Studies on a Zig-zag Method of Planting using a Japanese-made Potato Planter

Abstract

We developed a method of zig-zag planting of potato using commercial Japanese-made planters and examined its accuracy. Also, we cultivated potatoes in a field by zig-zag planting using improved zig-zag planters and an improved rotary hiller. The new commercial Japanese-made planter uses a newly developed blade to apportion seed potatoes in a zig-zag pattern. The device is placed below the seed-feeder of a commercial potato planter. We also improved the furrow-opener, press-roller, soil-coverer, and their attachments. With our semi-automatic zig-zag potato planter, seed potatoes are apportioned by using the potato's own weight; with our automatic planter this is done through connection to a drive wheel. The tine position on the commercial rotary hiller used was changed to avoid injury to seed potatoes just ridged after planting. The distance between fertilizer rows in zig-zag planting is 660 mm-shorter than in conventional planting (750 mm). Seed potatoes are planted on either side of the fertilizer row at 150-mm spacings. Just after planting, the soil is earthed-up at 1500-mm intervals, which include two fertilizer and four planting rows. Field experiments showed that both semi-automatic and automatic planters enabled zig-zag planting at the same regular working speed (3-4 km/h) as with a commercial planter. Planting accuracy with the automatic planter was comparable to that of conventional planters, but that with the semi-automatic planter was less than with conventional ones. In zig-zag planting, both number of tubers per plant and thus per-area yield of potatoes weighing 60 g or more were greater than with the conventional method. However, after a certain point of increase in tuber number per plant, potato size and weight tended to decrease. In addition, earthing-up with a rotary hiller had a problem whereby the tines of the hiller touched the seed potatoes, causing them to green.