To assess the feasibility of the sulla [Sulla coronaria (L.) Medik] forage legume in a new agroecosystem, its host-specific symbiotic interaction needs to be taken into account. This study aimed to investigate the effects of inoculation and nitrogen (N) fertiliser on productive performances and N-fixation ability of sulla established in a new habitat within a Mediterranean agropastoral area. Sulla plants, previously inoculated (with peat-based, liquid inoculants, and using soil from an existing sulla field) and unfertilised or N fertilised were evaluated in Sardinia (Italy). During 2013-2014, sulla plants were sampled at four growing stages, from vegetative stage to seed set, and shoot length, shoot dry matter (DM) yield and N content were monitored. Moreover, atom% 15 N isotopic excess, proportion of N derived from the atmosphere and fixed N of sulla shoots were quantified. Inoculation and N fertilisation both affected growth, DM and N yields, and N-fixation of sulla. Compared to the best inoculated treatment, the DM yield and fixed N of the control only represented 10 to 22% and 2 to 11%, respectively. Nitrogen fertilisation caused temporary decreases in the N fixing ability of sulla. Results pointed out that rhizobial inoculation is essential for the exploitation of sulla outside its traditional cropping area.

There is renewed interest in white lupine (Lupinus albus L.), which is appreciated for its high protein content, full range of essential amino acids and as N source to rainfed cropping systems. Unfortunately, information on its N 2 fixation ability is limited. This study aimed to: (i) quantify the N 2 fixation ability of white lupine crop at the plot field scale in three different environments of Sardinia (Italy)

Field bean (Vicia faba L. var. minor Beck) is cultivated in the Mediterranean basin in rotation with winter cereals for dry grain production for animal feed, green forage, hay, silage, or green manure. This study aimed to (i) quantify the field bean fixed N during 2 yr at two Italian locations under rainfed conditions, (ii) quantify the proportion of N and fixed N allocated by field bean to grain, straw, and recoverable roots, and (iii) estimate the potential contribution of field bean to the cropping system N balance. The mean N percentage derived from N 2 fixation of field bean grain and straw was 76%, corresponding to 114 kg ha -1 of fixed N in the aboveground biomass. On average, field bean fixed 42, 12, and 9 kg N Mg -1 dry matter in grains, straw, and roots, respectively. Recoverable roots contributed <5% of the total plant fixed N, but estimates did not take into account rhizodeposition and fine root turnover. The net N balance was positive for green manure (117 kg N ha -1 ) and grain field bean without straw removal (31 kg N ha -1 ) but negative (-31 kg N ha -1 ) when straw was removed. The N gain vs. a non-fixing species was 79, 62, and 117 kg ha -1 yr -1 for field bean used as grain without straw removal, grain with straw removal, and green manure, respectively. Our study indicated that field bean can play a significant role as a N source in rainfed cereal-based cropping systems.

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Sulla (Sulla coronaria [L.] Medik), a Mediterranean short-lived legume with tolerance to drought-prone environments, requires inoculation outside its natural habitat. Its leaves are appreciated for the bromatological composition and content of bioactive compounds. However, no information is available regarding the distinct effects of inoculation and nitrogen (N) applications on leaf dry matter (DM), fixed N, and bioactive compounds. Sulla leaves were sampled from the vegetative stage to seed set in Sardinia (Italy) during 2013-2014 and leaf DM, N content, and fixed N were determined. Compared to the best performing inoculated treatments, DM yield and fixed N values of the control only represented 8% to 20% and 2% to 9%, respectively. A significant relationship between fixed N and leaf DM yield was established, reaching 30 kg fixed N t -1 at seed set. Significant variations in leaf atom% 15 N excess and %Ndfa quantified decreases in leaf N fixation coupled with N application. Moreover, the petiole content of phenolic compounds markedly increased in the uninoculated control, suggesting deeper investigations on the relationship between bioactive compounds and inoculation treatments. Results highlighted substantial variation in DM, N yields, N-fixation ability, and content of bioactive compounds of sulla leaves caused by inoculation and N fertilization.