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).