Cultivation of Late-Planted Soybean with Narrow-Row and Dense-Sowing using Chisel Plow and Grain Drill to Manage Reclaimed Farmland Damaged by the Tsunami after The Great East Japan Earthquake in Miyagi Prefecture

Abstract

The number of farmers abandoning reclaimed farmland damaged by the tsunami following the Great East Japan earthquake has rapidly increased, and the few remaining farmers must manage substantial areas of reclaimed farmland by large scale farming. To develop a labor-saving cultivation technique to manage these fields, we investigated the suitability of two varieties of late-planted soybean, and appropriate row spacing, using a crop rotation system of rice–wheat–soybean every two years. Varieties “Akimiyabi”, a medium-maturing variety newly released in the Tōhoku Region; and “Tanrei”, an established, recommended variety were used. “Akimiyabi” had shorter and thicker stems than “Tanrei”, when planted in more narrow rows and high density. In addition, green stem disorder was reduced and harvest time was earlier in “Akimiyabi” than in “Tanrei”. The growth volume and yield were larger in “Akimiyabi” than in “Tanrei”. Seed protein content, inspection grade and seed size, were not influenced by row spacing within 24 cm to 36 cm, whereas the lodging in 24 cm row spacing was less than that in 36 cm row spacing. Our results suggest that “Akimiyabi” late planted at a high density with a row spacing of 24 cm is appropriate to obtain a stable high yield.