The Contribution of Subsoil Phosphorus to the Nutrition of Alfalfa as Influenced by Soil Temperature

Author

Reuel E. Lamborn, Utah State University

Date of Award:

5-1975

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Soil Science and Biometeorology

Committee Chair(s)

David W. James

Committee

David W. James

Abstract

High bicarbonate-soluble phosphorus (P) in some Utah subsoils may affect the validity of fertilizer recommendations based on plow layer samples. The primary objective of this experiment was to determine the proportion of plant P derived from subsoils at typical Utah soil P levels and soil temperatures.

A calcareous soil very low in bicarbonate-soluble P was treated with various amounts of P and packed into deep pots to provide 24 centimeters of "topsoil" and 27 centimeters of "subsoil". Water baths in a growth chamber were used to control soil temperatures at 14 centigrade and 20 centigrade. Light, air temperature and humidity were varied. The treated soils were analyzed for NaHCO₃-P before and after cropping, and changes were related to plant P uptake.

At a topsoil NaHCO₃-P level of 17 parts per million, subsoil apparently contributed no more than ten percent of the plant P in the harvested tops unless subsoil P was greater than five parts per million. At lower levels of topsoil P, subsoil P became more important. When topsoil P was five parts per million or less, 20 to 67 percent of the plant P came from the subsoils.

Checksum

93da425bc5b9f94dc98c555be0f0bdc3

Recommended Citation

Lamborn, Reuel E., "The Contribution of Subsoil Phosphorus to the Nutrition of Alfalfa as Influenced by Soil Temperature" (1975). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 3782.
https://digitalcommons.usu.edu/etd/3782