Crambe oil yield and soil physical properties responses to no-tillage, cover crops and chiseling

Soil compaction on no-tillage (NT) system is one of the main problems for sustainable grains production in clay soils. However, some Brassicas, such as crambe (Crambe abyssinica Hochst), may show tolerance to moderately-compacted soils. The objective of this study was evaluate the effect of cover crops and chiseling on the soil physical properties, grain yield and oil content of crambe. Five summer cover crops, pear millet (Pennisetum americanum), sunn hemp (Crotalaria juncea), pigeonpea (Cajanus cajan), sunn hemp (Crotalaria spectabilis), and velvet bean (Mucuna pruriens) and two soil management systems (chiseling and no-tillage) were evaluated for three years in Brazil. Chiseling soil management decreased soil bulk density and increased total porosity, but chiseling had short-term effects on soil physical properties (12 months). Cover crops showed no difference regarding the effects on soil physical properties. The traditional no-tillage system presented higher soil bulk density and lower total porosity, which did not affect crambe grain and oil yield. Crambe presented expected grain and oil yield regardless of the adopted management and cover crops.