Comparison of nitrogen fertilizer demand for wheat production between humid and semi-arid portions of the Argentinean Pampas using a mass balance approach

N. ROMANO; . R. ALVAREZ; A. BONO; H.S. STEINBACH

archives of agronomy and soil science

Taylos and Francis

Año: 2014

0365-0340

The Argentinean Pampa is an important grain production region in which nitrogen availability restricts wheat (Triticum aestivum L.) yield. We performed 46 experiments in the Semi-arid Pampa for evaluating soil nitrogen supplying capacity using a mass balance approach. The information generated was combined with published results from 58 experiments performed in the Humid Pampa. Average rainfall was 50% lower under semi-arid conditions and soils had half of the clay+silt and total nitrogen (N) contents than those of humid environments. Wheat yield under humid scenarios doubled yield attained under semi-arid ones, and N and rainfall use efficiencies were also higher. A model could be fitted with good performance for estimating N supplying capacity from mineral and organic soil pools (R2= 0.53-0.93), absorbed N (R2= 0.70), and yield (R2= 0.57). This methodology can be used for estimating fertilizer needs under defined climate and site specific scenarios. For the average yields, rainfall and soil conditions of the experimental networks, targeted N supply (soil mineral+fertilizer N) was estimated as 160 kg N ha-1 in the Humid Pampa and 50 kg N ha-1 in the Semi-arid Pampa. Current N rates applied by farmers need to be increased under humid conditions and overfertilization occurs under semi-arid ones.