Thinking About Collecting Yield Data With Your Combine?

By Eric Anderson

There are two general ways to measure yield during grain harvest. The simplest, low-tech method is to transfer each load from the combine to a grain cart equipped with load cells or a truck that is then taken to local scales to get a per-load weight. In this case, a grain sample should be measured with a calibrated moisture tester to calculate bushels per acre at standard moisture levels (13% for soybean, 15.5% for corn, 13.5% for wheat).

Yield can only be determined for the area harvested with a given load, or for the entire field, which is perfectly fine if that is your only goal. However, to take measurements continuously across the field to generate a yield map, a system of yield monitoring must be in place and maintained properly. We work with farmers using both methods in the Michigan Soybean On-Farm Research Program. However, this article will focus on the latter system.

Yield monitors have been available since the early 1990s, although for many years most farmers were only generating “pretty pictures” of yield with little actionable usefulness. More recently, farmers and agronomists have been using yield data to create management zones and prescriptions for planting and making applications of lime and fertilizer.

Another reason for creating quality yield maps is to track profitability over time across a crop rotation. Collecting accurate yield data from the combine is essential because it provides a detailed view of crop productivity, highlighting areas of high, medium, and low yield over time (Figure 1). Using these data, we can calculate net profitability by subtracting production costs from the revenue (yield multiplied by grain price). The result is a profitability map that shows where we’re making or losing money in the field. Creating zones based on these yields can help farmers make management decisions with land use to determine ways to improve their profitability of entire fields.

Yield data is a critical input for generating these tools, so it is important to make sure the data are accurate and precise. You have likely heard the phrase “garbage in, garbage out” applied to crop harvest data quality and the ability to make management decisions based on yield maps, so here are several steps you can take to prepare to collect quality yield data.

Before harvest season

• Scout fields in-season to look for patterns or areas of concern, e.g., ponding/saturation, wildlife damage, sandy/dry ridges, intense insect/disease pressure.
  • Consider capturing aerial imagery to overlay onto yield map, or create .shp files using GIS software.
  • Use this information to decide what areas to remove from data analysis when performing comparative trials, e.g., varieties, fertilizer or pest management products.
• Back up all precision data collected in past years in separate folders for each year and clear old data from the yield monitor to make data download faster at the end of the season.
• Ensure all farm employees have basic training on how to use monitors and that all monitors are feeding properly into your data management platform, if applicable, especially if more than one combine will be used in a given field.
• Inspect combine and grain handling equipment, repair areas where leaks may occur.
• Make sure monitor firmware is up to date.