How To Do Small Grain Stand Counts

A stand count at the two to three leaf stage of wheat, barley or oats will verify if your efforts at planting paid off

By Dr. Jochum Wiersma,
University of Minnesota Small Grains Specialist
wiers002@tc.umn.edu

To achieve maximum grain yield potential, it is important that you begin with an optimal plant population.  Wheat (as other small grains) has the ability to tiller and produce several stems that can produce grain. Research has shown, however, that the main stem and the first tiller contribute the majority of the grain yield. It is therefore important that the population planted is such that most plants will produce only a main stem and one or two tillers. 

An additional advantage is that the crop will be largely in the same growth stage, or at least relatively close, as tillers develop sequentially.  This narrower window for each crop stage improves the timing for crop inputs like herbicides or fungicides, especially if the inputs are growth-stage sensitive.

In the Northern Plains, the average optimum stand for hard red spring wheat when planted early is between 28 to 30 plants per square foot or approximately 1.25 million plants per acre.  This number should increase by 1 to 2 plants per square foot for every week planting is delayed (or 1% for each day planting is delayed) past the early optimum seeding date. This increase in seeding rate will partially compensate for the decrease in grain yield, and the reduction in tillering, as the crop will go through its development faster as average temperatures increase during the growing season.

To attain an optimum stand, calculate a seeding rate and calibrate your drill accordingly (for more information on variety specific seeding rates, see the March 2001 Prairie Grains, archived online at www. smallgrains.org). Expected stand loss even under good seedbed conditions is 10% to 20% and will increase with a poor seedbed or improper seed placement due to poor depth control.

After the crop has come up, how do you know if the stand is sufficient enough for maximized yield potential? A stand count at the two to three leaf stage of wheat, barley or oats will verify if your efforts at planting paid off. This is probably the easiest time to do a stand count since tillers are not visible yet, and counting is easier. You can also combine this with scouting for weeds.

To do a stand count, use one of the following two methods:

1. Count the number of plants in a foot of row at several locations in the field. Take an average and convert in plants per acre using Table 1.

Table 1. Average number of plants per foot of row for different row spacing and plant densities per acre. Row Width Plants per acre (times 1 million)   0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 6” 9.2 10.3 11.5 12.6 13.8 14.9 16.1 17.2 7” 10.7 12.1 13.4 14.7 16.1 17.4 18.7 20.1 10” 15.3 17.2 19.1 21.0 23.0 24.9 26.8 28.7 12” 18.4 20.7 23.0 25.3 27.5 29.8 32.1 34.4

2. Take a hula-hoop, let it fall, and count the number of plants inside the hoop.  Repeat this at random several times across the field and calculate an average. Use Table 2 to convert the count to an approximate population per square foot or acre.

Table 2. Adjustment factors to multiply the number of plants inside a hoop and convert the number to number of plants per acre. Hoop Diameter Multiply by 30” 8,900 32” 7,800 34” 6,900 36” 6,200 38” 5,500

Deciding Whether to Replant
Assume you wanted a stand of 1,300,000 plants per acre. That requires at least 30 plants per square foot. Replanting costs must be recovered from a later maturing crop that has a lower yield potential than original crop. Plus, replanting uses extra moisture as a function of soil disturbance.

Use the following guidelines to determine whether replanting is worthwhile:

1. If reduced stand is uniform (no big skips or holes) keep stands of 15 plants per square foot. This is a bare minimum and yield reductions will occur as compared to the optimum stand.

2. If skips are large (3 to 6 ft.), or holes are 4 to 6 feet in diameter and stand is 18 plants per square foot or less, then replant if moisture is adequate.

3. After June 1 in northern Minnesota, and May 15 in southern Minnesota, a replant decision should be to a crop other than wheat or barley since yields are reduced by about 50% when planting after these dates compared to normal planting dates.

You’ll find more small grain production tips from “The Minnesota Small Grains Production Field Guide,” published by the University of Minnesota and the Minnesota Wheat Research and Promotion Council. The Minnesota Wheat Checkoff sponsored the development of 10,000 copies of this book, distributed to grain growers throughout Minnesota and made available online, at www.smallgrains.org.