Determining a critical nitrogen dilution curve for sugarcane |
| |
Authors: | Emídio Cantídio Almeida de Oliveira Glauber José de Castro Gava Paulo Cesar Ocheuze Trivelin Rafael Otto Henrique Coutinho Junqueira Franco |
| |
Institution: | 1. Federal Rural University of Pernambuco (UFRPE), Agronomy Department, Soil Science Area, Rua Dom Manoel de Medeiras, Zip Code 52171‐900, Recife, PE, Brazil;2. S?o Paulo State Agribusiness Technology Agency (APTA), Mail Box 66, Zip Code 17201‐970, Jaú, SP, Brazil;3. Center for Nuclear Energy in Agriculture (CENA), Stable Isotope Laboratory, Av. Centenário 303, Mail Box 96, Zip Code 13400‐970, Piracicaba, SP, Brazil;4. “Luiz de Queiroz” College of Agriculture (ESALQ), Av. Pádua Dias 11, Mail Box 9, Zip Code 13418‐900, Piracicaba, SP, Brazil;5. Brazilian Bioethanol Science and Technology Laboratory (CTBE), Mail Box 6170, Zip Code 13083‐970, Campinas, SP, Brazil |
| |
Abstract: | Adequate measurements of the nitrogen (N) concentration in the aboveground biomass of sugarcane throughout the growth cycle can be obtained using the critical N dilution curve (CNDC) concept, which provides an N‐nutrition index (NNI). The aim of this work was to determine the CNDC value for Brazilian sugarcane variety SP81‐3250, establish the critical concentration of N, and determine the NNI in the aboveground biomass throughout the cane plant and first ratoon crop cycles. The study was performed in three experimental areas located in São Paulo, Brazil, during the crop cycles of 2005/2006 (18‐month cane plant) and 2006/2007 (first ratoon). The plant cane crop was fertilized with treatments of 40, 80, or 120 kg N ha–1 and a control treatment without N. After the plant cane harvest, rates of 0, 50, 100, or 150 kg N ha–1 were applied to the control plot and the 120 kg N ha–1–treatment plot in a split‐plot experimental design with four repetitions. Throughout both sugarcane cycles, measurements of aboveground biomass were used to determine the dry‐mass (DM) production and N concentration for each treatment. CNDC varied between the growth cycles, with a higher N concentration observed in the initial stages of the first ratoon and a lower N dilution observed throughout the plant cane cycle. The NNI value indicated excessive N storage in the initial stages and limiting concentrations at the end of the growth cycle. CNDC and NNI allow for the identification of the N‐nutrition variation rate and the period in which the nutrient concentration limits the production of aboveground biomass. The equations for the critical N (Ncr) level obtained in this study for plant cane (Ncr = 19.0 DM–0.369) and ratoons (Ncr = 20.3 DM–0.469) can potentially be used as N‐nutritional diagnostic parameters for sugarcane N nutrition. |
| |
Keywords: | N fertilization potential equation critical nitrogen level N nutrition index Saccharum spp |
|
|