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

Accueil du site → Doctorat → États-Unis → 1986 → CLIMATE, TOPOGRAPHY, AND CULTIVATION EFFECTS ON CARBON, NITROGEN, AND PHOSPHORUS DYNAMICS IN CENTRAL GREAT PLAINS SOILS

Colorado State University (1986)

CLIMATE, TOPOGRAPHY, AND CULTIVATION EFFECTS ON CARBON, NITROGEN, AND PHOSPHORUS DYNAMICS IN CENTRAL GREAT PLAINS SOILS

HONEYCUTT, CHARLES WAYNE

Titre : CLIMATE, TOPOGRAPHY, AND CULTIVATION EFFECTS ON CARBON, NITROGEN, AND PHOSPHORUS DYNAMICS IN CENTRAL GREAT PLAINS SOILS

Auteur : HONEYCUTT, CHARLES WAYNE

Université de soutenance : Colorado State University

Grade : Doctor of Philosophy (PhD) 1986

Résumé
The importance of organic matter in maintaining soil productivity is widely recognized. A serious decline in organic matter is often observed upon cultivation. This study was conducted to evaluate the interactions of climate, topography, and cultivation on soil carbon, nitrogen, and phosphorus in the semiarid U.S. Central Great Plains. Paired rangeland and cultivated catenas were examined at 39, 44, and 51 cm of mean annual precipitation while holding parent material, cropping history, cropping pattern, range condition, slope gradient, and aspect relatively constant. The rangeland soils were used as a baseline to assess the effects of long-term cultivation. While holding mean annual temperature constant and progressing from 39 to 44 cm of precipitation, organic carbon and total nitrogen increased by 31 and 19%, respectively, on the rangeland summits. With a 0.8(DEGREES)C increase in mean annual temperature and an increase in precipitation from 44 to 51 cm, organic carbon and total nitrogen declined by 10 and 1%, respectively. Organic phosphorus was highest at 51cm of precipitation. In addition, the distribution of organic phosphorus with depth differed from organic carbon and total nitrogen. Consequently, organic phosphorus accumulation may be independent of organic carbon and total nitrogen accumulation. Upon progressing from summit to footslope positions within a given rangeland catena, organic carbon and total nitrogen increased by as much as 19 and 16%, respectively, indicating that topography exerts a significant control on these nutrient levels within a given macroclimate. Following long-term cultivation, losses of organic carbon, total nitrogen, and organic phosphorus generally appear to follow soil losses. Consequently, erosion may be the most significant process altering these nutrient contents, and their losses vary with topographic position primarily as a result of variable soil losses within a catena. Increased losses of organic carbon and total nitrogen were observed with increased effective precipitation on cultivated summit positions. This appears to reflect a climatic control on the initial carbon and nitrogen levels prior to cultivation, the predominant erosional process, the total amount of soil loss, and possibly the mineralization process.

Mots clés : Agronomy, Biological sciences

Search Oxford Libraries On Line (SOLO)

ProQuest : Dissertations & Theses

Page publiée le 11 avril 2015, mise à jour le 19 novembre 2018