Crop Rotation System for Improving Spinach Yield in Summer

Abstract

In the Tohoku district of Japan, spinach is cultivated 4 or 5 times from spring to autumn, but production in summer has become increasingly unreliable. The objective of this study was to establish a system of crop rotation to improve summer spinach yield without chemical treatment. Eight rotation systems were tested for the preceding cultivations in spring: immature soybean, immature kidney bean, burdock, carrot, lying fallow, lying fallow (April to mid-May) followed by spinach crop, spinach (April to mid-May) followed by a fallow period, and spinach followed by komatsuna (Brassica rapa L. Perviridis Group) crop. Compared with the two spring spinach cultivations (April to June) as a control, the dry matter yields of the first summer spinach crop were greater in the systems using soybean, kidney bean, burdock, carrot, and lying fallow for the entire spring. The other systems did not have any clear effect. On the other hand, differences in dry matter yield of the second summer spinach crops between the control cultivation and the eight rotation systems were small. These results indicate that a) the yields of the first summer spinach crop could be improved by avoiding spinach cultivation for the entire spring; and b) lying fallow for the half period of spring is not effective on the yield of summer spinach. Spinach cultivation should be avoided in spring to increase theyield of summer spinach.