To Dry or Not to Dry?

If drying is unavoidable, consider allowing crops to dry in the field as much as possible to reduce energy costs. Keep in mind, however, that there is a point where field losses will increase. The University of Kentucky’s Grain Storage System Website provides a calculator to estimate the cost of harvest losses versus drying costs [1]. This tool also links to a publication by Huitink on estimating field losses [2].

The moisture content of the standing grain at harvest initiation will depend on weather conditions, the amount of grain to harvest and harvest and drying capacity. Corn kernel mechanical damage during harvest is usually lowest between 19 percent to 24 percent moisture [3,4].

It is important not to dry more than necessary. Drying grain to a moisture content lower than required removes water that would otherwise be sold (0.65 pounds per percentage point of moisture per bushel).When grain is dried more than is necessary, drying costs will rise while income from grain sales will be reduced. If 1000 bushels of corn was dried to 12% instead of 15%, this would result in a 3.4% shrink loss or a reduction of 34 bushels to sell [6]. Table 1 lists the recommended grain moisture levels depending on the expected length of storage.

When using mechanical drying, grain with large amounts of foreign material should be cleaned before drying to reduce the amount of energy used to dry foreign material and to increase airflow during drying and storage. Using heat recovery, using the maximum plenum temperature and dryers with features such as grain turners or staged temperature dryers can also help reduce energy use. Processes such as combination drying, in-bin cooling and dryeration can increase dryer capacity, reduce energy use and improve grain quality.

Drying with warmer outdoor air temperatures reduces the energy required to dry for both natural-air/ambient-air drying and high temperature drying. Higher relative humidity or colder air temperature will increase drying costs.

 

Table 1. 1) Reduce by 1% if grain in poor condition at time of storage 2) If temperatures are maintained at less than 40°F 3) South of 40 degree latitude, storage moisture contents should be reduced by about 1 percent (3). Source: Scott Sanford