Castor bean husk as substrate for plantsCastor bean husk (CBH) is a residue generated in large amounts in the castor bean processing. The aim of this study was to evaluate the chemical and physical characteristics of CBH and its effect used as substrate for plants. CBH characteristics were evaluated in a (2x3) factorial randomized block design, consisting of a combination of two husk types (CBH fresh and composted) and three grades (mesh 3 mm, 5 mm e 10 mm). Macro and micronutrient contents, pH, electrical conductivity, wet density, dry density, total porosity and air space were evaluated. The evaluation of CBH as substrate for plant growth was carried out using tomato (Lycopersicon esculentum Mill.) seedlings and golden dew drop (Duranta repens L.) cuttings as indicator species. Tomato seedlings were grown on CBH 3 mm grade, fresh or composted, mixed to Plantmax ® in five ratios [0:100; 25:75; 50:50; 75:25; 100:0 (v/v)]. Rooting of golden dew drop cuttings was carried out on CBH, fresh or composted, using three grades (3, 5 and 10 mm). The composted 3 mm grade Casca do fruto da mamoneira como substrato para as plantas 1A casca do fruto da mamoneira (CFM) é um resíduo gerado, em grande quantidade, no beneficiamento da mamona. O objetivo desta pesquisa foi avaliar as características físicas e químicas da CFM e seu efeito, como substrato, para plantas. A avaliação das características da CFM foi realizada em um experimento fatorial (2x3), constituído da combinação de dois tipos de casca (CFM in natura e compostada) e três granulometrias (peneiras 3, 5 e 10 mm de malha), em delineamento de blocos ao acaso. Os teores de macro e micronutrientes, condutividade elétrica (CE), pH, densidade seca (DS), densidade úmida (DU), porosidade total (PT) e espaço de aeração (EA) foram avaliados. A avaliação da CFM