A ley-farming system for marginal lands based upon a self-regenerating perennial pasture legume

Abstract

Annual-based farming systems represent some of the most highly disturbed terrestrial ecosystems on the planet. They are also highly exposed to climate variability. Many wheatbelt systems of southern Australia rotate annual crops with annual pastures, where the productivity of both is reliant upon seasonal rainfall. Perennial plants, in contrast, are less reliant upon both consistent rainfall and annual establishment, so one approach to decrease exposure to climate variability and disturbance in agriculture is to increase the proportion of the farm sown to perennial species. Perennial pasture or forage species offer immediate possibilities for transformation of agricultural ecosystems as they offer high protein feed to animals, often when green feed is most limiting, and concomitantly restore soil fertility. However, there are no perennial forage legumes adapted to acid and infertile soils in lowrainfall regions of the developed world, either in temperate or Mediterranean climates. Here, we review the recent research efforts to domesticate a perennial legume for these regions. Reasons for the lack of success are provided by a comparison of the attributes of the legumes evaluated in recent research programs and the limitations of these legumes as assessed by reviews and publications. This manuscript outlines an alternative approach to domestication of perennial forage legumes for acid soils and introduces new concepts in ley farming in an Australian context that might support the development of more sustainable agro-ecosystems. It highlights situations where very hard-seeded annual legumes have been successfully included in modern intensive cropping systems, and where perennial legumes may underpin ley-farming systems on infertile soils that normally produce low crop yields. Both innovations require the legume and their nodule bacteria to be sown only once in decades and address concerns about the sustainability of modern agro-ecosystems.

Rethinking soil water repellency and its management

“…Success in this approach has recently been reported by Edwards et al (2019). Thus, SWR could have marked potential benefit in water-limited ecosystems.…”

Productivity and nutritional value of 20 species of perennial legumes in a low‐rainfall Mediterranean‐type environment in southern Australia

“…Perennials also have capacity to mitigate dryland salinity, by reducing rainfall seepage to the water table (Ward & Micin, 2006). Perennial legumes offer a significant advantage over grasses and forbs due to the ability of their root nodule bacteria (rhizobia) to assimilate atmospheric nitrogen (Edwards et al, 2019).…”

“…Finding locally adapted and productive perennial legumes, with effective and persistent rhizobia, remains a research priority in southern Australia (Dear & Ewing, 2008;Edwards et al, 2019;Porqueddu et al, 2016).…”

The history and distribution of nodulating Paraburkholderia, a potential inoculum for Fynbos forage species

“…Therefore, conditions at the site where the potential forage legumes will be grown could be quite important to the success of the accompanying rhizobial symbiont, which in turn will most probably affect legume establishment. The commercial development of Lebeckia ambigua in Western Australia was predicated upon selecting Paraburkholderia capable of surviving in the acid, infertile soils therein (Edwards et al, 2019;Howieson et al, 2013). Another issue to consider is that the loci responsible for nodulation and nitrogen fixation are carried on mobile genetic elements that can be transferred horizontally among species (Andrews et al, 2018).…”