RESUMEN
The present study was undertaken to evaluate the effects of phosphorus (P) application and arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae) on growth, foliar nitrogen mobilization, and phosphorus partitioning in cowpea (Vigna unguiculata cv. Vita-5) plants. The experiment was conducted in a greenhouse in pots containing a mixture of vermiculite and sterilized quartz sand. Mycorrhizal and non-mycorrhizal cowpea plants were supplied with three levels of soluble P (0.1 (low P), 0.5 (medium P), or 1.0 mM (high P)).Cowpea plants supplied with low P fertilization showed significantly (p < 0.05) higher root colonization than those with medium and high P fertilization at both the vegetative and pod-filling stages. P uptake and growth parameters of cowpea plants were positively influenced by mycorrhizal inoculation only in the medium P fertilization treatment at the vegetative stage. Lack of these effects in the other treatments may be linked to either a very low P supply (in the low P treatment at the vegetative stage) or the availability of optimal levels of freely diffusible P in the substrate towards the pod-filling stage due to accumulation with time. The N concentration in leaves of all cowpea plants were lower at the pod-filling stage than at the vegetative stage, presumably as a result of N mobilization from vegetative organs to the developing pods. This was however not influenced by AM fungal inoculation and may be a consequence of the lack of an improved plant P acquisition by the fungus at the pod-filling stage.
Asunto(s)
Fabaceae/microbiología , Fabaceae/fisiología , Micorrizas/fisiología , Nitrógeno/metabolismo , Fósforo/metabolismo , Hojas de la Planta/metabolismoRESUMEN
Biosolids recovered from yard-scale vertical-flow constructed wetlands used for faecal sludge dewatering in Cameroon, were analyzed to assess their degree of maturity, nutrient and heavy metals contents, as well as their hygienic quality. Six beds were loaded weekly at nominal loading rate of 100, 200, and 300 kg TS/m2/year. The quality of the biosolids accumulated in the beds was monitored during 6 additional months of resting period prior to final harvest. Results showed that C/N ratio (11.3), humification index (14%), humification rate (1.8%), and degree of polymerization (3.7) of the biosolids generated were comparable to those of mature composts. Biosolids quality appeared to having high fertilizing value (N: 2%, P2O5: 2.3%, CaO: 1%, MgO: 0.14%, K2O: 0.03, and Na2O: 0.09%) with low heavy metals contamination (63, 14, 26, 2.4, 575, 703, 186, and 32 mg/kg for Pb, Ni, Cr, Cd, Cu, Zn, Mn, and Se, respectively). The concentration of fertile ascaris was reduced from 40 eggs/g TS after one month storage to <4 eggs/g TS after six month of storage, a level which does not significantly increase health risk exposure as compare to the WHO guidelines.