Effect of fertilizer-N application and seed coating with rhizobial inoculants on soybean yield in eastern Paraguay

Nitrogen removal in soybean grains at harvest may exceed biological N2 fixation, particularly if grain yields are as high as typically achieved on "Terra Rossa" soils of Eastern Paraguay. Applying N fertilizer or coating seeds with rhizobial inoculants that enhance nodulation may represent a way of balancing the N budget. However, the effects of such treatments appear to be highly site-specific. The objective of this study was to examine the effects of N application (N) and rhizobial inoculation (I) on nodulation, N accumulation and soybean yields in Eastern Paraguay. Field experiments were conducted in two consecutive soybean seasons. Dry conditions in the first year delayed sowing and reduced plant number m-2 and pod number plant-1. Grain yields were generally below 2 t ha-1 but the +N+I treatment increased yields by about 75%. In the second year favorable conditions resulted in yields of around 4 t ha-1 and the treatments had no effect. Nitrogen accumulation was higher in the first year and could therefore not explain the observed yield differences between years and treatment combinations. The positive effect of the +N+I treatment in year one was associated with a more rapid root growth which could have reduced susceptibility to intermittent drought stress. Nodule biomass decreased between flowering and pod setting stages in the +I treatment whereas further increases in nodule biomass in the -I treatment may have led to competition for assimilates between nodules and developing pods. Based on these preliminary results we conclude that N application and seed inoculation can offer short-term benefits in unfavorable years without negative effects on yield in favorable years.

Report on a special investigation of the Eastern Iowa Center for Problem Gambling for the period May 1, 2007 through April 30, 2009

Report on a special investigation of the Eastern Iowa Center for Problem Gambling for the period May 1, 2007 through April 30, 2009

Graduate labor mismatch in Central and Eastern Europe

[cat] Utilitzant l’enquesta REFLEX/HEGESCO, aquest article explora la probabilitat de desajustament entre educació i treball a l’Europa de l’Est i Central. Classifiquem els països en dos grups segons la transparència dels títols educatius al mercat de treball. Polònia, la República Txeca i Eslovènia formen el grup amb més transparència, i Hongria, Lituània i Estònia formen el grup amb més opacitat. Analitzem tres tipus de desajustaments: el vertical (infra‐, sobre‐educació), l’horitzontal (desajustament del camp d’estudi) i el desajust en habilitats. Focalitzem l’anàlisi en l’efecte dels camps d’estudi i les competències dels individus en el desajustament del mercat laboral en aquests països. Els resultats mostren importants diferències entre els dos grups de països estudiats.

Effects of vapour pressure deficit and soil water content on leaf water potential between selected provenances of Eucalyptus microtheca in an irrigated plantation, eastern Kenya

Summary

EFFECT OF WATER AVAILABILITY ON SOIL MICROBIAL BIOMASS IN SECONDARY FOREST IN EASTERN AMAZONIA

Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO2-SMB). The metabolic quotient (qCO2) and ratio of microbial carbon:organic carbon (CMIC:CORG) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.