Accuracy of plant response potential to fertilization in nutritional diagnoses for phosphorus in sugarcane

Abstract

The Plant Response Potential to Fertilization (RPF) method, as it has been interpreted, may result in nutritional diagnoses with low efficiency. In this regard, this work aimed to validate the RPF criterion and determine the percent value to be considered as culm yield increase based on the accuracy of nutritional diagnoses for nutrient P in sugarcane by the CND method. The study used data collected from five experimental areas located in three municipalities in the state of São Paulo, Brazil, in 2013 crop year. Database comprised productivity and leaf contents of nutrients obtained from the reference population that indicated yields over 172 tons ha⁻¹. The CND indices were interpreted by the RPF criterion, with introduction of variable f, and accuracy was determined considering as insufficient diagnosis when the addition of P resulted in yields increase over 5; 10; 15; 20; 25; 30; 35 and 40% between the control situation and the response situation. The use of factor f = 0 in the IBNm adjustment allowed to obtain higher sugarcane culm yields or lower yield losses, which corresponds to the abandonment of interpretation of nutritional indices by the RPF method. The CND is effective in assessing the plants nutritional status when culm yield increases over 35 and 40% are used as reference between the control situation and the response situation with application of P in sugarcane crops.

Keywords:

• CND
• IBNm
• productivity
• validation
• Saccharum spp