In the field experiment in Rostock the bioavailable Pw and Pdl contents in soil (0-30 cm) were slightly increased following P supply (Table 2.10). Owing to a high standard deviation, these differences were not significant. The effects of the three ashes were similar. On average, slightly higher P values were measured for the CA treatment.

In Trenthorst the ashes also resulted in higher bioavailable P contents in soil (the differences were significant in spring 2008). Again, the highest increasing effect was found for the CA treatment (Table 2.11).

Like for the plant characteristics, the effects on the soil P pool were also found to be higher in the pot experiments than in the field experiments. Significant increases of high available P contents in the soil due to P application were measured at the end of the pot experiments.

In the pot experiments in 2007 with loamy sand the cultivated crops and interactions between crop and fertilization had also an effect. Cultivation of lupin resulted in the highest P values (Table 2.12). This can be partly explained by the

low P uptake of this species (Table 2.8). Furthermore, in many studies P mobiliza­tion effects were found for lupin, albeit mainly for white lupin (Shen et al. 2003; Kania 2005) owing to special root morphology (cluster roots) and root-induced chemical changes in the rhizosphere. According to results of Egle et al. (2003) and Pearse et al. (2007), blue lupin, which was used in the pot experiments, does not generate such “cluster roots”, but can enhance nutrient availability by means of carboxylate excretion into the soil and uptake of cations.

The decrease of the readily available P directly after phacelia harvest is probably only a temporary process. In a long-time field experiment with various catch crops, phacelia cultivation resulted in high levels of bioavailable P in the soil (Eichler — Lobermann et al. 2008a).

In the pot experiments with sandy loam (2008) the Pw and Pdl contents in the soil were also influenced by fertilization. The highest values were found after RMA, CA, and TSP application (Table 2.13).

Remarkably, in the experiments in 2007 and 2008 there were no differences in Pw contents of the soil between the P fertilizing treatments (TSP and ashes), even though commercial TSP fertilizer contains 80-93% water-soluble P (Mullins and Sikora 1995) and the water solubility of P in crop ashes is usually lower than 1% (Eichler-Lobermann et al. 2008b).

The P contents in soil were also related to the crop P uptake, namely high P uptakes usually resulted in P exhaustion in soil and in lower soil P contents. Thus, the relatively low P uptake of oil radish (Table 2.9) was related to rather high Pw and Pdl values (Table 2.13). Phacelia, which had the highest P uptake of all crops, showed comparably lower Pw and Pdl values. In contrast, high soil P contents were

found after buckwheat cultivation in the ash and TSP treatments (Table 2.13), despite the high P uptakes (Table 2.9).

The P fractionation method can provide additional information about the path­way of remaining ash P in the soil and helps to predict its presumable availability. In the pot experiments the highest soluble P fractions (resin P and NaHCO3P) were increased by the ashes as well as by TSP, as was shown, for example, for the loamy sand (see Fig. 2.2). The less available P fractions (NaOH P, H2SO4 P, and residual P) however, were not affected (data not shown). In comparison with the control, the total P content increased when P was supplied (Fig. 2.2).

2.4 Conclusions

According to our results, a high fertilization effect of biomass ashes can be expected. In the pot experiments and in the field experiment in Rostock, biomass ashes led to raised P uptakes of the crops and increased contents of the more easily available P pools in soil (Pw, Pdl, resin P, NaHCO3 P). Interactions of biomass ashes and cultivated crops had an additional effect on the utilization of P in ashes and should be considered for practical fertilization decisions. Provided that the ashes do not contain harmful substances, the utilization of biomass ashes in crop production is an important method for the recirculation of nutrients in agriculture and may save nutrient resources.

Acknowledgements This project was supported by the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV), Germany (support code 22016206) (2007-2009). The project execution organization was the Agency for Renewable Resources (FNR), Germany. The project was accomplished in cooperation with the following project partners: the Institute of Organic Farming of the Johann Heinrich von Thunen-Institute (vTI)/Federal Research Institute for Rural Areas, Forestry and Fisheries, and the Leibniz Institute for Agricultural Engineering Potsdam — Bornim, Germany.

Since the problem of acid soil low fertility status has been known for long, many agricultural practices have been recommended to overcome the problem.

In 2006, 1.3 million tonnes of combustion residues was produced (estimate for 2008: 1.5 million tonnes) and almost 80% was utilised. A summary of the quantities and types of combustion residues is provided in Table 11.1. The presentation is split into more categories than is usual in surveys, because mixtures of fuels, some of

them particular to a type of industry and to type of furnace, are important for the properties of the residues.

As one may see, the problem for a provider of materials is that the sources are numerous and small. For example, the 600,000 t/year of MSW incineration (MSWI) residues is produced by more than 25 plants. Many district heating plants produce less than 2,000 t of mostly wood-based ash per year. The smallest ones, as well as small sawmills, do not produce more than 1 t/year. The really small capacity furnaces are not included in these figures, e. g. pellet furnaces in individual homes, or farm units firing agricultural residues.

If one sums up all categories of solid biofuels and mixtures, the total quantity of ash from solid biofuels is of the order of 370,000 t/year.

All types of furnaces are used, grate furnaces, pulverised fuel (PF) furnaces and fluidised bed furnaces, the latter being perhaps more common in Sweden than in the rest of Europe. The capacities range from a few hundred kilowatts to a couple of hundred megawatts on a fuel basis. Small furnaces up to 10 MW fuel are usually grate furnaces, and fluidised bed furnaces are preferred from 20 MW fuel and upwards. PF furnaces are not so common in Sweden. All these types of furnaces have their particularities, which affect the properties of the residues; see Sect. 11.2.4.

The hypothesis that carbon amendment increased the ability of C. sphagnetorum to resist wood ash disturbance because of enhanced microbial production is supported by the large increase in the abundance of microbial-feeding nematodes (Nieminen 2008b), which is in accordance with the results of earlier field experiments. Baath et al. (1995) found that wood ash application reduced the ratio of fungi to bacteria in pine forest soil. In a field study the ratio of fungal to bacterial phospholipid fatty acids was lower in forests treated with loose ash than in forests treated with hardened ash, although the difference from the control was not significant (Perkiomaki and Fritze 2002). Further, ash treatment was shown to alter the carbon utilization pattern of bacteria in a microcosm study, indicating changes in the bacterial community structure (Fritze et al. 2000). Although wood ash increases CO2 evolution rates (Perkiomaki and Fritze 2002), Jokinen et al. (2006) concluded that not all microbial groups are equally stimulated by wood ash. In other words, by increasing the soil pH, wood ash application can favour fast-growing microbial species (Zimmermann and Frey 2002), which are not necessarily preferred food sources for dominant animals in forest soil (e. g. bacteria over fungi). An increase in microbial activity can also result from the bacterial decomposition of microbial residues. In particular, because the dominant enchytraeid species C. sphagnetorum is a litter feeder dependent on fungal activity, it is plausible that a shift towards the dominance of r-strategist bacteria has a negative influence on it. In accordance with this reasoning, Nieminen (2009) observed a tendency towards a lower proportion of bacterial-feeding nematodes in the sucrose treatment. We do not know whether sucrose increased the numbers of the same microbes that were negatively affected by wood ash, or if it increased other possible food sources for enchytraeids. On the basis of these and the present results, it seems that loose wood ash affects enchytraeids to some extent through a change in microbial community structure, and that sucrose counteracts this effect.

A moderate wood ash disturbance in the autotrophic experiment (Nieminen 2009) had little direct effect on decomposer animals. Since enchytraeids only persisted in sucrose-amended pots, the interaction of wood ash and carbon avail­ability could not be tested. Although wood ash did not affect enchytraeid biomass, it did increase the size of individual worms, indicating that there were fewer but larger enchytraeids in the ash-treated microcosms. Because C. sphagnetorum reproduces asexually by fragmentation, a large individual size may be indicative of delayed reproduction. On the other hand, a higher wood ash application rate led to significantly smaller enchytraeid body size in the heterotrophic experiment (Nieminen 2008b), suggesting that when these organisms reproduce, they produce smaller offspring. This reasoning is supported by the data obtained by Nieminen and Haimi (2010), who found that enchytraeid populations originating from an ash — treated plot had a lower propagation rate (smaller fragmentation frequency) than populations from adjacent untreated control forest even when the animals were transferred to laboratory microcosms containing untreated organic soil. Also, the body size dynamics differed between populations with different disturbance his­tories. The overall length variation of the disturbed populations was smaller than that of the control populations, and, hence, the mean enchytraeid length could be either smaller or greater than that of control, depending on the sampling date (Nieminen and Haimi 2010).

Two scenarios have been examined and compared in this study. These scenarios are:

— Scenario 1 (Fig. 8.1): The cacao shells are combusted in a bioenergy plant in the Netherlands. The ash produced is transported to a sea port in the Netherlands. From this port the ash is shipped to Cote d’Ivoire. The ash is transported by truck to a cacao plantation. The ash is used as fertilizer. The ash contains no nitrogen and not enough phosphorous and potassium. Therefore, extra NPK-containing fertilizer is used to fulfill the nutrient demand. This NPK fertilizer is produced in Cote d’Ivoire.

— Scenario 2 (Fig. 8.2): The cacao shells are combusted in a bioenergy plant in the Netherlands. The ash produced is transported to a mine in Germany as filling material. The fertilization of the cacao plantation is performed by means of an artificial fertilizer (NPK). The fertilizer is produced in Cote d’Ivoire.

The system has to be bounded for the analysis. The boundaries determine the scope of the study. There are four subsystems in this study of importance:

1. The cacao plantation subsystem

2. The cacao shell combustion subsystem

3. The cacao shell ash subsystem

4. The fertilizer production subsystem

Fertilisation of coniferous forest soil with wood ash (5 t ha-1) was demonstrated to affect microbial biomass (on the basis of phospholipid fatty acid analysis). Fungi reacted more sensitively to wood ash treatment than bacteria, which was reflected by decreasing fungal-to-bacterial phospholipid fatty acid ratios (Baath et al. 1995). Because ectomycorrhizal fungi are known to play an important role in the nutrient supply of trees, Hagerberg and Wallander (2002) investigated the effect of wood ash amendment on a Norway spruce forest floor and revealed an increase in ectomycor — rhizal biomass. The ectomycorrhizal fungus Piloderma sp. was found to frequently colonise granulated wood ash in a wood-ash-fertilised spruce forest, suggesting a direct impact on nutrient mobilisation (Mahmood et al. 2001, 2002). Piloderma sp. was moreover assumed to affect short-term storage of Ca derived from wood ash granules, whereas no effect on P storage or release was discovered (Hagerberg et al. 2005). Gaitnieks et al. (2005) reported a positive effect of wood ash (6 t ha-1) on Suillus sp. when it was applied prior to planting of Scots pine seedlings; this was accompanied by increased root and needle biomass of the seedlings.

In a long-term study on different forest sites, wood ash fertilisation (5-8 t ha-1) led to increased CO2 production caused by enhanced microbial activity but did not influence N2O emissions, although nitrification and denitrification may have been affected by wood ash application (Maljanen et al. 2006a, b). This effect was shown by Ozolincius et al. (2006) in a Pinus sylvestris stand in Lithuania, revealing an increase of ammonifying, nitrifying and denitrifying microorganisms after wood ash application (1.25-5 t ha-1). In contrast, Saarsalmi et al. (2010) did not find changes in net nitrification when investigating the effect of wood ash (3 t ha-1) combined with N (0.15 t ha-1) on soil microbial processes in two coniferous stands in Finland 15 years after application.

The soils under study are acid, as are most forest soils in the region, mainly due to the instability of the parent rock and to the strong leaching of the base cations. Also, the plant growth itself generates soil acidity. This implies a great obstacle to the growth of forest species since it reduces the availability of essential nutrients such as P (Sanchez-Rodriguez et al. 2002; Merino et al. 2005).

In this study, the application of ash slightly and temporarily increased the pH of the solid soil fraction, resulting in higher availability of elements such as K, Ca, and Mg. The availability was proportional to the quantity of ash applied. The concen­tration of Ca increased greatly after the second application. Thus, a direct relation­ship between the application and the availability of the element was observed.

Nevertheless, the increases were less than those reported for soil treated with fly ash (Ohno and Erich 1990; Saarsalmi et al. 2001; Hytonen 2003; Solla-Gullon et al. 2006).

The behavior of P was different, and a low response to the different treatments was observed. This may be due to the low availability of P in the ash, as well as to the chemical and biological reactions that this element undergoes in the soil. In acid soils, phosphate ions tend to precipitate with Fe and Al, forming insoluble com­pounds and thus reducing the concentrations of H2PO4 and H2PO4 taken up by plants (Garcia-Rodeja and Gil-Sostres 1997). It is also possible that the availability of P decreases owing to microbial immobilization, a process that is accelerated by the application of organic waste to the soil (Salas et al. 2003).

The brick production process in itself has remained unchanged for a very long time: a shapeable mass is formed into a brick, assumed to be a small, regularly shaped unit that a bricklayer can grasp with one hand while picking up mortar with the other. A typical modern production process is shown in Fig. 9.1.

Additions to the brick feed can take place either at the beginning of the process or in later steps.

In the trial runs explained later, biomass ashes were introduced as a substitution displacing quarried raw materials. They were mixed with the other raw materials right at the beginning of the process.

Quarried raw materials Body fuels

La La ih

Packaging

Transport to final point of use

Fig. 9.1 Brick manufacturing process

Trond Knapp Haraldsen, Per Anker Pedersen, and Arne Gr0nlund

Abstract Bottom wood ash (BWA) contains high concentrations of Ca, Mg, K and P, whereas meat and bone meal (MBM) has been found to be a good N and P fertilizer. In a pot experiment on soils with low contents of readily available K and P, the effects of a mixture of MBM and BWA were compared with those of mineral NPK (21-4-10), MBM, MBM plus K and Mg mineral fertilizer, and MBM and different types of crushed K — or Mg-rich rock.

The mixture of MBM and BWA gave the highest yield of barley, at the same level as mineral for NPK, and significantly higher than for MBM alone. For the yield of spring wheat there was no significant difference between the treatments with BWA or other K-rich additives to MBM, MBM used alone and mineral NPK. Compared with the other treatments, the MBM and BWA mixture significantly increased the pH of the soils by 0.5 units. MBM plus BWA represents an interesting concept for development of recycled NPK fertilizer of organic origin.

3.1 Introduction

Many by-products from the food industry and waste products from industry and bioenergy plants contain high concentrations of plant nutrients. The degree of recycling of these plant nutrients differs, but there is an untapped potential for use of by-products and waste products as fertilizers. The bottlenecks for use are partly lack of knowledge of fertilization and liming effects, logistic problems, relatively cheap disposal of ash at landfills, heavy metal content and restrictions due to governmental regulations (see Chap. 1, Knapp and Insam 2011; Chap. 8,

T. K. Haraldsen (H) and A. Gr0nlund

Soil and Environment Division, Norwegian Institute for Agricultural and Environmental Research, Frederik A. Dahls vei 20, 1432 As, Norway e-mail: trond. haraldsen@bioforsk. no

P. A. Pedersen

Department of Plant and Environmental Science, Norwegian University of Life Sciences, P. O. Box 5003, 1432 As, Norway

H. Insam and B. A. Knapp (eds.), Recycling of Biomass Ashes,

DOI 10.1007/978-3-642-19354-5_3, © Springer-Verlag Berlin Heidelberg 2011

Saraber et al. 2011). In Norway the regulations for use of organic fertilizers and related material also apply for ash materials (Norwegian Ministry of Food and Agriculture 2003). These regulations are based on quality classes of heavy metals on a dry matter basis. Ash has increased concentrations of metals on a dry matter basis compared with the original organic material, and the regulations therefore strongly limit use of ash. In Norway most of the bioenergy plants collect bottom and fly ash in one container, giving a blend ash with higher concentrations of heavy metals than are allowed to be used on agricultural land.

Ash from bioenergy plants has mainly been considered as liming material because of its high content of Ca, although the Mg, K and P content may also be of importance. Owing to the strict regulations, ash has hardly been used in agriculture in Norway in recent years. Risse (2002) reviewed use of wood ash in agriculture in the USA, and referred to several investigations where liming with wood ash gave better growth than use of traditional limestone. The liming effects of ashes vary between 8 and 90% of the total neutralizing power of lime. Etiegni et al. (1991a, b) found that wood ash had positive effects as K fertilizer and as a liming agent, but the amounts should be restricted in accordance with the plants’ need for K, and should not elevate the pH of the soil too much. The pH was the most important rate-limiting component. Saarelaa (1991) found that high application rates of wood ash supplied K in excess, and consequently decreased the Ca contents of plants. Mozaraffi et al. (2000) found that ash significantly increased K and decreased Mg concentrations in corn, and concluded that ash was a potentially good K source and a potential liming agent for acid soils. Different investigations on ash used as K or P fertilizer have shown different effects: almost the same of effect as wood ash as mineral K fertilizer (Erich 1991; Ohno 1992), whereas the P effects were better correlated with the citrate P than the total P in comparison with mineral P fertilizer (Erich 1991; Hansen 2004). Clapman and Zibelske (1992) found that plant uptake of Mg, K, Mn and P increased as the wood ash amendment increased. Meyers and Kopecky (1998) found land application of wood ash to be an environmentally safe alternative to landfilling, which may replace conventional limestone and K fertilizer for forage crop production.

Meat and bone meal (MBM) contains appreciable amounts of N, P and Ca, making it interesting as fertilizer for various crops. MBM has good effects as N fertilizer (Salomonsson et al. 1994,1995; Jeng et al. 2004), and has a positive effect on baking performance of wheat (Fredriksson et al. 1997, 1998). Jeng et al. (2006) showed that the relative P efficiency of MBM was 40-50% compared with P in superphosphate (YARA P8) in experiments with cereals and rye grass, and Ylivainio et al. (2008) found MBM suitable as a long term P supply to perennial crops. Because use of MBM as feed to produce animals is banned in the European Union, the meat industry has focused on an alternative use of MBM. The interest in the use of MBM as fertilizer will increase if MBM is included in an organic mineral fertilizer which has a predictable NPK effect similar to a compound mineral NPK fertilizer. The annual production of MBM of category 3 material is about 30,000 t. MBM of category 3 material is allowed for use as fertilizer in Norway for all crops, except grassland which is used for grazing or mowing, but can also be used for grassland if it is mixed with other fertilizer materials (Norwegian Ministry of Food and Agriculture 2007). Combining animal bones, feathers and wood ash to make mineral NPK fertilizers was described by Chojnacka et al. (2006), but the fertilizers had high P content relative to N content.

The aim of this investigation was to test different mixtures of MBM and additives of mineral K, crushed K-rich or Mg-rich rock and bottom wood ash (BWA), and to compare the effects with those from the use of compound mineral NPK fertilizer (Yara Fullgjpdsel® NPK 21-4-10) and an unfertilized control. The results should be used for development of organic mineral fertilizers based on MBM and BWA or other suitable K-rich material, which give a predictable NPK effect similar to that of mineral NPK. The investigation also aimed to find suitable types of BWA with low concentrations of heavy metals and high concentrations of K and Mg which satisfy the quality requirements for use on agricultural land in Norway (Norwegian Ministry of Food and Agriculture 2003).

Liming is defined as the application of ground calcium and/or magnesium carbo­nates, hydroxides, and oxides. Liming the soil is the most common and oldest method for reducing soil acidity. Liming is often performed through high-dose applications of products such as calcitic lime (CaCl2) and dolomitic lime [CaMg (СОз)2]. The aim is to increase the soil pH and therefore to modify the physical, chemical, and biological parameters of the soil. Studies have shown that liming materials affect the activity and composition of microbial populations and can create better environmental conditions for the development of nonacidophilic microorganisms, resulting in increased microbial biomass and soil respiration (Neale et al. 1997; Tate 2000). Nevertheless, liming has some limits; the effec­tiveness of surface application of lime to soils under a particularly no-till system withregard to subsoil acidity is uncertain, agricultural liming materials are rela­tively insoluble, and lime effects may be restricted to the top few centimeters of the soil surface for many years (Shainberg et al. 1989; Costa and Rosolem 2007).

Large quantities are generally required to improve plant growth, and for many resource-poor farmers in the tropics carrying out semisubsistence agriculture, its use is effectively prevented by the unavailability or the high cost of lime, or both (Haynes and Mokolobate 2001).