Poor adoption of ley-pastures in south-west Queensland: biophysical, economic and social constraints

Abstract

The present review identifies various constraints relating to poor adoption of ley-pastures in south-west Queensland, and suggests changes in research, development and extension efforts for improved adoption. The constraints include biophysical, economic and social constraints. In terms of biophysical constraints, first, shallower soil profiles with subsoil constraints (salt and sodicity), unpredictable rainfall, drier conditions with higher soil temperature and evaporative demand in summer, and frost and subzero temperature in winter, frequently result in a failure of established, or establishing, pastures. Second, there are limited options for legumes in a ley-pasture, with the legumes currently being mostly winter-active legumes such as lucerne and medics. Winter-active legumes are ineffective in improving soil conditions in a region with summer-dominant rainfall. Third, most grain growers are reluctant to include grasses in their ley-pasture mix, which can be uneconomical for various reasons, including nitrogen immobilisation, carryover of cereal diseases and depressed yields of the following cereal crops. Fourth, a severe depletion of soil water following perennial ley-pastures (grass + legumes or lucerne) can reduce the yields of subsequent crops for several seasons, and the practice of longer fallows to increase soil water storage may be uneconomical and damaging to the environment. Economic assessments of integrating medium- to long-term ley-pastures into cropping regions are generally less attractive because of reduced capital flow, increased capital investment, economic loss associated with establishment and termination phases of ley-pastures, and lost opportunities for cropping in a favourable season. Income from livestock on ley-pastures and soil productivity gains to subsequent crops in rotation may not be comparable to cropping when grain prices are high. However, the economic benefits of ley-pastures may be underestimated, because of unaccounted environmental benefits such as enhanced water use, and reduced soil erosion from summer-dominant rainfall, and therefore, this requires further investigation. In terms of social constraints, the risk of poor and unreliable establishment and persistence, uncertainties in economic and environmental benefits, the complicated process of changing from crop to ley-pastures and vice versa, and the additional labour and management requirements of livestock, present growers socially unattractive and complex decision-making processes for considering adoption of an existing medium- to long-term ley-pasture technology. It is essential that research, development and extension efforts should consider that new ley-pasture options, such as incorporation of a short-term summer forage legume, need to be less risky in establishment, productive in a region with prevailing biophysical constraints, economically viable, less complex and highly flexible in the change-over processes, and socially attractive to growers for adoption in south-west Queensland.

Validating economic and environmental sustainability of a short-term summer forage legume in dryland wheat cropping systems in south-west Queensland

“…Land managers in the region have experienced many failures in establishing stands of small-seeded lucerne and other grasses (L. Ward, unpubl. data), resulting in poor adoption of ley-pastures in the semiarid regions of southwest Queensland (McCowan et al 1988;Singh et al 2009). A large-seeded lablab can be directly drilled deeper into the moist soil, with a high probability of successful germination and establishment, which meet the criteria of desirable pasture species characteristics as noted by Dear and Ewing (2008).…”

“…Nevertheless, growing a forage lablab in summer to its full potential, with a 90% probability of a successful forage crop, or limiting the production of forage, to leave more stored water in the soil profile for a subsequent wheat crop (with a probability of only 50% success), or practicing the old fallow-wheat system (with a poor economic return and being detrimental to the environment in long-term) would be the decision made by the land managers. The process of making this decision is very complex and many complicated factors interact, such as social, financial and environmental considerations (McGuckian 2008;Singh et al 2009).…”

“…Highworth), with an additional P supply into a wheat cropping system would improve the economic and environmental benefits in southwest Queensland. A crop of forage lablab in summer would not only provide an effective ground cover and prevent likely soil erosion, runoff and deep drainage (which are the norms because of episodic rainfall events in summer), but it would also generate economically profitable quality forage 90% of the years (see Singh et al 2009). In addition, an opportunistic double-cropping with wheat in 50% of the years would also add substantially to the economic and environmental benefits.…”

“…However, uncertainties in economic and environmental benefits from the existing medium-to long-term (3-5 years) use of ley-pastures have resulted in poor adoption, particularly in the cropping paddocks. The biophysical, economic and social constraints, such as poor and erratic rainfall events, shallow soil with subsoil constraints, increased cost of livestock management, the loss of cash crop production during the interchange phase, higher grain prices and complex decision-making processes during the changeover from crop to ley-pasture and vice versa have primarily limited the confidence of growers in the ley-pasture technology (McCowan et al 1988;McGuckian 2008;Singh et al 2009). However, greater livestock prices in comparison to grain prices are more likely to favour the adoption of ley-pasture and proportion of years for livestock enterprises in a mixed farming system; livestock production would be more profitable when grain prices are low and vice versa (Bell et al 2008).…”

“…Additionally, a forage legume can be used as a good-quality feed for intensive livestock production and a medium to fix atmospheric N into the soil. Furthermore, greater ease of decision making and a less labourintensive technology, such as incorporation of a short-term summer forage legume, may favour a more rapid adoption of the ley-pasture technology in the cropping paddocks (Armstrong et al 1999;Singh et al 2009). On the other hand, disadvantages of using the summer rainfall by the legumes might include concerns about less soil water being stored in the profile before the sowing of the wheat crop.…”