CC BY
13
УДК 631.452;631.41;631.8
ВЛИЯНИЕ ОТХОДОВ ГОРЕНИЯ И КОМПОСТА ИЗ ОСАДКОВ СТОЧНЫХ ВОД НА СОДЕРЖАНИЕ МАКРОКОМПОНЕНТОВ В ПОЧВЕ
Е. Кшивы-Гавронска
Западно-Померанский технологический университет в Щецине, e-mail: [email protected]
Однофакторный эксперимент проведен в 2008-2010 гг. на Станции Оценивания Перемен в Щецине-Домбье. Почва, на которой был проведен опыт, была образована из легкого песчанистого суглинка. С точки зрения гранулометрического состава ее относят к категории легких почв, комплекса сельскохозяйственной пригодности IVb, хорошей ржаной. В опыте применен отход горения в виде пепла от бурого угля, а также компост, произведенный с участием бытовых осадков сточных вод методом GWDA. Схема исследований включала в себя шесть объектов-удобрений. Тестируемым растением была многолетняя трава мискантус сахарный (Miscanthus sachariflorus). Наивысшее среднее повышение содержания азота установлено в почве на объектах, удобряемых компостом дозой 250 кг/га с добавлением пепла от бурого угля, введенного в первый год исследований и следующих годах соответственно на 23,3 и 27,7% по сравнению с объектами с введенным карбонатом кальция или пеплом бурого угля, используемыми в начале опыта. Положительный эффект на показатели плодородия почвы был получен после использования компоста из бытовых осадков сточных вод с ежегодным введением в почву пепла от бурого угля с высоким содержанием кальция. В почвах вариантов, удобренных компостом без и с добавлением пепла бурого угля, увеличилось содержание pHKCl и содержание органического угля, общего N, P, K и S, а также форм усвоения P, K и Mg.
Ключевые слова: пепел, осадки сточный вод, компост, почва, общее содержание макроэлементов, содержание форм усвоения.
EFFECT OF THE COMBUSTION WASTES AND MUNICIPAL SEWAGE SLUDGE COMPOST ON THE CONTENT OF MACROELEMENTS IN SOIL E. Krzywy-Gawronska
A single-factor field experiment was carried out The Cultivar Evaluation Station in Szczecin-Dqbie in 2008-2010. The soil on which this experiment was set up is formed from light loamy sand (lls). Regarding its granulometric composition, the soil is classified to the category of light soils, of soil quality class IV b and good rye complex. In the experiment, a combustion waste in the form of high-calcium brown coal ash was used, as well as a compost produced from municipal sewage sludge by the GWDA method. The study design included six fertilisation objects. A test plant was perennial Amur silver grass (Miscanthus sachariflorus). The highest average increase in the nitrogen content in soil in 2008-2010 was observed in the objects fertilised with municipal sewage sludge compost at a dose corresponding to 250 kg N-ha'1 with addition of high-calcium brown coal ash being introduced into soil in the first year of study and in next years, respectively by 23.3% and 27.7%, when compared to those with calcium carbonate or high-calcium brown coal ash being applied at the beginning of experiment. The positive effect in soil richness indices was obtained after the application of municipal sewage sludge compost with annual introduction of high-calcium brown coal ash into soil. In the soil of objects being fertilised with municipal sewage sludge compost without and with addition of high-calcium brown coal ash, the pHKCl value and the content of organic carbon and total N, P, K and S increased, as well as that of assimilable P, K and Mg forms.
Keywords: waste, sewage sludge, compost, soil, total content of macroelements and assimilable forms.
Many authors paid attention to the possibility of ecological and agricultural use of high-calcium brown coal ash for soil de-acidification and fertilization by Gilewska (2006), Siuta (2001), Rethman et al. (2001), Kruger (2003), Yoshia-ki i Kazuo (2003). Power industry ash contain no organic matter or nitrogen. The source of organic matter and some nutrients for cultivated plants may be municipal sewage sludge and composts produced from it by He et al. (2009), Ngole (2007), Walter et al. (2006), Chiba et al. (2009), Singh and Agrawal (2008). The composting process is a relatively cheap, environmentally safe and agriculturally attractive technology by Cai et al. (2007), Haroun et al. (2007), Hua et al. (2009), Zorpas and Loizidou (2008), Wong and Selvan (2006). It is of great importance since a strong complexing of heavy metals with stabilized organic matter occurs. The net result is that heavy metals from composts, getting into the soil, occur in chemically stable combinations and thus become less assimilable by plants Nair et al. (2008), Rosik-Dulewska (2008). Organic substances oc-
curring in the compost undergo decomposition to environmentally less toxic or non-toxic pollutants by Marttinen et al. (2004). Therefore, they may be used as organic fertilizer for soil fertilization since they positively affect its properties by Tom et al. (2009), Hargreaves et al. (2008), Izewska (2007). However, they must meet the standards specified in the Regulation of the Minster of the Environment to have no negative impact on the environment.
Introduction of the soil-applied composts produced from municipal sewage sludge has many positive features, being expressed, among others, in the increase of soil microbiological activity or the improvement of its physicochemical properties by Weber et al. (2007) and Krzywy et al. (2005).
The purpose of the study being taken up was to determine some changes in the physical and chemical properties that had occurred in soil after application of high-calcium brown coal ash and municipal sewage sludge compost after a three-year cultivation of Amur silver grass.
Material and research methods. The chemical charac-
teristics of high-calcium brown coal ash coming from the P^tnow-Adamow-Konin Power Plant Complex and used for soil fertilization, as well as that of municipal sewage sludge compost produced by the GWDA method and soil before setting up this experiment, was published in the paper by Krzywy-Gawronska (2012, 2012a).
When achieving the research purpose, a single-factor field experiment being set at the Cultivar Evaluation Station in Szczecin-D^bie was carried out in 2008-2010. The study design included 6 fertilization objects. The content of macroelements in soil was determined in average samples from four replications of each fertilization object after Amur silver grass harvest in each year (2008, 2009 and 2010). N, organic carbon and S contents were determined on a Coestech CNS elemental analyzer, while that of assimilable P and K forms by the Egner-Riehm method, assimilable Mg content according to the Polish standard PN-R-04024, total P content according to the Polish standard PN-98/C-04537-14, total K content by the method of flame photometry. The stock solution was obtained after previous wet mineralization of soil material according to the Polish standards PN-ISO 11466 and PN-ISO 11047. Total contents of assimilable forms of macroelements was processed statistically by the analysis of variance method using Statistica 8.0 PL computer software package. In case of significant differences, the Tukey's test was used at significance level p = 0.05.
Results and discussion. Calcium carbonate, high-calcium brown coal ash being applied at the beginning of study and each year, and municipal sewage sludge compost without and with addition of high-calcium brown coal ash did not signifi-
cantly vary the total content of N, Mg and S in soil (Tab. 1 and 2). Because of the long descriptions of objects fertilizers letter abbreviations adopted for municipal Sewage Sludge Compost (SSC) from and for the Brown Coal Ash (BCA) which were used in the discussion of research results.
Total Mg and S contents in soil slightly fluctuated during the three years of study when compared to their initial contents (Tab. 1). Statistical analysis of the total P and Ca contents being determined after three years of study showed a dependence of the amount of these chemical elements on fertilization system. Significant increase in P, K and Mg contents was obtained in the objects being fertilized with municipal sewage sludge compost without and with addition of high-calcium BCA when compared to those where calcium carbonate or high-calcium BCA had been introduced into soil. Increase in the content of P, K, Ca and Mg was observed in the second year of study when compared to the first and the third year of study (2008 and 2010).
The highest average increase in the P content in 2008-2010 was obtained in the fertilization objects being fertilized with municipal SSC at a dose corresponding to 250 kg N-ha-1 without and with addition of high-calcium brown coal ash by 24.4% and 17.8% respectively, when compared to that where high-calcium BCA had been applied each year. In other fertilization objects, differences in the phosphorus content after Amur silver grass harvest were not significant (Tab. 1).
The most K was found in soil in the second year of test plant cultivation (2009), while a slight decrease in the content of that chemical element was observed in the third year of study, i.e. in 2010 (Tab. 1). Increase in the potassium content
1. The P, K, Ca, Mg and S contents in g^kg-1 d.m. in soil after cultivation of Amur silver grass. Data for 2008-2010
Parameters Initial values Study Fertilization objects Mean LSD0,05
years I* II III IV V VI
Total content in g-kg" d.m.
2008 0.46 0.50 0.57 0.54 0.48 0.48 0.50 n.s.
P 0.45 2009 0.48 0.47 0.60 0.59 0.55 0.51 0.52 0.09
2010 0.44 0.43 0.50 0.51 0.44 0.50 0.47 n.s.
mean 0.46 0.47 0.56 0.53 0.45 0.49 0.50 0.07
2008 0.64 0.66 0.69 0.65 0.68 0.66 0.66 n.s.
K 0.62 2009 0.66 0.68 0.71 0.73 0.70 0.74 0.70 0.32
2010 0.62 0.64 0.68 0.70 0.66 0.72 0.67 0.49
mean 0.64 0.66 0.69 0.69 0.68 0.71 0.68 n.s.
2008 0.82 0.88 0.60 0.89 0.85 0.84 0.68 0.20
Ca 0.78 2009 0.84 0.91 0.90 0.93 0.90 0.94 0.86 0.15
2010 0.80 0.80 0.82 0.85 0.84 0.86 0.89 0.25
mean 0.82 0.86 0.86 0.89 0.86 0.86 0.82 0.09
2008 0.65 0.68 0.66 0.65 0.67 0.68 0.66 n.s.
Mg 0.62 2009 0.68 0.70 0.72 0.73 0.74 0.75 0.72 n.s.
2010 0.66 0.67 0.69 0.70 0.68 0.72 0.69 n.s.
mean 0.66 0.68 0.69 0.71 0.69 0.72 0.69 n.s.
2008 0.09 0.10 0.12 0.10 0.12 0.13 0.11 n.s.
S 0.08 2009 0.08 0.08 0.09 0.08 0.09 0.08 0.08 n.s.
2010 0.08 0.09 0.11 0.11 0.10 0.11 0.10 n.s.
mean 0.08 0.09 0.11 0.09 0.10 0.11 0.10 n.s.
*Description of fertilization objects: I - Carbonate lime (CaCO3) at a dose corresponding to 1.5 Mg CaO-ha"1 , II - High-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1, III - Municipal SSC at a dose corresponding to 250 kg N-ha-1, IV - Municipal SSC at a dose corresponding to 250 kg N-ha-1+ high-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1 in the first year of experiment V- High-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1 in the first year of experiment, with 0.75 Mg CaO-ha-1 in next years each, VI- Municipal SSC at a dose corresponding to 250 kg N-ha-1+ high-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1 in the first year of experiment, with 0.75 Mg CaO-ha-1 in next years each.
by 9.23% was recorded in soil between the object with application of municipal SSC at a dose corresponding to 250 kg N-ha-1 with addition of high-calcium BCA and those with calcium carbonate or high-calcium BCA.
The average content of Ca in soil after Amur silver grass harvest was highest in 2010 and amounted to 0.89 g-kg-1 d.m. The highest average increase in the calcium content in soil after Amur silver grass harvest, by 8.53%, was obtained in the object being fertilized with municipal sewage sludge compost at a dose corresponding to 250 kg N-ha-1 with addition of high-calcium BCA applied in the first year of study when compared to that with calcium carbonate. The calcium content in soil in the objects with municipal sewage sludge compost and addition of high-calcium BCA being applied at the beginning of study and each year as well as with high-calcium BCA being introduced into soil each year was significantly higher when compared to the object being fertilized with calcium carbonate. The Mg and S contents in soil after Amur silver grass harvest during the three years of study differed slightly. Calcium carbonate and high-calcium BCA being applied at a dose corresponding to 1.5 Mg CaO-ha-1, as well as exclusive organic fertilization at a dose corresponding to 250 kg N-ha-1, did not have any significant effect on the increase in the Mg content in soil. Municipal SSC being introduced into soil with addition of high-calcium BCA applied in the first year of study and each year induced a small average increase in the Mg content, by 9.10%, when compared to the object being fertilized exclusively with calcium carbonate. The highest average Mg content in soil was obtained in all fertilization objects in the second year of study (0.72 g-kg-1 d.m.). The average increase in the content of that chemical element after Amur silver grass harvest in the second year of study was higher by 9.10% when compared to the first year and by 16.1% when compared to its initial value (Tab. 1).
The highest average S content in soil was observed in the objects with exclusive organic fertilization and municipal SSC with addition of high-calcium BCA being applied in the first year of study and in next years. Its average content in soil in other fertilization objects ranged from 0.08 to 0.10 g-kg-1 d.m. The least S content in soil after Amur silver grass harvest was obtained in the second year of study (0.08 g-kg-1
d.m.) - see Tab. 1. The applied high-calcium BCA being used each year induced an increase in the total S content as against to its initial content.
The field experiment being carried out demonstrates that soil fertilization with municipal SSC with addition of high-calcium BCA affected the increase in the soil pHKCl from 5.3 to 6.3, which finds confirmation in the studies by Kovacik et al. (2011) and Nowak and Gotkiewicz (2001). After three years of experiment, the soil reaction increased by 1.0 unit. The objects fertilized exclusively with calcium carbonate or high-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1 being applied at the beginning of study increased the soil pHKCl to 5.6 after three years of study (Tab. 2). High-calcium BCA being introduced into soil in a dose corresponding to 1.5 Mg CaO-ha-1 in the first year of experiment and to 0.75 Mg CaO-ha-1 in next years increased the value of soil pHKCl to 6.2. Exclusive organic fertilization increased the value of pHKCl by 0.55 unit when compared to the its initial value (Tab. 2). In the objects with high-calcium BCA being introduced into soil at a dose corresponding to 1.5 Mg CaO-ha-1 in the first year and to 0.75 Mg CaO-ha-1 each year and municipal SSC with addition of high-calcium BCA being applied each year, the value of soil pHKCl was significantly higher when compared to those where calcium carbonate or high-calcium BCA had been introduced into soil. No significant differences were found between the objects being fertilized exclusively with calcium carbonate, high-calcium BCA or municipal SSC. Changes in the soil reaction were induced by considerable calcium and magnesium contents in the ash being applied Gibczynska et al. (2007). The study by Gilewska et al. (2006) showed that introduction of the high-calcium BCA coming from the P^tnow-Adamow-Konin Power Plant Complex into soil induced its de-acidification to the same extent as calcium fertilizers. The soil being fertilized with calcium carbonate or high-calcium BCA was classified to acid soils (pH 5.55), while that being fertilized with municipal SSC with addition of high-calcium BCA to slightly acid soils (pH from 6.20 to 6.30). Similar research results were obtained by Zukowska et al. (1999) who observed an increase in the soil reaction from acid to slightly acid (Tab. 2).
2. The pHKCl value, organic carbon and nitrogen contents in g^kg-1 d.m. and C:N ratio in soil after
cultivation of Amur silver grass. Data for 2008-2010
Parameters Initial values Study Fertilization objects Mean LSD0,05
years I* II III IV V VI
pHKCl 2008 5.50 5.55 5.65 5.90 6.05 6.10 0.15
5.30 2009 5.55 5.58 5.92 6.00 6.20 6.18 x 0.35
2010 5.60 5.60 5.80 6.10 6.20 6.30 0.54
Total content in g-kg-1 d.m.
2008 0.70 0.68 0.76 0.84 0.74 0.85 0.76 n.s.
Nitrogen 0.72 2009 0.68 0.66 0.73 0.81 0.70 0.83 0.73 n.s.
2010 0.65 0.65 0.72 0.80 0.64 0.81 0.72 n.s.
mean 0.67 0.66 0.74 0.82 0.70 0.83 0.74 n.s.
2008 8.54 8.55 8.60 8.62 8.48 8.81 8.60 n.s.
C org. 8.52 2009 8.60 8.47 8.75 8.72 8.45 8.78 8.62 n.s.
2010 8.38 8.40 8.80 8.78 8.39 8.75 8.58 0.11
mean 8.51 8.47 8.72 8.70 8.40 8.78 8.60 0.03
2008 12.2 12.6 11.3 10.3 11.5 10.4 11.4 0.04
C:N 11.8 2009 12.6 12.8 12.0 10.8 12.1 10.6 11.8 0.06
2010 12.8 12.9 12.2 11.0 12.3 10.8 12.0 0.28
mean 12.5 12.8 11.8 10.7 11.9 10.6 11.7 0.22
* Description of fertilization objects is given in Table 1.
The content of organic carbon in soil in the object with high-calcium BCA being introduced into soil at a dose corresponding to 1.5 Mg CaO-ha-1 after three years of study was higher by 0.03 unit when compared to the result from before the experiment set-up. Calcium carbonate and high-calcium BCA being applied in the first year of study and each year in respective experimental objects did not significantly vary the content of organic carbon. The application of organic fertilization without and with addition of high-calcium BCA affected the increase in the content of chemical element being discussed to the greatest extent in the second and the third year of study (i.e. in 2009 and 2010) when compared to the first year (2008). The highest increase in the organic carbon content in 2008 was observed between fertilization objects I and VI by 0.27 unit, in 2009 between fertilization objects V and VI by 0.33 unit, and in 2010 between fertilization objects I and III by 0.33 unit. After three years of experiment, a decrease occurred in the organic carbon content in the objects with calcium carbonate and high-calcium BCA being applied, on average by 1.55%, as against its initial value (Tab. 2). In the objects with municipal SSC introduced into soil at a dose corresponding to 250 kg N-ha-1 without and with addition of high-calcium BCA, an increase was obtained in the organic carbon content after three years of study, by 3.28% and 3.05% respectively, when compared to its initial value (Tab. 2). The results obtained in the third year of study indicate a gradual decrease in the content of organic carbon in soil after Amur silver grass biomass harvest when compared to the first year of study (Tab. 2).
The highest average increase in the N content in soil in 2008-2010 was obtained in the objects fertilized IV and VI respectively by 23.3% and 27.7%, when compared to those with calcium carbonate or high-calcium BCA being introduced into soil in the first year of study (2008), applied at the beginning of experiment. Differences in the N content in soil in other fertilization objects were not significant (Tab. 2). When analyzing the effect of applied fertilization on the changes in the N content in soil during a three-year experiment, a gradual decrease in its content was observed. The N content decreased by 5.30% between 2010 and 2008. Most probably, the reason for a decrease in the N content is fast mineralization of its organic compounds and its uptake by Amur silver grass biomass.
The soil before the experiment set-up was characterized
by the carbon-to-nitrogen ration amounting to 11.8. After three years of study, the carbon-to-nitrogen ratio enlarged by 1 unit in the objects with calcium carbonate or high-calcium BCA (12.8 and 12.9, respectively), while in those being fertilized exclusively with municipal SSC or high-calcium BCA by 0.45 unit. On the other hand, in the objects fertilized with municipal SSC with addition of high-calcium BCA being applied in the first year of study and each year, this ratio narrowed and amounted respectively to 11.0 and 10.8 (Tab. 2).
Assimilable P, K and Mg contents in the soil being fertilized with municipal SSC without and with addition of high-calcium BCA changed after three years of study (Tab. 3). An increase occurred in the content of assimilable P, K and Mg forms (on average by 4.83%, 9.16% and 7.23%, respectively).
The content of assimilable phosphorus form in soil in the objects III, IV, VI and I, II, V at the beginning of study and each year. Differences in the content of assimilable phosphorus form between respective objects in the above-mentioned groups were not significant (Tab. 3). Sewage sludge and composts produced from it are abundant with P and therefore the content of that chemical element in the humus layer of soil increases after their application. This increase is being maintained in the first year, and even in the following years, after the application of that type of organic fertilization. Similar results were obtained by Zukowska et al. (1999).
The fertilization with municipal SSC at a dose corresponding to 250 kg N-ha-1 with high-calcium BCA being additionally introduced into soil each year induced the highest increase in the assimilable K content in soil by 15.8% when compared to its initial content (Tab. 3). On the other hand, its content in soil decreased in next study years. The drop being recorded in the assimilable K content in soil is connected with a small amount of that chemical element in sewage sludge and composts produced from it as well as in combustion wastes (Baran et. al 2006). The content of assimilable K in soil was significantly smaller in 2009 and 1010 in the objects being fertilized with calcium carbonate or high-calcium BCA at a dose corresponding to 1.5 Mg CaO-ha-1 when compared to other fertilization objects and was similar to the vale from before the experiment set-up (Tab. 3). Annual introduction of high-calcium BCA induced a significant increase in the content of assimilable K form in soil when compared to the objects with calcium carbonate or high-calcium BCA being applied at the beginning of experiment - see Tab. 3.
3. The content of assimilable P, K and Mg forms in mg^kg-1 d.m. in soil after cultivation of Amur ___ silver grass. Data for 2008-2010___
Parameters Initial values Study Fertilization objects Mean LSD0,05
years I* II III IV V VI
content of assimilable in mg-kg-1d.m.
2008 24.9 25.3 26.2 26.5 25.6 26.6 25.9 0.15
P 24.8 2009 24.7 24.9 25.9 26.1 25.1 26.3 25.5 0.20
2010 24.5 24.6 25.8 25.9 24.8 26.0 25.2 0.31
mean 24.5 24.9 25.9 26.2 26.2 26.3 25.5 0.04
2008 128 130 136 138 131 139 133.7 1.28
K 120 2009 126 125 131 133 128 135 129.7 1.10
2010 120 121 128 129 124 131 125.5 2.16
mean 124.7 125.3 131.7 133.3 127.7 136 129,6 0.09
2008 49.5 49.8 50.6 51.2 49.3 51.3 50.3 1.04
Mg 47.0 2009 49.9 49.1 50.9 50.8 49.8 50.8 50.2 0.90
2010 48.1 48.2 49.4 50.4 48.6 50.4 49.2 1.64
mean 49.1 49.0 50.3 50.8 49.2 50.8 49.9 0.07
* Description of fertilization objects is given in Table 1.
When evaluating the average content of assimilable elements in soil with the method of threshold values, used by Chemical and Agricultural Research Laboratories, it was found that the content of assimilable phosphorus was low and that of magnesium was medium in the objects being fertilized with municipal SSC without and with addition of high-calcium BCA, which means that no changes were observed in the soil abundance class. The content of assimilable potassium in soil pointed to a medium class of its abundance, whereas the soil classification regarding the content of assimilable potassium form changed as affected by the fertilization being applied from medium abundance class to high abundance one.
The most assimilable Mg form was contained by the soil of objects fertilized with municipal SSC with high-calcium BCA being applied at the beginning of study and each year. When compared to these objects, the soil of objects with calcium carbonate and high-calcium BCA being applied at the beginning of study and each year contained significantly less assimilable Mg form.
When analyzing the physical and chemical properties of soil before and after this study, it is possible to state that respective systems of municipal SSC and high-calcium BCA application had a varied effect on most soil richness indices. The fertilization with municipal SSC without and with addition of high-calcium BCA has a favorable effect on the preservation of soil environment stability and the improvement of soil chemical composition.
More P, K, Ca, Mg and S was contained by the soil after cultivation of Amur silver grass biomass when compared to their initial values. This was induced by translocation of macroelements from Amur silver grass at the end of vegetation to its roots and then to the soil. Calcium carbonate and high-calcium BCA being introduced into soil at the beginning of study did not vary the content of macroelements in the soil under examination.
Conclusions. 1. The greatest positive effect in soil richness indices was obtained after the application of municipal sewage sludge compost with annual introduction of high-calcium BCA into soil. Slightly weaker effects were obtained as affected by municipal SSC and high-calcium BCA being introduced into soil at the beginning of study.
2. In the soil of objects being fertilized with municipal SSC without and with addition of high-calcium BCA, the pHKCl value and the content of organic carbon and total nitrogen, phosphorus, potassium and sulphur increased, as well as that of assimilable phosphorus, potassium and magnesium forms.
3. As affected by municipal sewage sludge and high-calcium BCA, the soil classification regarding the content of plant-assimilable potassium form changed from the category of medium content to the high content one. In the objects fertilized exclusively with calcium carbonate or high-calcium BCA being applied at the beginning of study, this system of fertilization did not significantly vary the content of macroelements in the soil under examination.
* Part of this study was conducted within the framework of a research and development project No. 0397/R/P01/2008/04
REFERENCE
1. Baran S., Zukowska G., Wojcikowska-Kapusta A. (2006) Zmiany zawartosci metali ci^zkich w osadzie sciekowym kompostowanym z popiolem w^gla kamiennego. Zesz. Probl. Post. Nauk Roln. 512:39-46.
2. Cai Q.-Y., Mo C.-H., Wu Q.-T., Zeng Q.-Y., Katsoyiannis A. (2007) Concentration and speciation of heavy metals in six different sewage sludge-composts. J Hazard Mat., 147: 1063-1072. DOI: 10.1016/j.jhazmet.2007.01.142.
3. Chiba M.K., Mattiazzo M.E., Oliveira F.C. (2009) Sugarcane field in Untisol, Rusing sewage sludge as a phosphorous Skurce. Acta Sci-Agron, 31(3):495-501.
4. Gibczynska M., Meller E., Hury G. (2007) Oddzialywanie popiolu z w^gla brunatnego na wybrane wlasciwosci fi-zyczno-chemiczne gleby lekkiej. Zesz. Probl. Post. Nauk. Rol., 518:53-61.
5. Gilewska M. (2006) Przetwarzanie i wykorzystanie popiolow wysokowapniowych. Parametry jakosciowe w^gla brunatnego i popiolow powstaj^cych w wyniku jego spalania w elektrowni. Materialy Mi^dzynarodowego Seminarium Nauko-wo-Technicznego. Wyd. Ekotech Belchatow, 285-293.
6. Hargreaves J.C., Adl M.S., Warman P.R. (2008) A review of the use of composted municipal solid waste in agriculture. Agric. Ecosys. Environ., 123: 1-14. DOI. 10.1016/j.agee.2007.07.004.
7. Haroun M., Idris A., Syed Omar S.R. (2007) Characterization and composting of tanery sludge. Malaysian J. Soil Sci., 11: 71-80. DOI:10.1016/j.wasman.2006.09.006.
8. Hua L., Wu W., Liu Y., McBribe M.B., Chen Y. (2009) Reduction of nitrogen loss and Cu and Zn mobility during sludge composting with bamboo charcoal amendment. Environ Sci. Pollut. Res Int., 16(1): 1-9.
9. He M., Tian G., Liang X. (2009) Phytotoxicity and speciation of copper, zinc and lead during the aerobics composting of savage sludge. J. Hazard. Mater. 163: 671-677.DOI: 10.1016/j.jhazmat.2008.07.013.
10. Izewska A. (2007) Wplyw nawozenia obornikiem, osadem sciekowym i kompostem z osadow sciekowych na wlasciwosci gleby. Zesz. Probl. Post. Nauk Roln. 518: 85-92.
11. Kovacik P., Macak M., Ducsay L., Halccinova M., Jancich M., (2011). Effect of ash-fly ash mixture application on soil fertility. J. Elem. 16(2):215-225. DOI: 10.5601/jelem.2011.16.2.05.
12. Krzywy E., Woloszyk Cz., Mazur T., Krzywy J. (2005) Changes in contents of calcium, magnesium and sulphur du ring decomposition of composts prepared from potato pulp with addition of municipal sewage sludge, straw and sawdust. Chemistry for agriculture, vol. 6, 695-700.
13. Krzywy-Gawronska E. (2012) The effect of industrial wastes and municipal sewage sludge compost on the quality of virginia fanpetals (SIDA HERMAPHRODITA RUSBY) biomass. Part 1. Macroelements content and their uptake dynamics. Polish Journal of Chemical Technology 14(2):9-15. DOI:10.2478/v10026-012-0064-7.
14. Krzywy-Gawronska E. (2012a) The effect of industrial wastes and municipal sewage sludge compost on the quality of virginia fanpetals (SIDA HERMAPHRODITA RUSBY) biomass. Part 2. Heavy metals content, their uptake dynamics and bioaccumulation. Polish Journal of Chemical Technology 14(3):8-14. DOI:10.2478/v10026-012-0078-1.
