Do agricultural grasses bred for improved root systems provide resilience to machinery‐derived soil compaction?

Abstract

The increasing frequency of droughts and floods on grasslands, due to climate change, increases the risk of soil compaction. Soil compaction affects both soil and forage productivity. Differing grasses may counteract some effects of compaction due to differences in their root architecture and ontogeny. To compare their resilience to soil compaction, three Festulolium (ryegrass and fescue species’ hybrids) forage grass cultivars comprising differing root architecture and ontogeny were compared in replicated field plots, together with a ryegrass and tall fescue variety as controls. Pre‐compaction soil and forage properties were determined in spring using > four‐year‐old plots to generate baseline data. Half of each field plot was then artificially compacted using farm machinery. Forage dry matter yield (DMY) was determined over four cuts. After the final harvest, post compaction soil characteristics and root biomass (RB) were compared between grasses in the non‐compacted and compacted soils. Pre‐compaction data showed that soil under Festulolium and ryegrass had similar water infiltration rates, higher than soil under tall fescue plots. Tiller density of the Festulolium at this time was significantly higher than fescue but not the ryegrass control. Forage DMY was significantly lower (p < .001) with compacted soil at the first cut but, by the completion of the growing season, there was no effect of soil compaction on total DMY. Tall fescue had a higher total DMY than other grasses, which all produced similar annual yields. Soil bulk density and penetration resistance were higher, and grass tiller density was lower in compacted soils. Root biomass in compacted soils showed a tendency for Festulolium cv Lp × Fg to have higher RB than the ryegrass at 0–15 cm depth. Overall, findings showed alternative grass root structures provide differing resilience to machinery compaction, and root biomass production can be encouraged without negative impacts on forage productivity.

Persistency, yield, and silage quality of Festulolium cultivars over a consecutive five-year period under a mild Atlantic climate

“…In terms of yield in this study, the hybrids yields appear to more closely follow their Lolium component than their Festuca component. This was also observed when foliar characteristic and DMY were observed in Festulolium hybrids and compared to that of Lolium pure species (Humpreys et al 2014, Muhandiram et al 2020 This may be due to breeding strategy, genome instability after successive generations, or disparity between integration of source genomes, such as ampliploid or introgressed hybrids. We did observe some variability among hybrid cultivars, where some cultivars exhibited comparable yields to Festuca while others out yield Lolium, though these cases were not found to be significant.…”

Soil structure recovery following compaction: Short‐term evolution of soil physical properties in a loamy soil

“…Although we have not attempted to separate pores created by roots or earthworms in our analysis here, results show that macroporosity increased after compaction (Figure 6), which improved fluid transport properties with nearly no changes in total porosity (Figure 5). We note that the potential to modify soil structure differs between plant species (Bengough et al., 2011; Helliwell et al., 2019; Muhandiram et al., 2020). A potential mechanism involving root growth that would contribute to increasing total porosity is upward lifting of soil via root heave as exemplified with tree root growth (Philips & Marion, 2006), but it is unknown whether a similar process occurs in arable crops and ley with much finer roots (Table 2).…”

Designing agricultural grasses to help mitigate proteolysis during ensiling to optimize protein feed provisions for livestock

“…Further research to understand the potential impact of growth ontogeny during the growing season, and the effects of respiration rates and silica content on wilting rates specific to Festulolium to investigate the need for change to management practice of forage post‐harvest will help to optimize use of these new grass cultivars for conservation purposes. More generally, grasses such as the L. perenne × F. arundinacea var glaucescens hybrid offer new opportunities to fully exploit their diverse and holistic properties (Humphreys & Zwierzykowski, 2020 ; Muhandiram et al, 2020 ). These include not only their capabilities for productive and high‐quality forage, and their efficient protein provisions but also, at a time of climate change and need for more sustainable grassland management, their multiple ecosystem service provisions.…”

“…McDonald et al (1991) showed that rapid pH reduction during ensiling reduced the extent of protein breakdown. Secondary plant compounds in forages, such as tannins in birdsfoot trefoil (Lotus corniculatus) (Marley et al, 2006) and polyphenol oxidases in red clover (Trifolium pratense) (Jones et al, 1995;Marley et al, 2003) also reduce proteolysis during ensiling (Niderkorn & Jayanegara, 2021).…”