Anthropogenic Vanadium-Chromium-Iron and Cerium-Lanthanum-Iron Particles in Settled Urban House Dust: CCSEM Identification and Analysis

There is continuing concern over the health threat posed by theinhalation of ambient, transition-metal-containing particulatematter. Here, we report on the collection of two types ofanthropogenic, airborne particles, composed of iron with vanadiumand chromium (FeVCr) and iron with the rare earth metals ceriumand lanthanum (FeCeLa), respectively. Bi-weekly deposition platesamples were collected on indoor window sills of residentiallocations in inner-city Syracuse, NY. Sampling was continuous ateach location for two months during the spring of 1999. Themetal-bearing particles were identified, analyzed, and sizedin situ on each deposition plate using computer controlledscanning electron microscopy (CCSEM). Approximately 17% of thoseanalyzed by CCSEM fell into the inhalable size fraction. Particle loading varied between locations and changed over time.This was probably a function of various factors affectingparticle deposition rates. Notwithstanding, the plate loadingsfor the FeVCr-bearing particles tended to peak during the middleof the sampling period, suggesting that a single source/processwas operating to produce the FeVCr particles. The large sizeattained by some of these particles (greater than 50 μm inaggregates) suggest that long range transport was probably notinvolved.     

Temporal changes of resource use,soil fertility and economic situation in upland Northwest Vietnam

Agricultural land in lowland Vietnam is scarce due to population growth. Hence, cultivation is increasingly practised on the steep upland slopes. Factors affecting resource use, soil fertility and household economics were studied in six villages of the Black Thai ethnic group in northwest Vietnam. Farmers were interviewed about their individual household situation. Yield development of major crops and cropping patterns in upland cultivation over the last 50 years were recorded in group discussions. In addition, soil fertility was analysed on different land‐use units. Formerly predominant upland rice changed to maize and cassava production at present. Decreasing soil fertility and a shift from subsistence to market‐oriented production, facilitated by new maize varieties and better access to markets are major causes. The Black Thai farmers economy has improved in recent years. The decline in soil fertility is concealed by higher maize yields from new varieties, and soil fertility conservation ranks low among farmers' priorities. The improved economy of the individual households might be of short duration if farmers cannot be sensitized to new resource management options. These have to be developed in line with farmers' priorities and the fragile environment of Vietnam's uplands. Copyright © 2002 John Wiley & Sons, Ltd.     

伊朗西部不同土地利用方式下钙质土壤疏水性研究

Soil wettability and water repellency, two important soil physical properties, play an important role in water retention and water conductivity in arid and semi-arid regions. To date, there is a lack of information on soil water repellency in calcareous soils of western lran. In this study, soil water repellency and its affecting factors were studied using 20 soil series collected from Hamadan Province~ western Iran. The effects of soil properties including organic carbon content （SOC）, total nitrogen （TN）, C：N ratio, texture, CaCO3 content, and both fungal and bacterial activities on water repellency were investigated using air-dried, oven-dried and heated soil samples. Water repellency index （WRI） was determined using the short-time sorptivity （water/ethanol） method. To distinguish the actual effects of SOC, a set of soil samples were heated at 300 ~C to remove SOC and then WRI was measured on the heated samples. Relative water repellency index （RWRI） was defined as the change of WRI due to heating relative to the oven-dry WRI value. Results of the WRI values showed that the soils were sub-critically water-repellent. Pasture soils had higher WRI values compared to tilled soils, resulting from high SOC and TN, and high activities of bacteria and fungi. It was observed that SOC, TN, fungal activity, and SOC：clay ratio had significant positive impacts on WRI. Strong positive correlations of RWRI with SOC, TN and fungal activity were also observed. Pedotransfer functions derived for predicting WRI showed that the WRI values had an increasing trend with the increases in fungal activity, salinity, alkalinity and fine clay content, but showed a decreasing trend with increasing bacterial activity.     

Effect of temperature on the decomposition rate of labile and stable organic matter in an agrochernozem

An hypothesis about the different temperature dependences of the decomposition of the labile and stable organic carbon pools has been tested using an agrochernozem sampled from an experimental plot of 42-year-old continuous corn in Voronezh oblast. The partitioning of the CO₂ loss during the decomposition of the labile and stable soil organic matter (SOM) at 2, 12, and 22°C in a long-term incubation experiment was performed using the method of ¹³C natural abundance by C3–C4 transition. On the basis of the determined decomposition constants, the SOM pools have been arranged in an order according to their increasing stability: plant residues < new (C4) SOM < old (C3) SOM. The tested hypothesis has been found valid only for a limited temperature interval. The temperature coefficient Q ₁₀ increases in the stability order from 1.2 to 4.3 in the interval of 12–22°C. At low temperatures (2–12°C), the values of Q ₁₀ insignificantly vary among the SOM pools and lie in the range of 2.2–2.8. Along with the decomposition constants of the SOM, the new-to-old carbon ratio in the CO₂ efflux from the soil and the magnitude of the negative priming effect for the old SOM caused by the input of new organic matter depend on the temperature. In the soil under continuous corn fertilized with NPK, the increased decomposition of C3 SOM is observed compared to the unfertilized control; the temperature dependences of the SOM decomposition are similar in both agrochernozem treatments.     

Diversity among melon (Cucumis melo L.) landraces from the Indo-Gangetic plains of India and their genetic relationship with USA melon cultivars

We report here the first broad genetic characterization of farmer-developed landraces of melon (Cucumis melo L.) from the Indo-Gangetic plains of India, an area overlooked in previous melon genetic diversity analyses of Indian melon germplasm. Eighty-eight landraces from three melon Groups in two subspecies (C. melo subsp. agrestis Momordica Group, and C. melo subsp. melo Cantalupensis Group and Reticulatus Group) were collected from the four agro-ecological regions (six sub-regions) of two northern states of the Indo-Gangetic plains of India, Uttar Pradesh and Uttarakhand. Significant differences were found among the landraces and eight USA Reticulatus Group reference cultivars for 18 plant and fruit traits: no. of primary branches per plant, days to marketable maturity, sex expression, fruit shape, flesh colour, netting, no. of fruit per plant, fruit weight, shelf life, total soluble solids (°Bx), ascorbic acid (mg/100 g), titratable acidity (%), fruit length and diameter, seed cavity length and diameter, flesh thickness, and resistance to Cucumber mosaic virus. The three melon groups differed significantly for 10 of the plant and fruit traits. Cantalupensis Group and Reticulatus Group accessions were andromonoecious, and the Momordica Group was monoecious. Neighbour-joining (NJ) tree and factorial correspondence analysis (FCA) of simple sequence repeat loci also revealed a high level of genetic variability in this germplasm. The 96 melon genotypes clustered into five groups in the NJ tree analysis: the 16 Indian Reticulatus Group accessions and eight USA reference cultivars formed a distinct group; and the 60 Cantalupensis Group accessions clustered in four other groups with the 12 Momordica Group accessions in a distinct subgroup of one of the Cantalupensis groups. The FCA plot largely confirmed the NJ tree with three distinct groups, one for each melon group. The close affinity of the Indian and USA Reticulatus melons was not unexpected, but it is not clear whether it was inherent in the group and maintained as Reticulatus melons moved from India through Central Asia and Europe to North America, or the result of recent intercrossing of Indian landraces with the USA-derived cultivars and selection for a broad range of Reticulatus type melons.     

Carbon flux from decomposing 13C-labeled transgenic and nontransgenic parental rice straw in paddy soil

Purpose

Genetic modification of Bt rice may affect straw decomposition and soil carbon pool under flood conditions. This study aims to assess the effects of cry gene transformation in rice on the residue decomposition and fate of C from residues under flooded conditions.

Materials and methods

A decomposition experiment was set up using ¹³C-enriched rice straws from transgenic and nontransgenic Bt rice to evaluate the soil C dynamics and CH₄ or CO₂ emission rates in the root and non-root zones. The concentrations and stable carbon isotope compositions of the soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), CH₄, and CO₂ of the root and non-root zones were determined from 7 to 110 days after rice straw incorporation.

Results and discussion

Rice straw incorporation into soil significantly increased the SOC, DOC, and MBC concentrations and the CH₄ and CO₂ emission rates. The percentage of ¹³C-SOC remaining in the root zone was significantly lower than that in the non-root zone with rice straw decomposition. The DOC and MBC concentrations significantly increased in both the root and non-root zones between 0 and 80 days after rice straw incorporation. However, no significant differences were found after Bts (Bt rice straw added into soil) and Cks (nontransgenic Bt rice straw added into soil) incorporation in the root and non-root zones. This result may be attributed to the priming effects of sufficient oxygen and nutrients on straw degradation in the root zone.

Conclusions

Bt gene insertion did not affect the SOC, DOC, and MBC concentrations and the CH₄ and CO₂ emission rates in both the root and non-root zones. However, rice straw incorporation and root exudation significantly increased the SOC, DOC, and MBC concentrations and the CH₄ and CO₂ emission rates.     

不同种植方式对红壤旱地土壤水分及抗旱能力的影响

通过3年田间小区试验,研究不同种植方式对红壤旱地土壤水分及抗旱能力的影响.结果表明：1）与种植花生相比,种植苎麻可显著提高土壤有机质质量分数（28.44％）、田间持水量（10.06％）和总孔隙度（5.65％）,土壤密度则显著降低7.20％;2）监测期内,花生地各层土壤以及整个0～ 100 cm土体水分变异系数普遍高于苎麻地,苎麻地0 ～ 100 cm土体水分的时间稳定性和空间协调性优于花生地;3）苎麻地0～ 40 cm土壤较花生地延长抗旱时间7d以上,但随着土层的加深,差异越来越小;4）红壤坡耕地种植苎麻有利于提高红壤旱地土壤抗旱能力,特别是中、上层土壤.从扩充土壤水库的角度考虑,红壤旱地种植苎麻优于种植花生,该研究结果可为挖掘红壤区深层土壤水分提供参考.     

Effect of Harvest Timing on Yield and Mineral Nutritional Value of Kabuli Type Chickpea Seeds

Chickpea (Cicer arietinum L.) seeds are a good source of protein and mineral nutrients. However, there is no information regarding harvest timing on yield and mineral composition of chickpea seeds. The effect of harvest timing on seed yield, some yield components and mineral nutritional value of seeds of field grown chickpea plants in two different sites were studied. The mineral composition of chickpea straw depending on harvest timing was also evaluated in order to explain the variations of seed mineral concentrations in sink-source relationship manner. Yield and mineral nutritional value of chickpea were significantly affected by harvest timing. When compared to the seed yield at optimal harvest time, seed yield was 18% and 9% lower in the early harvest and 27% and 31% in the late harvest in Site 1 and Site 2, respectively. Late harvest of chickpea crops resulted in significant pod dropping and shattering. Generally, protein, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and manganese (Mn) concentrations of the seeds in optimal harvest were found to be greater than in early and late harvested plants. Harvest timing also results in significant variations in straw mineral nutrient concentrations of the plants. As the results of this study, it was concluded that the harvest timing is critical for yield losses and mineral nutritional value of chickpea seeds.     

Effects of Zeolite on Soil Nutrients and Growth of Barley Following Irrigation with Saline Water

ABSTRACT

Soil salinity is a major abiotic factor limiting crop production but an amendment with synthetic zeolite may mitigate effects of salinity stress on plants. The objective of the study was to determine the effects of zeolite on soil properties and growth of barley irrigated with diluted seawater. Barley was raised on a sand dune soil treated with calcium type zeolite at the rate of 1 and 5% and irrigated every alternate day with seawater diluted to electrical conductivity (EC) levels of 3 and 16 dS m^?1. Irrigation with 16 dS m^?1 saline water significantly suppressed plant height by 25%, leaf area by 44% and dry weight by 60%. However, a substantial increase in plant biomass of salt stressed barley was observed in zeolite-amended treatments. The application of zeolite also enhanced water and salt holding capacity of soil. Post-harvest soil analysis showed high concentrations of calcium (Ca^{2 +}), magnesium (Mg^{2 +}), sodium (Na⁺), and potassium (K⁺) due to saline water especially in the upper soil layer but concentrations were lower in soils treated with zeolite. Zeolite application at 5% increased Ca^{2 +} concentration in salt stressed plants; concentrations of trace elements were also increased by 19% for iron (Fe^{2 +}) and 10% for manganese (Mn^{2 +}). The overall results indicated that soil amendment with zeolite could effectively ameliorate salinity stress and improve nutrient balance in a sandy soil.     

Significant Nitrogen by Sulfur Interactions Occurred for Canola Grain Production and Oil Concentration in Grain on Sandy Soils in the Mediterranean-Type Climate of Southwestern Australia

The nitrogen (N) by sulfur (S) interaction for canola (Brassica napus L.) grain production and oil concentration in grain has been quantified in temperate climates, but it is not known if these results also apply to sandy soils common in the Mediterranean-type climate of southwestern Australia where canola is now a major crop. Seventeen field experiments were undertaken with canola in the region during 1994 to 2005 in which 4 rates of both N (0–138 kg N/ha) and S (0–34 kg S/ha) were applied. Significant grain yield responses to applied N occurred in all experiments and the responses increased as more S was applied. Grain yield responses to applied S only occurred when N was applied and tended to increase as more N was applied. When no S was applied the two largest rates of N applied, 69 and 138 kg N/ha, induced S deficiency reducing grain yields. The oil concentration in grain tended to decrease as more N was applied and increased as more S was applied, particularly when the two largest rates of N were applied. Consequently significant N × S interactions were obtained in all experiments for grain production and in 15 experiments for oil concentration in grain.