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Forage brassicas are currently widely used in temperate–humid livestock systems; however, they offer potential to diversify crop rotation and forage options in the drier, mixed crop–livestock zone of Australia. A literature review highlighted that in these hotter and more arid environments, forage brassicas are more likely to fit as autumn-sown forage crop where they offer an energy-rich, highly digestible feed source that could be used during periods of low production and nutritive value of other forage sources. However, brassicas can also accumulate several anti-nutritional compounds that require gradual introduction to livestock diets, thereby reducing potential health risks and optimising animal performance. Preliminary experimental and commercial evaluations in subtropical Australia found high production of some forage brassica genotypes (>5 t DM/ha with growth rates of 50–60 kg DM/ha.day), comparable or superior to widely used forage cereal or forage legume options. Several forage brassicas showed moderate to high resistance to the root-lesion nematode, Pratylenchus thornei , and hence are likely to provide break-crop benefits compared with susceptible species (e.g. wheat). Together, this evidence suggests that forage brassicas have significant potential for wider use in crop–livestock farming systems in Australia. However, research is needed to identify genotypic adaptation and to match different forage brassica genotypes to production environments or system niches, especially some of the new genotypes that are now available. There is also a need to develop regionally-relevant recommendations of agronomic and grazing management that optimise forage and animal production, and mitigate potential animal health risks. Forage brassicas are widely used to provide high-quality forage in temperate, high-rainfall livestock systems but are rarely used in crop–livestock systems in drier regions. We find that forage brassicas have several attributes suited to wider use in crop rotations, and preliminary experiments demonstrate favourable productivity compared with other forage options. This work demonstrates the wider potential and research needs for forage brassicas to be used throughout Australia's mixed crop–livestock systems. [ABSTRACT FROM AUTHOR]

• Tropical forage legumes were grown in rotation or relays with maize and rice. • Subsequent maize yields increased by up to 80 % if legumes were retained as mulch. • Maize yield increased less (15−35% higher) after legume forage was harvested. • Forage legumes grown in rotation with rice increased subsequent yields by 40–70 %. • Clitoria ternatea proved the most beneficial forage legume for diverse systems. In temperate systems, it is well known that forage legumes can improve both nitrogen (N) supply and yields of subsequent cereal crops. While this is assumed to be true in tropical systems, it is less well tested, particularly in smallholder settings where forage is often cut and removed from the field. This paper confirms the potential of short phases of tropical forage legumes to provide N to subsequent crops in seasonally dry tropical farming systems. Across five experiments, maize and rice grain yields increased by up to 80 % after 4−8 month rotations of forage legumes, but the benefits were smaller when legume growth was reduced, biomass was removed for forage, or the yield potential of cereal crops was lower. We found that the additional N cycling from legumes can last for at least 2 years, although the benefit diminishes with time. When all legume material was retained as mulch, the estimated additional N provided to subsequent no-till maize crops was the equivalent of 9−15 kg urea-N per tonne of above-ground legume biomass produced but fell to 1.5−3 kg urea-N/t if forage was removed. After shoot removal, more legume N cycled to a subsequent rice crop (equivalent of 11–13 kg urea-N/t of legume biomass) than to a no-till maize crop, presumably because more below-ground material mineralised. Of the legumes tested, Clitoria ternatea grew best across a variety of environments and use patterns and provided the largest yield benefits to subsequent crops. This research demonstrates the potential to integrate short phases of tropical herbaceous forage legumes into smallholder crop-livestock systems in the seasonally dry tropics, and, in doing so, improve or maintain staple grain crop production and household food self-sufficiency. [ABSTRACT FROM AUTHOR]

Dorycnium hirsutum (L.) Ser. and Dorycnium rectum (L.) Ser. are Mediterranean perennial legumes that may have potential as alternative forage plants to Medicago sativa (lucerne, alfalfa) for low rainfall dryland agriculture. Strategies for surviving periods of water deficit are vital for perennial plants in water-limited environments. This experiment compared leaf physiological and morphological adaptations to increasing water deficit among D. hirsutum, D. rectum and M. sativa. Plants were grown in the glasshouse in large pots (7.8 L, 1 m deep, 10 cm diameter) containing a sandy clay loam (14% available water content) to limit differences between root foraging among the species. Watering was withheld for 21 days and predawn and midday leaf water and osmotic potential were determined. Mid-morning rates of gas exchange were measured at five times as soil water was depleted. After 35 days of withholding water, plant recovery was measured. D. hirsutum and M. sativa reduced stomatal conductance at leaf water potentials below −1.8 MPa and water-stressed D. hirsutum osmotically adjusted by up to 0.68 MPa. D. rectum differed from the other species; leaf water potential was maintained at high levels until soil water content had reached low levels, and reductions in stomatal conductance and photosynthesis were not associated with leaf water potential. D. hirsutum and M. sativa displayed leaf morphological adaptations that may contribute to greater resistance of water deficit. Only one of five D. rectum plants survived the water-stress treatment compared to five of five for D. hirsutum and four of five for M. sativa. The water relations and physiology of D. hirsutum observed in this study suggest that it possesses adaptations suitable for arid environments. On the other hand, the poor survival and water relations of D. rectum indicate that it is poorly adapted to situations where water deficit is common. [ABSTRACT FROM AUTHOR]

Dorycnium hirsutum and D. rectum are perennial legumes which may have potential for use as pastures for the control of groundwater recharge in southern Australia. Little is known about the quality of the forage of Dorycnium species for grazing livestock or how these species respond to cutting. The effect of cutting height on plant survival, production of dry matter (DM), the proportion of leaf, edible stem (approximately <5 mm diameter) and woody stem in the DM and the nutritive value of the edible components was investigated. Biomass above five cutting-height treatments (uncut, ground level, 5–8 cm, 10–15 cm and 15–30 cm above ground level) was removed at 8-week intervals from plots of D. hirsutum and D. rectum from September 2002 to July 2003. In both species, plants subjected to lower cutting height treatments produced less DM above the height of the cut than those cut at higher heights. DM production declined over time in all treatments. Plants cut to ground level failed to regrow after the second harvest in D. hirsutum and the fourth harvest in D. rectum. Thus, these Dorycnium species were susceptible to high severity defoliations at 8-week intervals. Negligible inedible woody stem was present in regrowth of both species after 8 weeks but D. hirsutum regrowth had a higher proportion of leaf (0·72) than D. rectum (0·56). Plants left uncut accumulated a large proportion of inedible woody stem in the DM (0·69 in both species) by July 2003, particularly at the base of the plant. Edible DM from regrowth of D. hirsutum and D. rectum had crude protein (CP) concentrations of 120 and 150 g kg−1 DM; dry matter digestibility (DMD) values of 0·45 and 0·58; organic matter digestibility (OMD) values of 0·50 and 0·64; neutral-detergent fibre (NDF) concentrations of 370 and 290 g kg−1 DM; and acid-detergent fibre (ADF) concentrations of 260 and 210 g kg−1 DM, respectively. Medicago sativa, grown under similar conditions, had higher digestibility values (0·63 DMD and 0·66 OMD) and similar CP concentrations to D. rectum (140 g kg−1 DM), but higher concentrations of NDF and ADF (410 and 290 g kg−1 DM). Leaf material from both Dorycnium species had a higher nutritive value than edible stems, with DMD and OMD values of leaf of D. rectum being 0·68 and 0·74 respectively. Uncut plants had a much lower nutritive value of edible DM than the regrowth from cut treatments; older material was also of a lower nutritive value. The relatively low nutritive value of even the young regrowth of Dorycnium species suggests that forage quality is a major limitation to its use. Forage of Dorycnium species could be used during periods when other sources of forage are in short supply but infrequent grazing it is likely to produce forage of a low nutritive value. [ABSTRACT FROM AUTHOR]

Pulses have emerged as important rotation crops in Australia. Some are in demand in agricultural production systems due to their high potential market value, because of their roles as grain or forage crops, their nitrogen fixation capability, and because they provide a disease break or improve soil health. While several pulse crops have been identified for winter-season cropping, there are few adapted legumes apart from mungbean that are appropriate for dryland summer cropping. Currently, short-duration crops of mungbean are commonly used, but yields are highly variable and susceptible to drought. Here, we propose that cowpea has the potential to become an alternative rotation crop in dryland summer cropping zones, providing a competitive and profitable alternative pulse crop option where its drought tolerance could enable better performance under inconsistent in-crop rainfall. We demonstrate that cowpea has nutritional properties and putative uses that could prove valuable in emerging plant-based protein and aquaculture markets. [ABSTRACT FROM AUTHOR]