This study compared the field performance of red clover germplasm UK2014, selected for 2,4-D tolerance, to Kenland, a standard variety grown in the transition zone of the United States. UK2014 and Kenland were seeded in the spring of 2017 and 2018. Single applications of 0, 1.12, or 2.24 kg ae ha−1 2,4-D-amine were made in June, August, or October. One week after the treatments, yields were determined. Visible herbicide injury ratings were made prior to harvest and regrowth was visibly assessed 1 wk after harvest. Red clover stands were visibly assessed the following spring. Kenland, across all application timings, was injured by 2,4-D more than UK2014, with mean injury ratings of 39% and 63% compared with 26% and 37% at 1.12 and 2.24 kg 2,4-D ae ha−1, respectively. At equivalent rates, Kenland regrowth was less than UK2014 at all application timings. UK2014 regrowth after 2,4-D treatment ranged from 65% to 91%, whereas Kenland regrowth ranged from 12% to 72%. Applications of 2,4-D in October were the most damaging to stands of both UK2014 and Kenland the following spring, but Kenland stands were reduced much more than those of UK2014. Kenland and UK2014 had similar season total yields when not treated with 2,4-D (means of 7,550 and 7,880 dry matter kg ha−1, respectively in 2017 and 5,280 dry matter kg ha−1 for both in 2018). Kenland season total yield in 2017 was reduced by both 2,4-D rates applied in June or August and at all timings in 2018. UK2014 season total yield in 2017 was reduced only when 2.24 kg 2,4-D ae ha−1 was applied in August. In 2018, 2.24 kg ae ha−1 2,4-D resulted in reduced UK2014 season total yield across application timings. UK2014 has greater 2,4-D tolerance than Kenland, but additional selection might be beneficial.

The bacterial community is important for shaping the fermentation characteristics of silage. This study aimed to investigate the fermentation characteristics, bacterial community and predicted functional characteristics of red clover (Trifolium pratense L.) silage. First-cutting red clover was collected at the early bloom stage, wilted for 5 h and then ensiled in 10 litre-capacity silos. Triplicate silos were sampled after 1, 3, 7, 15, 30 and 60 days of ensiling, respectively. The bacterial communities on days 3 and 60 were assessed through high-throughput sequencing technology, and 16S rRNA-gene predicted functional characteristics were analysed based on the KEGG using Tax4Fun. After 60 days of ensiling, red clover silage was fermented well, as indicated by high lactic acid (~77.3 g/kg DM), and low concentrations of butyric acid (~3.73 g/kg DM) and ammonia nitrogen (~55.0 g/kg TN). During the initial stage of ensiling, fructose and glucose were more preferred than sucrose for microbes. The predominant genus Lactococcus (0.542) on day 3 was replaced by Lactobacillus (0.553) on day 60. The metabolism of amino acids, energy, cofactors and vitamins was inhibited, while the metabolism of nucleotides and carbohydrates was enhanced after ensiling. High-throughput sequencing technology combined with 16S rRNA gene-predicted functional analyses revealed the differences during the early and late stages of red clover silage not only for distinct bacterial compositions but also for specific functional traits. Our results could provide a comprehensive insight into bacterial community and their functional profiles to further improve the silage quality.

Field studies were conducted to determine the possible rate and timing of nicosulfuron to suppress annual ryegrass (ARG) seeded as a cover crop at the time of corn planting without affecting corn performance near Ridgetown, ON, Canada, in 2016 and 2017. Nicosulfuron was applied at rates from 0.8 to 50 g ai ha–1 when the ARG was at the two- to three- or four- to five-leaf stages, or approximately 3 or 4 wk after emergence of both corn and ARG. There were no differences between the two application timings in grain yield responses or ARG suppression. As the rate of nicosulfuron increased from 0.8 to 50 g ai ha–1, ARG was suppressed 6% to 76% and 5% to 96%, at 1 and 4 wk after application (WAA), respectively. At 4 WAA, ARG biomass decreased from 29 to 1 g m–2 as the rate of nicosulfuron increased from 0.8 to 50 g ai ha–1, compared to 36 g m–2 in the untreated control. Where nicosulfuron was not applied to ARG, grain corn yield was reduced by 6% compared to the ARG-free control; similar effects on corn yield were observed with nicosulfuron at the lowest rate applied at 0.8 g ai ha–1. Grain corn yield was reduced by 2.5% with the application of nicosulfuron at 25 g ai ha–1 (label rate for corn) compared to no ARG control, but this was not statistically significant. This study identified rates of nicosulfuron that suppressed ARG when emerged approximately the same day as corn, but there was evidence that grain corn yields were lowered because of interference, possibly during the critical weed control period. Based on this study, an ARG cover crop should not be seeded at the same time as corn unless one is willing to accept a risk for corn grain yield losses for the sake of the cover crop.

Tolerance and subsequent yield response of established alfalfa, red clover, alsike clover, sainfoin, birdsfoot trefoil, and cicer milkvetch to sethoxydim and fluazifop spring applied and to hexazinone, metribuzin, and terbacil fall applied were determined in a field study. All legumes tolerated sethoxydim. Fluazifop was safe on all legumes except sainfoin. Alfalfa and cicer milkvetch tolerated hexazinone, metribuzin, and terbacil. Alfalfa dry matter yield was not affected by any of the herbicide treatments, but cumulative cicer milkvetch yield increased 9% over a 3-yr period with hexazinone applications. Sainfoin yield increased 20% with hexazinone and terbacil treatment. Hexazinone injured red clover and reduced yield. Alsike clover was the most susceptible legume to the residual herbicides. Weed dry matter yield associated with the legumes indicated that alfalfa and sainfoin were the most and the least competitive species, respectively. Plots treated with hexazinone contained the least amount of weeds, regardless of the legume species. Field peas seeded in rotation was not affected by herbicide residues; however, residues from terbacil applied at 1.0 kg/ha reduced seed yield of lentils.

Weeds of the genus Orobanche parasitize many dicotyledonous species, causing severe damage to vegetable and field crops worldwide. In Oregon, the number of red clover fields contaminated with small broomrape has increased in recent years. Small broomrape parasitism in red clover is temperature related. In this study, the temperature-dependent relationship was developed into a predictive model based on growing degree-days (GDD) for small broomrape parasitism in red clover. The model was developed in greenhouse studies and validated in the field during three growing seasons. A strong relationship between GDD and parasite size allowed for the creation of a simple predictive model for tubercle number based on GDD. The proposed model is based on a temperature range realistic to western Oregon climatic conditions and predicts lag, log, and maximum phases for four parasitism sizes in relation to GDD. Small broomrape parasitism in red clover began at about 400 GDD, but red clover biomass accumulation was not affected by parasitism before 1,200 GDD. Small broomrape flower stalk emergence began at about 1,100 GDD. Field studies validated that GDD could be a predictive parameter for small broomrape parasitism and could be used to time detection surveys and herbicide applications.

The root-parasitic broomrape species cause severe damage to field and vegetable crops worldwide. This study evaluated the relationship between small broomrape development and temperature with red clover as a host plant. Red clover plants were grown in soil artificially infested with small broomrape seed in temperature-controlled growth chambers. Parasite development was quantified at 48 different accumulated growing degree days (GDD). Small broomrape parasitism and temperature were strongly related. Small broomrape tubercle initiation was delayed by low temperature. Tubercle development initiated at about 750 GDD and peaked at about 1,100 GDD. Small broomrape biomass accumulation correlated with the increase in tubercle number over time. Parasitism stages were divided into lag, log, and maximum phases that were strongly related to GDD. Development of a predictive system for parasitism growth stage is needed to allow precise herbicide application for effective control before small broomrape shoot emergence.

Green manure crops must produce high biomass to supply biological N, increase organic matter and control weeds. The objectives of our study were to assess above-ground biomass productivity and weed suppression of clover (Trifolium spp.) green manures in an organic soybean [Glycine max (L.) Merr.]-winter wheat (Triticum aestivum L.)-corn (Zea mays L.) rotation in eastern Nebraska in three cycles (2011–12, 2012–13, 2013–14). Treatments were green manure species [red clover (T. pratense L.) and white clover (T. repens L.)] undersown into winter wheat in March and green manure mowing regime (one late summer mowing or no mowing). We measured wheat productivity and grain protein at wheat harvest, and clover and weed above-ground biomass as dry matter (DM) at wheat harvest, 35 days after wheat harvest, in October and in April before clover termination. Winter wheat grain yields and grain protein were not affected by undersown clovers. DM was higher for red than for white clover at most sampling times. Red clover produced between 0.4 and 5.5 Mg ha−1 in the fall and 0.4–5.2 Mg ha−1 in the spring. White clover produced between 0.1 and 2.5 Mg ha−1 in the fall and 0.2–3.1 Mg ha−1 in the spring. Weed DM was lower under red clover than under white clover at most sampling times. In the spring, weed DM ranged from 0.0 to 0.6 Mg ha−1 under red clover and from 0.0 to 3.1 Mg ha−1 under white clover. Mowing did not consistently affect clover or weed DM. For organic growers in eastern Nebraska, red clover undersown into winter wheat can be a productive green manure with good weed suppression potential.

Genetic diversity of a red clover global collection was assessed using 36 simple sequence repeat (SSR) primers representing all seven linkage groups (LGs). The number of fragments amplified ranged from 1 to 6 for all the primers. Primer RCS0060 detected highest number of fragments, whereas four SSRs viz., RCS0899, RCS1594, TPSSR40 and RCS6927 amplified single fragment. Size range of amplicons generated by all the primers varied from 100 to 400 bp. Polymorphism information content values ranged from 0.301 to 0.719 with an average value of 0.605. LG wise diversity analysis showed that LG 3 was most diverse (I = 0.65, Ht = 0.44), whereas LG-1 showed minimum diversity (I = 0.48, Ht = 0.26) for the microsatellites used. Bayesian model-based clustering inferred three genetically distinct populations in the red clover germplasm holding and showed considerable admixture in individuals within clusters. Neighbour-joining analysis showed intermixing of accessions within groups. Principal component analysis plot complemented the clustering shown by Structure and distinguished three populations to greater extent. Analysis of molecular variance showed that 91% of the genetic variation was residing within populations, while 9% variation was among populations. Overall, the results showed that a high level of genetic diversity is prevailing in this worldwide collection of red clover, which can be exploited for its genetic improvement through breeding approaches.

Organic producers are interested in developing a no-till system for crop production. In this study, we examined management tactics to convert perennial legumes to annual crops without tillage. Our hypothesis was that reducing carbohydrate production in the fall by mowing would favor winterkill. Mowing treatments were imposed in the fall of the third year of alfalfa or red clover, and corn planted in year 4. The conventional practice of tillage to convert legumes to cropland was also included as a treatment. Mowing in autumn reduced red clover biomass 93% compared with alfalfa when measured 3 weeks after corn planting (WAP). Red clover biomass was still 75% less than alfalfa 6 WAP. Fall mowing suppressed red clover sufficiently to enable corn seedlings to establish, but corn seedlings did not survive in mowed alfalfa due to alfalfa competition. Corn grain yield following red clover was similar in the mowed and tilled treatments when weeds were present. Late season clover and weed growth reduced corn yields 46% compared with weed-free corn. Weed emergence in corn was three times higher after tillage compared with the mowed treatment. Converting red clover to annual crops with fall mowing will support a no-till system for organic farming.

The study aimed to determine the effects of red clover (Trifolium pratense) silage with high phyto-oestrogen content on ewe performance during their first breeding season. Red clover silage containing formononetin, biochanin A, genistein, and daidzein was fed to 10 nulliparous ewes of the prolific Finnish Landrace breed before, during and after the breeding season, for a total of 5 months. A control group of 10 ewes was fed with grass silage. The mean numbers of foetuses per pregnancy were 2.1±0.7 and 2.2±0.8 for the red clover and control groups, respectively. The total mass of the uterus with its contents was significantly greater in ewes of the red clover group compared with those of the control group. This difference was mainly explained by the greater volume of foetal fluids. Serum progesterone concentration in the red clover group was significantly lower over the entire period analysed than in the control group. In conclusion, the fecundity of the ewes was not reduced by red clover feed with high phyto-oestrogen concentrations. The volume of foetal fluids increased that could increase the risk for vaginal prolapse before the term.

Most often, farmers consider red clover an unattractive forage because of its low ensilability. Nevertheless, several in vivo and in vitro experiments also showed advantages of red clover silages such as decreased rumen biohydrogenation of polyunsaturated fatty acids. This has been attributed to a possible protective role of protein-bound phenols, with polyphenol oxidase playing a key role in their formation. This enzyme is active in red clover, but not in other green forages, such as, for example, perennial ryegrass. Therefore, the aim was to study the lipid metabolism within red clover/ryegrass mixtures in lab scale silages and during in vitro rumen batch incubations. Ensilability of red clover increased with higher proportions of ryegrass in the silage mixture. However, the lipid-protecting mechanism of red clover does not seem to occur in the co-ensiled ryegrass as lipolysis of polar lipids linearly increased with increasing proportions of ryegrass (86.0%, 91.6%, 89.9%, 93.1% and 95.6% in 60-day-old silages with 100/0, 75/25, 50/50, 25/75 and 0/100 red clover/ryegrass, respectively). Rumen lipolysis and biohydrogenation of C18:3n-3 and C18:2n-6 were negatively related to red clover proportions in the silage mixtures. The lipid-protective mechanism in red clover silages is confirmed, but it seems not to be transferred to lipids in co-ensiled forages.

Recent volatility in supplies and prices of natural gas and synthetic nitrogen (N) fertilizer suggests a need to develop and refine alternative strategies for supplying N to corn. In this study, conducted in north-eastern Iowa, we examined the use of red clover and alfalfa green manures as means of supplying N to a succeeding corn crop. Red clover intercropped with oat produced significantly more biomass and contained more N than alfalfa intercropped with oat. Tilling green manures in the fall or delaying tillage until the following spring did not have a consistent effect on green manure N content. Without N fertilizer, corn grain yield following oat–red clover and oat–alfalfa was 25–63% greater than following oat grown alone, but at the highest fertilizer rate (202 kg N ha−1), there was no difference in corn yield between oat–legume and oat-alone treatments. These patterns support the premise that legume green manure effects on corn yield were N-related. Red clover green manure had an N fertilizer replacement value for corn of 87–184 kg N ha−1; alfalfa supplied corn with the equivalent of 70–121 kg N ha−1. At a fossil energy cost for N fertilizer of 57 MJ kg−1 N, reducing synthetic N fertilizer applications to corn by 70–184 kg N ha−1 would represent a fossil fuel savings of 3990–10,488 MJ ha−1, equivalent to the energy content of 104–274 m3 of natural gas. These types of savings are likely to become increasingly important as fossil energy supplies become scarcer and fertilizer prices rise.

Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO’s lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid encapsulation in protein–phenol complexes would lead to an effective protection of lipids against ruminal biohydrogenation. From several studies it has also become apparent that the degree of PPO activation could influence the mode and degree of protection. In conclusion, this review demonstrates that protein-bound phenols and encapsulation in protein–phenol complexes, induced by PPO-mediated diphenol oxidation, could be of interest when aiming to protect lipids against pre-ruminal and ruminal degradation.

The impact of fresh legume types or silage on the composition of milk fatty acids and transcription of enzymes involved in the synthesis of milk fat in cows was studied. Three groups of cows grazed high proportions of white clover, red clover and lucerne, respectively. A fourth group of cows was fed maize/grass silage. The cows grazing high proportions of legumes produced significantly more 18:1 trans-11, 18:2 cis9-trans11, 18:2 trans10-cis12 and 18:3 fatty acids than cows fed silage. White clover and lucerne grazing resulted in significantly lower output of 18:1 trans9 in milk than red clover grazing and maize/grass silages. Transcription of stearoyl-CoA desaturase (SCD) in mammary tissue was significantly increased by grazing high proportions of legume whereas fatty acid synthase and acetyl-CoA carboxylase were not affected by type of feeding. Furthermore, average milk fat globule diameter was correlated to daily milk fat yield but was not affected by feeding. Although the fresh forage affected the transcription of SCD in mammary tissue, the largest effects were on the trans11-based fatty acids. It is concluded that type of forage, i.e. fresh or silage, had a greater impact on rumen fermentation pattern than on transcription of enzymes involved in the synthesis of milk fat.

In addition to soya-derived preparations, red clover-based dietary supplements have gained considerable interest as an alternative isoflavone (IF) source. While metabolism and bioavailability of the main IF from both sources have already been investigated, studies are still lacking on the biokinetic behaviour of IF, which are present in red clover in minor amounts. In the present pilot study, in which seven volunteers ingested a single dose of a commercial red clover dietary supplement, we focused on the absorption of three such IF, irilone (IRI), prunetin (PRUN) and pseudobaptigenin (PBAP). The compounds were measured as aglycones after enzymatic hydrolysis. A single intake of an amount of as low as 3·8 mg IRI (out of 38·8 mg IF in total) resulted in an IRI plasma concentration of 0·35 (sd 0·16) μm at 6.5 h post-ingestion. Compared to the plasma concentrations found for daidzein (0·39 μm) and genistein (0·06 μm), expected to be the main IF metabolites in plasma, the present findings indicate that IRI might possess a relatively high bioavailability. Furthermore, PRUN and PBAP were detected in human plasma for the first time.

The intake of isoflavones and the resulting equol contents of both plasma and milk of the same red clover-fed cows are reported for the first time in cyclic change-over design study. Cows were fed four different red clover silages and two timothy–meadow fescue silages as controls. The red clover silages contained daidzein, formononetin, biochanin A and genistein, whereas the timothy–meadow fescue silages contained no isoflavones. We found a strong association (y = 0·071x+2·75, R 2 0·71) between the formononetin intake (x) and equol concentration (y) in the plasma, while the formononetin intake and milk equol concentration were weakly associated (y = 0·0035x+0·358, R 2 0·20). This means that a small part of the total formononetin in the silage is secreted into milk as equol. The mean equol contents in plasma and milk of cows fed red clover silage diets were in the range of 4·6–8·4 mg/l and 458–643 μg/l, respectively, while the respective values for the control diets were in the range of 0·8–1·5 mg/l and 171–287 μg/l. We showed that shorter growing periods of red clover resulted in higher silage formononetin contents and plasma and milk equol contents, suggesting that the equol content of milk can be manipulated by varying the harvesting strategy of red clover. We conclude that milk equol is derived from the formononetin of red clover silage and that milk from red clover-fed cows can be considered as a source of equol in human nutrition.

Absorption, distribution and elimination of 14C-labelled isoflavone-containing extracts from kudzu (Pueraria lobata) root culture and red clover (Trifolium pratense) cell culture were investigated in an in vivo rat model. The predominant isoflavones in the kudzu extract were the glycosides puerarin, daidzin and malonyl daidzin, while in the red clover extract, the major isoflavones were formononetin and its derivatives, genistein and biochanin A, with radioactivities of 3·770 and 7·256 MBq/g, respectively. Male Sprague–Dawley rats, implanted with a jugular catheter and a subcutaneous ultrafiltrate probe, were orally administered with 14C-labelled isoflavone extracts from either kudzu or clover cell cultures. Serum, interstitial fluid (ISF), urine and faeces were collected using a Culex® Automated Blood Collection System for 24 h. Analysis of bone tissues revealed that radiolabel accumulated in the femur, tibia and vertebrae at 0·04, 0·03 and 0·01 % of the administered dose, respectively, in both kudzu and red clover treatments. The liver accumulated the greatest concentration of radiolabel among the tissues tested, at 1·99 and 1·54 % of the administered kudzu and red clover extracts, respectively. Serum and ISF analysis showed that both extracts were rapidly absorbed, distributed in various tissues, and largely eliminated in the urine and faeces. Urine and faeces contained 8·53 and 9·06 % of the kudzu dose, respectively, and 3·60 and 5·64 % of the red clover dose, respectively. Serum pharmacokinetics suggest that extracts from kudzu may undergo enterohepatic circulation.

Red clover and fish oil (FO) are known to alter ruminal lipid biohydrogenation leading to an increase in the polyunsaturated fatty acid (PUFA) and conjugated linoleic acid (CLA) content of ruminant-derived foods, respectively. The potential to exploit these beneficial effects were examined using eight Hereford × Friesian steers fitted with rumen and duodenal cannulae. Treatments consisted of grass silage or red clover silage fed at 90% of ad libitum intake and FO supplementation at 0, 10, 20 or 30 g/kg diet dry matter (DM). The experiment was conducted with two animals per FO level and treatments formed extra-period Latin squares. Flows of fatty acids at the duodenum were assessed using ytterbium acetate and chromium ethylene diamine tetra-acetic acid as indigestible markers. Intakes of DM were higher (P < 0.001) for red clover silage than grass silage (5.98 v. 5.09 kg/day). There was a linear interaction effect (P = 0.004) to FO with a reduction in DM intake in steers fed red clover silage supplemented with 30 g FO/kg diet DM. Apparent ruminal biohydrogenation of C18:2n-6 and C18:3n-3 were lower (P < 0.001) for red clover silage than grass silage (0.83 and 0.79 v. 0.87 and 0.87, respectively), whilst FO increased the extent of biohydrogenation on both diets. Ruminal biohydrogenation of C20:5n-3 and C22:6n-3 was extensive on both silage diets, averaging 0.94 and 0.97, respectively. Inclusion of FO in the diet enhanced the flow of total CLA leaving the rumen with an average across silages of 0.22, 0.31, 0.41 and 0.44 g/day for 0, 10, 20 or 30 g FO/kg, respectively, with a linear interaction effect between the two silages (P = 0.03). FO also showed a dose-dependent increase in the flow of trans-C18:1 intermediates at the duodenum from 4.6 to 15.0 g/day on grass silage and from 9.4 to 22.5 g/day for red clover silage. Concentrations of trans-C18:1 with double bonds from Δ4–16 in duodenal digesta were all elevated in response to FO in both diets, with trans-11 being the predominant isomer. FO inhibited the complete biohydrogenation of dietary PUFA on both diets, whilst red clover increased the flow of C18:2n-6 and C18:3n-3 compared with grass silage. In conclusion, supplementing red clover silage-based diets with FO represents a novel nutritional strategy for enhancing the concentrations of beneficial fatty acids in ruminant milk and meat.

Changing from a conventional livestock production system, based on fertilized grass swards, to an organic management system requires the establishment of legume-based swards to replace the purchased fertilizer nitrogen. This paper reviews experimental-based research on both the comparative economics of legume-based systems and grass swards and also the economic advantage that forage legumes confer on organic systems. A methodology to determine the production costs and economic values of a variety of forage legume systems is outlined. The resultant methodology is then applied to experimental results from trials, conducted at a wide range of sites in northern Europe, to determine the comparative profitability of different legume-based systems of silage production under conventional management. The results indicate that potentially red clover (Trifolium pratense L.), and to a lesser extent white clover (Trifolium repens L.), and lucerne (alfalfa) (Medicago sativa L.), can produce higher profits per hectare than grass-based systems using high levels of nitrogen fertilizer. Galega (Galega orientalis Lam) and lotus (Lotus corniculatus L.) can, in certain circumstances, be economically competitive with fertilized grass swards, but would generally not be the forage legumes of first choice. From an economic standpoint, forage legumes are probably best grown in a mixture with grass. As some of the experimental sites involved organic treatments, the analysis has been extended to include an assessment of the comparative economics of organic systems of production based on forage legumes, relative to conventional grass-based systems. Thus, the third part of the paper is concerned with quantifying the economic advantage to organic systems conferred by forage legumes. The results indicate that, under careful management, their use for silage can produce higher profits per hectare for organic dairy systems than those obtained from conventional grass-based systems. While the relative performance of organic systems is strongly influenced by the price premium paid for organic milk, which has declined in recent years, not all the projected economic advantage of legume-based organic dairy systems is eroded by this trend. However, economic advantage is not enough to secure the widespread adoption of forage legumes. This will depend on technological developments and management practices which reduce the risks associated with both more difficult crop establishment and higher nitrate leaching of forage legumes as compared to grass swards.