Use of nitrogen‐15 microplots for field studies of maize nitrogen‐use efficiency

Abstract

Choice of minimum size of nitrogen (¹⁵N) microplots is essential in studies of maize (Zea mays L.) N uptake, translocation, assimilation, and accumulation patterns using the ¹⁵N isotopic technique. The objectives of this field experiment were to determine if: i) plants adjacent to restricted ¹⁵N microplots (0.76 m × 0.23 m × 0.25 m deep, centred on a plant) were ¹⁵N‐enriched, ii) growth of plants in microplots was hampered, and iii) the estimated fertilizer N recovery (FNR) was lower than that previously reported. There was no detectable enrichment by applied ¹⁵N in maize plants adjacent to the microplots. Root and aboveground biomass and N content of plants in the microplots were similar to plants in the main plot at harvest (P>0.1). The FNR in the aboveground plants was 29% for 200 kg N ha^‐1 and 38% for 100 kg N ha^‐1 treatment with 18 and 26% in the corresponding grains. These values were similar to those reported in the literature where larger non‐restricted or restricted microplots were used. Our data suggest that single‐plant microplots are appropriate for ¹⁵N tracer studies on maize and provide good estimates of N utilization.

Notes

CLBRR Contribution No. 94–89.