Selected physical properties of 13 coconut coir dusts from Asia, America, and Africa were compared to physical properties of sphagnum peat. All properties studied differed significantly between and within sources, and from the peat. Coir dusts from India, Sri Lanka, and Thailand were composed mainly of pithy tissue, whereas most of those from Costa Rica, Ivory Coast, and Mexico contained abundant fiber which was reflected by a higher coarseness index (percentage by weight of particles larger than 1 mm in diameter). Coir dust was evaluated as a lightweight material, and its total porosity was above 94% (by volume). It also exhibited a high air content (from 24% to 89% by volume) but a low easily available and total water-holding capacity which ranged from <1% to 36% by volume and from 137 to 786 mL·L ^–1 , respectively. Physical properties of coir dust were strongly dependent on particle size distribution. Both easily available and total water-holding capacity declined proportionally with increasing coarseness index, while air content was positively correlated. Relative hydraulic conductivity in the range of 0 to 10 kPa suction dropped as particle size increased. Coir dusts with a particle size distribution similar to peat showed comparatively higher aeration and lower capacity to hold total and easily available water. An air–water balance similar to that in peat became apparent in coir dust at a comparatively lower coarseness index (29% vs. 63% by weight in peat). Stepwise multiple regression analysis showed that particles with diameters in the range of 0.125 to 1 mm had a remarkable and highly significant impact on the physical properties studied, while particles 1 mm had only a slight or nonsignificant effect.

The influence of particle size (diameter between 2 mm) on the physical, physico-chemical and chemical properties of a coconut coir dust from Mexico was studied. Particle size significantly affected the physical properties, especially the air–water relationships. Air content increased and water-holding capacity (total and readily available) decreased with increasing particle diameter. The easily-available water content did not reveal a clear pattern of variation, showing the largest value in the fraction 0.125–0.25 mm. Particle size equivalent to 0.5 mm brought about an important and highly significant change in the physical properties studied. Coconut coir dust particle size also affected the physico-chemical and chemical characteristics, but to a lesser degree. Both the electrical conductivity and the available macro- and micro-element concentrations were significantly higher in the smaller size ranges, the largest values being obtained in the finest particle size fraction (<0.125 mm).

The use of compost with high salt concentration was evaluated, under commercial conditions, as a potential growing media constituent for vegetable transplant production. Two composts were prepared from sweet sorghum bagasse, pine bark, and either urea (compost A) or brewery sludge (compost B) as N source. Three vegetable species — broccoli (Brassica oleracea), tomato (Lycopersicum esculentum), and onion (Allium cepa) with different tolerance to salinity were used. Eleven substrates were formulated and tested: a control consisting of a moss peat-based commercial substrate; compost A; compost B; and, eight mixtures containing 33 or 67% by volume of each compost with either raw peat moss or commercial substrate as diluent. All the substrates prepared had suitable physical, physicochemical and chemical properties for use as growing media, except for the electrical conductivity (ranging from 3.20 to 13.21 dS m⁻¹) which was above the reference levels for soilless cultivation. Broccoli was the least affected by substrate salinity whilst tomato was the most. Onion transplants had an intermediate response to saline conditions. Tomato seed germination was markedly reduced when compost A, with a higher salt concentration, was used at a rate higher than 67%. Media prepared with either of the composts, and mixed with either a commercial substrate or peat in a rate up to 67%, did not cause any detrimental effect on the growth and nutritional status of broccoli, tomato and onion transplants, despite the high initial salinity of the substrates. These composts appear to be acceptable substitutes for Sphagnum peat in seed sowing mixtures.

The use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay, NALFIA). Prior to the detection with NALFIA, a rapid amplification method with tagged primers was applied. In the evaluation of the optimised NALFIA strips, no cross-reactivity was found for any of the antibodies used. The limit of detection was higher than for quantitative PCR (q-PCR), in most cases between 10⁴ and 10⁵ colony forming units/mL or 0.1–0.9 ng/μL DNA. NALFIA strips were applied to 48 isolates from cattle faeces, and results were compared to those achieved by q-PCR. E. coli virulence factors identified by NALFIA were in very good agreement with those observed in q-PCR, showing in most cases sensitivity and specificity values of 1.0 and an almost perfect agreement between both methods (kappa coefficient larger than 0.9). The results demonstrate that the screening method developed is reliable, cost-effective and user-friendly, and that the procedure is fast as the total time required is <1 h, which includes amplification. Results achieved with multi-analyte NALFIA for E. coli virulence factors. First strip: blank; second to sixth strip: each of the STEC factors; seventh strip: all factors