Two ECONUTRI partners, JHI and UTAD are elaborating on novel intercropping technologies to maximize N₂ input in organic cropping. The work of each partner institution on these technologies is described in the following two sections.

1. The Centre for Sustainable Cropping (CSC), James Hutton Institute

Short Description of the Technology

The Hutton’s Centre for Sustainable Cropping (CSC; www.csc.hutton.ac.uk/) long-term experiment takes an innovative, whole-systems and nature-based approach to designing regenerative cropping systems for economic, environmental and ecological benefits. The platform has been running since 2009 as a field-scale comparison of regenerative cropping against standard agronomic practice over multiple arable rotations. The novel, regenerative design stacks best practice interventions as a single system that integrates innovations of: reduced tillage, organic matter amendments, mixed legume-based cover and companion cropping, threshold pest and disease monitoring, targeted crop protection, biofortification and nutrient budgeting. This approach aims to reduce reliance on chemical interventions by simultaneously promoting soil health, crop fitness and biodiversity. Together, these enhanced in-field characteristics result in improved resource uptake and use efficiency and reduced losses in the form of runoff, greenhouse gas emissions, leaching and erosion. Key indicators are used to compare this regenerative system with a conventional ploughed system that follows standard commercial practices of blanket fertiliser applications and prescriptive, prophylactic pest and disease treatments. Replication is year-on-year, but a split-field experimental design and large field sizes allow commercially realistic estimates of relative differences in costs and benefits. Trends in soil properties, biodiversity, crop yield and financial margins are used to review how well the sustainability objectives are met and guide an iterative approach to improvements in system design to optimize overall sustainability.

Innovative Features

This long-term experiment is the first of its kind to design, test and demonstrate a whole-systems, field-scale approach to arable sustainability improvement. Most examples of similar LTEs focus on one or a few variables (e.g., soil or IPM or biodiversity) and tend to be designed at a plot rather than field scale. The CSC platform allows detailed investigation of specific research questions within the context of the whole in-field cropping system at commercially relevant spatial and temporal scales.

Type of Contribution

Data on the effect of the regenerative cropping system on a suite of sustainability indicators will be provided to evaluate changes in nutrient use, uptake and losses. Key indicators relevant to Econutri include soil nutrient supply (plant available nutrients), nutrient concentrations in soil pore water, soil physical structure and carbon content, greenhouse gas emissions, crop health and yield, economic costs and financial margins based on tractor time, fuel use and input costs versus product sale prices. These specific measures are set in the context of wider field-scale biodiversity, yields and crop rotation.

Benefits

The whole-systems design approach provides multiple benefits while aiming to minimise trade-offs between different management goals.

1. Nutrient input efficiency is achieved by: (a) using soil nutrient supply (SNS) calculations to determine required fertilizer rates: (b) undersowing winter crops with legumes to reduce the need for winter nitrogen application thereby enabling any fertiliser inputs to be timed with main spring crop growth period; and (c) a legume-based rotation (cash, cover and undersown crops) for ‘biological nitrogen fixation contribution to SNS.
2. Improved resource uptake efficiency is achieved by: (a) conservation tillage to improve soil physical structure and enhance plant root architecture; and (b) organic matter inputs (compost, crop residue, cover crops) which stimulate microbial and invertebrate -driven soil biological processes resulting in improved plant nutrient availability.
3. Minimising losses is achieved by: (a) improved soil biophysical structure resulting in better infiltration and less runoff and erosion; (b) cover crops over winter prior to spring sown crops to retain soil and nutrients within the field; and (c) field margins and buffers designed to trap run-off and silt, reducing the leaching of nutrients into nearby water courses.

These measures together result in less requirement for fertiliser inputs and reduced pollution whilst maintaining crop yields comparable to those typical of standard commercial practice.

2. University of Trás-os-Montes and Alto Douro, Portugal

Short Description of Technology

UTAD evaluated the introduction of legumes in intercropping with warm-season grasses intended for forage or grain use as an innovative practice that allows the improvement of the nitrogen value of forage, reducing the need to import protein-rich foods to balance the diets of ruminants or others and presenting economic, ecological and environmental advantages in livestock and/or cereal production systems. Maize is a growing crop on the European continent and stands out for its productive potential. Maize is often grown under intensive systems, which increases crop resilience to synthetic inputs (e.g., fertilizers, pesticides and irrigation) causing environmental damage including greenhouse gas emissions (GHG), soil and water contamination, and decreased biodiversity. Hence, there is a great need to establish more sustainable maize-based cropping systems while maintaining their agronomic and economic viability. The studies included the selection of legume species that best adapted to intercropping with maize for forage or grain production.

Innovative Features

Legumes have the ability to fix atmospheric nitrogen through association with bacteria of the genus Rhizobium, which also makes them interesting from an economic point of view, given that nitrogen fertilizers represent a high cost on forage crops. From an ecological/environmental point of view, they improve soil structure and phosphorus availability, increase biodiversity, help control weeds and reduce GHG emissions and nitrogen leaching from the soil.

Type of Contribution

The studies included the choice of legume species and varieties best adapted to intercropping cultivation with maize and the effects on the quantity and quality of the production obtained. Other parameters relevant to Econutri that will be evaluated include the ability of legumes to provide N to the companion crop and to the subsequent winter crop (residual effect on triticale), greenhouse gas emissions and nitrate losses through leaching. A brief analysis of the economic consequences of the introduction of legumes will also be carried out.

Benefits

The cultivation of leguminous species, such as common beans (Phaseolus vulgaris) and lablab (Lablab purpureus) in association with corn allows to:

– Maintain forage production yields at high levels;

– Improve the protein content of the forage obtained;

– The previous cultivation of legumes allows for high production in subsequent triticale crops without the application of nitrogen fertilizers;

– Reducing yield-scaled GHG emissions.