N Leaching in Manured and Ammonium Nitrate Fertilized Lysimeters in Zimbabwe

Leaching of N was measured in eight lysimeters with maize (summer 1991/92) and wheat (winter 1992). In 1991/92, 100kg N ha−1 was applied as manure or ammonium nitrate in each set of four lysimeters and rainfall amounted to 391 mm. Wheat received 100 kg Nha−1 ammonium nitrate in combination with either 772 mm or 927 mm water. Although wheat received more water than maize, it lost less N through leaching (0.2–2.7 and 0.1–1.7 kg ha−1) and had greater aboveground-N (88–116 and 93–141 kg ha−1) in the low and high water treatments than the manured and fertilized maize (52–l84 and 55–91 kg ha−1) which lost more N (1.4–4.2 and 4.7–8.6 kg N ha−1) through leaching. Leaching of ammonium-N never exceeded 0.5 kg ha−1.