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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #363804

Research Project: Sustainable and Resilient Cropping Systems for Midwestern Landscapes

Location: Agroecosystems Management Research

Title: Use of a micro-capillary system to evaluate nutrient dynamics in rhizosphere soil solution of maize and soybean

item Kovar, John
item SITZMANN, TOMAS - Iowa State University
item MCDANIEL, MARSHALL - Iowa State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/11/2019
Publication Date: 7/11/2019
Citation: Kovar, J.L., Sitzmann, T.J., Mcdaniel, M.D. 2019. Use of a micro-capillary system to evaluate nutrient dynamics in rhizosphere soil solution of maize and soybean [abstract]. Rhizosphere 5. p. 161.

Interpretive Summary:

Technical Abstract: Knowledge of rhizosphere processes is essential for characterizing soil nutrient availability. The objective of this study was to evaluate macronutrient dynamics in the rhizosphere of juvenile maize (Zea mays L.) and soybean (Glycine max L. Merr.). Plants were grown in soil collected from a long-term phosphorus (P) fertilizer trial, with and without tillage. Undisturbed blocks of soil (3x9x33 cm) were collected from plots that had received no P fertilizer and plots that had received 33 kg P ha-1 y-1 for 25 years. Soil blocks were placed in two-chamber mini-rhizotrons, maize seedlings were transplanted at the two-leaf stage, and grown for ten days. Soybean seeds were sown directly into the rhizotrons, and grown for 12 days. Micro-capillaries (1-mm diameter; 15 per chamber) were used to collect rhizosphere soil solution that is to be analyzed for pH, P, potassium (K), calcium (Ca), and magnesium (Mg), as well as phosphatase and organic acids (citrate, oxalate, malate). Samples are collected on a daily (24-h) basis. In preliminary research, maize shoot dry matter production was two-fold greater in P-fertilized soil (1.43 g plant-1 versus 0.75 g plant-1). Further, mean rhizosphere solution pH and P concentrations decreased with time in both amended and unamended soil. Within each treatment, P concentrations in rhizosphere solution were similar in surface versus subsurface soil layers, but were lower at the root surface than in bulk soil. When sample analysis is complete, results will allow us to evaluate the effects of long-term fertilizer P application on soil pH, nutrient cycling in the rhizosphere, and the response of maize and soybean roots to differing soil P supply.