Modelling – a support tool for getting those nutrient balances ‘just right’

NDICEA—a decision support tool for farming for soil

Organic crop yields in the UK are static, or even declining and are significantly lower than elsewhere in Europe. This session will discuss the latest ideas on soil analysis, use of manures, fertility building crops and mineral fertilisers. It considered the use of nutrient budgeting, including the use of self-use tools, to help plan and refine crop rotations for improved productivity

This session focused on enhancing crop rotations, understanding and making better use of soil analysis, and utilising modelling to explore nutrient use and help planning. The importance of monitoring and managing soil pH and structure was highlighted to help look after the crop’s roots and a diversity of crops within the rotation can help enhance soil microbial communities and help solubilise nutrients for crop uptake. Soil Biology shouldn’t be neglected in nutrient considerations, with small manure additions, large green manure additions and wherever possible, covered soil to feed the soil biota and improve nutrient cycling and availability. The merits and deficiencies of the Albrecht approach were discussed with nutrient ratios potentially unhelpful and large amounts of inputs seen as counter to organic principles, but a more comprehensive analysis of nutrients along with plant tissue analysis could prove very helpful. Long term, regular soil monitoring should be undertaken to help establish on farm trends and changes in management can be tested through modelling tools to guide planning and evaluate rotations from a nutrient perspective.

The discussion that followed the presentations brought out the following points:

• Optimise soil pH and soil structure to help look after plant roots
• Incorporate as much Diversity as possible in the rotation to enhance soil microbial community
• Integrating livestock can help improve nutrient supply to crops
• There is a need to regularly monitor soils, with each field done at least once a rotation with some fields assessed more regularly to investigate long term trends.
• Still not enough evidence of the benefits of the Albrecht approach and it is very input heavy and managing nutrient ratios might be impractical, though comprehensive soil analysis looking at all nutrients complimented by tissue analysis could be helpful.
• Feed soil through small amounts of farm yard manure and large amounts of green manure and keep soil covered as much as possible.
• Open access nutrient modelling tools such as Ndicea can help assess and improve rotations to maximise nutrient availability while helping limit adverse environmental impacts
• The model can be used to test scenarios and the impact of making a future management change
• Be consistent with long term soil monitoring using the same lab and testing at the same time of year and keep different soil types separate
• Different soils have varying capacity for storing carbon so important to know your soil and monitor to stop any reductions in organic matter content.

Action points

• Could Government support regular monitoring and improvements in soil organic matter or penalise organic matter declines?
• More support for diverse rotations (spatially and temporally)