The Effects of Difference of Rotalion on the Yield of Crops and on the Soil Properties

Abstract

The effects of the difference of crop rotation on the yields of crops and the soil fertility were investigated. The results obtained were as follows: i) In the rotation containing the soybean the yield of corn was higher but the yields of wheat and barley, especially the forwes, were lower than those in continuously cropping of corn. From the viewpoint of changes of chemical and physical properties of soil, it seemed that the top soil had been relatively good conditions, while subsoil were quite opposite. ii) The yields of corn, wheat and barley in the rotation containing sweet potato were either lower or the same as those of continuous croppings. It was observed that in top and sub soils the consumption of organic matter and nitrogen was remarkable. iii) In the rotation containing potato radish and hairly vetch the yields of corn and wheat were higher than those of continuous, cropping and tended to increase grodnally with years. These were supported by the fact that the properties of top and sub soils were remarkably favorable conditions. iv) The yield of corn in the rotation containing hairly vetch showed very high level. Though it was recognized that top and sub soil were very fertile in nitrogen, they showed strong acidity and lacked in exchangeable bases and phosphorus.