367-5 Field Correlation and Calibration of Soil Nitrogen Tests in Sugarcane Production.

See more from this Division: SSSA Division: Nutrient Management & Soil & Plant Analysis
See more from this Session: Advances in Soil and Plant Analytical Techniques

Wednesday, November 18, 2015: 12:05 PM
Minneapolis Convention Center, 103 DE

Eduardo Mariano, Center for Nuclear Energy in Agriculture, University of Sao Paulo, Araras, SP, BRAZIL, Rafael Otto, Department of Soil Science, University of Sao Paulo, Piracicaba, Sao Paulo, BRAZIL, Heitor Cantarella, Soils and Environmental Resources Center, Agronomic Institute of Campinas, Campinas/SP, Brazil and Paulo C. O. Trivelin, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba/SP, Brazil
Abstract:
Currently, the recommendation of fertilizer N for sugarcane (Saccharum spp.) in Brazil is performed based on the concept of expected yield. The identification of a soil test that can predict N mineralization can help to improve N fertilizer use efficiency by this crop. The objectives of this study were to correlate and calibrate soil N tests with sugarcane N response parameters obtained under field conditions. Between 2006 and 2013, 21 sugarcane N-response trials were performed in the state of São Paulo, Brazil. Soil sampling was taken at 0-20 and 20-40 cm depths in control check plots (no N added). The following biological, chemical, microbiological and isotopic (15N) methods were tested: anaerobic incubation (ANI), permanganate oxidizable C (POXC), hot KCl extractable N (HKCl), phosphate-borate buffer at pH 11.2 extractable N (PBB), direct steam distillation (DSD), Illinois Soil N Test (ISNT), basal respiration (BR), induced basal respiration (BRi), soil microbial biomass C (SMB-C), induced metabolic quotient (qCO2i), microbial quotient (qMic), and gross N mineralization (GNM). The methods used to predict soil N supply were then correlated with stalk yield and N accumulation in the control treatment, relative stalk yield (RSY) and the N rate required to achieve 90% of the RSY of sugarcane (NR 90% RSY). No method was able to predict the soil N mineralization in sugarcane fields. Weak correlations were verified between ANI and stalk yield, and HKCl and PBB with N accumulation by the crop. Indexes did not correlate with RSY or NR 90% RSY, even when sites were grouped based on soil texture, fertilizer and by-product management or soil organic matter content. Thus, it can be concluded that none of the methods studied is recommended for adjusting N fertilizer rates to sugarcane ratoons in the state of São Paulo, Brazil.

See more from this Division: SSSA Division: Nutrient Management & Soil & Plant Analysis
See more from this Session: Advances in Soil and Plant Analytical Techniques

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