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Intercropping using mixtures of dryland crop species for grain or seed production was investigated in southern Australia across a range of rainfall zones over three years. The objective was to understand the productivity and profitability of intercropping in extensive, high-input grain cropping systems. Previous research has shown large productivity benefits of mixtures; however, few farmers practice intercropping in Australia, and an analysis of profitability is needed to support future potential adoption. Experimental results showed strong mixture responses (in terms of yield, value and land equivalence), but not all were profitable compared to an equivalent share of monoculture crops (as measured by gross margins). The most promising mixtures were those containing high-value crops (canola) and legumes (field pea or faba bean) at the wetter sites where the additional gross margin over equivalent monoculture crops ranged from $12/ha to $576/ha. Mixtures containing highly competitive crops (wheat or barley) were generally unprofitable. Mixtures involving cereals were doubly disadvantaged by the aggressiveness of these lower-value crops in the mixtures we examined and the high grain separation costs post-harvest. Cost reduction in mixture systems involving high-value crops that are synergistic (grain legumes) should provide enduring opportunities for intercropping in southern Australia. [ABSTRACT FROM AUTHOR]

Lucerne (Medicago sativa L.) has a large taproot to store and release starch, carbohydrates and nutrients during the plant's growth. Recommended management of the lucerne crop aims to keep the taproot stable subject to the demands for feed provision and stand longevity. Field experiments were conducted in Victoria, Australia, to examine the effects of recovery period on taproot mass and nutritive status. Both experiments used established SARDI Seven lucerne crops and were either cut every 21 days (short recovery SR) or every 42 days (long recovery LR). At each defoliation, taproots were extracted for determination of DM yield and starch, water‐soluble carbohydrate (WSC) and nitrogen (N) concentration and DM yield. At both sites, WSC and N DM yields along with total taproot DM yield did not change greatly as the experiment progressed. Starch was responsive to herbage accumulation with both concentration and DM yield, increasing when herbage accumulation rates were high and decreasing when herbage accumulation rates were low. At both sites, LR taproots had starch levels equal to or higher than those of SR taproots. We conclude that short intervals between defoliations disrupt the energy cycling between shoots and roots. This is likely to reduce lucerne productivity, particularly during periods of rapid growth. [ABSTRACT FROM AUTHOR]

Lucerne (Medicago sativa L.) is an important temperate legume for livestock production systems. Lucerne requires a recovery period after a defoliation event so that taproot energy and nutrient stores can be replenished. A field experiment examined the effects of recovery period management following defoliation, on lucerne herbage production and nutritive value at two contrasting sites in Victoria, Australia. Sites were established at Rutherglen and Hamilton, using established SARDI Seven lucerne stands. Treatments were short recovery (SR; plots cut at 21‐day intervals), long recovery (LR; plots cut at 42‐day intervals), new shoots (NS; plots cut when new shoots from the crown were at least 2 cm long) and new shoots + flowering (NSF; as for NS but plots were left to grow to reach late flowering from late summer to mid‐autumn). At each defoliation, measurements were made of phenology, dry matter production and herbage nutrient concentrations (neutral detergent fibre, crude protein, metabolisable energy and water‐soluble carbohydrate %). Persistence was measured at approximately 6‐month intervals. At both sites, lucerne persisted equally well in all treatments although SR showed some decline at Hamilton at the final measurement. LR led to a more productive pasture (in terms of cumulative dry matter, neutral detergent fibre, crude protein, metabolisable energy and water‐soluble carbohydrate %) than the three other treatments. The results indicate that phenological management systems that allow lucerne to replenish reserves through late summer and autumn are unnecessary in mild winter environments. [ABSTRACT FROM AUTHOR]

Lucerne (alfalfa; Medicago sativa L.) is the key forage for grazing in dryland temperate regions around the world. While rotational grazing of lucerne is recommended, in southern Australia the intervals between grazing events are often chosen in an opportunistic manner, to meet livestock production targets and utilise excessive spring and summer growth. To assess whether the persistence of lucerne is sensitive to variations in rotational grazing management practice, we report on an experiment with four sheep grazing treatments that was conducted for 2.5 years, including three summers, in southern New South Wales. The grazing management treatments were a crash-grazing control, frequent grazing, feed-based rotational grazing and time-based rotational grazing, replicated four times. The number of grazing events, percentage of time under grazing, lucerne top dry matter (DM) at the beginning and end of grazing periods and plant density were measured. The results relating to number of grazing events, percentage of time grazing and DM removed during grazing indicated that four grazing practices had been achieved. The treatments all had significant periods of rest for at least 73% of time and were empirically different in their approach but resulted in similar grazing pressures, in terms of overall pasture removed during grazing. Nevertheless, there was little difference in lucerne densities between grazing treatments over the life of the experiment. We conclude that there is flexibility in the rotational management of grazed lucerne provided adequate rest periods are part of the management program. [ABSTRACT FROM AUTHOR]

Intercropping is considered by its advocates to be a sustainable, environmentally sound, and economically advantageous cropping system. Intercropping systems are complex, with non-uniform competition between the component species within the cropping cycle, typically leading to unequal relative yields making evaluation difficult. This paper is a review of the main existing metrics used in the scientific literature to assess intercropping systems. Their strengths and limitations are discussed. Robust metrics for characterising intercropping systems are proposed. A major limitation is that current metrics assume the same management level between intercropping and monocropping systems and do not consider differences in costs of production. Another drawback is that they assume the component crops in the mixture are of equal value. Moreover, in employing metrics, many studies have considered direct and private costs and benefits only, ignoring indirect and social costs and benefits of intercropping systems per se. Furthermore, production risk and growers' risk preferences were often overlooked. In evaluating intercropping advantage using data from field trials, four metrics are recommended that collectively take into account all important differences in private costs and benefits between intercropping and monocropping systems, specifically the Land Equivalent Ratio, Yield Ratio, Value Ratio and Net Gross Margin. [ABSTRACT FROM AUTHOR]

Lucerne (Medicago sativa L.) persistence is important for farming systems in south east Australia. Defoliation of lucerne that is too frequent (arguably more than once every six weeks) reduces yield and accelerates stand decline. Three experiments were conducted in south east Australia (Burraja, New South Wales; Rutherglen and Hamilton, Victoria) to investigate different cutting regimes on lucerne persistence. At Burraja lucerne was cut 16 (lax) or 33 (severe) times over three years at different plant densities. At Rutherglen and Hamilton lucerne was cut every 21 days (short rotation), every 42 days (long rotation), when new shoots (2.5 cm long) emerged (new shoots) or cutting when new shoots emerged but allowing the lucerne to flower in autumn (new shoots flowering). It was hypothesised that the frequent cutting of lucerne would result in lower plant densities. At Burraja there was little difference between treatments at any density or assessment. At Hamilton, apart from the assessment in June 2016, there was no difference (p > 0.1) between treatments. At Rutherglen, there was no difference (p > 0.1) between treatments at any assessment although plant numbers declined in 2016 from waterlogging. The results provide evidence that lucerne has intrinsic mechanisms that protect it from cutting, often at short intervals, thus promoting its persistence over three to four-year periods. [ABSTRACT FROM AUTHOR]