Impacts of P and N fertilizers on common beans (Phaseolus vulgaris L.) growth, nodulation and P and N uptake in a pot experiment
1991
Talavera, S.F.T. (Universidad Nacional Agraria, Managua (Nicaragua))
A pot experiment was conducted with a Nicaraguan volacanic soil to study the response of common bean (Phaseolus vulgaris L.) to applications of single superphosphate (P) and triple superphosphate (TSP), in amounts equivalent to 60 kg P2O5/ha and of urea (N), 20 kg N/ha. The P and N were placed singly or together on the surface (Ps, Ns, Ps, Ns) or 6 cm below the surface (P6, N6, P6, N6), or one was placed on the surface and the other 6 cm below it. In addition, TSP and N were placed together on the surface or 6 cm below it. All treatments, including the control, were triplicated. Shoot and root dry weights (DW) of the flowering plants and their P and N contents were recorded. P and N, applied singly or together, significantly (P less than or =5%) and consistently increased shoot DW, regardless of the application method used. Root DW was also increased significantly, but with less consistency. Dry matter production was highest in the PsNs treatment. Nodulation was three times higher in the Ps treatment than in the control, and markedly higher than in the P6, PsNs, P6Ns, P6Ns and P6N6 treatments. By contrast, the Ns and N6 treatments decreased nodulation 8 and 35 times respectively. Whereas fertilization did not significantly affect the tissue concentration of P and its transport indices, in most cases it increased tissue concentrations of N and N transport indices. Single superphosphate was more effective than triple superphosphate at increasing bean DW.
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