|BORTOLON, LEANDRO - Embrapa|
|THOMPSON, MICHAEL - Iowa State University|
|GIANELLO, CLESIO - Federal University Of Rio Grande Do Sul|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2015
Publication Date: 6/26/2015
Citation: Bortolon, L., Kovar, J.L., Thompson, M.L., Gianello, C. 2015. Nutrient depletion from rhizosphere solution by maize grown in soil with long-term compost amendment. Rhizosphere 4 Proceedings. In: van Veen, H. Rhizophhere 4 Proceedings. June 21,25, 2015, Maastrict, The Netherlands. Available: http://www.rhizo4.org/sites/default/files/ALL%20ABSTRACTS_0.pdf.
Technical Abstract: Improved understanding of rhizosphere chemistry will enhance our ability to model nutrient dynamics and on a broader scale, to develop effective management strategies for applied plant nutrients. With a controlled-climate study, we evaluated in situ changes in macro-nutrient concentrations in the rhizosphere of juvenile maize (Zea mays L.) grown in soil (fine-loamy, mixed, superactive, mesic, Typic Hapludoll) amended with cattle (Bos taurus L.) manure compost. Soil was collected from two depths within a 10-yr. no-till study, so that nutrient stratification could be investigated. Maize seedlings at the two-leaf stage were transplanted into mini-rhizotrons, and grown for five days. Moist soil (550 g dry weight) collected from the 0-5 cm layer was placed in one compartment of a vertically divided mini-rhizotron, and soil from the 5-10 cm layer was placed in the other compartment. Micro-capillaries (15 per chamber) were used to collect rhizosphere and bulk soil solution at 24-h intervals. Samples were analyzed for pH and phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentrations. Shoot dry matter production was similar in the two soil materials (0.65 g/plant in the 0-5 cm layer and 0.60 g/plant in the 5-10 cm layer), suggesting that nutrient availability was not limiting. Phosphorus concentrations in solution were similar in the two soil layers, but were lower at the root surface. Potassium concentrations were higher in the surface soil material, but did not change with distance from the root surface. Solution pH and Ca and Mg concentrations did not differ among the soil layers and distances from the root surface. From a practical perspective, results indicate that significant differences in rhizosphere solution chemistry can develop quickly. From a crop production point of view, the use of compost can be a means to reduce the inputs of mineral P and K fertilizer.