Fernando Fornes

Composting versus vermicomposting: A comparative study of organic matter evolution through straight and combined processes

Changes in physical and chemical characteristics of an organic waste (tomato crop waste) throughout composting (COM), vermicomposting (VER) and the combination of both processes (C+V) were assessed at five selected stages. COM consisted of a combination of the static Rutgers system with forced aeration and pile turning. For VER Eisenia worms were fed with the raw material. For C+V pre-composted material was added to the worms. Particle size decreased during COM, yet it increased during VER and C+V due to the amalgamation of small particles. pH was alkaline throughout the processes. Heavy irrigation during vermicomposting resulted in greater decrease of EC and greater leaching of organic matter, total nitrogen and most macronutrients in VER and C+V than in COM. Final materials were not phytotoxic but compost could have salinity related problems. Thus, COM, VER and C+V produced treated organic material, which could be suitable for horticultural purposes.

Leaching composted lignocellulosic wastes to prepare container media: Feasibility and environmental concerns

The leaching of salt and mineral elements from three composts prepared with residual vegetable crop biomass (melon, pepper or zucchini) was studied using methacrylate columns and distilled water. The benefits of the leached composts to be used for ornamental potted plant production were also analysed. After leaching 5 container capacities of effluent, both the electrical conductivity and the concentration of soluble mineral elements in compost leachates decreased substantially and remained close to the target levels. Composts reacted differently to leaching due to differences in the raw waste sources and the composting process and hence, in their physical and chemical characteristics. At the end of the experiment, after pouring 8 container capacities of water, the leaching efficiency of the salts was 96%, 93% and 87% for melon, pepper and zucchini-based composts, respectively. Mineral elements differed in their ability to be removed from the composts; N (NH(4)(+) and NO(3)(-)), K(+), Na(+), Cl(-), and SO(4)(2-) were leached readily, whereas H(2)PO(4)(-), Ca(2+), and Mg(2+) were removed hardly. Leached composts showed a range of physico-chemical and chemical characteristics suitable for use as growing media constituents. Potted Calendula and Calceolaria plants grew in the substrates prepared with the leached composts better than in those made with the non-leached ones. Finally, special emphasis must be paid to the management of the effluents produced under commercial conditions to avoid environmental pollution.

Acidifying Composts from Vegetable Crop Wastes To Prepare Growing Media for Containerized Crops

The effects of adding five rates of powdered elemental sulfur (S0) or ferrous sulfate (FeSO4.7H2O) on the acidification process of three alkaline composts prepared with residual vegetable crop biomass (melon, C1; pepper, C2; and zucchini, C3) were investigated. Composts reacted differently to the application of the amendments, the acidification efficiency averaging 43%, 50% and 35% for C1, C2 and C3, respectively. S0 was more efficient than FeSO4.7H2O for lowering the pH, and a saturation-like effect within the range of amendment rates studied was found. The pH decrease reached in the composts varied between 0.24 and 3.03 units. The pH reduction brought about by the amendments was paralleled by an increase in compost salinity, especially with S0. pH declined slowly and gradually with S0, whereas FeSO4.7H2O caused a rapid drop in compost pH soon after its application, followed by a progressive increase and subsequent stabilization. The drop in compost pH following S0 amendment was related to the decrease in CaCO3 contents and to the rise in CaSO4 levels. In addition, a remarkable increase in autotrophic bacteria population and a slight increase in heterotrophic bacteria along with the acidification process were recorded. Amended composts showed a range of physico-chemical and chemical characteristics suitable for use as growing media ingredients for containerized crops.

Effects of the extractants on the characteristics of a humic fertilizer obtained from lignite

Abstract A humic fertilizer containing humic and fulvic acids was extracted from lignite. The effects of the extractants on the yield of extraction and on the characteristics of humic acids were investigated. The following extractants were used: 0·1, 0·25, 0·5 and 1·0 m KOH and 0·1 m NaOH. Acid pretreatments were performed with 0·1 m HCl prior to the extraction with either 0·1 m NaOH or 0·1 m KOH. Also, 0·1 m HNO3 was used prior to the extraction with 0·25 m KOH. Acid pretreatment of lignite increased the yield obtained after further extraction with 0·1 m KOH, but the largest yield was achieved when 0·5 m KOH was employed. Humic acids released by 0·25 m KOH following the 0·1 m HNO3 treatment exhibited higher H:C and O:C ratios, greater contents of functional groups and higher molecular size than humic acids obtained without the acid pretreatment. Iron content of the humic fertilizer was increased by acid pretreatments of lignite, the extent of such an effect depending on the type and concentration of the acid employed.

Composted organic wastes from the pharmaceutical and agro-food industries induce soil bioactivity and nodulation in alfalfa

BACKGROUND Environmentally friendly agriculture needs to reduce the use of synthetic fertilizers and to reclaim nutrients from organic wastes. In this study the effect of five doses (0, 12, 24, 48 and 96 t ha(-1) ) of two two-phase olive mill waste (TPOMW)-based composts on the bioactivity and chemical characteristics of an agricultural soil and their potential to fertilize alfalfa (Medicago sativa) and stimulate nodulation were assessed during a two-year incubation experiment. The two composts were prepared either with the olive mill waste alone (compost A), which served as control, or mixed with a liquid fatty-proteinaceous hydrolyzate waste (FPH) from the pharmaceutical industry (compost AH). RESULTS Compost AH resulted in greater N immobilization than compost A because the former supplied the soil with easily degradable C and N, which increased microbial biomass and activity. Both compost mineralizations during the first year of incubation supplied the soil with more nutrients (mainly N), more so with A than with AH. Nevertheless, plant growth was similar in soils amended with either A or AH. Both composts induced nodulation similarly and the highest dose (96 t ha(-1) ) increased the formation of nodules by a factor of 11 compared with the four lower doses. CONCLUSION TPOMW serves as an effective ground material for co-composting with liquid wastes such as FPH. TPOMW supplies key nutrients and stimulates nodulation in alfalfa.

Assessment of biochar and hydrochar as minor to major constituents of growing media for containerized tomato production

BACKGROUND Chars are emerging materials as constituents of growth media. However, chars of different origin differ in their characteristics and more studies are needed to ratify them for such a role. The characteristics of coir mixed with 0%, 10%, 25%, 50%, 75%, and 100% (v/v) of two biochars, from forest waste (BCH-FW) and from olive mill waste (BCH-OMW), and one hydrochar, from forest waste (HYD-FW), and their effects on growth, yield and fruit quality of two tomato cultivars (Gransol RZ and Cuarenteno) were assessed. RESULTS Chars negatively affected plant growth and yield but not fruit quality. The effect was related to the char dose and was larger in HYD-FW and BCH-FW than in BCH-OMW, despite the high salinity of the latter, and more acute in Cuarenteno than in Gransol RZ. The results were discussed on the basis of the large particle size of BCH-FW, which could have caused low nutrient solution retention and, hence, reduced plant nutrient uptake, and the high water-holding capacity, poor aeration and large CO2 emission of HYD-FW, which could lead to root anoxia. CONCLUSION BCH-OMW can be used at high proportion in media for tomato cultivation. The use of BCH-FW at a high proportion might be taken into consideration after adjusting particle size, yet this needs additional assays. HYD-FW is inadequate for soilless containerized tomato cultivation.

Identification of actinomycetes with antifungal activity isolated from soil amended with composts

The search for new antifungal biocontrol strategies to inhibit the growth of phytopathogenic fungi has been focused on the genus Streptomyces and related species. Actinomycetes were isolated on starch casein agar (SCA), arginine glycerol salts agar (AGSA), and glycerol asparagine agar (GAA), and co-cultured with phytopathogenic fungi in potato dextrose agar (PDA) and yeast extract malt extract agar (YMA). In this work, we have isolated 52 actinomycete strains, 13 of them showing high inhibitory activity against the phytopathogenic fungi tested. Isolated strains were identified by chemotaxonomic procedures, 16S rDNA sequences analysis, and morphological methods. These strains belongs to the species Streptomyces variegatus, S. griseoruber, S. lusitanus, S. roseogriseus, S. coeruleorubidus, S, griseoruber, S. lincolensis, S. aureoverticilatus, S. speibonae, and Lechevalieria xinjiangensis.