Effects of soil cultivation on the growth and yield of winter wheat. V—effects of cultivation on the nitrogen uptake and growth of crop in unfertilized and fertilized soils

Abstract

Abstract1. Cultivation experiments were conducted for two years on four soils in the Midlothians, differing markedly in fertility and other physical and chemical conditions.Cultivation treatments consisted of ploughing to a depth of 8 in. and shallow and deep cultivation with a tined cultivator to depths of 2 and 4 in. respectively.2. The crop removed greater amounts of nitrogen and produced greater growth and greater yields in the ploughed plots than in the tine‐cultivated soil in the unfertilized plots of two of the soils. When the plots were manured the differences between the cultivation treatments disappeared in the richer soils but persisted between ploughing and one or both types of tine cultivation in poor soils, according to the fertility status of the soil.3. The type of cultivation affected the vegetative growth of the crop more than the grain production in the unfertilized plots of the richer soil: straw/grain ratios differed significantly, varying from 1.53 for deep ploughing to 1.42 and 1.35 for deep and shallow tine‐cultivation respectively; the grain yields, however, showed no significant difference due to cultivation treatment.No such cultivation effects on straw/grain ratios were apparent in the poor soil.4. The response of the crop to nitrogenous fertilizer varied with the type of cultivation; in the tine‐cultivated plots, it was twice as great as in the ploughed plots, indicating a greater nitrogen deficiency in the cultivated plots. Factors contributing to this are discussed.5. The level of fertility of a soil seemed to be the determining factor in its response to different types of cultivation. In a well drained and fertile soil, tine‐cultivation to a depth of 4 in., but not to a depth of 2 in., could replace ploughing if an application of nitrogen fertilizer was made to counteract the deficiency in nitrogen.