Compost effects on microbial biomass and soil P pools as affected by particle size and soil properties

Previous studies have shown that finer composts release nutrients more quickly than coarse composts, but little is known about the nutrient release from different size fractions of a compost. To assess if compost size fractions differ in their effect on microbial biomass and soil P pools, a compost from garden waste was separated by sieving into different particle size fractions (> 5 mm, 3-5 mm and 5 mm fraction and in microbial biomass C and P with the < 3 mm fraction. The size of the P pools was mainly affected by soil type, the compost fractions had similar effects on soil P pools except for a greater increase in available P concentration by the finest fraction compared to the coarser size fractions. Soil A with the highest organic matter content had the highest concentrations of Fe/Al associated P (NaOH-P) and organic P whereas Ca-associated P (HCl-P) dominated in the alkaline soil C. The size of most P pools, even the so-called stable P pools changed over time in amended and non-amended soils. It can be concluded that the size of P pools is more strongly affected by soil properties such as organic matter content, texture and pH than by the compost fractionsS. Lata Verma, P. Marschne

Effect of residue mixtures on response of cumulative respiration to salinity

The study aimed to investigate the response of soil respiration to salinity when amended with mixtures of rapidly and slowly decomposable residues. Two incubation experiments were carried out with loam soils having EC1:50.1, 1.0, 2.5 and 3.3 dS m-1. In experiment one, the four soils were amended with 20 g kg-1 soil as sawdust (C/N 114) or kikuyu (C/N 19) alone or mixed at different ratios. In all mixtures, the decrease in cumulative respiration at 1 dS m-1compared to non-saline soil was smaller than with sawdust alone. In experiment two, three soils (EC1:50.1, 1.0 and 2.5 dS m-1) were amended once or three times to a total addition rate of 10 g C kg-l soil either with sawdust alone, kikuyu alone or mixtures. In the treatments with mixtures, the decrease in cumulative respiration from non-saline to EC 1 dS m-1 was smallest in the treatments with three residue additions where 25% kikuyu was added on day 0 or on day 14 after addition of 50% sawdust on day 0. We conclude that even a relatively small proportion of rapidly decomposable residue in a mixture is sufficient to alleviate the negative impact of salinity on soil respiration.H. Hasbullah, P. Marschne

Clay addition to sandy soil - effect of clay concentration and ped size on microbial biomass and nutrient dynamics after addition of low C/N ratio residue

Addition of clay-rich subsoil to sandy soil has been shown to increase crop production on sandy soils. The added clay is present as peds ranging in size from a millimetre to several centimetre. In thisexperiment clay soil (73% clay) was added to sandy soil (3% clay) at 10 and 20% clay w/w as 1, 3 and 5 mm peds. Shoots of young Kikuyu grass (C/N 20) were ground and added at 10g kg-1, and soils were incubated for 45 days at 80% of water holding capacity.The study confirmed that clay addition to sandy soil increased soil organic carbon retention but decreased cumulative respiration and available P compared to sandy soil alone. Ped size had little effect on respiration and nutrient availability. Over the course of 45 days peds broke down and organic C was bound to the < 53 μm fraction. The greatest proportion of peds and total organic carbon (54-67%) was in the initially added ped size. The TOC content of < 53 μm fraction of initially added peds was 0.38% and at the end of the experiment (after 45 days) the TOC had increased by 24, 19 and 10% in 1, 3 and 5 mm peds respectively.Shermeen Tahir and Petra Marschne

Effect of incorporated or mulched compost on leaf nutrient concentrations and performance of Vitis vinifera cv. Merlot

Compost can reduce evaporation and increase nutrient uptake by plants, but it is not clear if it can increase soil water holding capacity or stimulate leaf gas exchange, water use efficiency and yield of vines. To study these effects, compost from garden and food waste was incorporated or mulched in a vineyard at a rate of 100 m3 ha-1, three months before the measurements. The vineyard received irrigation during spring and summer. Soil water content was monitored regularly with a capacitance probe. Photosynthesis, transpiration, stem water potential and leaf area index were measured several times during the vegetation period. At harvest, yield, berry weight and quality as well as chlorophyll, N, P and K concentrations in leaves were determined. Only mulched compost increased soil water content at 10 cm depth, but the water content in the deeper layers was not affected by compost addition. Compost also did not affect transpiration rate and stomatal conductance during the vegetation period, but mulched compost increased the photosynthesis per plant at flowering, pea size and maturity periods. Compost amendment, particularly mulching, increased yield, specific berry weight, and leaf N and P concentrations, and reduced the number of chlorotic leaves at harvest. Berry quality was not affected by compost amendment. It can be concluded that mulched compost has a positive effect on grapevine yield and can be an alternative fertiliser source for vines with no adverse effect on berry quality.T.-T. Nguyen, S. Fuentes, P. Marschne

Advances in electrical high current connections for electrical propulsion systems

Many countries strongly support electric propulsion for various fields of transportation, be it people or goods on land, at sea or in the air. Although electric drive systems appear much simpler than (internal) combustion systems, they exhibit their own challenging development tasks. This becomes obvious when an ever-increasing efficiency, performance or production rate is required, just to name a few. The new challenges can be tackled with the help of new electromagnetic manufacturing processes. High speed processes with their well-known unique capabilities offer promising approaches. However, development is required in order to deliver the required performance. High-speed forming with electromagnetic tools allows the production of sharp-edged battery housings. For body panels, sharp edges are mainly a design feature. For batteries, however, sharp edges allow for an almost ideally rectangular housing, enabling a higher energy density. Increases in the range of up to 10 % are achievable. When it comes to packaging, the liquid cooling and heating of battery packs is of equally large importance. The channels for the medium must not consume too much space. The integration of channels inside the aluminium or steel frame of the battery pack is a promising approach. Due to the high welding speeds of up to 500 mm per second at optimum conditions and at the same time the ability to weld aluminium to aluminium or even steel without any loss in strength, electromagnetic pulse welding offers a promising solution. The conduction of high electrical currents with for example the strong demand to save weight and thus use as little material as possible also requires new processes. Electromagnetic pulse welding of aluminium to aluminium and aluminium to copper is well known, investigated and already used in mass production. However, this is suitable for bus bars only. The connection of terminals to cables is mostly done by crimping. Using a pulsed force for crimping improves the compaction and thus the resistance of the joint, especially of cables with large cross sections. This allows for smaller connectors and reduced cable cross sections

Phosphate solubilizing bacteria from the rhizosphere of Theobroma grandiflorum (Willd. ex Spreng.) Schum. and Bactris gasipaes H.B.K.: potential for plant growth promotion.

We have isolated bacteria from the rhizosphere of two perennial crop plants (Bactris gasipaes and Theobroma grandiflorum) growing on the SHIFT experimental site near Manaus

Vitamin B2 and Innovations in Improving Blood Safety

Although transfusion of blood components is becoming increasingly safe, the risk of transmission of known and unknown pathogens persists. The application of vitamin B2 (riboflavin) and UV light to pathogen inactivation has several appealing factors. Riboflavin is a naturally occurring vitamin with a well-known and well-characterized safety profile. This photochemical-based method is effective against clinically relevant pathogens and inactivates leukocytes without significantly compromising the content and the efficacy of whole blood or blood component. This chapter gives an overview of the innovative technology for pathogen inactivation, the Mirasol® pathogen reduction technology (PRT) System, based on riboflavin and UV light, summarizing the mechanism of action, toxicology profile, pathogen reduction performance and clinical efficacy of the process