Nitrogen, Phosphorus, and Potassium Availability in Manure- and Sewage Sludge–Applied Soil

A field experiment with wheat (Triticum aestivum L.) was established over two growing seasons where farmyard manure and sewage sludge, along with conventional fertilizer, were added to soil. We found that ammonium N was at greater concentrations in the organic amendments treatments, indicating more beneficial dynamics (i.e., it can be taken up by plants for a greater amount of time) and thus a longer lasting effect as a nutrient for the test crop. We found that nitrogen (N), phosphorus (P), and potassium (K) uptake increased with added organic amendments. This means that when organic matter along with nutrients are added to soil, productivity may increase beyond preset targets because soil conditions greatly improve, not only chemically but also physically. Nitrates left over at the end of the growing season (residual N) were greater in the high sewage sludge and manure treatments, but not proportionally.