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

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

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

Effects of charcoal-enriched goat manure on soil fertility parameters and growth of pearl millet (Pennisetum glaucum L.) in a sandy soil from northern Oman

The effect of charcoal feeding on manure quality and its subsequent application to enhance soil productivity has received little attention. The objectives of the present study therefore were to investigate the effects of (i) charcoal feeding on manure composition, and (ii) charcoal-enriched manure application on soil fertility parameters and growth of millet (Pennisetum glaucum L.). To this end, two experiments were conducted: First, a goat feeding trial where goats were fed increasing levels of activated charcoal (AC; 0, 3, 5, 7, and 9% of total ration); second, a greenhouse pot experiment using the manure from the feeding trial as an amendment for a sandy soil from northern Oman. We measured manure C, N, P, and K concentrations, soil fertility parameters and microbial biomass indices, as well as plant yield and nutrient concentrations. Manure C concentration increased significantly (P0.001) from 45.2% (0% AC) to 60.2% (9% AC) with increasing dietary AC, whereas manure N, P, and K concentrations decreased (P0.001) from 0% AC (N: 2.5%, P: 1.5%, K: 0.8%) to 9% AC (N: 1.7%, P: 0.8%, K: 0.4%). Soil organic carbon, pH, and microbial biomass N showed a response to AC-enriched manure. Yield of millet decreased slightly with AC enrichment, whereas K uptake was improved with increasing AC. We conclude that AC effects on manure quality and soil productivity depend on dosage of manure and AC, properties of AC, trial duration, and soil type

Food and nutrition status of households with homegardens in the Nuba Mountains of Sudan

Sudan is one of the least developed countries and many people particularly in South Kordofan suffer from food insecurity. Food production from homegardens (HG) and wild collections are seen as key elements in strategies to overcome nutrient deficiencies. Food intake 24h-recalls were conducted to evaluate the status quo of households (HHs) and the contribution from four HG and wild collection during three seasons in Sama in South Kordofan, Sudan. Dietary diversity as well as nutrient intake was determined and food samples were taken. On average people consumed 16 food items belonging to eight food groups, which is adequate or higher than reported in other studies. Mean daily intake was 1438 kcal energy, 36 g protein, 182 μg vitamin A, 23 mg vitamin C, 9 mg iron and 5 mg zinc. This indicates a nutrient deficiency, especially in vitamins. Differences between traditional and commercial (marketoriented) HGs were small. Households which considered HGs to be important for their daily life had a better nutrient intake, but less diverse diet than those with a reduced importance of HGs. Thus the perceived importance of the HGs seemed to affect HH nutrition more than the level of their commercialization. In total twelve food items from HGs (mostly green leafy vegetables, high in vitamin A) and seven from the wild (mainly Ziziphus spina-christi (L.) Willd, high in vitamin C) were used within the three weeks interview period. The results show the importance of the HG to HH´s nutrition and also indicate the importance of wild collection for the dietary status of HH in the Nuba Mountains of Sudan

Effect of NaCl Salinity on Growth and Mineral Composition of Ziziphus spina-christi (L.) Willd.

Ziziphus spina-christi (L.) Willd. is a fruit tree species growing wild in arid and semi-arid areas of Asia and Africa where rural populations intensively use its fruits, leaves, bark and wood. However, little is known about the effects of salinity, a widespread problem in these regions, on early growth and mineral composition of this species. This study was conducted under controlled conditions to contribute to filling this gap. Six weeks old seedlings of Z. spina-christi germinated in a full strength Hoagland solution were subjected to 0, 40, 80 and 160 mM NaCl. Compared to the unstressed control salinity levels of 80 and 160 mM reduced plant height, leaf number, leaf chlorophyll, total leaf area and dry matter by 50%. Salinity levels of 40, 80 and 160 mM enhanced leaf water contents by 14, 16 and 17%, respectively and 160 mM NaCl raised the concentration of Na and Cl ions in leaf tissues 81- and 21-fold. The K/Na ratio, in contrast, was hardly affected by increasing salinity indicating adaptation or tolerance of Z. spina-christi to low or moderate NaCl salinity. These results suggest that Z. spina-christi could be an interesting species for re-vegetation of moderately degraded saline lands