Leaching of nitrogen, potassium, calcium and magnesium in a sandy soil cultivated with sugarcane

Abstract

A lysimeter experiment was carried out with sugarcane aiming to evaluate the leaching of nitrogen derived from either urea (¹⁵N) or the soil/sugarcane crop residues. The leaching of K⁺, Ca²⁺, and Mg²⁺ was also evaluated. The experiment was a factorial 2x4. The influencing factors were: firstly, the differential addition of two kinds of sugarcane remains to the soil, simulating conditions of cane- plantation renewal after the cane crop harvest, with and without previous straw removal by burning; secondly, four doses of N: 0, 30, 60, and 90 kg ha^-1. During the experimental period the total volume of water received by the sugarcane-soil system was 2,015 mm, with 1,255 mm as precipitation and 760 mm as irrigation. The loss of N by leaching from the fertilizer (¹⁵N) was not detected. In the first three weeks the largest losses of N by leaching occurred, originating from the soil/sugarcane remains-N. The mean of leached N during the experimental period of 11 months was of 4.5 kg ha^-1. The mean losses of K⁺, Ca²⁺, and Mg²⁺ were of 13, 320 and 80 kg ha^-1, respectively.