Em4885 irrigation management practices to protect ground water

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CHAPTER 4
IP 3.02.05 - Apply Seasonal Fertilizer Requirements with Multiple Applications
Objective
Reduce amount of nutrients available for detachment and transport through leaching
or surface runoff.
Description
This practice seeks to reduce the amount of nutrients available for leaching or runoff by
reducing the amount of nutrients in the root zone at any one time. Depending on the crop
there may be yield and quality benefits either because of not over-fertilizing at any one
time during the season or because of improved nutrient availability during latter parts of
the season.
The economics of this Practice include the cost of multiple applications versus the savings
in unavoidable nitrogen losses due to leaching, denitrification, or volatilization, and the
possible yield and quality benefits.
The multiple applications should be done with guidance from soil, plant, and material
testing as per IPs 3.02.01, 3.02.02, 3.02.03, and 3.02.04. Multiple applications are only
beneficial if the applications are not excessive.
IP 3.02.06 - Use Slow-Release Nitrogen Fertilizers
Objective
Reduce amount of nitrate-nitrogen in the root zone.
Description
+ - Nitrification converts nitrogen in the ammonium form (NH ) to the nitrate form (NO3 ).
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The nitrate form is highly soluble and moves readily with soil water. Thus, it is highly
susceptible to leaching. Slow-release fertilizers release nitrogen slowly to the root zone
at a rate closer to the rate of plant utilization. Hence, the amount of nitrate-nitrogen
available for leaching is reduced.
There are several factors that may affect the actual rate of nitrogen released. These include
soil temperature and soil water content. The rate of release must match crop requirements.
The effectiveness of this practice depends on site conditions and type of crop. Conditions
contributing to effective use are a light soil and a crop that requires relatively low
concentrations of nitrogen over a long period of time.