Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Afrique du Sud → 2001 → The effects of surface-applied poultry manure on top- and subsoil acidity and selected soil fertility characteristics.

University of KwaZulu-Natal (2001)

The effects of surface-applied poultry manure on top- and subsoil acidity and selected soil fertility characteristics.

Judge, Angus

Titre : The effects of surface-applied poultry manure on top- and subsoil acidity and selected soil fertility characteristics.

Auteur : Judge, Angus.

Université de soutenance : University of KwaZulu-Natal

Grade : MASTER OF SCIENCE IN AGRICULTURE 2001

Résumé partiel
The effects of surface applications of poultry manure on pH, exchangeable AI, exchangeable Al saturation and levels of available macronutrients in the surface and subsurface layers were investigated in some acid soils from the KwaZulu-Natal Midlands. Three field sites with a history of long-term applications of poultry manure were compared with adjacent fields where no manure had been applied. Results generally showed an increase in pHwater, pHKCI, exchangeable Ca, Mg, and K and extractable P and a decrease in exchangeable Al and exchangeable Al saturation in the surface soil to the depth to which the manure had been incorporated. Results also provided evidence for substantial downward movement of Ca and Mg into the subsoil layers (i.e. 30-60 cm) and their accumulation in exchangeable forms. There was a concomitant general increase in pHKcl and pHwater and decrease in exchangeable Al and exchangeable AI saturation in the subsoil layers. These results demonstrate that, under field conditions, surface applications of poultry manure can cause the amelioration of subsoil acidity. This is an extremely important finding since subsoil acidity is characteristically extremely difficult and costly to ameliorate. A leaching column study was subsequently conducted to investigate the mechanisms by which surface applications of poultry manure ameliorate both top- and subsoil acidity. The soil used, originating from one of the field sites, had not previously been treated with poultry manure and had a subsoil pHKCI of 4.25 and an exchangeable acidity concentration of 1.79 cmolJkg. Three forms of poultry manure (layer, broiler and free range) were incorporated into the surface 5 cm of soil columns at rates equivalent to 5, 10 and 30 Mg/ha. Columns were maintained in glasshouse conditions for a period of 108 days and over that period they were leached on four separate occasions (receiving a total of 825 mm of simulated rainfall). At the conclusion of the experiment, the soil columns were cut into sections for chemical analysis. Applications of poultry manure to the surface soil markedly increased pHwater, pHKcl, exchangeable Ca, Mg, K and Na concentrations and decreased exchangeable Al levels in the surface 5 cm layer. They also increased the concentrations of soluble C, soluble salts, total Al and organically-complexed Al in soil solution.

Présentation

Version intégrale (5,7 Mb)

Page publiée le 5 mars 2021