Evaluation of nitrogen status of agricultural soils in Java,Indonesia

Abstract

To evaluate the content of nitrogen (N) fractions of agricultural soils in Java, Indonesia, in relation to soil type and land use, 46 surface soil samples, 23 from paddy and 23 from upland, were collected throughout Java to include various types of soils. Soil N was separated into four fractions according to form and availability: inorganic extractable nitrogen (Iex-N), fixed ammonium nitrogen (Ifix-N), organic mineralizable nitrogen (Omin-N) and organic stable nitrogen (Osta-N). The total-N content was determined by the dry combustion method. The Iex-N content was determined by extraction with a 2 mol L^?1 potassium chloride (KCl) solution and the Ifix-N content by extraction with an hydrofluoric and hydrochloric acid (HF-HCl) solution after removal of organic-N. The Omin-N content was evaluated as the potentially mineralizable N based on a long-term incubation method. The Osta-N content was calculated as the difference between the contents of total-N and the three other fractions. The total-N content was 2.06 g kg^?1 on average. The contents of Iex-N, Ifix-N, Omin-N and Osta-N were 25.8, 99.1, 103 and 1,832 mg kg^?1, respectively, and corresponded to 1.3, 4.8, 5.0 and 88.9% of the total-N. Hence, available (Iex-N and Omin-N) and stable (Ifix-N and Osta-N) fractions accounted for 6.3% and 93.7% of the total-N, respectively. Correlation analysis indicated that the contents of total-N and Osta-N had positive correlation with (Alo + 1/2Feo) as an index of amorphous minerals (p < 0.01), suggesting strong influence of volcanic materials for the accumulation of organic matter in Java soils. The content of Ifix-N had a positive correlation with nonexchangeable potassium (K) content (p < 0.01), suggesting the contribution of 2:1 clay minerals which can fix both ammonium (NH₄⁺) and K⁺ in their interlayer sites. On the contrary, Omin-N did not have any significant correlation with soil properties, implying the importance of management for the improvement of the available N level in soils, rather than intrinsic soil properties. Soil N status further showed strong topographical trends depending on the elevation where soil developed. The contents of total N, Iex-N, Ifix-N, Omin-N and Osta-N in Java soils were on average 80, 69, 90, 65 and 80% of those in Japanese soils, respectively, suggesting that the soil N level in Java was lower than that in Japan, probably due to accelerated decomposition of organic matter, especially degradable fractions, reflecting high temperature, but that the level was relatively high for tropical soils due to the effect of volcanic materials. In conclusion, these results should be taken into account for the sustainable management of soil N in agricultural fields in Java, Indonesia.     

Synthesis and insecticidal activity of benzoheterocyclic analogues of N'-benzoyl-N-(tert-butyl)benzohydrazide: Part 1. Design of benzoheterocyclic analogues

The N'-benzoyl group of N-tert-butyl-N'-benzoyl-3,5-dimethylbenzohydrazide (1) was converted to a series of benzoheterocyclecarbonyl groups in order to investigate the potential usefulness of superimposing a hydrazine insecticide on 20-hydroxyecdysone. A series of analogues with benzodioxole, benzodioxane, benzodioxapine, indole, benzoxazole, benzoxazine or benzothiazole instead of the phenyl group of (1) were synthesized and tested for their insecticidal activity against the common cutworm (Spodoptera litura F). N-tert-Butyl-N'-(3,5-dimethylbenzoyl)-1,3-benzodioxole-5-carbohydrazide and N-tert-butyl-N'-(3,5-dimethylbenzoyl)-2,3-dihydro-1,4-benzodioxine-6-carbohydrazide showed high insecticidal activities, superior to that of (1) and equal to that of the commercial insecticide tebufenozide (RH-5992).     

Synthesis and insecticidal activity of benzoheterocyclic analogues of N'-benzoyl-N-(tert-butyl)benzohydrazide: Part 2. Introduction of substituents on the benzene rings of the benzoheterocycle moiety

A series of N'-benzoheterocyclecarbonyl-N-tert-butyl-3,5-dimethylbenzohydrazide analogues possessing a variety of substituents on the benzene rings of the benzoheterocyle moieties were synthesized and tested for their insecticidal activity. The introduction of a methyl group at the R1 position of the benzoheterocycle moiety strongly increased the insecticidal activity. Among the analogues synthesized, N'-tert-butyl-N'-(3,5-dimethylbenzoyl)-5-methyl-6-chromanecarbohydrazide showed the highest insecticidal activity (LC50 = 0.89 mg litre(-1)).     

Aberrant expression of cyclin D1 in pulmonary proliferative lesions induced by high doses of urethane in transgenic mice carrying the human prototype c-H-ras gene

In our previous study, when rasH2 mice and non-transgenic (non-Tg) littermates were injected intraperitoneally with 1,000 mg/kg of urethane once or three times at two-day intervals, the incidence of lung proliferative lesions in rasH2 mice given triple doses of urethane was significantly increased, compared to that in rasH2 mice given a single dose of urethane, and the mutation frequency of the transgene in lung tumors in rasH2 mice given triple doses was lower than that in rasH2 mice given a single dose of urethane. In the present study, differential immunohistochemical expressions of Cyclin D1 and PCNA, that lead to abnormal cell proliferation and tumor development due to uncontrolled G1-S transition in the cell cycle, as well as p53 tumor suppressor gene in pulmonary proliferative lesions obtained from our previous study were investigated. Over-expression of Cyclin D1 in hyperplasias in rasH2 mice given triple doses was significantly increased, compared to that in the single-injection group, but no significant differences in Cyclin D1 between the single and triple injection groups were observed in hyperplasias in non-Tg mice or lung tumors in either rasH2 or non-Tg mice. There were no differences in the PCNA labeling index of hyperplasias in rasH2 or non-Tg mice between the triple-injection and single-injection groups, while the PCNA labeling index tended to be increased in the tumor, compared with that in hyperplasias. There was neither mutation of p53 nor an increase in immunoreactivity of wild type p53 in these proliferative lesions. These results suggest that cyclin D1 over-expression in alveolar/bronchiolar hyperplasias in rasH2 mice in the triple-injection group is not only indicative of a high cell proliferation rate but also of an important role in the process of malignant transformation.     

Pathogenicity of a new neurotropic equine herpesvirus 9 (gazelle herpesvirus 1) in horses

Pathogenicity of equine herpesvirus 9 (EHV-9), a new type of equine herpesvirus isolated from Gazella thomsoni, in horses was investigated by intranasal inoculation of EHV-9 (10(7) pfu) to two conventionally reared 8-months old half-bred weanling horses. Fever higher than 39 degrees C was recorded. Virus was recovered from nasal swabs and peripheral blood mononuclear cells. Both horses developed neutralizing antibody to EHV-9. Perivascular infiltration of mononuclear cells and glial reaction were found in the olfactory and limbic systems. The results suggested that EHV-9 has a pathogenicity in horses.     

Protection conferred by a vaccine derived from an inactivated Egyptian variant of infectious bronchitis virus: a challenge experiment

Tropical Animal Health and Production - The current study investigated the protective efficacy of a formalin-inactivated infectious bronchitis virus (IBV) vaccine derived from the field strain...     

Differences in vernalisation responses in onion cultivars

Onions normally form bulbs in the first year of growth; however, exposure to low temperatures can induce flowering (vernalisation) before bulbs are produced. Based on the cultivation data of onions grown in Japan, we evaluated and validated a reported model describing the onion vernalisation response. The observed bolting rates of ‘Sapporoki’, which was used in the construction of a previous model, were a good fit to the model, whereas, the bolting rates of one of the overwinter-type cultivars, ‘Momiji No.3?, were lower than the predicted value. The difference between the predicted and observed bolting rates in ‘Momiji No.3? was caused by a larger VD_0.5, the coefficient in vernalisation response models that represents the time point when half of the plants have bolted. Overwinter-type and/or bolting resistant cultivars can have parameters that indicate a further vernalisation requirement for bolting. The parameters in our model can be customised to the cultivar being investigated, and our study suggests the viability of modelling onion bolting by using air temperature.