See more from this Session: Phosphorus and Potassium Management: I
Placement of solid cattle manure (SCM) may influence the supply of inorganic nutrient ions at the soil surface that are available for biological uptake and interaction with run-off water. The objective of this study was to determine the effect of different SCM placement methods on soil PO4 –P and NO3-N supply rates at the soil surface over two growing seasons. Anion exchange membrane probes (PRSä) were inserted at a depth of 1 cm for a 2 hr period every 2 weeks over an 8 week period in plots that had SCM applied in the spring at 60 t ha-1 using broadcast alone, broadcast and incorporated and subsurface injection placement methods. During the first 30 days after seeding, the application of SCM significantly (p≤0.10) increased the supply of P compared to control treated plots. In subsurface injection treatment in 2008, the soil PO4-P supply increased from 1.17 µg P cm-2 2hr-1 immediately following seeding operations to 2.12 µg P cm-2 2hr-1 six weeks after seeding. Overall, there was no significant effect of placement method on surface soil phosphate supply. Eight weeks after seeding in 2009, soil NO3-N supply rates ranged from 0.45 µg NO3-N cm-2 2hr-1 in the broadcast alone treatment to 0.92 µg NO3-N cm-2 2hr-1 in the subsurface banded treatment. Placement of SCM in subsurface bands resulted in higher supply rates of NO3-N compared to other placement methods possibly due to enhanced mineralization when manure is placed below the surface.