Skip to main content Skip to navigation

Soil Fertility and The Cropping System

Posted by Blythe Howell | December 9, 2020
Soil fertility practices can enhance or limit crop growth and affect plant health, crop yield, and quality. Best practices for fertilizer applications are summarized by the ‘4Rs’ guideline: right source, right rate, right timing, right placement. However, dialing in the right rate, source, timing, and placement of added nutrients to optimize crop outcomes can be a challenge.

Primary, secondary, and micronutrients are all essential for crop health and yield. Primary nutrients such as nitrogen (N), phosphorous (P), and potassium (K) are required by plants in the highest quantities and are most commonly applied for crop production. Secondary nutrients are calcium (Ca), magnesium (Mg), and Sulphur (S) along with micronutrients are also essential for plant growth and health but are needed in smaller quantities. These nutrients are available in different forms, which affects plant availability, susceptibility to losses, contribution to soil acidity, and cost. Applying the right form of these nutrients for a farm’s management goals is the first step in the ‘4Rs’ of nutrient management.

For optimum nutrient management, plant health, and crop production it is important that soil retains its function as a vital living ecosystem. Soil organic matter is essential for soil health and fertility, water holding capacity, nutrient storage and cycling, and plant growth. Post-harvest residue management plays a key role in supporting nutrient cycling and organic matter accumulation. While plants rely on getting the essential elements of carbon dioxide (CO2) and oxygen (O) from the air, the bulk of plant required nutrients is found and cycled through the soil. Sources for nutrient inputs can vary: Nitrogen is synthesized into fertilizer from the air through the Haber-Bosch process, fixed by legume symbionts or free-living N-fixing microbes, and found in organic amendments such as manure and compost. Phosphorous and potassium are both mined from the ground and as a result, are non-renewable, but organic amendments can be an effective alternative for reducing nutrient loss by recycling them through ag systems.

Under-fertilizing leaves yield on the table, while over-fertilizing is inefficient and cuts into profit margins while being detrimental to the environment. Incorporating diversity into the cropping system is important for soil health and can support various management goals. Alternative crops have different nutrient requirements than wheat which can be a barrier to incorporating new crops into a system. Soil and tissue analysis and effective interpretation is a cornerstone of a solid fertility management program whatever the cropping system. Timing and placement are also important for getting the most out of a farm business’s investment in fertility. Improper placement can lead to a yield hit from root burn or reduced germination. Varying fertility inputs across the farm, based on production potential, is another opportunity for leveraging placement decisions to optimize profit margins. Enhanced efficiency fertilizers can be potentially beneficial to reduce nutrient loss and improve nutrient use efficiency, however, their effectiveness is impacted by many factors such as weather, soil, application time and methods, fertilizers the products are used with, just to name a few. Digging into answering these questions can be helpful for choosing the right products.

The WSU Farmers Network soils education series works to support producers and ag professionals by offering high-quality, relevant content from experts across the inland PNW. This winter all workshops have all moved online. Our team is excited that this year’s information will not be limited by cost or geographic boundaries with content that should be relevant to anyone interested in soils in the Inland PNW.

The Soil Fertility and the Cropping System series is coming up quickly. Among the topics covered will be Avoiding Root Burn, Residue Management, Wheat and Alternative Crop Fertility Management, Enhanced Efficiency Fertilizers, and Fertility Trends in Eastern Washington. The live event will be offered at no cost via Zoom from 9-11 am PST on Dec. 14-17, with recorded sessions to be offered through our continuing education platform for CCA credit following the event for a small fee. For more information and to register for the live events, please visit the WSU Farmers Network Webinar page and stay tuned as we roll out the final agendas for our upcoming Soil Health: Measuring and Managing from January 11-14, and Decision Making Using On-Farm Data that will be offered February 8-11.

Related WSU Wheat Beat Podcast Episodes:


Haiying Tao
For questions or comments, contact Haiying Tao via email at haiying.tao@wsu.edu with the Department of Crop and Soil Sciences at Washington State University.

Leave a Reply

Your email address will not be published. Required fields are marked *

Washington State University