Is Inadequate Rooting Limiting Resource Capture and Yield?

Keywords: Oilseed rape, root length density, wheat, water, yield enhancement, nutrients.

Average yields of combinable crops in Western Europe have not been increasing. Whilst there is little direct evidence that this is due to poor rooting, good rooting is clearly vital to arable crops for efficient capture of soil resources – both nutrients and water. Limited rooting at any stage of a crop’s life can have an impact on crop growth and ultimately on yield, especially in challenging conditions caused by high evaporative demands and /or intermittent rainfall, and especially if the crop’s genetic potential depends upon crop longevity.

A survey of commercial wheat and oilseed rape crops grown between 2004 and 2013 has shown that root length density (RLD; the length of root per unit soil volume) is often less than the critical RLD of 1 cm cm^-3 for full water capture below ~0.4 m soil depth. This suggests that a significant proportion of arable sub-soils are not fully explored by roots. A simple water uptake and yield model indicated substantial impacts of reduced water capture in water limited scenarios.

Insufficient soil exploration by roots can also limit nutrient uptake, especially that of the less soil mobile nutrients. The need to increase farm productivity by 50% and approach the biophysical yield potentials of crops on farm will require long-term farming strategies to enhance capture (as well as conversion) of water and nutrients by roots. This will be needed to support capture of extra light energy for crop growth. Improved strategies for better rooting are likely to be essential to increase yields, involving concerted use of rotations, soil drainage and management, machinery choice and management and chemical stimulation, as well as genetic innovations.

Charlotte A. White¹, Roger Sylvester-Bradley² and Peter M. Berry³

¹ADAS UK Ltd, Gleadthorpe, Meden Vale, Mansfield, Nottingham, UK.

²ADAS UK Ltd, Boxworth, Cambridge, UK.

³ADAS UK Ltd, High Mowthorpe, Duggleby, Malton, North Yorkshire, UK.

28 pages, 2 figures, 3 tables, 111 references