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Water Management Key To Maximizing Yield

Resource:  2017 Crop -Tech Consulting Inc Corn & Soybean College notes

Along with air, sunlight, and soil (for nutrients), water is a necessity for plant growth.  However, besides wishing for rain when conditions are dry or hoping for sunshine when conditions are wet, we often overlook how we can manage water on our farms. 

Before we can manage water movement we have to understand soil and how plants access soil water for growth.  Soil type (sand / silt / clay) is defined by particle size which determines pore space and water holding capacity.  Sand has large pore spaces which is great for infiltration but poor for holding onto water.  Silt has smaller pores than sand but water can still infiltrate silt soils fairly quickly.  With smaller pores silt soils have a higher water holding capacity than sand.  Clay soils have the smallest pores which often causes very slow infiltration or ponding on the surface.  Yet, clay soils have the greatest water holding capacity of the 3 soil particle sizes.

Plants prefer to feed on nutrients and water in the top few inches of the soil profile.  There is the highest amount of root activity in this shallow zone, however plants will also have deep roots that they use during dry times and in-between rains to draw water from deeper in the soil profile.  If there is a sudden soil density change or compaction layer, plant roots may not be able to reach the subsurface water.  Horizontal tillage (disk, plow, etc.) will create a sudden soil density change, especially when tilled in the spring.  All tillage equipment will create a compaction layer if done when conditions are too wet.  Compaction layers stop water infiltration and root growth.  The soil above a compacted layer will dry out more quickly stressing plants whose roots are trapped above that layer, unable to reach subsurface water.

Another component of the water cycle that we can influence is water loss through evaporation and transpiration in our fields.  “Transpiration draws water from the plant leaves, drawing new water and nutrients into the plant.” Crop -Tech Consulting  Simply put, just like us plants sweat when standing out in the sun all day.  “Evaporation draws water from the soil surface.  This water leaves the root zone without benefiting the plant at all.” Crop -Tech Consulting   It is important to get canopy cover as early in the season as possible, to reduce water loss through evaporation and maximize plant usage of water through transpiration.  Management options to maximize canopy cover include: choosing hybrids or varieties with wide leaves and plant structure that allows for more row coverage; narrow row spacing; higher populations; earlier planting dates; and starter fertilizer to promote early plant growth.

On each farm our water management goals should include:

Resource:  2017 Crop -Tech Consulting Inc Corn & Soybean College notes

  1. Maximizing available soil water
  2. Maximizing root accessibility to available water
  3. Maximizing sunlight interception
  4. Minimizing water loss
  5. Maximizing fertility in soil zones of water uptake