Nitrogen Fixed Research Articles

Differential Response of Cylindrospermum musicola, Calothrix javanica and Westiellopsis prolifica to Endotaf (Endosulfan, 35%), an Organochlorine Pesticide

The effect of Endotaf (Endosulfan, 35%) pesticide was studied on nitrogen fixation efficiency of Cylindrospermum musicola, Calothrix javanica and Westiellopsis prolifica at different concentrations of pesticide in the nitrogen free BG-11 medium. Total nitrogen fixed by blue-green algal species was estimated by conventional Micro- kjeldahl method in the laboratory cultures at each concentration of Endotaf pesticide. The results obtained during the present investigation indicated a progressive decrease in the total nitrogen content of the tested blue-green algae with increasing concentrations of the Endotaf pesticide. However, nitrogen fixation of most of the blue-green algae was also increased at the lower doses of pesticide. The consequences of the results revealed that Calothrix javanica was emerged as most compatible and tolerant to the increasing Endotaf pesticide doses than the other tested blue-green algal species. On the other hand, Cylindrospermum musicola was found to be highly susceptible as even at 2.5 ppm of Endotaf. Calothrix species was capable to tolerate upto 10 ppm of Endotaf while in Westiellopsis prolifica and Cylindrospermum musicola, the pesticide tolerance range was found to be upto 5 ppm and 2.5 ppm with Endotaf, respectively. Further increase in pesticides concentrations a gradual decline in the total nitrogen content occurred in all the tested blue-green algal strains. It is concluded that indiscriminate use of these pesticides may cause adverse effects on the nitrogen fixing blue-green algae of various crop fields, which has a direct influence on total productivity. Since it is essential to screen efficient blue-green algal strains those are capable of growing and fixing nitrogen at higher rate even in presence of recommended doses of the agrochemicals including pesticides, before their inoculation into the field.

CULTIVATION OF LEGUME CROPS IN THE CONTEXT OF SUSTAINABLE AGRICULTURE

Crop production processes are increasingly focused on the proper use of the natural environment. Therefore, the main purpose of this paper was to identify factors determining farmers' decision to cultivate legumes on their farms. Additionally it was decided to estimate economic benefits resulting from atmospheric nitrogen fixing by plants. The value of economic benefits was calculated by multiplying the price per kg of pure nitrogen and the amount of nitrogen fixed in the soil after the crop residues are ploughed. This paper relies on empirical studies which covered 180 selected legume farms across the country. As shown by the calculation, the value of biological benefits for the cultivation of peas was 140 PLN/ha and 58 PLN/ha more for lupins. The farmers surveyed cited improved soil texture and the beneficial impact of legumes on the yield of subsequent crops as the main reason for introducing legumes into their cropping patterns.

Isolation and characterization of free-living nitrogen fixing bacteria from alkaline soils

Free living nitrogen fixing bacteria were isolated from soil on Jensen agar plates and were characterized phylogenetically by 16S rDNA sequence analysis. All the isolates (VS1, VS2, VS3, VS4) were Gram –ve, rod shaped. Antibiotic test revealed VS2 to be resistant to ampicillin and VS4 was resistant to both ampicillin and kanamycin; otherwise all the isolates were sensitive to chloramphenicol. Nitrogen fixation was studied by the estimation of total nitrogen and available nitrogen fixed by cultures in the medium and compared with the control culture of Azotobacter CBD15 (Azo) procured from IARI. VS2 and VS3 fixed 12.02 ppm/ml and 10.635 ppm/ml as available nitrogen content and 14.44 ppm/ml and 18.73 ppm/ml as total nitrogen content. 16S rDNA studies revealed identification of the isolates- Pseudomonas sp. (VS2) and Paenibacillus sp. (VS3 and VS4). VS3 and VS4 showed 98% similarity with P. borealis. Soils from which these microbes isolated were also characterized to understand the environment of these microbes. The pH and chemical characterization (Organic Carbon, Phosphorus, Sulphur, heavy metal analysis of different metals e.g. Zn, Cu, Cr, Pb, Ni and water holding capacity) of the soils showed them to be slightly alkaline and clayey loamy. Cloning of VS2 was done successfully with plasmid pMMB277 isolated from E. coli 2842.The significance of this study lies in the isolation of those bacteria which are comparable in their nitrogen fixing potential to Azotobacter.

Nutrient contents of soyabeans: A guide for sugarcane growers under fast track land reform programme [FTLRP] in Zimbabwe

Soyabean biomass, stover and roots when incorporate d into the soil can improve the organic matter and the carbon ( C): nitrogen ( N) ratio of the soil. Of its total N, 60 - 90% is translocated into the see d. This research was conducted on sandy clay loams of the lithosol group under the Zimbabwe soil classification system at The Zimbabwe Sugar Association Experiment Station (Z.S.A.E.S) in the South Eastern Lowveld, the leading sugarcane producing region in Zimbabwe . The objectives of this research were to: 1) analyse the nutrient content of the soyabeans under study, 2) assess the contributions of the various soyabean parts to soil fertility, 3) determine the liming potential of the soyabeans and 4) determine the forage potential of the two soyabean varieties as livestock feeds. The following parameters were measured: 1) nutrient composition of the vegetable and grain soyabeans, soyabean biomass 2) nitrogen fixed by both grain and vegetable soyabeans . Vegetable soyabeans (variety S114) and grain soyabeans (variety Storm ) were used for this study . Vegetable soyabeans had higher nitrogen, phosphorus and potassium while grain soyabean s had higher calcium and magnesium. This shows that vegetable soyabeans a s a nitrogen fixing crop have Plural? the potential to ameliorate soil fertility . However, grain soyabeans seem to have better liming potential than vegetable soyabeans. Forage Storm can improve the magnesium and calcium constituency of livestock while vegetable soya beans can influence the phosphorus content . The two elements are critical to lactating cows and young stock. The crops have high levels of calcium and magnesium , which are the critical elements for the improvement of soil pH. Interestingly , high nitrogen (N), phosphorus ( P) and potassium ( K) contents were observed in grain soyabeans. These nutrients in grains are not returned to the soil as the grains are sold as a commercial crop. The economic benefits of growing soya beans accrue from the nutrients that remain in the leaves, petioles, stems and shells that are ploughed into the soil during land preparation.

Contribution of nitrogen fixation to the external nitrogen load of a water quality control reservoir (Kis-Balaton Water Protection System, Hungary)

To reduce external nutrient loading by the greatest nutrient transporter to Lake Balaton, the Kis-Balaton Water Protection System commenced operation in 1985. Cyanobacterial blooms (Cylindrospermopsis raciborskii, Aphanizomenon sp. and Anabaena sp.) cause N-loading via nitrogen fixation, which can exceed the total external N-load to the reservoir during the summer. Nitrogen fixation of phytoplankton in the system in 2009 was measured using the 15N-isotope technique. The light dependence of fixation was described by an exponential saturated curve which was then used to calculate daily nitrogen fixation. The total amount of nitrogen fixed during summer months (July–August) exceeded 170 t for the 21 km2 of open water area, which was more than three times higher than the external load by inflows. Total nitrogen:total phosphorus mass ratios (2.5–11.5) favoured the development of a N2-fixing cyanobacterial bloom, the contribution of which to the total algae biomass varied between 50 and 90%. The estimated primary production of phytoplankton was used to calculate the contribution of nitrogen fixation (0.01–28%) to algae N-demand. Nitrogen fixing cyanobacteria were found to play a key role in addressing the N-demand of phytoplankton.

Aftereffect of nitrogen fixed by different genotypes of macrosymbiont

The nitrogen regime of gray forest and meadow chernozem soils has been studied, with emphasis placed upon the genotype of macrosymbiont and the aftereffect of nitrogen fixed by it from the air. The pea precursors with more active, genetically conditioned, symbiotic nitrogen fixation show a high efficiency. The productivity of wheat plants increases, depending on foregoing crops possessing nitrogen fixing ability, by a factor of 1.4–2.6 in comparison with a mutant devoid of nodules. The aftereffect from various genotypes of pea was not observed in the second year of a green conveyor.

Nitrogen fixation in L. leucocephala L. as affected by rooting volume and competition with E. camaldulensis

Fast growing trees, in particular nitrogen fixing trees, are essential for the establishment of sustainable agroforestry practices by resource-poor and/or environmentally conscious aarmers. An important selection factor for trees is therefore high N2 fixing capability. This study was conducted to examine biological nitrogen fixation (BNF) in Leucaena leucocephala L., as affected by growth in pots containing 4, 10, 15 and 30 kg soil and when grown together with Eucalyptus camaldulensis. BNF was measured by the 15N isotope dilution technique. Leucaena and Eucalyptus were grown either sole (SL, SE) or in two mixtures (1:1 - L1:E1 and 1:2 - L1:E2) for a period of 6 months. Planting pattern influenced (P < 0.05) dry matter and N content of shoot and roots of Eucalyptus, as the sole planted trees gave the highest yield. Dry matter, N content and total amount of N fixed by Leucaena significantly decreased with decreasing rooting volume. Also, the smaller the rooting volume (or soil weight), the higher was the proportion (%) of N derived from the atmosphere (%Ndfa) by leucaena. For each rooting volume, the sole or mixed planting pattern did not significantly influence either the proportion (%) or amount of N fixed by leucaena. For these trees, therefore, rooting volume rather than cropping pattern influenced the proportion and amount of nitrogen fixed.

Genetic variability in symbiotic nitrogen fixation between provenances ofAcacia nilotica (L.) Willd. ex Del.

Differences in nitrogen fixing abilities of 18 provenances (16 from India, 2 from Israel) ofAcacia nilotica (L.) Willd. ex Del. were assessed in sterilized sand in chillum jars and unsterilized field soil in earthen pots, at Hisar (29°10′N lat., 75°46′E long., 215 m alt.), India. There were significant differences in growth and amount of nitrogen fixed and stored in plants (P < 0.01) between provenances. The values ranged from 10 to 34 mg N/plant in sterilized sand, and 11 to 44 mg N/plant in unsterilized soil. Maximum nodulation and nitrogen fixation occurred in Sirsa provenance followed by Pali, Coimbatore and Chandigarh provenances. Medinipur, Hisar (local provenance) and two exotics fixed significantly (P < 0.01) lower amounts of nitrogen. These differences attributed to genetic variability among provenances ofAcacia nilotica. There were strong and positive correlations between number and mass of nodules with total nitrogen fixed in the plants. The results are important from the point of view of exploiting the genetical variability inA. nilotica in amelioration of wastelands.

Biological nitrogen fixation in trees in agro-ecosystems

The integration of trees, especially nitrogen fixing trees (NFTs), into agroforestry and silvo-pastoral systems can make a major contribution to sustainable agriculture by restoring and maintaining soil fertility, and in combating erosion and desertification as well as providing fuelwood. The particular advantage of NFTs is their biological nitrogen fixation (BNF), their ability to establish in nitrogen-deficient soils and the benefits of the nitrogen fixed (and extra organic matter) to succeeding or associated crops.

Amount of nitrogen fixed by forage, pasture and grain legumes in Cyprus, estimated by the A-value and a modified difference method

The increasing need for protein at low cost has created a need to evaluate the biological nitrogen fixing potential of legumes in Cyprus. In field studies which were conducted over the growing years of 1982–3 and 1983–4, legumes which are traditionally grown in the country were evaluated for dry matter and nitrogen yield and biological nitrogen fixation (BNF). The legumes studied were medic (Medicago truncatula Gearth), ochrus vetch (Lathyrus ochrus L.), bitter vetch (Vicia ervilia L.) and faba bean (Vicia faba L. var major) in the first year and in addition chickpea (Cicer arietinum L.), woollypod vetch (Vicia dasycarpa Ten.) and tickbean (Vicia faba L. var minor) in the second year.

Etude de la dynamique de l'azote à haute altitude. I. Fixation d'azote (réduction de l'acétylène) par Alnus viridis

During two vegetative seasons (1977, 1978), Alnus viridis Chaix root nodules were incubated in the field and assayed for nitrogen fixing activity by acetylene reduction method. In green alder the nitrogenase activity took place with the first opening of buds (June); maximum values were attained in July–August; the activity decreased steadily until leaf fall, and then ceased. Diurnal fluctuations in acetylene reducing activity were observed, the 1400-hour values were twice those of 1000 hours. The optimal temperature for nitrogenase activity was below 20 °C; this fact would be in relation with better adaptation of Alnus viridis to cold climate. The nodular biomass being only 40 kg/ha, the nitrogen fixed during the vegetative season (mid-June to mid-October) was only about 8 kg/ha. Symbiotic fixation accounted for only 10% of the nitrogen requirements of green alder.

Activatory Effect of some Rare Earths on Microbial Nitrogen Transformations

Lanthanum sulphate induced enhancement of nitrogen fixation by bacteria. The carbon consumption rate was similarly increased. In three microbial specimen the rate of mg. nitrogen fixed per g. carbon consumed was greater in presence of the metal ion, while in one case the rate decreased appreciably. Praseodymium sulphate inhibited the nitrogen fixation values in one sample, while three specimen showed activation. Appreciable increase in respiratory rate was perceived in all the cases studied. Inhibition was apparent in data of nitrogen fixed/carbon consumed. Lanthanum ions clearly acted as promotors in nitrogen fixing bacteria. Lanthansulfat bewirkte eine Zunahme der Stickstoffbindung durch Bakterien, auch der Kohlenstoffverbrauch nahm in ähnlicher Weise zu. Bei drei Isolaten N-bindender Mikroorganismen war die Menge des fixierten Stickstoffs (mg) pro Gramm verbrauchten Kohlenstoffs in Anwesenheit von Metallionen höher, während in einem anderen Falle der Wert merklich verringert war. Praseodymsulfat hemmte die Stickstoffixierung in einem Isolat, während drei andere Isolate Aktivierung zeigten. Eine bemerkenswerte Zunahme der Atmung wurde in allen Fällen beobachtet. Eine Hemmung war erkennbar im Verhältnis Stickstoffixierung : Kohlenstoffverbrauch. Lanthanonen wirkten deutlich als Förderer stickstoffbindender Bakterien.