Successful Spring Seedings
Spring crops are short-cycle crops that need to have rapid growth. Therefore, the soil must be sufficiently warmed to ensure a quick start of the crop but also to allow good biological activity synonymous with nutrient release.
Context
In spring, the soil is cold after the winter months and the warming is slower due to the soil's inertia. In no-till, this phenomenon is accentuated and the soil can be 2°C to 3°C cooler than tilled soil.
Impact of superficial tillage
"Scratching the soil" helps to warm the soil and accelerate mineralization. It therefore effectively allows a faster start for spring crops. It also has another benefit, namely, leveling the soil occasionally in the rotation and helping to limit holes caused by wild boars and voles. Working the soil to a depth of 5 cm will achieve all these objectives without damaging the deep structure that has been worked during winter by earthworms and the cover.
Avoiding soil tillage
Soil tillage is not always necessary and several factors can help reduce its importance:
- Late sowing (1 to 2 weeks on average after the usual sowing dates in the region) can be enough to recover the few degrees needed. Be careful, this sowing delay is not without risk regarding the risk of water stress at the end of the cycle. However, this should be put into perspective: a 2-week difference in sowing date only translates to a few days difference at flowering for barley, for example. Still, these few days can make a difference. The earliness of the varieties planted could be adjusted to compensate for this.
- Fertilizer placement close to the plant based on NP (or even NPS) allows the plant to receive early some of the units that could have been provided by mineralization caused by soil tillage.
- Choosing species to plant later: spring species (spring barley, faba beans, peas...) are sown early on very cold soil. Tillage is often recommended. Summer species, such as sunflower, are sown later and may need it less. Finally, on summer mixed crops or sowings of sorghum at the end of May, the soil has warmed sufficiently and this mineralization aspect becomes less important.
- The choice of cover can also influence soil warming. Faba beans and phacelia, for example, have dark straw that better utilizes light radiation. This can raise soil temperature by 1 or 2°C.
Weed management
The choice to till the soil can be influenced by weed infestation issues on the farm, the soil structure (depending on the success of the cover).
If weed control is not always achieved in the plot in question, and if the structure allows it thanks to the work of the cover, it is better to delay the sowing date and direct seed to limit weed emergence (especially grasses).
Many factors come into play and need to be discussed together depending on the crops, varieties, and the state of covers and soils before sowing.
Sources
Does superficial soil work help secure emergence for spring sowing?, AgroLeague
