Changes in the subsoil of long-term trials in Halle (Saale), Germany, caused by mineral fertilization

Abstract

Four long‐term mineral fertilization trials (50 years) on a Haplic Phaeozem derived from sandy loess were conducted. Fertilization caused changes to the plough layer (0—25 cm) and to the undisturbed subsoil. Without lime, most remarkable acidification occurred in the plough layer, but only slight effects were evident in the subsoil. Where lime was applied, a considerable amount of Ca‐sulphate was formed. This leached out of the plough layer and accumulated throughout the profile, especially in dry years. Where fertilization was not adequate, there was a substantial contribution of K and P from the subsoil (mainly of its upper parts). Where the supply of these two elements continously exceeded their removal, a distinct increase of available K and P at depths of about 50 cm indicated transfer of both elements to the subsoil. Due to the high fixing capacity of both P and K in layers beneath 50 cm, leaching out of the rooting zone can be ignored. Mg and especially Na, applied with some of the fertilizers, were more mobile than K.

Phosphorus fractions in bulk subsoil and its biopore systems

“…This study's first aim was to quantify the contents and stocks of P in the subsoil and its biopore systems. The amount of total P allocated below the Ap horizon (68%) was in the same range as found in earlier studies of German loess soils (Garz et al , ), and indicates the importance of subsoil P resources. As P contents varied only a little between soil depths, the large contribution of the subsoil at 30–105 cm to the overall P stocks was mainly caused by the larger soil volume of the subsoil relative to that of the Ap horizon.…”

Occurrence, formation, and micromorphology of gypsum in soils from the Central-German Chernozem region

“…Similar observations on the occurrence of gypsum have been described by Garz et al (2000) for the longterm mineral fertilization trials in Halle (Saale), which are situated in the eastern part of the Central-German Chernozem region, about 15 km NE of the studied area. For the different fertilization trials, it was found that the amount of gypsum is related to the kind of fertilizer applied.…”

“…The formation of these relatively large amounts of gypsum cannot be explained by effects from mineral fertilization alone. Garz et al (2000) assumed that a considerable part of gypsum was formed by the reaction of atmogenic sulfuric acid with different Ca-sources, exchangeable Ca 2+ from the soil, calcareous dust from the air, and applied CaCO 3 . Because of limited leaching, gypsum accumulated at N40 cm depth.…”

“…The presence of gypsum in the Haplic Phaeozem of the long-term trials in Halle (Saale), which are located in the eastern part of the Central-German Chernozem region, was reported by Garz (1995) and Garz et al (2000). About 200 km east of Halle (Saale), noticeable amounts of gypsum are described for pyritic mine soils of the Lusatian lignite mining district around Cottbus (Heinkele et al, 2001;Neumann, 1999).…”

Phosphorus in Agriculture: 100 % Zero

“…This shows the importance of unaccounted soil reserves, e.g., P from the subsoil (Garz et al 2000), and its buffering capacity in practice. This shows the importance of unaccounted soil reserves, e.g., P from the subsoil (Garz et al 2000), and its buffering capacity in practice.…”