Tadao Ando

Measurement of soil microbial biomass phosphorus by an anion exchange membrane method

Abstract A method to measure soil microbial biomass phosphorus (biomass P) in granitic soils and andosols of high P retention capacity is described. Strips of anion exchange membrane (AEM) were shaken with suspensions of soil in (1) distilled water, (2) a mixture of distilled water and alcohol free chloroform (CHCl3) liquid, and (3) a standard inorganic P solution (2.5 mg KH2PO4P1−1), to estimate the recovery of CHCl3-released P. After shaking, the AEM strips were rinsed with distilled water to remove the soils from the AEM strips. Phosphorus adsorbed by the AEM strips was then eluted by 0.5 m HCl, and determined colorimetrically. The amount of CHCl3-released P was calculated from the difference between the amount of inorganic P adsorbed by AEM in unfumigated and fumigated soils. The high P retention capacity of soils, and the dark color of the extracts solution due to humic substances did not interfere with the measurement of P by this method. Biomass P was calculated from: biomass P = Ep Kp × 100 R , where Ep = (inorganic P released by CHCl3 and extracted by distilled water) minus (inorganic P released from unfumigated soil), Kp = Biomass P released by CHCl3 and extracted as inorganic P by distilled water (Kp = 0.40 at 25°C), R = percentage recovery (82.0–91.2%) of added P. Compared to the original CHCl3-fumigation extraction (FE)-method, the AEM-method is simpler, more accurate, and more flexible, allowing assay of biomass P in soils of high P retention capacity, e.g. andosols. The use of AEM allows quick and efficient adsorption of P in the soil suspensions, and is analytically very convenient.

Plant Nutrition for Sustainable Food Production and Environment

Plant Nutrition for Sustainable Food Production and Environment , Plant Nutrition for Sustainable Food Production and Environment , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Relative importance of protons and solution calcium concentration in phosphate rock dissolution by organic acids

Abstract A series of experiments was conducted to quantify the relative contribution of protons and other mechanisms to the dissolution of phosphate rocks (PRs) from six countries in solutions of low-molecular-weight-aliphatic organic acids. The amounts of P and Ca released after 3 d of incubation at 28°C were determined in all the experiments. In the first experiment the solubility of the PRs < 500 μm particle size) in 100 M (25 mL g-1 PR) oxalic, tartaric, and citric acids was compared with that in three mineral acids and four chelating compounds. There were no differences in the amount of P released by the mineral acids, but the organic acids released more P than could be accounted for by protonation. The chelating compounds were the least effective. In the second experiment, 1 g each of Sri Lanka and Togo PRs was incubated with 2.5 mmol of the organic acids using three acid concentration (mM) : acid volume ratios (250:10, 100:25, and 25:100). The amount of P dissolved from the PRs and the amount of ac...

Phenolic Acids as Potential Seed Germination-Inhibitors in Animal-Waste Composts

Abstract A laboratory experiment was conducted to investigate the presence of phenolic acids in some animal-waste composts as well as their biological activity on the germination of sorghum (Sorghum bicolor Moench) seeds. Nine samples of composts, three in each group of cattle-, chicken-, and hog-waste composts, were extracted with deionized water at the rates of 10, 40, and 80 g L-1. The seeds were imbibed in deionized water or respective compost extracts for 4 h. The content of water soluble phenolic acids in the compost extracts showed a negative correlation with the water uptake (r=- 0.88**), α-amylase activity (r=-0.82**), and subsequent germination % (r=- 0.81**) of sorghum seeds. The germination-inhibitory effects of the composts were observed in the acidic fraction of the compost extracts which contained the phenolic acids. The commercial phenolic acid preparations reduced the germination of sorghum seeds at a higher concentration (> 50 mg L-1) than the total phenolic acid content estimated in the...

Correlation among microbial biomass s, soil properties, and other biomass nutrients

Abstract The soil physicochemical characteristics and amounts of microbial biomass C, N, and S in 19 soils (10 grassland, 2 forest, and 7 arable soils) were investigated to clarify the S status in granitic regosols in Japan, in order to determine the relationships between biomass S and other soil characteristics and to estimate approximately the annual Sand N flux through the microbial biomass. Across the sites, the amount of biomass C ranged from 46 to 1,054, biomass N from 6 to 158, and biomass S from 0.81 to 13.44 mg kg-1 soil with mean values of 438.8, 85.8, and 6.15 mg kg-1 soil, respectively. Microbial biomass Nand S accounted for 3.4–7.7% and 1.1–4.0% of soil total Nand S, respectively. The biomass C: N, C : S, and N : S ratios varied considerably across the sites and ranged from 3.0–10.4, 32.5–87.7, and 5.0–18.8, respectively. Microbial biomass S was linearly related to biomass C and biomass N. The regression accounted for 96.6% for biomass C and 92.9% for biomass N of the variance in the data. Th...

Critical sulphur concentration and sulphur requirement of microbial biomass in a glucose and cellulose-amended regosol

Abstract The critical S concentration and S requirement of the soil microbial biomass of a granitic regosol was examined. S was applied at the rate of 0, 5, 10, 20, 30 and 50 μg S as MgSO4·7H2O, together with either 3000 μg glucose-C or 3333 μg cellulose-C, 400 μg N, and 200 μg P g –1 soil and 200 μg K g–1 soil. Microbial biomass, inorganic SO42–-S, and CO2 emission were monitored over 30 days during incubation at 25  °C. Both glucose and cellulose decomposition rates responded positively to the S made available for microbial cell synthesis. The amounts of microbial biomass C and S increased with the level of applied S up to 10 μg S g–1 soil and 30 μg S g–1 soil in the glucose- and cellulose-amended soil, respectively, and then declined. Incorporated S was found to be concentrated within the microbial biomass or partially transformed into soil organic matter. The concentration of S in the microbial biomass was higher in the cellulose- (4.8–14.2 mg g–1) than in the glucose-amended soil (3.7–10.9 mg g–1). The microbial biomass C:S ratio was higher in the glucose- (46–142 : 1) than in the cellulose-amended soil (36–115 : 1). The critical S concentration in the microbial biomass (defined as that required to achieve 80% of the maximum synthesis of microbial biomass C) was estimated to be 5.1 mg g–1 in the glucose- and 10.9 mg g–1 in the cellulose-amended soil. The minimum requirement of SO42–-S for microbial biomass formation was estimated to be 11 μg S g–1 soil and 21 μg S g–1 soil for glucose- and cellulose-amended soil, respectively. The highest levels of activity of the microbial biomass were observed at the SO42–-S concentrations of 14 μg S g–1 soil and 17 μg S g–1 soil, for the glucose and cellulose amendments, respectively, and were approximately 31–54% higher during glucose than cellulose decomposition.

Antifungal Activity of Oosporein from an Antagonistic Fungus against Phytophthora infestans

An antifungal metabolite, oosporein, was isolated from the culture of Verticillium psalliotae that produced the antagonistic effects on Phytophthora infestans. Oosporein exhibited a significant growth-inhibitory effect on P. infestans in comparison with other phytopathogenic fungi.

Minimum available N requirement for microbial biomass P formation in a regosol

A soil incubation experiment was conducted to determine the effects of N application on microbial biomass C and P and to estimate the minimum requirement of available N for microbial biomass P formation. A granitic regosol soil was amended with N (as (NH4)2SO4) at rates of 0, 200, 400 or 800 mg N kg−1, C (as rice straw) at 2100 mg C kg−1 and P (as KH2PO4) at 500 mg P kg−1 soil. With increasing N application up to 200 mg N kg−1 soil, microbial biomass C significantly increased and remained constant or slightly decreased at higher N rates, while microbial biomass P increased up to 400 mg N kg−1 soil and remained constant or slightly increased at the highest N contents. The concentration of P in microbial biomass (assuming that dry biomass contained 50% C) increased with increasing N rate and ranged from 32 to 76 mg g−1. Among the P fractions in soil, microbial biomass P and inorganic P (available P) fractions increased with increasing N rates, whilst the Ca–P fraction decreased. The critical P concentration in microbial biomass (defined as that required to achieve 80% of the maximum synthesis of microbial biomass C) was estimated to be 60±4.1 mg P g−1 biomass. The corresponding minimum amount of available N in the soil required to increase the biomass was estimated as 425±12 mg N kg−1 soil. The specific respiration of the microbial biomass was little affected by the N concentration and was very high even above an N concentration considered to be the optimum for microbial biomass C and P but also microbial activity.

Selective inhibitors of germination of legume seeds in activated sludge compost

Water extracts of the compost produced from activated sludge and coffee residue were found to be selectively inhibitory to seed germination of some legumes. Germination rate of white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) seeds were reduced to 2, 29 and 73% of the control, respectively, by water extracts of the compost (20 g l−1). However, the extracts did not show any inhibition to seed germination of sorghum (Sorghum bicolor Moench), African millet (Eleusine coracana Gaertn.), and Komatsuna (Brassica rapa L.) at the same concentration. The inhibitors in the compost extracts were separated by ion-exchange chromatography and reverse-phase high performance liquid chromatography (HPLC) and the inhibitory activities of seed germination were tested with white clover seeds. Five inhibitors were isolated and identified as 3,4-dichlorophenylacetic acid (3,4-DCP), 3,4-dichlorobenzoic acid (3,4-DCB), 3,4,5-trichlorophenylacetic acid, 3,4,5-trichlorobenzoic acid and mono-2-ethylhexylphthalate by 1H-, 13C-NMR spectroscopy and mass spectrometry. The inhibitory activities of some authentic chemicals of the inhibitors and the related compounds were compared. The results indicated that the main inhibitor in the compost could be 3,4-DCB, which was contained at the concentration of 6.58 mg kg−1 compost and showed the strongest inhibitory effect on seed germination of white clover among the tested compounds.

Alpha-Amylase and Protease Activities and Water Relations in Germinating Sorghum (Sorghum bicolor Moench) Seeds as Affected by Animal-Waste Composts

Abstract Effect of animal-waste composts on α-amylase and protease activities of sorghum (Sorghum bicolor Moench) seeds was investigated under laboratory conditions using several cattle, chicken and hog-waste composts. The sorghum seeds were imbibed in 1, 4, and 8% (w/v) water extracts of the composts for 4 h. Alpha-amylase activity of the non-imbibed seeds increased by 46% during the 4-h imbibition in water. The increase of the amylase activity of the seeds imbibed in the majority of the germination-inhibitor composts, however, remained at a level between 50 and 66% of the increase observed in the water control. The amylase activity of the imbibed seeds showed a linear correlation with amount of water absorbed by the seeds (r = 0.82**) and also with the rate of subsequent seed germination (r = 0.85**). The protease activity was not affected by the addition of animal-waste composts. Starch degradation and the sugar and amino acid contents of the compost-imbibed seeds were in good agreement with the respec...