Year-Round Forage Yield Stability through a System Combining Triple-Maize Crops with Winter Barley in Kyushu, Japan

Reduction of feeding cost for the beef and dairy cow industry is an urgent matter requiring the intensification of summer and winter forage cropping in Kyushu, Japan. Forage maize is a prominent high-yield summer crop in the region, where it used to be sown from late March to early August. Due to global warming, maize cropping in the common hot summer now easily suffers from heavy rain and typhoons and this contrasts with the need of expanding the growth periods suitable for maize cropping. This study tested the cropping of triple (spring, summer and autumn) maize crops with winter barley to determine its suitability to be cultivated in the region. Winter barley, sown into inter-rows of the previous row crops in mid-November, was harvested from late February to late March, when spring maize was sown earlier than the current season, after the danger of late frost has passed. Summer maize was sown from early June to early July and autumn maize which was sown from late August to mid-September was harvested in mid-to late November. Winter barley yielded 900-1090 g dry matter (DM)/m² with 22% ear DM. Early-planted spring maize which was sown in early March yielded 1600-1880 g DM/m² with 16-28% ear DM and summer maize yielded 900-1280 g DM/m² with 19-39% ear DM. However, the autumn maize yield varied from 130-300 g DM/m² without seed maturation to 740-880 g DM/m² with 51-54% ear DM due to typhoon and cool weather damage. Therefore, triple maize with winter barley cropping can produce a yield of more than 4000 g DM/m², especially from 2600 g DM/m² from winter barley and spring maize crops sown in early March, leading to the conclusion that spring maize sown in early March can be harvested without high risk from weather disasters in the region (290 words ≤ 300 words, upper-limit).