Selecting the right sowing time in arable cultivation of cowpea (vigna unguiculata) (Deliverable 6.4)

Cowpea tolerates heat and extreme drought well. However, it is highly intolerant of competition, with any significant emergence of natural flora leading to a noticeable yield reduction. Post-sowing cold spells or insufficient soil temperatures can cause delayed germination and reduced seedling emergence. While cowpea can tolerate some thinning, excessive gaps in plant coverage — especially due to delayed germination — can give weeds a competitive edge, negatively impacting the entire cultivation cycle. Achieving uniform plant coverage is essential, and the key to this lies in selecting the right sowing time with optimal soil temperatures. Ideal germination occurs when soil temperatures are at least 15-18°C. However, sowing later rather than earlier is recommended to avoid the risks associated with cool soil conditions. Effective weed control measures are also crucial for a successful yield. Delay sowing until late May or early June, when soil temperature is as high as 20°C. This will,ensure moist seedbeds, or applying irrigation to promote germination can result in an explosive emergence. In conventional farming systems, a single post-emergent herbicide treatment can help maintain a relatively weed-free crop. In organic farming, shallow tillage is crucial for spontaneous flora management. This latter practice preserves moisture in the soil while removing emerging weeds from the top layer without bringing up new weed seeds. Additionally, two rounds of inter-row cultivation can keep the field largely weed-free. Any significant weed presence will result in a marked reduction in yield.