Soil preparation is critical for alfalfa growth

Alfalfa requires specific soil conditions to grow successfully. According to Mickaël Venot, head of the forage department at Arvalis, selecting the right plot is essential because alfalfa cannot thrive in all soil types or pH levels. The soil should be well-aerated and have good structure, as compacted soil can hinder root development and the function of rhizobium bacteria, which are vital for nitrogen fixation.

Soil pH is a key factor for alfalfa

Before sowing, checking the soil pH is crucial. Alfalfa performs best when the pH is between 6.2 and 6.5. If the pH drops below 6.2, it is recommended to apply lime within the top 10 to 15 centimeters of soil to adjust it to the optimal range. This helps ensure the plant can access necessary nutrients and function properly.

Sowing date influences alfalfa establishment

The timing of sowing has a significant impact on alfalfa growth. Sowing should ideally be done as early as possible, preferably at the end of summer or the beginning of autumn. This allows the plant to establish itself before winter. However, sowing too early can create challenges with straw management, and drought in August may hinder germination.

Sowing density and variety selection are important

To ensure a strong alfalfa population, Arvalis recommends aiming for 500 plants per square meter. This corresponds to a sowing dose of 20 kg/ha in spring and 25 kg/ha in late summer or autumn, accounting for potential germination losses. If the soil has not hosted a legume in over three years or has low potential, inoculating with rhizobium bacteria can help secure the crop at a cost of about 10 €/ha.

Weed management affects alfalfa performance

Effective weed management is crucial for alfalfa productivity. Trials show that thinning reduces weed germination and yield loss. However, without chemical weeding under favorable conditions, yield losses can occur quickly. Alfalfa also has high nutrient demands, particularly for potassium and phosphorus, which can be supplemented through fertilization.

Alfalfa variety mix improves yield stability

Ongoing trials at the Bordes experimental farm since 2021 indicate that no single type of alfalfa variety consistently outperforms others. Mixes of 50% "North" and 50% "South" varieties have shown better yield stability year after year compared to plots with only one type. This strategy appears to be the most effective in adapting to climate variability.