Wirkungen meliorativer Gaben von Gesteinsmehlen und Gesteinssanden auf das Wachstum verschiedener landwirtschaftlicher Kulturpflanzen sowie auf physikalische Kennwerte eines Sandbodens und eines Tonbodens

Effect of amelioration doses of rock powder and rock sand on growth of agricultural plants and on physical characteristics of sandy and clay soil The effect of rock powder to increase the water holding capacity and adsorption degree of sandy soil and the influence of rock sand to augment the aeration and improve the workability of clay soil were tested in pot experiments. Additions of different rock powders (Basalt, Grauwacke, Kuselit, Muschelkalk and Porphyr) from 5 to 20 weight percent to sandy soil increased the field capacity; the increase in values ranged from 12 to 23% as compared to control. An 11% increase in coarse pore volume (< pF 1.8) of clay soil was noticed when 10 weight percent rock sand was mixed in it. The shear strength of clay soil was hardly decreased. In short time tests five different plants reacted mostly positive to rock powders in sandy soil, the degree of reaction being different depending on rock type and amount used whereas in clay soil the reaction was slightly negative. Ten percent weight additions were better than 20 percent. Up to 67% increase in spring barley grain yield was registered in sandy soil with addition of 10 weight percent of different rock powders both at about 40 and 80% field capacity water levels. High N-application i.e., 1600 mg N/7 kg soil caused a depression in yield at control whereas it increased the dry matter yield in treated pots. In clay soil at 80% field capacity an increase in grain yield was registered only in Grauwacke and Basalt treatments, which was off set at high N-level. Porphyr and Kuselit treatments produced yield depressions. Addition of 10 weight percent of rock powders in sandy soil in the first year of experiment reduced the amount of leachate and nitrate leached between 8 to 29% in fallow treatments, but in planted treatments these were dependant on plant type and rock type even showing an increase in one case.