indirect contacts (April 2018–
April 2020).