How Veolia helps farmers make the soil 8% more fertile with simulation optimization

Customer stories Agriculture Simulation Optimization

Léa Optimization Scientist February 15, 2021

Veolia is a French transnational company whose activities include the management, treatment, and disposal of waste, as well as the recycling, reclamation, and re-use of waste products, including compost. Veolia chose Hexaly Optimizer to help them develop a simulation optimization tool to help farmers transition toward smart and sustainable agriculture via organic fertilization. Indeed, selecting a soil enrichment strategy relying on compost improves the soil’s physical properties, thus facilitating and reducing the fertilization of plants in the future.

The benefits of organic fertilization

In order to grow well, plants need mineral nutrients such as nitrogen, potassium, or phosphorus. Using synthetic fertilizers is the easiest way to provide crops with those nutrients. However, when used in excess, they become toxic to the soil’s microfauna and cause groundwater pollution.

A more sustainable alternative to those synthetic fertilizers can be found in organic soil amendment and fertilization via compost. The organic matter that makes up the compost is degraded by soil bacteria and binds to the clay naturally present in the soil. This process enables the retention of nutrients in the soil, which are progressively released according to the crop’s needs. The benefits of this method are many: resistance to erosion, improvement of water retention and resilience to droughts, and improvement of soil permeability and water infiltration, which helps prevent floods.

Veolia’s simulation optimization problem

Data collection

The first step toward building solutions well-suited to each client’s specific needs and constraints is gathering relevant data. On the one hand, it is crucial to know as much as possible about the farm itself. Veolia’s experts realize a diagnosis of the soil’s initial conditions using spectrography techniques. The farmer must also provide information about their agricultural practices, such as crop rotation and fertilizing strategy.

On the other hand, Veolia’s experts collect data about the farm’s geographical area. Relevant information includes climate and typical weather conditions, soil composition, or local environmental regulations.

Simulation and optimization model

All the collected data is fed to an optimization module relying on Hexaly. This module aims to build a sustainable fertilization plan over several years (typically 10 to 30 years). The decision variables are the quantity of synthetic and organic fertilizer spread onto the crops each month.

The main objective is to reach a certain level of organic matter in the soil. Other objectives and constraints include ensuring the plants have enough nutrients, respecting environmental regulations, ensuring the crops’ yield meets the farmer’s expectations, and minimizing fertilization costs.

Solving this problem is possible through simulation optimization with Hexaly. Indeed, predicting the quality of the soil after several decades with a given fertilizing strategy is very complex. Therefore, the values of some of the constraints and objectives cannot be directly expressed inside the optimization model. Instead, Hexaly delegates this task to an external function: an external “black-box” algorithm. This algorithm is a complex simulator that generates predictions about the soil’s evolution over the years. It yields predictions about various properties of the soil, such as its concentration of different nutrients essential to the plants’ growth. The solver then chooses the values of the decision variables so as to optimize the simulator’s output.

Recommendation and advice

Thanks to Hexaly, Veolia’s technical salespeople can provide farmers with solutions that both meet their goals in the short term and are sustainable in the long term, helping them define an amendment and fertilization strategy best suited to their needs. They can rely on the web interface to help them illustrate the advantages of an organic amendment strategy, thanks to visualization tools to compare different scenarios.

For example, the figure above illustrates the advantages of using organic fertilizers by simulating the evolution of the carbon amount in the soil over eight years. Thanks to Hexaly, the farmer can apply a fertilization strategy resulting in 8% more carbon in the soil than their original plan and 10% more than synthetic fertilization only, making the soil more fertile in the long term.

Why Hexaly?

At the start of the project, Veolia made an invitation to tender, which Hexaly won by demonstrating the flexibility and efficiency of its mathematical optimization solver coupled with a high-end service offering. Veolia’s team was thrilled with Hexaly’s short running times: solving their largest simulation optimization problems with 30-year planning horizons, with 5,000 continuous and discrete variables to decide, only takes minutes. They also greatly appreciated Hexaly’s ability to customize and industrialize the resulting optimization engine through a complete web application with superb graphical user interfaces.

Developing and deploying a tool like Smart Agri took less than three years. This digital simulation and optimization tool for integrated and organic fertilization was initiated in mid-2015 and has today reached the initial business solution rollout phase. We can support knowledge projects with extremely long-term goals and effectively develop new tools on behalf of our clients and operational performance.

Maria Albuquerque Project Manager, Veolia

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