Rotary Tilling and Ridge-Making Methods for Heavy Clay Soil

Abstract

In wet rice fields with heavy clay soil, the decrease of the rate of soil pulverization and excess moisture injury are major constraints on the cultivation of vegetables as alternative crops. Deep tillage which is very important for the consolidation of the paddy field soil structure leads to the decrease of the soil pulverization and small clod rates, resulting in the increase in power requirement. In this study, implements based on a reverse-rotating tiller (up-cut rotary tiller) equipped with tines differing in length, were developed. The use of the implements enabled to perform deep tillage in the ridges and shallow tillage in the inter-ridge spaces. It became possible to cultivate soil and make ridges simultaneously. The working efficiency was 2-3 times higher than that by other methods. Also the trafficability of the implements in the inter-ridge spaces was improved. The developed implements did not require a large amount of power and did not lead to a decrease in the soil pulverization rate. The rooting zone of the ridges expanded and the soil water content inside the ridges decreased. Furthermore, the oxygen concentration in the ridge soil increased and cabbage yield increased.