Quadrant Count Method to Quantify within Field Variability of Corn Silage on Three New York Farms.

To improve yield and nitrogen (N) management of corn (Zea mays L.), knowledge about within field as well as whole field yield and yield stability over years is essential. Yield monitor data from self-propelled forage harvesters can be used to assess forage yield and to monitor yield over time. Here we propose a way to analyze corn yield data obtained over a minimum of three years to develop yield-based management zones that incorporate both yield level and yield stability (coefficient of variance (CV) of yield over years). Field from three case study farms were divided in one of four quadrants: (1) high yield, low CV (Q1); (2) high yield, high CV (Q2); (3) low yield, high CV (Q3); and (4) low yield, low CV (Q4). Within-field variability was estimated using a 10 m grid size for two fields per farm. The fields from Q1 had a higher percentage of area of the field that was high yielding/low variability. Likewise, fields that were in Q3 had a higher percentage of the field that was low yielding/high variability. However, each field, independent of whole farm average, contained variability in yield and yield stability that was large enough to justify use of precision agriculture technologies.