Effects of nitric and ammonium fertilizers on the transport of NO-3 and NH+4 in a field grown with Vigna unguiculata (L.) Walp

Abstract

The transport and the distribution of NO-3 and NH+4 ions were studied in a field with TE soil ("Terra Roxa Estruturada") when different doses of nitric and ammonium fertilizers were applied. The soil was sampled in 4 depths (0-20, 20-40, 40-60, 6O-8O cm) and the concentrations of NO-3 ions were determined at each depth. NO-3 contents increased with the increase of soil depth and fertilization increased levels of N-NO-3/ha. The highest contents of NO-3 ion were found at 60-80 cm depth being 2.46; 3-72; 7.25 and 10.22 ppm for the fertilization of 50, 100, 200 and 400 kg/ha of N-NO3, respectively. On the other hand, the highest contents of NH+4 ion were found in the soil at 0-20 cm depth. At this depth, 5.42; 7.75; 7.43 and 9.26 ppm of NH+4 were found respectively when N-NH+4 rates of 50, 100, 200 and 400 kg/ha were applied. The "transport" of NH+4 ion was lesser than that of NO-3 ion even when the soil received high rates of N-NH+4.