Ohio usually is not considered to be a dry state, but periods of dry weather are often capable of stressing crops and limiting yields. Rainfall usually exceeds crop water use during spring and early summer. However, in most areas of the state, late-season water use by crops exceeds what is supplied by precipitation, creating the potential for stress unless a reserve of moisture has been accumulated from previous rains. Several practices can help make the best use of the water available throughout the growing season.
Practices that promote vigorous rooting allow plants to explore the soil to a maximum extent and utilize much of the water in the soil profile. Practices that limit compaction will limit the occurrence of impenetrable zones in the soil. Subsurface drainage improvements on wet soils allow roots to penetrate more deeply into the soil and make better use of water deeper in the profile. Rotating crops also can promote more extensive rooting by reducing root predation by soil insects and pathogens, and possibly by reducing the concentrations of autotoxic substances in the soil.
Crop residues on the soil surface do more than increase infiltration on crusting soil; they also reduce evaporation of soil water. This results in more soil water being potentially available for crop use. Adopting tillage and cropping systems that leave significant quantities of residues on the soil surface is beneficial, particularly on well-drained soils; however, on more poorly drained sites, such systems are most effective when used in conjunction with a drainage system that quickly removes excess water as it accumulates. Yield reductions can occur if too much water accumulates in the soil.
Proper timing of forage harvests can save large quantities of water for later growth. As forage crops approach the recommended stages for cutting, the amount of dry matter produced for every gallon of water used declines rapidly. Water is being used to maintain plants rather than to support further accumulation of useful forage. Harvesting at the recommended time reduces the total amount of water used by that cutting, conserving moisture to support future growth.
Matching plant densities to soil conditions helps convert the available water into the best possible yields. Whereas high densities may be appropriate on soils rarely subject to drought—such as Kokomo or Pewamo—densities on sands, eroded knobs, and other drought-prone soils should be lower. This allows the overall population of plants to make the most grain per gallon of water available. When planting at low densities, it is important to plant varieties that have an acceptable yield potential at lower populations.