Natasha E. Macnack1, Jonathan Kelly1, Jeremiah Mullock1 and William Raun2, (1)Plant and Soil Science, Oklahoma State University, Stillwater, OK (2)Plant and Soil Sciences, Oklahoma State University, Stillwater, OK
The algorithm presently used at Oklahoma State University for nitrogen (N) fertilizer recommendation utilizes the normalized difference vegetative index (NDVI) to predict yield potential. Besides NDVI other parameters such as plant height and stalk diameter can be utilized to predict yield. The objective of this study was to evaluate the use of stalk diameter and plant height to predict by-plant yield potential and thus refine current mid-season fertilizer recommendations. In this 3 year study conducted at five locations several rows of maize with varying rates of pre-plant fertilizer nitrogen (N) and varying plant densities were selected. Pre-plant N rates ranged from 0 to 160 kg N ha-1. Stalk diameter, plant height, plant spacing, and NDVI measurements were collected at growth stages V6, V8, V10, V12, and VT.
Results show that plant height x stalk diameter was highly correlated with by-plant grain yield and could thus be used to improve mid-season N recommendations in maize.