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Abstract
Composts are stabilized organic residues that are expected to decompose slowly in soil. When applied annually, they may increase the load of organic nitrogen that will eventually mineralize, and subsequently nitrates in excess of crop demand will be leached towards ground waters. A 4-year field experiment was conducted on a Xerosol in the Central Negev in Israel, in which composted municipal solid waste (CMSW) was added as mulch each year to conserve water for rain fed crops. Our objective in this study was to evaluate the amount of mineral N released from the CMSW and the buildup of soil organic matter (SOM), in order to minimize the hazard of nitrate contamination under this practice. CMSW was spread over the soil surface (100 and 300 m3 ha−1) each autumn prior to seeding, and in the following year the residual material was incorporated into the soil at seedbed preparation. We measured: (i) emission of CO2 from the soil surface during 2 months commencing after the first heavy rainstorm, (ii) SOM content below the CMSW mulch twice a year, and (iii) concentrations of available nitrogen and phosphorus 3–4 times during each cropping season. In the 100 m3 ha−1 CMSW treatment, SOM increased by 21% of the organic matter added by CMSW in 3 years, whereas the increase in CO2-C emission due to this CMSW treatment was only 12% of the C applied. Both measured parameters were not proportional to the amount of CMSW applied, thus indicating that the gap between measured mineralization and gain of SOM in the treatment of 300 m3 ha−1 CMSW was even larger than in 100 m3 ha−1. The concentrations of available N and P in soil were sufficient for wheat (Triticum aestivum L.) during its main growth period, and were also disproportional to the amount of CMSW added. Loss of nitrate from the root zone during the growth period of wheat was twice the amount of estimated N uptake, if we assumed that only the soluble N of the composts became available. However, the small gain in SOM implied that more N than the soluble N was mineralized and lost, although the distribution of nitrates with depth did not show considerable leaching. Annual mulching with 100 m3 ha−1 CMSW, which was adequate for water preservation, provided sufficient available N and P for rain fed wheat. Larger amounts than needed for sufficient mulching could potentially contaminate ground water with excess nitrate. Possibly smaller amounts of CMSW than 100 m3 ha−1 should be considered for safe, long-term annual application in light textured soils with a small capacity to retain SOM and in warmer temperatures during the rainy season.
Because of inadequate nutrient and water supply, soils are often unproductive in Northwest China. We studied the effects of manure application at low (LM 7.5 t ha–1), medium (MM 15 t ha–1), and high (HM 22.5 t ha–1) rates combined with fixed levels of chemical fertilizers on maize growth and rainfall use efficiency compared with chemical fertilizers (CK) under semi-arid conditions over a three-year period. HM and MM treatments could significantly increase soil water storage (0–120 cm) at tasseling stage of maize compared with LM treatment and CK (P < 0.05). Dry matter accumulation and rainfall use efficiency increased as manure application rate increasing (P < 0.05). HM treatment significantly increased rainfall use efficiency by 6.5–12.7% at big trumpeting – tasseling stage compared with LM and MM treatments. HM and MM treatments increased rainfall use efficiency by 8.6–18.1% at tasseling – grain filling stage compared with CK. There was no significant difference on biomass between HM and MM treatments at grain filling and maturity stages of maize in 2009 and 2010.
The Parnaiba River Delta is the largest open sea delta in the Americas, having a unique ecological importance for the conservation of wildlife and fisheries resources. However, little is known about the biogeochemistry of this ecosystem. This study estimates N and P emissions to the delta using emissions factors, calibrated with field samples and N and P concentrations in different compartments of the delta. The estimated loads totaled 14.517 t N year−1 and 8.748 t P year−1, indicating that anthropogenic N and P emissions outweigh natural emissions by approximately 5 and 10 times, respectively. The activities that contribute the most to this result are livestock farming, agriculture and the release of untreated domestic sewage. The flows of N and P from the estimated loads corresponded to 339 kg N km−2 year−1 and 204 kg P km−2 year−1, so the region can be classified as “meso-active” and “eury-active” with regard to the transfer of nutrients. These results are consistent with the coastal megabasin design (COSCATs) proposed by Meyback et al. (2006). This article presents a first approach to the calculation of an estimated annual emissions inventory of N and P for the lower basin of the Parnaíba River and its coastal region, representing an approach that has been satisfactorily used in assessing the sensitivity of estuarine systems in northeastern Brazil.
Municipal solid waste compost has been widely utilized in Israel in the production of field crops and reclamation of saline soils. This paper reviews laboratory and field studies defining the conditions under which an added compost improves the physical properties of soils and increases yields of crops. Specific attention is given to how applications of MSW compost to compacted, structurally deficient soils can lead to consistent improvement. Data are also provided on optimum C/N ratios of composts and optimum application rates under conditions studies in the research.
This study tested the hypothesis that the decomposition of applied residue C in soil is not determined by soil texture per se but by the degree of saturation of the protective capacity of a soil. Soil protective capacity is defined as the maximum amount of C associated with clay and silt (<20 μm) in grassland and uncultivated soils. To test this hypothesis, 14C-labeled ryegrass (grown in a phytotron and continuously labeled with 14CO2; specific activity 546 Bq mg-1 C) was mixed with 11 soil samples differing in texture and saturation deficit, the latter being the difference between the actual and the maximum amount of C associated with the <20-μm fraction. After 3 d of incubation, the percentage of applied 14C that had respired showed a significant correlation (r = -0.85) with the saturation deficit. After 53 d of incubation, the amount of 14C respired showed a significant correlation with the saturation deficit of the fine-textured soils (r = -0.88), but not with those of coarse-textured soils. The correlation between 14CO2 production and soil texture was weak. The results confirm the hypothesis that the degree of saturation of the protective capacity of a soil predicts the decomposition rate of residue C better than does soil texture alone.
An the livestock production in Japan is industrialized, a tremendous amount of animal wastes is being produced annually, resulting in serious environmental pollution problems. Animal wastes could be pollutants, but they are also important sources of fertilizer nutrients and organic matter. Composting is an effective way of promoting the increased utilization of animal wastes. The characterization of maturing process during composting is important in order to improve the composting technology and to develop and efficient method to estimate the degree of maturity. The rise and fall in temperature, and changes in the constituents of the compost, reflect the maturing process and may serve as indicators for maturation. In addition, the detection of nitrate by diphenylamine, the determination of cation-exchange capacity (CEC), and the germination test, are also recommended as the methods of estimating the degree of maturity. The heavy applications of animal manure and compost may cause an adverse effect on soils and crops. When excess manure is applied, the nitrogen will be accumulated in soil, resulting in accumulation of nitrate in crops and pollution of the groundwater. Guidelines for application rates are recommended, to maintain soil productivity and quality of crops, and to prevent the environmental pollution.
Composted municipal solid wastes (CMSW) could potentially be used as a mulching material to control runoff and soil erosion. The effects of mulching with CMSW on water percolation and rate of compost decomposition were studied using laboratory rainfall simulator. Samples of typical loess soil (Calcic Haploxeralf) were packed in boxes and either covered with 0, 100, 200 and 300 m3 ha−1 of CMSW, or mixed with 200 m3 ha−1 of CMSW. The soil boxes were subjected to six consecutive simulated rainstorms of distilled water, totaling 260 mm. Rate of CMSW mineralization and microbial activity were estimated from CO2 evolution and dehydrogenase (DHG) and fluorescein diacetate (FDA) activities, respectively, during the drying periods between rain storms. With the surface CMSW treatments, 85 percent of the rain water percolated into the soil, compared with 42 and 52 percent in the control and incorporated CMSW treatments, respectively. Rate of CMSW mineralization, estimated from CO2 evolution throughout the drying periods between six consecutive rainstorms, was 19, 13 and 11 percent of C added, in the 100, 200 and 300 m3 ha−1 of surface applied CMSW, respectively. The degradation of the compost had not ceased at the end of the experiment, as indicated by continuing enzyme activities and respiration simulated by the compost. Although 100 m3 ha−1 of CMSW was enough to control runoff efficiently in the laboratory, in the field, larger amounts may be needed to provide complete mulching of the soil surface.
Two different composts, a cattle manure compost (CMC) and a municipal waste compost (MWC), were applied at a rate of five percent or 15 percent to two soils, differing in their mineralization capacity, and incubated for 33 weeks at 30°C and optimal soil-water content. Periodically, CO2 evolution rates and inorganic N concentrations were measured in the soils. The rate of compost-N recovered as inorganic N was independent of the soil and compost application rate. The recovery after 33 weeks (w) was 22 percent of MWC-N and 23 to 27 percent of CMC-N, of which 13 percent was initially inorganic. The recovery of compost-C as CO2 depended on the compost application rate and to a lesser extent on the soil, reaching values of 13 to 15 percent and eight percent for the low and high application rates, respectively.
Manure pellets have the advantage of convenience in handling and application in the field, as well as combining basic fertilization and manure application when enriched with fertilizers. A reduction in NaHCO3-extractable P has been observed in soils amended with manure pellets compared with ground manure, particularly in superphosphate-enriched pellets. The objective of this study was to explain this reduction and to evaluate P fertilizers as manure-enriching materials. Fertilizer-enriched manures were incubated in soil for 7 and 60 d and their NaHCO3 extractability was compared with extractable P of fertilizers and unenriched manure. An index was suggested to evaluate the extractability of fertilizer P added to manures.
The availability of the P from manure and from KH 2 PO 4 was estimated by extraction with NaHCO 3 following incubation in soils for 15, 30, and 45 days. In two alkaline sandy soils the availability of the P from manures was equal to that from KH 2 PO 4 . The availability of manure P relative to P from KH 2 PO 4 increased as the pH increased and as the sand content increased, i.e., as the clay plus silt increased. The relative availability of the manure P increased in some soils as the time of incubation increased.
Influences of ammonium, nitrate, organic N sources and organic C amendments on microbial respiration, N transformations and gaseous losses were measured under natural environmental conditions in two field experiments. Microbial respiration was increased by addition of wheat straw and barley grain. Addition of N as ( ¹⁵ NH 4 ) 2 SO 4 and K ¹⁵ NO 3 alone did not increase CO 2 evolution significantly.
Significant immobilization of added inorganic‐ ¹⁵ N occurred with few exceptions in all treatments except nitrate alone. Organic‐ ¹⁵ N in soils amended with wheat straw increased with increasing N rates with both inorganic N sources. Inorganic‐ ¹⁵ N was practically void in both soils at the end of 12 months. Mineralization of ¹⁵ N‐labeled barley grain occurred but at a very low rate and no significant accumulations of inorganic‐ ¹⁵ N were observed.
Gaseous losses of N at the end of 12 months varied from 73 to 94% of the inorganic‐N added alone, with the greatest loss occurring from K ¹⁵ NO 3 . The incorporation of wheat straw stimulated immobilization of added N and reduced gaseous losses to 30 to 86% of the total N applied and the smallest loss occurred with ( ¹⁵ NH 4 ) 2 SO 4 . The average loss of mineralized organic‐ ¹⁵ N derived from barley grain for the two soils was 19% of the total N added. Most of the gaseous losses occurred within the first 3 months, the period of the measurable rainfall.
Analyses of subdivided soil sections (0–5 and 5–10 cm) showed that 95 to 100% of ¹⁵ N remaining in the soil was in the upper 5‐cm layer indicating that leaching was not appreciable in any treatment.
Rates of decomposition and inorganic N release from composted manures should be known and predictable on the basis of their composition for their proper use as a source of available N. Four composted cattle manures were analyzed for their inorganic N, soluble organic C and N, and total N and organic matter contents. The composts were incubated in soil for 32 wk at 30°C and 60% water-holding capacity. Inorganic N and CO2 evolution were determined periodically. Inorganic N released from the composts after 32 wk ranged from 11 to 29% of their total N content, 2 to 12% of total N were initially inorganic, and 1 to 5% were soluble organic N. The rates of decomposition of the composts were computed by the simulation model NCSOIL by minimizing the deviation of the model output from the periodically measured CO2 and inorganic N release and by using the soluble and insoluble organic C and N contents of the composts as input. The soluble components decomposed before the end of the first week. The decomposition rate constant obtained for the insoluble components of three composts was 4 to 5 x 10-4 d-1, whereas for one compost it was 1 x 10-3 d-1, indicating that this compost was much more stable. To obtain universal rate constants that will fit any compost, components of the insoluble material must be better defined.
Routine monitoring of landfill leachates has been extended to include characterization of suspended solids recovered by filtration. Calcite is consistently identified as a suspended solid, with less frequent reports of quartz and clays (kaolinite, illite, chlorite). Morphologically, calcite occurs as discrete grains, coatings on quartz sand and as microconcretions. Preliminary stable isotope data for seven samples generally show positive 13C values (relative to PDB) up to +3.5% and 18O values between -5 and -8%, consistent with an origin through precipitation from leachate. Geochemical modelling of leachate compositions for the same samples indicates that the leachates are saturated with respect to calcite, and that the degree of supersaturation decreases for older samples. Mass balance considerations show that the proportions of methane and carbon dioxide observed for landfill gas do not reflect the amount of bicarbonate that is potentially available from the anaerobic decomposition of putrescible waste. Overall, putrescible waste has the potential to form a maximum of 1.9 g of calcite for every gram of waste, although values less than this are likely to be achieved in practice. From these differing lines of evidence, there can be no doubt that calcite precipitation should be expected to take place within landfill systems as an essential part of the waste degradation and stabilization process, and should be considered in modelling both gas evolution and carbon emissions.
The stability and maturity of compost prepared from municipal solid waste (MSW) at a full-scale composting plant was assessed through chemical, physical, and biological assays. Respiration bioassays used to determine stability (Oâ and COâ respirometry) were sensitive to process control problems at the composting plant and indicated increasing stability with time. Radish (Raphanus sativus L.) and ryegrass (Lolium perenne L.) growth bioassays revealed that immature compost samples inhibited growth. Growth of ryegrass in potting mix prepared with cured compost not amended with fertilizer was enhanced as compared to a pest control. Garden cress (Lepidium sativum L.) seed germination, used as an indicator of phytotoxicity, revealed inhibition of germination at all compost maturity levels. The phytotoxicity was though to be salt-related. Spearman rank-order correlations demonstrated that Oâ respirometry, water-soluble organic C, and the water extract organic C to organic N ratio, significantly correlated with compost age and best indicated an acceptable level of stability. Oxygen respirometry also best predicted the potential for ryegrass growth, and an acceptable level of compost maturity. 31 refs., 4 figs., 5 tabs.
Fresh farmyard manure (C-to-N ratio = 20.3) was composted in the presence of 15N-labelled (NH4)2SO4 using a bench-scale reactor under temperature conditions which reproduce the evolution of compost in a pile. C and N mineralization of composted farmyard manure (C-to-N ratio = 12.5) was monitored in two silty soils during an aerobic incubation at 28°C and 100% of WHC for 76 weeks. C mineralization of compost was assumed to come from a labile and a recalcitrant fraction which decomposed according to 1 and 0 order kinetic reactions, respectively[Cm = Clabile.(1-e)+Kresistant.t]. The size of the labile fraction (Ciabiie) represented 31.3 and 19.9% of compost-C for the two soils, and its mineralization rate constant (kiabiie) ranged from 0.03 to 0.09 day. N-mineralization was assumed to come from only one labile fraction [Nm = Niabiie.(l-e)]. This fraction ranged from 34 to 25% of compost-N for the two soils; its mineralization rate constant did not vary with soils (0.006 day). Composted farmyard manure produced under these laboratory conditions may not have been completely mature when added to soil and totally representative of comparable material composted in a pile. Nevertheless, it was considered as fairly mineralizable and its mineralization was greatly influenced by soil type.
Understanding environmental and residue influences on decomposition and nutrient dynamics under diverse conditions is critical for efficient resource management. Our objective was to evaluate the influence of water on decomposition and N dynamics for surface and buried residues. Decomposition of alfalfa (Medicago sativa L.), grain sorghum (Sorghum bicolor [L.] Moench), and winter wheat (Triticum aestivum L. emend. Thell.) residues in fiberglass bags on the surface or buried at 120 mm in Pullman soil (fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX, was measured from May 1990 to May 1991. A line-source sprinkler provided five water regimes (336, 287, 166, 60, and 5 mm) while precipitation provided 305 mm water. Decomposition coefficients (k) were greater for alfalfa than for wheat or grain sorghum and were greater for buried than for surface residues. Rate coefficients increased linearly with water applied. The increase was greater for alfalfa than for sorghum and wheat. Net N mineralization occurred from alfalfa residues throughout the study. Net N immobilization was longer than 1 yr for surface wheat and sorghum and about 0.33 yr for buried residues. Both Nmax (grams N immobilized per kilogram of original biomass) and Neqv (grams N immobilized per kilogram of biomass loss) were influenced by crop and placement but not water regime. The Nmax value was similar for surface wheat and sorghum residues but was 50% lower for buried wheat than for sorghum. The Neqv indicated the N requirement of microoganisms was less for buried than for surface residues. Water and residue quality interactions affecting decomposition and N dynamics should be considered in residue management strategies for soil protection and nutrient cycling.
A study was conducted under laboratory conditions to determine the quantity of N mineralized from four composted manures incorporated into 2.7 kg of St-Jude sand or Tilly silty loam at rates of 0.05%, 0.10% and 0.20% of total N. With one exception (a hog slurry-sawdust based compost), net cumulative mineralization of N (Nm) during successive incubation periods increased with incubation time and with the rate of addition. After four months of incubation, Nm values varied from 0 to 14% of total added N. A significant third order interaction on Nm values was obtained with compost type, application rate and soil type. Net immobilization of N was apparent at all incorporation rates of hog slurry compost in the two soils. To evaluate C mineralization, composts were applied at the highest N rate and CO2 production measured periodically. One to 8.2% of total added C from manure composts was mineralized after 28 days of incubation. For each compost type, C mineralization was higher with the sandy than with the loamy mixtures. With composted sheep manure and immature cow manure compost, which contained the highest amounts of potentially mineralizable C, the highest application rate to sandy soil promoted loss of N.
Four irrigation treatments: no irrigation; early irrigation (150 mm); late irrigation (150 mm); and early+late irrigation (275 mm), with 363 mm of rain; and four basic applications of nitrogen (0, 60, 120, 180 kg ha−1), with and without an additional nitrogen top dressing of 60 kg ha−1, were applied to autumn-sown wheat.
For any given total nitrogen rate, there was no difference between the single and the split application.
Grain yields ranged from 3040 kg ha−1 for the unirrigated, zero-nitrogen treatment to 6340 kg ha−1 for the two irrigations, 180 kg ha −1 N treatment. There was a strong interaction of irrigation and nitrogen on grain yields which was due mainly to the late irrigation: in the absence of the late irrigation the optimal nitrogen rate was 120 kg hat, followed by a marked decline in yield with additional nitrogen, whereas the application of the late irrigation shifted the optimum nitrogen rate to 180 kg ha−1. In the absence of the late irrigation, increasing the nitrogen rate from 0 to 240 kg ha −1 reduced kernel weight from 42 to 32 mg, whereas late irrigation largely prevented this decrease (42 to 39 mg). The reduction in kernel weight was evident even at the first nitrogen increments, in the range where grain yield was still increasing. Lack of nitrogen reduced soil moisture extraction during the grain filling stage, particularly from soil layers deeper than 60 cm.
Stomatal aperture in the irrigated treatments was markedly larger in nitrogen-supplied than in nitrogen-deficient wheat, although the leaf hydration was similar; in the unirrigated treatment, the nitrogen-supplied plants had a lower hydration and smaller stomatal aperture than nitrogen-deficient plants.
Effective use of organic wastes for agricultural production requires that risks and benefits be documented. Two types of sewage sludge, household compost and solid pig manure were studied under field and greenhouse conditions to describe their fertilizer value and effects on soil properties and soil biota, the fate of selected organic contaminants, and their potential for plant uptake. A 3-year field trial on two soil types showed no adverse effects of waste amendment on crop growth, and a significant fertilizer value of one sludge type. Accumulation of N and Pi was indicated, as well as some stimulation of biological activity and micro-arthropod populations, but these effects differed between soil types. There was no detectable accumulation of polycyclic aromatic hydrocarbons (PAH), di(2-ethylhexyl)phthalate (DEHP), nonylphenol and ethoxylates (NP+NPE) or linear alkylbenzene sulfonates (LAS) after three repeated waste applications, and no plant uptake was suggested by analysis of the third crop. A plot experiment with banded sludge was conducted to examine sludge turnover and toxicity in detail. Less than 5% of NP or LAS applied in organic wastes was recovered after 6 months, and less than 6% of DEHP applied was recovered after 12 months. Potential ammonium oxidation (PAO) at 0–1 cm distance from the banded sludge was stimulated despite toxic concentrations in the sludge, which suggested that contaminants were degraded inside sludge particles. Phospholipid fatty acid (PLFA) profiles suggested a gradual shift in the composition of the microbial community within sludge, partly due to a depletion of degradable substrates. A pot experiment with sludge-amended soil and soil spiked with contaminants showed no plant uptake of NP, DEHP or LAS. Degradation of LAS and NP added in sludge was delayed and the degradation of DEHP was faster than when the contaminants were added directly to the soil. In conclusion, adverse effects of organic waste application on soil or crop were not found in this study, and for some waste products positive effects were observed.
Dry-land farming in arid and semiarid regions requires minimization of rainwater losses. Major causes for the loss of rainwater are: (i) runoff due to seal formation by raindrop impact, and (ii) evaporation from the wet soil surface. Mulching the soil surface is an effective way to prevent seal formation and water losses. We hypothesized that composted municipal solid waste (CMSW) could be used for mulching arable lands and minimizing rainwater losses without posing a hazard to the environment. Our objective was to study the effects of annual application of CMSW at the soil surface on rainwater retention in the soil, crop production and some hazards to the environment. The experiments were conducted during 1996–2000 in commercial rain fed wheat (Triticum aestivum L.) field of a xerosol (Calcic Haploxeralf) in the Central Negev, Israel. Amounts of 0, 100 and 300 m3 ha−1 CMSW were added annually to the soil surface prior to the rainy season. Water content in the soil was determined four times, soil salinity, and sodicity were determined twice and heavy metals in the soil and the yield of wheat were determined once every year. Yield was determined at the end of each growing season. Application of CMSW increased available water in the root zone mainly due to reduction in evaporation, and almost doubled the yields. No considerable increase in salinity, sodicity and heavy metals was noted in the root zone following CMSW application. Our observations suggested that annual application of CMSW at the rate of 100 m3 ha−1 was enough to significantly minimize rainwater losses and increase yield under dry-land conditions, without posing specific hazards to the environment.
The use of composted municipal refuse on agricultural land requires prior knowledge of the interactions among compost, soil, and plants. Research into the availability of N in highly matured municipal refuse compost is particularly important considering the current concern about groundwater contamination by NO
inf3sup--N. A greenhouse pot bioassay was conducted to determine the percentage of short-term apparent bioavailable N of a highly matured refuse compost and its relative efficiency in supplying inorganic N to the soil-plant system in comparison with NH4NO3. Municipal refuse (after 165 days of composting) was applied at rates equivalent to 10, 20, 30, 40, and 50 t ha-1 to a ferrallitic soil from Tenerife Island (Andeptic Paludult). NH4NO3 was applied at rates equivalent to the total N content of the compost treatments. Perennial ryegrass (Lolium perenne L.) was grown in 3-kg pots and the tops were harvested at regular intervals after seedling emergence. The compost increased dry matter yield, soil mineral N, and plant N uptake proportional to the applied rate. These increases were significantly higher than the control at an application rate of 20 t ha-1. After 6 months the apparent bioavailable N ranged from 16 to 21%. The relative efficiency was 43% after 30 days. This suggests that large inputs of inorganic N into soil can be obtained with high rates of this kind of compost, with a potential for NO
inf3sup--N contamination. However, applied at moderate rates in our bioassay (<50 t ha-1), compost showed a low N-supplying capacity to ryegrass, i.e. a small fraction of the mineralized compost N was used by plants in the course of time. This was ascribed to a partial biological immobilization. This pattern of N availability in highly matured municipal refuse compost, positive net mineralization but partial immobilization, is similar to the pattern of N availability in biologically active soils and is therefore extremely interesting for the conservation of N in agro-ecosystems.
Nitrogen management in organic farming
- A Hadas
Hadas, A., 1997. Nitrogen management in organic farming. In: Mortvedt, J.J. (Ed.), Proceedings of the Dahlia Greidinger International Symposium on Fertilization and the Environment, Technion, Israel Institute of Technology, Haifa, Israel, March 24–27, pp. 233–241.
Irrigation and nitrogen fertilization interaction on semi-dwarf wheat; Gilat 1972
- D Shimshi
- U Kafkafi
Shimshi, D., Kafkafi, U., 1973. Irrigation and nitrogen fertilization interaction on semi-dwarf wheat; Gilat 1972. Research report 022 to the Water Council of Israel, A.R.O., Bet Dagan, Israel. (Hebrew with English abstract).