Soil response to perennial herbaceous biofeedstocks under rainfed conditions in the northern Great Plains, USA

- Perennial herbaceous biofeedstocks (PHBs) can alter soil condition and function.
- PHBs were evaluated for their influence on soil chemical and physical properties.
- Soil properties in PHB monocultures and mixtures were not different after 5 years.
- Over time, PHBs decreased soil P, increased soil C, but didn't alter soil pH or EC.
- Results suggest PHBs can remediate and/or stabilize degraded soils.

Perennial herbaceous biofeedstocks (PHB) have been proposed to confer multiple ecosystem services to agricultural lands. However, the role of PHBs to affect change in soil condition is not well documented, particularly for treatments with multiple species. The objective of this study was to quantify potential changes to soil properties resulting from PHB treatments in central and western North Dakota over a 5-yr period. Treatments with multiple perennial plant species were hypothesized to induce greater improvements in soil condition compared to monocultures. Soil properties were evaluated in seven PHB treatments (four monocultures, three mixtures) at five sites with sampling occurring immediately prior to treatment establishment in 2006 and again in 2011 across a 0 to 1.2 m depth. Perennial herbaceous biofeedstocks had minor and inconsistent effects on soil bulk density, electrical conductivity, and soil pH, and no effect on available P and soil organic C (SOC) in 2011. Contrasts between monoculture and mixtures in 2011 yielded no significant differences for any soil property at any site. However, PHB treatments did induce significant changes in soil properties between 2006 and 2011, with substantial declines in available P (> 10 kg P ha− 1 yr− 1) at sites with high initial P and modest increases in SOC (0.9-5.7 Mg C ha− 1 yr− 1) at sites with low initial SOC. Electrical conductivity decreased at two sites, though changes were minor (− 0.08 to − 0.18 dS m− 1). Soil pH did not change over the 5-yr study. Results from this study underscore the value of PHBs to remediate nutrient-laden and/or degraded soils, while concurrently resisting increased salinity and fertilizer-induced acidification.