Determination of sowing dates for hairy vetch (Vicia villosa) and rye (Secale cereale) cultivation in Korea north region

Crop productivity in North Korea's farmland is low due to cold climate and low soil fertility.Green manure is strongly recommended to improve soil fertility and crop yield as an alternative to chemical fertilizer.However, the optimum sowing date of green manure under North conditions has not been investigated yet.Therefore the objective of this study was to select the sowing date for Hairy vetch and rye considering North Korea's climate conditions.The sowing period consisted of 6 times autumn sowing, three times winter sowing, and one time spring sowing.Average minimum temperature (°C), germination rate (%), over wintering survival rate (%), and plant height (cm) were surveyed.Dry matter weight (kg ha -1 ) and nutrient input (kg ha -1 ) were also analyzed.The soil temperature at the experimental site, located near North Korea, was 5°C lower on the average temperature during the cultivation period compared to the central region of South Korea.According to the growth survey and production analysis, it was appropriate to sow hairy vetch and rye no later than September 27th and October 7th, respectively.Late sowing was negatively impacted by low temperatures, resulting in reduced crop growth and nutrients production.Considering climate conditions, selecting a proper sowing date could be a useful agricultural practice for maximizing green manure biomass.