Applied Soil Ecology 69 (2013) 56–60 Contents lists available at SciVerse ScienceDirect Applied Soil Ecology jo ur n al hom epa g e: www.elsevier.com/locate/apsoil Vermicomposting with rock powder increases plant growth Maria Eunice Paula de Souza a , André Mundstock Xavier de Carvalho a , Daniely de Cássia Deliberali a , Ivo Jucksch a , George Gardner Brown b , Eduardo Sá Mendonc ¸ a c , Irene Maria Cardoso a,∗ a Soil Science Department, Federal University of Vic ¸ osa, Av. P.H. Rolfs s/n, Campus universitário Vic ¸ osa, MG, CEP 36570-000, Brazil b Embrapa Forestry, Estrada da Ribeira Km. 111, C.P. 319, Colombo, PR, CEP 83411-000, Brazil c Federal University of Espirito Santo, Agriculture Science Center, Plant Production Department, 29500-000 Alegre, ES, Brazil a r t i c l e i n f o Article history: Received 19 December 2010 Received in revised form 28 December 2012 Accepted 21 January 2013 Keywords: Earthworms Rock powder Eisenia andrei Soil fertilisation Maize a b s t r a c t The growth of earthworms in substrates enriched with rock (gneiss and steatite) powder, and the poten- tial of vermicomposting in increasing solubilisation of minerals present in rock powder and in promoting plant growth were evaluated. Cattle manure (400 g), was enriched with 0, 5 and 20% of gneiss or steatite powder. Each pot with this mixture received nine earthworms (Eisenia andrei), at a density of 1000 indiv. m -3 . After 60 d, earthworms were collected, counted and weighed (fresh and dry). Maize was cultivated in a greenhouse in pots with an Oxisol that was fertilised with the vermicompost obtained above. Treatments with Oxisol fertilised with gneiss or steatite only and unfertilised soil were used as controls. Shoot length was measured weekly from the soil surface to the tips of the leaves. After 73 d, the plants were harvested, the roots washed from the soil and shoots and roots dried and weighed. Plants fertilised with vermicompost enriched with rock powder were taller and heavier than plants fertilised with non-enriched vermicompost. Plants grown on soil fertilised with rock powder but not with vermi- compost were larger than plants grown on unfertilised soil. Vermicompost enriched with steatite powder resulted in a larger effect on plant growth than the mere sum of applying vermicompost of non-enriched manure and steatite alone to the soil. A similar, but non-significant effect was also observed for gneiss. The different effects between gneiss and steatite may be associated with the lower resistance to chemical weathering of steatite minerals compared to gneiss minerals, as well as the former being softer than the latter. The effect of vermicompost on the optimisation of nutrient release from silicate rocks seems to depend on the rock type. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The use of earthworms in vermicomposting is designed mainly to recycle organic residues and produce stabilized organic fertil- izer (Aquino and Nogueira, 2001). Earthworms have the capacity to increase availability of nutrients present in the material they ingest (Bartz et al., 2010), which includes organic matter and the mineral components of soil. This occurs because these materials are crushed by the earthworms and subjected to digestive enzymes present in their intestines, including amylases, cellulases, proteases, lipases and chitinases (Michel and Devillez, 1978; Edwards and Fletcher, 1988). In addition, earthworms excrete excess mineralized calcium in the form of CaCO 3 through calciferous glands, thus increasing the ∗ Corresponding author. Tel.: +55 3138991045; fax: +55 3138992646. E-mail addresses: maria.paula@ufv.br (M.E.P. de Souza), andre.carvalho@ufv.br (A.M.X. de Carvalho), ddeliberali@yahoo.com.br (D.d.C. Deliberali), ivo@ufv.br (I. Jucksch), george.brown@embrapa.br (G.G. Brown), esmjplia@gmail.com (E.S. Mendonc ¸ a), irene@ufv.br (I.M. Cardoso). pH of the gut contents (Barois and Lavelle, 1986) and of the vermi- compost, making it more basic than organic compost (Longo, 1995) and contributing to changing the solubility of some nutrients. In addition to increasing the availability of nutrients, vermicom- posting allows for greater stabilization of organic residues, because these residues are converted to humic substances when sub- jected to enzymatic action (mainly microbial, but also-earthworm derived) in the earthworm gut and castings (Hartenstein and Hartenstein, 1981; Aira and Domínguez, 2010). Furthermore, ver- micompost has a high microbial load many of them plant growth promoters that increase soil quality (Domínguez et al., 2010a). Therefore, earthworm castings not only provide nutrients and sta- bilize organic compounds but also favour soil microbes and their activity. Inorganic residues such as rock powders also have the potential to increase soil nutrient reserves, but for this to occur the solubility of their minerals must be increased, in order to release nutrients (Melamed et al., 2007). The addition of rock powder in agricul- ture also favours plant resistance to biotic and abiotic stresses by improving their nutritional status (Melamed et al., 2007). 0929-1393/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsoil.2013.01.016