Effects of intercropping forage turnip (Brassica rapa L.) and basil (Ocimum basilicum L.) and applying vermicompost and biochar as soil amendments on quality and quantity of the forage turnip crop

ABSTRACT Intercropping is an ecological friendly technique that can increase sustainability of farming systems, whilst considered as low input systems. This 2-year (2018–2019) study aimed to assess the quality and quantity of forage production in intercropping systems with different densities of forage turnip and basil plants and with application of vermicompost and biochar. The treatments were: 100% forage turnip (monoculture); 90% forage turnip + 10% basil; 80% forage turnip + 20% basil; 70% forage turnip + 30% basil applied in main plots, and two vermicompost levels (15 and 18.5 t ha−1) and two biochar levels (0 and 5 t ha−1) applied in subplots. The highest dry matter yield, water-soluble carbohydrates, crude protein, digestibility of dry matter of leaf and root biomass parts of the turnip were recorded in the treatment with 70% forage turnip + 30% basil × vermicompost (18.5 t ha−1) × biochar. This treatment increased crude protein of the above-ground foliage (by 94.6%) and the root (by 87.5%) of the forage turnip, compared with monoculture. The highest acid detergent fibre and neutral detergent fibre were recorded in monoculture × vermicompost 18.5 t ha−1 × biochar and the highest ash was recorded in 80% forage turnip + 20% basil × vermicompost 18.5 t ha−1 × biochar. Intercropping forage turnip and basil with biochar and vermicompost at 18.5 t ha−1 was preferable to monoculture with vermicompost at 15 t ha−1. Intercropping turnip and basil with application of biochar and vermicompost can be suggested to farmers as an alternative to monoculture.