The Importance of Building Soil Structure

This summer, some parts of the country have experienced severe bouts of rain, while others are experiencing drought. Both extremes can have a devastating impact on crop production. 

In both situations, growers must work harder to find efficiencies in their fields. One way that growers can maximize resilience on their land is by strengthening the soil structure in their fields. 

We spoke with soil health expert Liz Haney to better understand why building soil structure is integral in weathering both droughts and storms. She also explained how regenerative and resilient agriculture practices help strengthen soil structure, and what that means on a microscopic level. Liz has a deep background in soil health and regenerative agriculture, including a PhD in ecosystem science and Management and a Master’s Degree in Soil Science.

Reduced Tillage Promotes Beneficial Fungal Communities

One of the ways growers can build soil structure is by reducing tillage on their farms. By transitioning to a minimum-till or no-till practice, growers provide the soil more opportunity to host beneficial bacterial and fungal communities.  Mycorrhizal fungi is beneficial to the soil in many ways. 

This fungal community is integral in building and maintaining soil structure because, according to Liz, it creates a sort of ‘glue’ that holds soil particles together.

This aggregation of soil particles increases pore space in the soil profile, thereby increasing water retention and infiltration.

‍Conservation Practices improve soil structure

Practices like reduced- or no-till farming and cover cropping allow more organic matter to become integrated into a grower’s soil system. Increased organic materials above ground and organic matter below ground are integral to enhancing soil structure in several different ways. 

First, the residue left on the surface of the soil creates a physical defense against erosion. And it’s not just wind, sheet and rill erosion growers have to worry about. According to Liz, it’s easy to conceptualize wind erosion (we can imagine the dust that blows off fields on dry, windy days), but microwater erosion is also a significant issue. Liz emphasizes that even the pressure exerted from each raindrop hitting bare soil can cause erosion. Rainfall induces disaggregation of soil at the surface, dislodging the soil from the surface and sometimes resulting in surface crusting, further increasing the potential for surface erosion.  Organic materials left on top of the soil, like residue in a no-till system or by integrating cover crops, reduces the damage done by both wind and water.

Organic matter in the soil promotes soil aggregation, resulting in improved soil structure . This improved soil structure increases water infiltration and the organic matter in the soil stores the water for use by plants. 

Organic matter can hold up to 90% of its weight in water.

Organic matter is also better-equipped to retain nutrients for plants to use in the future than soil particles alone due to its increased surface area. Studies by NRCS also show that organic matter can suppress disease organisms, making disease pressure less severe, and accumulated organic matter can lead to improved and more diverse biological activity, which increases plant health and vigor. ‍

‍The Effects of Better Water Infiltration‍

Strengthening soil structure can lead to increased fungal activity, organic matter and biological activity in soils. All of this allows the soil to retain the moisture it needs to maintain healthy, productive crops.

Increased moisture retention helps prevent against wind and water erosion by strengthening the topsoil. It also allows the soil to hold more nutrients for longer periods of time, and it can reduce both nutrient runoff and disease pressure. All of these factors ultimately lead to healthy, efficient crops that require fewer inputs. 

So, while this year has been difficult for growers in a number of ways, there are opportunities for growers to lessen crop stresses in the coming seasons. Promoting soil health through conservation practices can help growers guard against future stressors caused by severe weather events, like excessive rainfall and drought.

For more information on mitigating the effects of excessive rainfall, read our recent blog post.