Katja Schiemenz, Jurgen Kern, Hans-Marten Paulsen, Silvia Bachmann, and Bettina Eichler-Lobermann

Abstract The reutilization of biomass ashes in agriculture is important to create nutrient cycles. In field and pot experiments we investigated the fertilizing effects of different biomass ashes (rape meal ash, straw ash, and cereal ash) for eight different crops on a loamy sand and a sandy loam. Special emphasis was given to phosphorus (P). The ashes showed large differences in their elemental composition. The highest P contents (10.5%) were measured in the cereal ash, and lowest in straw ash (1% P). The solubility of P in water was low; however, about 80% of P was soluble in citric acid. Generally, the P fertilizing effect of ashes was comparable to that of highly soluble P fertilizers such as triple superphosphate. The ash supply resulted in an increase of P uptake of cultivated crops as well as in increased soil P pools (total P, water-soluble P, double-lactate-soluble P, oxalate-soluble P) and P saturation. The ash effects depended also on the cultivated crop. Good results were found in combination with phacelia, buckwheat, and maize. Provided that biomass ashes are low in heavy metals and other toxic substances, the ashes can be applied in agriculture as a valuable fertilizer.

2.1 Introduction

Renewable energy sources are important for reducing the EU’s dependence on fossil fuels and cutting greenhouse gas emissions and other pollutants. “Biomass is one of the most important resources for reaching our renewable energy targets.

K. Schiemenz, S. Bachmann, and B. Eichler-Lobermann (H)

Faculty of Agricultural and Environmental Sciences, University of Rostock, J.-von-Liebig-Weg 6,

18059 Rostock, Germany

e-mail: bettina. eichler@uni-rostock. de

J. Kern

Leibniz-Institut fiir Agrartechnik Potsdam-Bornim e. V., Max-Eyth-Allee 100, 14469 Potsdam, Germany

H.-M. Paulsen

Institute of Organic Farming vTI, Trenthorst 32, 23847 Trenthorst, Germany

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

DOI 10.1007/978-3-642-19354-5_2, © Springer-Verlag Berlin Heidelberg 2011

It already contributes more than half of renewable energy consumption in the European Union” said Gunther Oettinger, Europe’s energy commissioner in Feb­ruary 2010, when the European Commission adopted a report on sustainability requirements for the use of solid biomass and biogas in electricity, heating, and cooling (European Commission 2010).

In the context of increasing bioenergy production, the recycling of the residues in agriculture can contribute to realize nutrient cycles and reduce the necessity of commercial fertilizer application (see Chap. 3, Haraldsen et al. 2011; Chap. 7, Bougnom et al. 2011). This has special importance for phosphorus (P), since the P resources are strongly limited worldwide. Ashes from combustion of biomass are the oldest mineral fertilizer. Biomass ashes are nearly free of nitrogen but contain P and other nutrients needed for plant nutrition (Sander and Andren 1997; Vance and Mitchell 2000; Patterson et al. 2004; Uckert 2004). Furthermore, biomass ashes can also be used as liming agents (Muse and Mitchell 1995; Mandre 2006), and can stimulate microbial activities in the soil (Demeyer et al. 2001; see Chap. 1, Knapp and Insam 2011).

The nutrient compositions of ashes are affected by different factors. Particularly, the kind of biomass combusted influences the quality and the nutrient values of ashes. Besides the raw material used, the combustion process itself affects the chemical composition of the ashes. The P concentration in biomass ashes may range from less than 1% up to 10% (Table 2.1).

Positive effects of biomass ashes on crop yields were found in different studies. Among others, Krejsl and Scanlon (1996) found wood ashes to increase oat and bean yields. Phongpan and Mosier (2003) found positive effects of rice hull ash on rice yield, Ikpe and Powell (2002) reported positive impacts of millet ash on millet yields, and Haraldsen et al. (2011, see Chap. 3) found particularly positive combi­nation effects with meat and bone meal residues on barley.

Nutrient uptake efficiency and mobilization mechanisms of crops are important for high utilization of applied P (Schilling et al. 1998; Neumann 2007), and the utilization of P in ashes also depends on the cultivated crop. However, research findings concerning interactions between biomass ashes and crop species are rarely available.

In our studies we investigated three different crop biomass ashes and eight crop species within field and pot experiments. The objectives of our work were to evaluate the P fertilizing effect of biomass ashes on different soils, and to investi­gate possible interactions between the effects of ashes and cultivated crops.

Table 2.1 P contents in biomass ashes

Type of ash P content (%)

Bagasse ash (Jamil et al. 2004) 0.01

Alfalfa stem ash (Mozaffari et al. 2002) 0.90

Horticulture ashes (Zhang et al. 2002) 0.04-1.00

Wood ashes (Erich and Ohno 1992; Saarsalmi et al. 2001; Hytonen 2003) 0.90-1.70

Wheat straw ash (Hytonen 2003) 1.30

Rape straw ash (Hytonen 2003) 2.10

Poultry litter ash (Yusiharni 2001; Codling et al. 2002) 5.00

Cereal ash (Eichler et al. 2008b) 10.4