DAIRY MANURE AND NITROGEN FERTILIZER EFFECTS ON RESIDUAL NITRATE AND PHOSPHATE, AND WHEAT YIELD IN A SANDY CLAY LOAM SOIL

Abstract

Dairy manure (DM) rates of [0 (DM₀), 30 (DM₃₀₎), 60 (DM₆₀) Mg ha⁻¹] and three nitrogen (N) rates [0 (N₀), 125 (N₁₂₅), 250 (N₂₅₀) kg ha⁻¹] were tested in a sandy clay loam, to evaluate their effects on growth and yield of wheat crop (Triticum aestivum L.), residual nitrate nitrogen (NO₃-N) and phosphorus (P) concentrations in the surface soil, and selected soil physical measurements [saturated hydraulic conductivity (Ksat), and bulk density (BD)]. Increasing N and DM rates gave higher wheat yields, increased concentrations of residual NO₃-N and P in the surface soil and improved Ksat and BD. Highest grain yield of 3.8 Mg ha⁻¹ (70.3% more than the control) was observed in DM₆₀ × N₂₅₀ treatment. Residual accumulation of N-NO₃ and P in the surface soil at high N and/or DM application rates suggests the need to carefully manage N and DM inputs on farm fields to avoid environmental contamination.

Keywords:

• manure
• nitrogen
• phosphorus
• nitrate accumulation
• wheat yield