Methodology to estimate nitrate and potassium ion concentrations in soil using time domain reflectometry (TDR)

• Grant number: 08/05673-5
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2009
• End date: July 31, 2011
• Field of knowledge: Agronomical Sciences - Agricultural Engineering - Soil and Water Engineering
• Principal Investigator: Jarbas Honorio de Miranda
• Grantee: Jarbas Honorio de Miranda
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Monitoring ions in soil is one of the main practices of fertigation management, and there are few studies about the ionic condition evaluation of the soil solution generated by drip irrigation and usually have been used soil samples or for soil solution extractors, which present some limitations. In this sense, the Time Domain Reflectometry (TDR) is an alternative, once that allows the values obtaining of electric conductivity of the soil solution from the apparent electric conductivity, as well, the soil moisture. Therefore, allowing the establishment of relationships among solution electric conductivity of a specific ion in soil solution and relating with the apparent electric conductivity and soil moisture, with the estimated data, besides determining the ion distribution in soil profile in real time and with short time intervals, it's possible also to accomplish a nutritional balance of the respective ions in soil (nitrate and potassium, in case of the present research), being possible in futures stages to quantify the absorption of those nutrients by the plants. The main objective of the present research is the use of TDR for estimate, and proceed a nutritional balance of nitrate and potassium in soil. (AU)