 |
|
||
 |
|||
 |
Editorial |  |
|
THE EFFECT OF N SOURCE ON THE COMPOSTING OF GREEN WASTE AND ITS PROPERTIES AS A COMPONENT OF A PEAT GROWING MEDIUM M. J. Maher1 and M. Prasad2 1.Kinsealy Research Centre, Dublin, Ireland 2. Bord na Mona Research Centre, Newbridge, Co. Kildare, Ireland 1. ABSTRACT There is interest in using green waste as a component of peat based growing media as it is a renewable resource. The present study investigated the effects on the composting of green waste of two N sources calcium ammonium nitrate (CAN) and poultry manure. The inclusion of peat along with CAN was also studied. Green waste without any addition was the control treatment. The four treatments were composted over a 20 week period. Samples of each treatment were taken at 4 week intervals and stored under refrigeration. During composting there was an increase in pH, N content, CEC and FTIR peak ratio 1485/1056. The C/N ratio and organic matter content declined over time as did available N levels in the treatments where N was added. At the end of the composting period, samples of the four treatments from the five sampling dates were given a N dressing according to analysis and mixed with fertilised peat at rates of 0, 12.5, 25 and 50% by volume. The effects of these treatments on the growth of tomato seedlings was studied. At the 50% rate, plant performance was reduced in green waste composted without additional N and where the composting period was less than 16 weeks. At the lower rates of incorporation these effects were much less. Plant growth was positively related to N content and CEC of the green waste and negatively to the C/N ratio. |
|
|
TRANSFORMATIONS IN SOIL OF THE ORGANIC FRACTIONS FROM 15N LABELLED COMPOST AS REVEALED BY 13C AND 15N NMR SPECTROSCOPIES AND ANALYTICAL PYROLYSIS Francisco J. Gonzalez-Vila1, Pilar Tinoco2, M. Cristina Zancada2, Gonzalo Almendros2 1 Instituto de Recursos Naturales y AgrobiologÌa, CSIC, Sevilla, Spain 2 Centro de Ciencias Medioambientales, CSIC, Madrid, Spain 1. ABSTRACT A molecular assessment of different C and N forms from a compost-treated soil has been performed by NMR spectroscopy and pyrolysis-gas chromatography-mass spectrometry. A 15N-enriched mixture of urban compost (30%), wheat straw (64%) and K15NO3 (6%) incubated for 80 days was used to isolate different fractions: water-soluble (WS), humic acid-like (HA), fulvic acid-like (FA), and alkali-insoluble fractions. This compost (21.8% N as 15N) was added to a mineral soil and incubated for 80 days. These fractions and two particulate ones were isolated from the compost-treated soil.The stable isotope ratios (15N/14N) of each fraction were compared to monitor the N speciation patterns in soil. Most of the newly-formed N-compounds concentrate in WS (96% 15N) and in the insoluble residue (>25% 15N) but about 28% consists of amide N in the HA. According to spectroscopic and pyrolytic data the HA resembles to a lignoprotein, whereas the FA consists of a C=O-containing carbohydrate material. Alkyl compounds suggesting the presence of lipid macromolecules are released mainly by particulate fractions. The WS (1.7% of total N) showed heterogeneous composition yielding methoxyphenols, furans, fatty acids and N-compounds (mainly pyrroles). Our results suggest that non-selective biodegradation of the different C and N forms dominates over the formation of humic substances. |
|
|
SEWAGE SLUDGE EFFECTS ON PRODUCTION OF WILD LEGUME SHRUBS F.J. Gil11, E.F. de AndrÈs1, J.L. Tenorio1,2, F. MartÌnez2, and I. Walter2 1. I.N.I.A., Centro de Recursos FitogenÈticos, Alcal· de Henares, Spain. 2. I.N.I.A., Dpto. Uso Sostenible del Medio Natural, Madrid, Spain. 1. ABSTRACT The aim of the present study was to determine sewage sludge effects on growth and production in four species of wild legume shrubs: Colutea arborescens, Dorycnium hirsutum, Dorycnium pentaphyllum, and Medicago strasseri in a greenhouse experiment. The soils treated with sewage sludge had a relatively large amount of organic matter and phosphorus and a high quantity of heavy metals, but these were under the limits for agricultural uses, except for cadmium. In general, the growth of the wild legume shrubs was better on treated soils with sewage sludge than soils not treated or treated with mineral fertiliser. The application of sewage sludge has a great potential for the reclamation of degraded soils in combination with wild legume shrubs, since it improves the growth of plants and thus could contribute to controlling the desertification process. Heavy metals such Cd, Pb, Ni and Cr did not affect shrub growth. The micro nutrients Zn and Cu (very low in calcareous soils) could have been the reason for plant growth enhancement since the macro nutrients seemed to have slight effects. |
|
|
AGRICULTURAL USE OF THREE ORGANIC RESIDUES: EFFECT ON ORANGE CROP AND ON CHEMICAL PROPERTIES OF A SOIL OF THE COMARCA COSTA DE HUELVA (SW SPAIN) Burgos P., MadejÛn E., Murillo J. M., Cabrera F Instituto de Recursos Naturales y AgrobiologÌa Sevilla (IRNAS) (CSIC). Sevilla, Spain. 1. ABSTRACT Three organic residues (AC, olive mill waste water sludge compost; MWC, municipal solid waste compost and PS, paper sludge) were used in a 3-year field experiment involving orange production under two different irrigation regimes. The effect of their application on crop production and soil quality was investigated. Soil samples (0-30 cm depth) collected 11 month after the last soil amendment were analysed for: pH and EC, Kjeldahl-N, available-P, available-K, total organic carbon, total extractable carbon, humic acid carbon and available heavy metals. The orange yield was also evaluated at the end of each experimental period. Generally, the application of the MWC and PS increased orange yield when compared to the control. Moreover total organic carbon (TOC), total extractable carbon (TEC) and humic acids carbon significantly increased in soils treated with the organic amendments. Organic fertilisation increased the Kjeldahl-N and available P contents of the soil. The favourable effect on soil fertility was more noticeable in MWC and PS treatments under the reduced irrigation regime. Available heavy metal contents slightly increased in the top soil treated with MWC and PS, however, heavy metal mobilization toward deeper layer was not detected. The results indicate that the repeated application to the soil of moderate amounts of organic amendments, has positive effects on the chemical properties of soil, as well as in the orange yield. |
|
|
USE OF BIOSOLIDS FOR REFORESTATION IN THE REGION OF VALENCIA (E SPAIN). FIRST RESULTS OF A PILOT PROJECT. Valdecantos A., Cortina J., Fuentes D., Casanova G., DÌaz J. M., Llavador F., Vallejo V. R. 1. CEAM., Paterna, Spain. 2. Departament d'Ecologia, Universitat d'Alacant, Spain. 3. TRAGSA, Paterna. (Valencia), Spain. 4. Entitat P™blica de Sanejament d'Aig¸es Residuals de la Comunitat Valenciana, Valencia, Spain. 1. ABSTRACT Because of the more restrictive legislation dealing with waste water management, the production of biosolids (sewage sludge) in EU countries is expected to increase from 7.2 million tons (dry weight) in 1992 to more than 11 million tons in 2005. In the Region of Valencia (E Spain) the production of non-industrial biosolids was 90.420 tons dry weight in 1993, and increased to more than 300.000 tons in 1999. Most of the biosolids produced in this region are disposed in landfills or used in agriculture. Unlike other regions in Europe, USA, and Australia, in the Region of Valencia the application of biosolids in forests and woodlands has been restricted to research experiments. However, biosolids could help to restore the fertility of soils degraded by long-term uses, and could contribute to the fight against desertification, one of the major environmental threats in this area. Failure to incorporate biosolids as a routine amendment for the restoration of degraded lands is related to complex socio-economical factors. Among them, the perception that it could increase the cost of the already budget-constrained reforestation. However, to our knowledge no study has been performed as yet to discuss the technical and economical limitations of this practice. In this study we have assessed the costs and technical limitations to the use of biosolids in reforestation of degraded Mediterranean ecosystems. We selected a degraded area in the inland of Valencia for a pilot-project scale reforestation covering 2 ha. We applied domestic biosolids by using a back-hoe excavator, and planted one-year-old seedlings of Pinus halepensis and Quercus ilex ssp ballota. We assessed the economic and technical performance of different application types, and monitored survival and growth of introduced seedlings. Application costs (excluding transport) ranged from 23.62 to 41.17 Euro Mg-1 fresh weight, and could easily be reduced to one third of this amount with simple technical improvements. We discuss these, and recommend the best suitable techniques for the use of biosolids in restoration of degraded Mediterranean ecosystems |
|