Assessing potential damage, estimating wheat yields
With the lack of precipitation in late summer and fall in many areas of the state, winter wheat stands in some fields are questionable. This may be especially evident in continuous cropping situations. Dry conditions last fall and winter may have contributed to crown and root disease since dry soil warms up and cools down six times faster than moist soil. This alternating freezing and thawing will diminish the health of the wheat plant, damaging stands and decreasing yields.
This article will discuss two methods used to estimate wheat yields in the spring.
Understanding Seasonal Water Use
Winter wheat seasonal water use varies widely due to weather conditions, but generally it needs 16 to 24 inches. Using a midpoint of 20 inches, water use would be
- 4 inches from emergence to start of spring growth,
- 4 inches from start of spring growth to jointing,
- 2 inches from jointing to boot,
- 2.4 inches from boot to flower,
- 3 inches from flower to milk,
- 1.6 inches from milk to dough, and
- 3 inches from dough to maturity.
Normally it takes about 4-7 inches of water to get yield. For each inch of water above that, yield increases an average of 4-6.5 bushels per acre.
Estimating Wheat Yields Early
Wheat growers frequently need to estimate wheat yields in the spring to decide whether recropping is necessary. Determining a reasonable estimate of wheat yield allows growers to predict if it is in their best interest to destroy the wheat and plant a summer crop or leave the wheat for harvest. With little soil moisture in many areas of the state, the chance of a spring crop being successful is limited. In many situations, one will be better off leaving the winter wheat even though yield potential is low. The winter wheat crop usually has the field in better position for many crops that follow winter wheat. Before making such a decision, growers should be aware of any restrictions imposed by government programs, crop insurance, or previous herbicide use.
Several methods can be used to estimate winter wheat yield potential. This article will discuss two, both of which rely on several assumptions that may not be accurate for every season or situation. These assumptions presume that plants are healthy, soil moisture and nutrients are adequate, and that weeds, insects, and disease are not affecting yield. Added to the uncertainty of yield estimates is wheat’s ability to compensate for changes in the environment.