Influence of Nitrogen Form Supply on Soil Mineral Nitrogen Dynamics, Nitrogen Uptake, and Productivity of Sugarcane

Abstract

Current limitations on the use of conventional N fertilizers on sugarcane ( Saccharum spp.) in Brazil require the search for alternative sources with adequate N use efficiency. Field experiments were conducted in Typic Hapludox (TH) and Typic Eutrustox (TE) soils in São Paulo State, Brazil, to evaluate the dynamics of soil mineral N, N uptake, and sugarcane yield in response to N amendments including Ajifer‐8, ammonium chloride, ammonium nitrate, calcium ammonium nitrate (CAN), and urea applied on sugarcane ratoon at 100 kg N ha −1 . The experiments were arranged in randomized complete block design, with four replications. The treatments were applied at 105 and 122 days after harvest of plant cane (DAH) in the TH and TE soil. Ajifer‐8 exhibited higher NH 4 + –N availability in the 0‐ to 20‐cm soil layer 139 DAH in the TH soil. Ammonium nitrate and CAN resulted in the highest NO 3 − –N values in the soil within the same period. In the TE soil, the soil mineral N content remained unaltered during all of the sampling dates. The high values of accumulated N uptake by sugarcane in both soils indicates that a good portion of the soil mineral N was take up by the plants. The Ajifer‐8 and CAN fertilizers resulted in higher sugarcane yield in both experiments, and may be used as replacement for conventional N sources. In contrast, the use of ammonium chloride resulted in low values of soil mineral N and accumulated N uptake.