Barium in Water and Foraminiferal Shells: Indicator of Oceanographic Conditions in the Gulf of Mexico Since the Late Pleistocene.

The Gulf of Mexico offers an appropriate setting for studying the chemical dynamics at the continent-ocean interface. In addition, its sediments preserve the climatic records of the past. This study employs Ba as a tracer to examine several aspects of modern Gulf oceanographic processes and seeks to unravel Gulf paleoceanography using Ba/Ca ratios from fossil foraminiferal shells. Comparison of dissolved Ba in the Mississippi and Atchafalaya River mixing zones suggests different Ba distributions can occur as a result of hydrodynamic and morphologic variability. Rapid Ba desorption from suspended material occurs near the Mississippi River, while Ba input from the shallow shelf sediments is possible near the Atchafalaya River. Dissolved Ba measured in the southern Gulf of Mexico from the Yucatan entrance to the western Gulf reveals modern controls on the distribution of the trace element. Gulf surface waters contain elevated Ba, relative to the surface waters of the open Atlantic, due to river input and shelf-derived coastal inputs. Deep Gulf waters are largely homogeneous with respect to Ba and are rapidly flushed by waters from middle depths in the Atlantic. A Ba/Ca record for planktonic foraminifera indicates high Ba during the s 18O meltwater signal of the last deglaciation. This Ba/Ca anomaly is consistent with surface water freshening of 6 to 7%. Ba/Ca ratios decrease by 30% with water depth for Recent benthic foraminifera from deep basin waters having nearly uniform Ba concentration, salinity, and temperature. This decrease points to pressure as a probable control on metal contents in foraminifera. The downcore variation in Ba/Ca seen in Cibicides wuellerstorfi sampled from a core in the deep waters of the southern Gulf indicates the presence of the nutrient-depleted Glacial North Atlantic Intermediate Water in the Gulf of Mexico during the Last Glacial Maximum. During deglaciation low s 18C and high Ba/Ca suggest that the Gulf received a dominant contribution from Southern Ocean Water that was residing at intermediate depths. An ensuing Ba/Ca decrease through the deglaciation occurs coincident with the production of the North Atlantic Deep Water and represents the transition to an interglacial mode of ocean circulation

The Biofuel Debate – Status Quo and Research Needs to Meet Multiple Goals of Food, Fuel and Ecosystem Services in the Tropics and Subtropics

The current biofuel debate is characterized by concerns about the environmental effects of large-scale biofuel plantations, controversies about GMO-based feedstocks and the recent global food crisis. Predictions for the development of the biofuel sector are either departing from the supply-side or the demand-side, but are mostly based on modelling efforts with an unclear experimental basis and only broadly defined economic settings. Results vary widely and tend to undervalue technical progress in processing efficiency or management-related increases in biomass yields. Moreover, calculations often neglect the impact of climate change, the need for irrigation and processing water, for soil fertility maintenance and the importance of socio-economic issues. Against these shortcomings and in view of several decades to centuries of Ecosystem Carbon Payback Times of most biofuel plantations, their future as a large-scale replacement for hydrocarbons will strongly depend on improved matter conversion efficiencies and successful prevention mechanisms for conflicts over land use

Green Gram Rotation Effects on Maize Growth Parameters and Soil Quality in Myanmar

At present maize–green gram crop rotations are not widely practiced among farmers in Myanmar. However, this cropping system might become more popular in the future given raising prices for green gram and maize grain and scarcity of mineral nitrogen (N) fertilizers in this Asian country. The results of a cropping systems experiment with continuous maize versus a green gram-maize rotation, manure application (0 and 2 t ha−1) and phosphorus (P) fertilization (0 and 15 kg P ha−1) in each of five consecutive seasons revealed a strong decline in total dry matter and grains yields for both crops irrespective of the treatment. Treatment effects on yield components, nutrient concentrations, mycorrhizal infection and nematode infestation were small or negligible. The data show that in addition to manure used at 2 t ha−1, application of mineral N fertilizers is essential to maintain particularly maize yields. A comparison of different green gram cultivars did not indicate genotype specific effects on maize growth. The incorporation of legume residues, unless they are used as animal feed, is recommended to increase the recycling of N and to balance N fluxes when green gram is cultivated for seed

Soil fertility and nutrient status of traditional Gayo coffee agroforestry systems in the Takengon region, Aceh Province, Indonesia

Little is known about the traditional coffee cultivation systems in Central Aceh, Indonesia, where coffee production is a major source of income for local Gayo people. Based on field observations and farmer interviews, 14 representative agroforestry coffee plantations of different age classes (60-70 years, 30-40 years, and 20 years) as well as seven adjacent grassland and native forest sites were selected for this study, and soil and coffee leaf samples collected for nutrient analysis. Significant differences in soil and coffee leaf parameters were found between former native forest and Sumatran pine (Pinus merkusii) forest as previous land cover indicating the importance of the land use history for today’s coffee cultivation. Soil pH as well as exchangeable Na and Ca concentrations were significantly lower on coffee plantations compared to grassland and forest sites. Soil C, N, plant available P, exchangeable K, and Mg concentrations showed no consistent differences between land use groups. Nitrogen (N), phosphorus (P), and potassium (K) concentrations of coffee leaves were in the sufficiency range, whereas zinc (Zn) contents were found to be consistently below the sufficiency threshold and significantly lower in coffee plantations of previous pine forest cover compared to those of previous native forest cover. While the results of this study provided insights into the nutrient status of coffee plantations in Central Aceh, the heterogeneity of site conditions, limited sampling size, and scarcity of reliable data about the land use history and initial soil conditions of sampled sites preclude more definitive conclusions about the sustainability of the studied systems

Phosphorus Response and Amino Acid Composition of Different Green Gram (Vigna radiata L.) Genotypes from Myanmar

Mungbean or green gram (Vigna radiata L.) is an important component of rice-based cropping systems in Myanmar, where grain yields of around 800 kg ha^(-1) are much below its yield potential of 3000 kg ha^(-1). The reasons for this shortfall are as under-investigated as is the genotype-specific response of this crop to phosphorus (P) application, which is critically low in many Myanmar soils, and the genetic variation in grain quality. For green gram quality, the concentration of lysine, an essential amino acid is particularly important given its scarcity in many cereal-based diets of Southeast Asia. The purpose of this study therefore was to investigate the effects of P application on the root and shoot growth, yield and its components for a range of green gram varieties, and to analyse the protein concentration and amino acid composition in green gram seed of different origins. To this end from 2001 to 2003, field experiments were conducted under rain-fed conditions in Yezin and Nyaung Oo. Fifteen landraces and five introduced green gram cultivars were grown at two levels of P (0 and 15 kg ha^(-1)). There were large genotypic differences in P effects and a significant interaction between green gram genotypes and P for shoot and root growth. An unexpected benefit of P application was a reduction of pest and plant virus infestation in the field. Significant genotypic differences in the amino acid profile of seeds were also observed. The results indicate the potential for breeding efforts to increase seed yield and protein quality in green gram