How to Estimate Grain Harvest Losses

Studies have shown that losses off the combine can run as high as 20%, even with a properly adjusted machine when it is overloaded. A reasonable loss is considered to be 3% of the total crop or less. Total harvest losses are seldom if ever zero.Usually over 60% of the grain left in the field is due to shattering

of the crop and grain lost in getting it cut and into the combine header. Once the crop is in the combine, loss is very low with properly adjusted and operated equipment.

To keep harvest loss low, determine how much grain is being left in the field. A simple, accurate method to estimate losses requires the use of a one-foot square frame. Pick several typical areas in the field after the combine has passed and follow these steps.1. Count the kernels left directly behind the rear of the combine. Count several

separate square foot areas (A- Figure 1).2. Count the kernels already in the field due to shatter and cutter bar loss (B- Figure 1).3. Subtract (B) from (A).4. Divide the results of Step 3 by the ratio of: Width of windrower/header width (ft) Width of combine (ft).5. Divide the result of Step 4 by the number of kernels for the particular crop from the Table 1 (below) for one bushel per acre loss. This is the approximate machinery loss in bushels per acre.6. To find total loss, add the count in (B) to the result in Step 4. This gives the total seed count from shatter, cutter

bar and machine loss.7. Divide the total seed count of Step 6 by the number

of kernels for the particular

crop for one bushel per acre loss (Table 1). This will give the approximate total loss in bushels per acre.8. For a percentage loss, divide the loss in Step 7 (loss in bushels per acre) by the total yield (harvest yield plus loss) in bushels per acre for the field.

*These are average numbers from past seasons, and individual varieties or hybrids will vary among themselves as well as be influenced by environmental factors. Source: NDSU

Common Harvest Mistake: Leaving Too Much Residue in Windrows

We used to say that residue management started at harvest, but nowadays it is more prudent to say that residue management is an ongoing process. Knowing how much residue you are likely to have at the end of the harvest and making plans now to modify equipment to handle that residue will make residue management much easier.

Proper distribution of residue behind the combine is important. Wide combine headers (>15 feet) and high residue production with today’s varieties are two reasons a well-adjusted combine is critical to no-till farming. Without special attachments or modifications, combine headers of 20 to 30 feet or more are not adequately equipped to spread today’s volumes of residue uniformly.

The most common mistake made in the harvesting operation is to allow crop residue to accumulate in windrows behind the combine. This accumulation causes the soil under the windrows to stay wetter and cooler longer in the spring. Planting into windrows and chaff rows can result in uneven stands, because seeds take longer to germinate and grow, resulting in significant yield reductions. Other problems associated with improper combine residue distribution include:

Unsatisfactory weed control from herbicide interception.

Poor performance of planters, drills and tillage equipment (particularly in a no-till system).

Poor seed soil contact (usually from hair pinning of residue into the seed row).

Excessive residue laying directly over the seed furrow, resulting in conditions that could inhibit germination or growth.

Increased pest infestation (from insects and rodents). Increased weed seed concentration.

Poor plant nutrient uptake (from fertilizer tie-up or interception).

To avoid these problems, make sure you always check residue distribution patterns of your equipment, whether it is new or used. The other thing you can do is to consider incorporating some residue spreading attachments. A straw spreader uses rotating blades or rubber batts to throw or deflect whole pieces of crop residue. While the spreader typically distributes the residuemore uniformly, the straw chopper can provide more residue cover, since it chops the residue into small pieces before spreading. A straw spreader is effective in handling fine materials primarily from harvest of small grains.

The most commonly used chaff spreading attachments are hydraulically driven single or dual spinning disks that have rubber batts attached. Generally, single disk spreaders are most effective for headers under 20 feet, while dual spreaders are more effectivefor wider headers.

Rainfall, high temperatures, fall tillage, or knifed in fertilizer applications can all speed the decomposition of crop residues between harvest and planting. As long as moisture is available, decomposition can occur when temperatures are above 50F. Even when air temperatures drop below freezing, snow can actually act as an insulator and allow decomposition to continue. Residue from canola, beans, peas, fall-seeded cover crops, potatoes, sugar beets, and sunflower decomposes at a faster rate than residue from alfalfa, corn, grass hay, oats, sorghum, or wheat.