Zur Wirkung von Kalium auf ausgewählte bodenphysikalische Eigenschaften und den Wurzeltiefgang landwirtschaftlicher Kulturpflanzen

Abstract

Soil physical properties and root penetration (root depths, root growth rate) of various crops (sugar beet, corn, spring barley, winter barley) were studied in a long-term K-fertilization trial on loess chernozem in Bernburg, Germany. Over the last 14 years, annual K/Mg applications in the treatments were 0/0; 83.0/0; 41.5/4.5; 83.0/9.0; 124.5/13.5 kg ha⁻¹, respectively. In comparison with the unfertilized treatment, continuous K supply led to an increase in soil water content within the whole range of water retention function up to the permanent wilting point (pF 4.2). Higher soil K concentrations increased coarse pore volume and water capacity at comparable dry bulk density. At the highest K level (winter wheat), the storage capacity for plant-available soil water (available water capacity) of the topsoil (0–30 cm soil depth) increased by 6 mm (relatively 9%) in comparison with the unfertilized treatment. A favourable soil structure at the higher K level enhanced plant emergence and development in the early growth stages. This advance in plant development improved the root penetration of plough pan as well as the complete exploitation of the effective root zone. Plants with different root systems (tap roots or fasciculated root systems, respectively) showed similar response to increased K supply. Root growth rate was affected by annual weather conditions. K fertilization increased root growth rate within the first weeks after emergence, particularly in sugar beet and corn, but also in winter barley. The difference in spring barley was only significant in 2010.

Keywords:

• potassium
• long-term field trials
• rooting depth
• root penetration speed
• soil structure
• soil water retention function