In this inaugural blog post, I'd like to delve into a fascinating topic we're exploring in my forages class here at Purdue University: Alfalfa Autotoxicity. Much of the information I'll be discussing can be found in the Agronomy Guide or the Forage Field Guide, both publications from Purdue. So, let's dive in!
The planting window for alfalfa is approaching, spanning from March 1st to May 1st, with another opportunity from August 1st to September 1st. Over time, alfalfa stands tend to thin due to various factors such as pests, poor fertility, winterkill and stresses related to harvesting. While it may seem convenient to simply broadcast or drill more seed into the existing stand, did you know that alfalfa contains allelopathic chemicals? The extensive death of alfalfa seedlings when drilled into an established alfalfa field is referred to as Autotoxicity.
So, what exactly is Alfalfa Autotoxicity? To grasp this concept, it's essential to understand that alfalfa exhibits a form of allelopathy. Allelopathy refers to the effect of one plant on another through the production of chemical compounds that permeate the environment. Consider the black walnut tree, for instance. Have you ever noticed slow growth beneath its canopy? This phenomenon is attributed to the production of a compound called "hydrojuglone," which impedes growth in its vicinity. Similarly, if not managed correctly, alfalfa can exert a similar influence.
Numerous studies have demonstrated that alfalfa seedlings exhibit sluggish growth and often perish when placed in proximity to established plants. Despite extensive research, the specific chemical compound or compounds responsible for this phenomenon remain unclear. However, it's been observed that seedlings within an 8-inch radius tend to perish or grow slowly, whereas those positioned farther away typically fare better.
So, what's the key to mitigating alfalfa autotoxicity? Ultimately, time is the answer. Whether through chemical applications or thorough fieldwork, patience is paramount. Studies indicate that waiting at least 14 days after working the ground leads to successful stand establishment. For chemical applications, a waiting period of 21 days is recommended, especially if you intend to no-till alfalfa seed.
Thank you for taking the time to read my article, more information can be found in the link below.
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