Mineral Nutrition of Higher Plants, 2nd edition, H. Marschner. Academic Press, London (1995), 889, (ISBN 0-12-473543-6). Price: 29.95 Pound Sterling

Nitrogen fixation in faba bean (Vicia faba cv. Mesay) as affected by sulfur (S) fertilization (30 kg S ha–1) and inoculation under the semi-arid conditions of Ethiopia was studied using the 15N-isotope dilution method. The effect of faba bean–fixed nitrogen (N) on yield of the subsequent wheat crop (Triticum aestivum L.) was also assessed. Sulfur fertilization and inoculation significantly (p < 0.05) affected nodulation at late flowering stage for both 2004 and 2005 cropping seasons. The nodule number and nodule fresh weighs were increased by 53% and 95%, relative to the control. Similarly, both treatments (S fertilization and inoculants) significantly improved biomass and grain yield of faba bean on average by 2.2 and 1.2 Mg ha–1. This corresponds to 37% and 50% increases, respectively, relative to the control. Total N and S uptake of grains was significantly higher by 59.6 and 3.3 kg ha–1, which are 76% and 66% increases, respectively. Sulfur and inoculation enhanced the percentage of N derived from the atmosphere in the whole plant of faba bean from 51% to 73%. This corresponds to N2 fixation varying from 49 to 147 kg N ha–1. The percentage of N derived from fertilizer (%Ndff) and soil (%Ndfs) of faba bean varied from 4.3% to 2.8 %, and from 45.1% to 24.0%, corresponding to the average values of 5.1 and 47.9 kg N ha–1. Similarly, the %Ndff and %Ndfs of the reference crop, barley, varied from 8.5 % to 10.8% and from 91.5% to 89.2%, with average N yields of 9.2 and 84.3 kg N ha–1. Soil N balance after faba bean ranged from 13 to 52 kg N ha–1. Beneficial effects of faba bean on yield of a wheat crop grown after faba bean were highly significant, increasing the average grain and N yields of this crop by 1.11 Mg ha–1 and 30 kg ha–1, relative to the yield of wheat grown after the reference crop, barley. Thus, it can be concluded that faba bean can be grown as an alternative crop to fallow, benefiting farmers economically and increasing the soil fertility.

Wheat response to N2 fixed by faba bean (Vicia faba L.) as affected by sulfur fertilization and rhizobial inoculation in semi‐arid Northern Ethiopia

Can interaction between silicon and non–rhizobial bacteria help in improving nodulation and nitrogen fixation in salinity–stressed legumes? A review

Nitrogen fixation was measured in constructed old-field ecosystems that were exposed for 3 years to different combinations of elevated atmospheric [CO2] and temperature (300 ppm and 3°C above ambient, respectively), and ambient or reduced soil moisture (corresponding to 25 or 2 mm rainfall per week). The old-fields included seven planted herbaceous annual and perennial species, including two legumes (Trifolium pratense and Lespedeza cuneata). Potential asymbiotic N2-fixation by soils, measured in laboratory incubations, was significantly less under the “dry” treatment but was estimated to contribute little overall to annual ecosystem N budgets. Foliar N concentrations declined significantly under elevated [CO2]. Effects of the three environmental factors on the mean (±SE) fraction of legume N derived from atmospheric N2 (FN
 dfa) varied from year-to-year, and FN
 dfa ranged from 0.64 ± 0.05 to 0.94 ± 0.03 depending on species and growing season. High rates of symbiotic N2-fixation (4.6–12 g N m−2 y−1) that annually contributed from 44% to 51% to the aboveground N stock in the old-field community was an important process driving changes in species composition over the 3-year experiment. Lespedeza biomass increased over time at the expense of several other species, including the other N-fixer, Trifolium. The dominance of Lespedeza in our ecosystem was due to high symbiotic N2-fixation rates, as well as shading effects on other species. The high symbiotic N2-fixation rates were largely independent of manipulations of [CO2], temperature, and water. The relatively high percentage of the aboveground N stock in this ecosystem contributed by symbiotic N2-fixation suggests that non-legume species may have benefited indirectly via reduced community demands on soil N supplies. Species-specific traits were important in the constructed ecosystems, indicating that multi-species studies are required for understanding complex interactions among environmental factors and dynamic changes in community composition.

Role of N2-fixation in Constructed Old-field Communities Under Different Regimes of [CO2], Temperature, and Water Availability

A study was conducted in order to investigate yields in relation to seed inoculation of chickpea (Cicer arietinum L. cv. Aziziye-94) with eight Rhizobium leguminosarum ssp. ciceri strains isolated from wild chickpeas (C. anatolicum) of high altitudes (2000-2500 m) in comparison with standard bacterial culture, uninoculated control and mineral nitrogen fertilizer application in the growth room and in the field in 1999, 2000 and 2001 in Erzurum (29°55'N and 41°16'E at an altitude of 1850 m), Turkey.In the growth room trial, bacterial inoculations significantly increased shoot dry weight, N %, total N, N fixed and efficiency of symbiosis compared with the uninoculated control treatment depending on the strains. In the field trial, inoculations with HF 274 and HF 177 increased nodule dry weight, N %, chlorophyll, seed yield and total biomass yield depending on the strains, the lowest values being recorded in uninoculated plots. As an average of years, inoculation with HF 274, HF 177 and standard bacterial culture increased seed yields, respectively, by 23.3, 22.7 and 16.8 % over uninoculated control.In conclusion, rhizobial inoculation of chickpea with HF 274 and HF 177 strains isolated from wild chickpeas (C. anatolicum) of high altitudes may substitute costly N fertilizers in chickpea production even in cold highland areas such as Erzurum.

Chickpea Yields in Relation to Rhizobium Inoculation from Wild Chickpea at High Altitudes

The impact of three rates of potassium (K) fertilizer (0, 75, and 150 kg K2O/ha) on nodulation, dry matter production, and nitrogen (N2) fixation by fababean (Vicia faba L.) and chickpea (Cicer arietinum L.) was evaluated in a pot experiment. The plants were subjected to three soil moisture regimes (low, 45–50%; moderate, 55–60%; and high, 75–80% of field capacity). The 15N-isotope dilution method was employed to evaluate N2 fixation using a non-fixing chickpea genotype as a reference crop. Water restriction drastically affected dry matter production, nodulation, and N2 fixation by both plant species. The negative effect of water stress on %N2 fixed was more prominent in chickpea (11–58%) than in fababean (68–81%) under low and high % of field capacity, respectively. Plant species differed in their response to K fertilizer as a means of enhancing growth and overcoming the stress conditions. The higher level of K fertilizer increased both dry matter production and total N2 fixed in fababean, but did not ha...

Mohammed Al-Shamma

Papers

Nodulation, dry matter production, and n2 fixation by fababean and chickpea as affected by soil moisture and potassium fertilizer