Soil health practices like no-till and cover crops can play a large role on your water quality. But when exactly does nitrogen and phosphorus tend to leave a field? And when or what should you be doing when it becomes a problem?
“The months of January through March, occasionally even into April, witness significant surface runoff,” explains Amber Radatz, Extension Ag Water Quality Program Manager. “This is primarily caused by snow melts or rain on frozen ground, restricting soil infiltration. Additionally, late spring runoff, observed in April or May, is caused by intense storms or saturated soil from consecutive rainfalls.”
While nitrogen commonly leaches through the soil profile rather than running off directly, the leaching mostly occurs during off-seasons. This can span from fall to the subsequent spring when no crops are growing.
Understanding and measuring this leaching process remains a complex task. However the use of pan lysimeters buried within fields at specific depths aid in sampling water leaching through the soil profile. These steel boxes allow for water collection, offering insights into the nitrogen content and movement.
Efforts to enhance water quality often involve cost-effective measures. Simple adjustments like aligning nutrient applications closer to the crop’s needs, managing erosion, and encouraging cover crops’ establishment significantly impact nitrogen retention.
Looking ahead, Radatz says, “We aim to address phosphorus movement off the soil surface by implementing practices that hide phosphorus deeper in the soil. Our ongoing research continues to focus on soil health systems’ performance, particularly regarding cover crops’ impact on nutrient cycling and soil erosion.”
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