Relay Intercropping of Soybean and Winter Barley in Polish Climatic Conditions—Importance of Strip Width and Yearly Weather

Climate change and the increasing demand for food necessitate innovative agricultural methods. Relay intercropping, where one crop is sown into another already-grown crop, offers a promising alternative to traditional systems. In the 2021/22 and 2022/23 seasons, a field experiment was conducted to assess the relay intercropping of winter barley (Hordeum vulgare L. ssp. polistichon) with soybean (Glycine max (L.) Merr). This experiment took place at the Brody Experimental and Educational Station of the University of Life Sciences in Poznań, Poland. Soybean was sown into designated strips within the barley field, and both crops were cultivated simultaneously until the barley was harvested. After the barley harvest, the soybean plants continued to grow and were harvested at full maturity. The results varied between the two years of this experiment. In the first year, characterized by drought conditions, the soybean yield was completely lost, while the barley maintained a stable yield. In the second year, with more favorable weather, the yields of barley and soybean were interdependent. The use of the relay intercropping system did not increase the Land Equivalent Ratio (LER) above 1. Additionally, total protein yield remained consistent across different cultivation systems. Relay intercropping can serve as a method for protecting crop protein yields under adverse weather conditions and may offer a viable alternative for soybean cultivation in challenging climates.