Different leguminous pre-crops increased yield of succeeding cereals in two consecutive years

Leguminous pre-crops are an important source of green manure in organic crop rotations for improving soil fertility and achieving high yields of cereals. We aimed to study the potential of various leguminous species, other than the traditionally cultivated red clover (Trifolium pratense L.), as green manure pre-crops for subsequent cereals. The use of different legume species enables to exploit advantages of specific legumes in organic cereal production. In order to test the legumes as pre-crops for cereals, we carried out trials located in the temperate climate zone of northeast Europe (58°44′59.41″ N, 26°24′54.02″ E). We sowed the following perennial legumes as pre-crops: red clover, alsike clover (Trifolium hybridum L.) and Washington lupine (Lupinus polyphyllus Lindl.), biennial white sweet clover (Melilotus albus Medik.) and annual Alexandria clover (Trifolium alexandrinum L.), and crimson clover (Trifolium incarnatum L.). Timothy (Phleum pratense L.) was used as a control. The leguminous pre-crops were followed by three spring cereals (barley, oat and spring wheat) and two winter cereals (rye and winter wheat). We tested the first-year after-effect (all cereals) and second-year after-effect (only barley and oat) of pre-crops on the grain yield of cereals. Perennial and biennial legume species produced the highest dry matter yield and contained the highest amount of nutrients, especially nitrogen, compared to annual species. All subsequent cereals produced significant extra yields after each leguminous pre-crop in the following two years, although the effect was smaller in the second year. The most suitable pre-crops for spring cereals were red and alsike clover followed by lupine, whereas the best pre-crops for winter cereals were sweet clover and annual clovers. Our results show the potential of various leguminous pre-crop species as valuable sources of green manure in organic crop rotation.     

Mycorrhiza‐soil fertility effects on regrowth,nodulation and Nitrogenase activity of siratro (Macroptilium atropurpureum (DC) Urb.)

Siratro (Macroptilium atropurpureum (DC) Urb.) is a vigorous perennial forage legume with good potential for improving pastures in the extensive neotropical regions of the world. It is well adapted to a wide range of soil and climatic conditions. The objective of these studies was to determine effects of Glomus fasciculatum colonization, rigorous defoliation, and soil fertility treatments to a Psammentic Paleustalf (Eufaula) soil on growth, regrowth, nodulation, and nitrogenase activity (C₂H₂ red.) of Siratro inoculated with Rhizobium leguminosarum Frank. Top growth increased significantly with soil K and P amendment and with mycorrhiza colonization. Nodulation and nitrogenase activity were correlated with highly significant increases from G. fasciculatum, P treatments and K additions to 300 mg K kg^‐1 soil. Growth and peduncles of nonclipped plants increased about 4 fold from 90 to 225 day age with mature seed yield increasing about 10 fold; nodule mass and nitrogenase activity levels approximately doubled. Regrowth response of plants defoliated at 45 day intervals, following their initial 90 day age, was somewhat constant between clippings for magnitude of regrowth 12.3–13.8g, development in number of peduncles 4.0–6.8, seed yield 1.4–2.6g, nodulation 2.9–3.7g, and nitrogenase activity 73.9–95.8μ mol C₂H₄g^‐1 nodule. Multiple regression for nitrogenase = 0.55 g top wt. + 0.63 g nodule wt. + 1.91 day age ‐ 0.07 peduncle no., R² = 0.85 and C.V. = 14.3%. Favorable tripartite symbiosis with both effective Rhizobium and endophyte mycorrhiza were essential for high levels of symbiotic nitrogen fixation.     

Nitrogen fixation and beneficial effects of some grain legumes and green-manure crops on rice

Studies were conducted on paddy soils to ascertain N₂ fixation, growth, and N supplying ability of some green-manure crops and grain legumes. In a 60-day pot trial, sunhemp (Crotalaria juncia) produced a significantly higher dry matter content and N yield than Sesbania sesban, S. rostrata, cowpeas (Vigna unguiculata), and blackgram (V. mungo), deriving 91% of its N content from the atmosphere. Dry matter production and N yield by the legumes were significantly correlated with the quantity of N₂ fixed. In a lowland field study involving sunhemp, blackgram, cowpeas, and mungbean, the former produced the highest stover yield and the stover N content, accumulating 160–250 kg N ha^-1 in 60 days, and showed great promise as a biofertilizer for rice. The grain legumes showed good adaptability to rice-based cropping systems and produced a seed yield of 1125–2080 kg ha^-1, depending on the location, species, and cultivar. Significant inter- and intraspecific differences in the stover N content were evident among the grain legumes, with blackgram having the highest N (104–155 kg N ha^-1). In a trial on sequential cropping, the groundnut (Arachis hypogaea) showed a significantly higher N₂ fixation and residual N effect on the succeeding rice crop than cowpeas, blackgram, mungbeans (V. radiata), and pigeonpeas (Cajanus cajan). The growth and N yield of the rice crop were positively correlated with the quantity of N₂ fixed by the preceding legume crop.     

Indigenous rhizobia associated with native shrubby legumes in Taiwan

Root-nodulating bacteria were isolated and characterized from seven native shrubby legumes growing in Taiwan. Phenotypic characteristics measured included growth rates in various media, colony morphology, and tolerances to extremes of temperature, salt and pH. The isolates were very diverse phenotypically. Among the 83 isolates that were screened, the majority were fast-growing rhizobia. Twenty eight strains tolerated high concentration of salt (4.5% NaCl) and grew well between temperatures of 37 and 45 °C. The majority of the strains also tolerated extreme pH in their medium from 3.5 to 12. All strains formed nitrogen fixing nodules, and the highest activity was detected in the legume Hedysarum crinita L. PCR restriction fragment length polymorphism (PCR-RFLP) and sequencing of the small subunit ribosomal RNAs revealed that the majority of the isolates belonged to the genera Rhizobium, Bradyrhizobium and Agrobacterium. Only a single strain represented the genus Sinorhizobium. In addition, a strain related to Burkholderia from the β-class of the Proteobacteria (CC-CC-5) was found within nodules of the legume Catenaria caudatum. The study contributes to the understanding of symbiotic nitrogen fixation in selected wild legumes that are native to Taiwan and provides insights into the distribution of nodulating and nitrogen-fixing bacteria from other distinct lineages.     

Growth Analysis, Herbage and Seed Yield of Certain Forage Legume Species Under Rainfed Conditions

The need to increase forage production for the growing livestock population in the Mediterranean region necessitates the evaluation of various promising forage species with respect to maximum herbage yield, optimum time for harvest and seed yield. Seven forage legumes, woolly pod vetch ( Vicia villosa subsp. dasycarpa accession 683), narbon vetch (V. narbonensis accession 67), common vetch ( V. sativa selections 2541, 2037, 2020), common chickling ( Lathyrus sativus selection 439) and ochrus chickling ( L. ochrus selection 104) were compared over two years with contrasting rainfall. In both years the entries were sown in November and their primary growths sampled periodically during growth. For each sample, phenology, total dry matter, leaf area index (LAI) and, at maturity, total dry matter, seed yield and harvest index, were recorded.
In both seasons, narbon vetch attained the highest dry matter and seed yields, and there was very limited variability in the maximum dry matter yield of the other entries. In general, the maximum dry matter occurred at 20–50 % podding in woolly pod vetch, 100 % podding in common vetch selection 2541 (local), narbon vetch and common chickling and at maturity in common vetch selection 2037, selection 2020 and ochrus chickling.
Throughout the vegetative to early flowering stages, woolly pod vetch had the highest dry matter yield and LAI. Possible uses of each species as animal feed are discussed.     

Influence of Oil Seed Rape and Faba Bean as Green Manure on Nitrogen Utilization in a Spring Cereal Rotation

A lysimeter study was conducted to investigate how nitrogen uptake of spring wheat and oats and N leaching losses are differing when either oilseed rape or faba bean are grown as green manure. The experiment was conducted during 1982–1988, and fertilizer applied to the cereals was either farmyard manure, FYM, (6 and 12 g N/m²/year) or mineral fertilizer, MiF, at a rate of 6 g N/m². On average of the 7 year period faba bean increased N uptake of the cereals fertilized with FYM at harvest by 3–4 g/m². Differences between the two application rates were negligible. N-leaching losses increased twofold when faba bean was grown instead of oilseed rape. Growing faba bean after cereals supplied with MiF, too, increased N uptake of the cereals and significantly increased leaching losses.     

Forage chain arrangement for sustainable livestock systems in a Mediterranean area

Mediterranean forage systems suffer from limited availability of fresh forage because of water deficits and extreme temperatures. Consequently, fresh forage is unavailable for at least 6–7 months a year, and farmers must buy feed to support livestock production. With the aim of overcoming these limitations, a 2‐year trial was conducted on three distinct sites in Sicily (at 10, 600 and 1200 m elevation) with thirty‐four varieties of forage species belonging to nine biennial/perennial and thirteen annual species. Results showed that by integrating grasses and legumes, species from environments with different climatic conditions enable the season of forage production to be extended from mid‐April to mid‐November. Quality traits of forage in different areas varied in relation to species and varieties. In general, the sown‐forage quality was better than in pastures and fallows in the same areas commonly used to feed animals. This also leads to a reduction in the use of supplementary feeds. Among the tested species, Lolium multiflorum and Medicago sativa emerged as the most promising for filling the forage‐deficit periods, and Trifolium spp. and Vicia sativa were found to be superior for increasing forage quality. The results are discussed in the context of adapting Mediterranean forage supplies for ensuring greater sustainability of livestock production in mountain, hill and plain areas. The proposed forage chain arrangement represents part of local potential adaptation to climate limitations and climate change.     

Effect of wilting,silage additive,PEG treatment and tannin content on the distribution of N between different fractions after ensiling of three different sainfoin (Onobrychis viciifolia) varieties

Sainfoin (Onobrychis viciifolia) is a tanniniferous, leguminous plant that has potentially beneficial effects on protein utilization in ruminants. As ensiling causes protein breakdown and elevated levels of buffer soluble N (BSN), we studied the distribution of N before and after ensiling sainfoin. Three varieties of sainfoin were either direct‐cut and frozen directly or wilted and frozen before later ensiling in mini‐silos with and without acidification with Promyr (PM; an acidifying commercial mixture of propionic and formic acid) and with or without polyethylene glycol (PEG). Extractable tannins (ET) and protein‐bound tannins (PBT) were measured with an HCl/butanol method in an attempt to correlate tannin levels to N fractions. The sainfoin silages showed good ensiling characteristics and had relatively high concentrations of undegraded protein. The effect of wilting on BSN levels (g/kg N) was dependent on sainfoin variety (P < 0·001). PEG increased and PM decreased the level of BSN in the silages (P < 0·001). PM treatment also produced less non‐protein N and ammonia‐N (P < 0·05) as compared with no additive. Addition of PEG to the silage increased the BSN‐proportion 1·8‐ and 2·6‐fold for both DM stages. A strong tannin‐protein binding effect is, therefore, confirmed in sainfoin. However, correlations between tannin levels (ET and PBT) and BSN were poor in the (non‐PEG) silages, indicating either that the HCl/butanol method is unsuitable for measuring tannin in silages or that qualitative attributes of tannins are more relevant than quantitative. The HCl/butanol method seems therefore not to be useful to predict degradation of protein in sainfoin silages.     

Dry-matter production and botanical composition of multispecies and perennial ryegrass swards under varying defoliation management

Multispecies swards, comprised of different plant functional groups have comparable production potential to high N input L. perenne swards at reduced N when legumes are included. However, information on the appropriate management of multispecies swards is limited. The effect of differing management practices on the herbage dry-matter (DM) production and botanical composition of different sward types was investigated using a 3 × 2 × 2 factorial design plot experiment. The experiment consisted of three sward types: L. perenne-only receiving (LP; 250 kg N ha⁻¹ a⁻¹); L. perenne-Trifolium repens (LP-TR); multispecies sward containing L. perenne, Phleum pratense, Trifolium repens, Trifolium pratense, Plantago lanceolata and Cichorium intybus (MSS). LP-TR and MSS received 90 kg N ha⁻¹ a⁻¹. Harvesting of plot herbage took place every 21 or 28 days to a defoliation height of 4 or 6 cm, over two growing seasons (March to November 2020 and 2021 inclusive). Annual herbage produced by both LP and LP-TR was not significantly affected by defoliation frequency. However, MSS produced 1923 kg DM ha⁻¹ a⁻¹ more herbage when harvested less frequently. Unsown species contributed significantly less to the herbage DM of MSS compared to LP and LP-TR and remained similar in 2020 and 2021, whereas the contribution of unsown species to herbage DM increased in LP and LP-TR from 2020 to 2021, with noxious species more associated with LP and LP-TR than MSS. Results demonstrate the role of multispecies swards in improving the sustainability of grass-based agricultural systems in an environment of reduced fertilizer inputs.