Below ground nitrogen in fababean and chickpea

Isotopic and non-isotopic methods were used to quantify below ground nitrogen (BGN) for two winter legumes, fababean (Vicia faba) and chickpea (Cicer arietinum), under glasshouse and field conditions. In the glasshouse study, estimates of BGN for fababean and chickpea, respectively, were 13 and 10% of total plant N (physical recovery), 11 and 52% (soil 15N dilution), 30 and 52% (mass N balance), 39 and 53% (15N-shoot labelling), 37 and 42% (adjusted 15N shoot labelling), and 33 and 43 % (15N balance). In the field experiment, values were 25 and 77% (15N-shoot labelling), 24 and 68% (adjusted 15N shoot labelling) and 29 and 60% (15N balance). When averaged across all estimates (other than physical recovery), BGN of glasshouse-grown plants represented 31% of total plant N for fababean and 48% for chickpea. By comparison, the mean values for BGN as percent of total plant N in the field study using the two methods considered likely to give the most reliable results (adjusted 15N shoot labelling and 15N balance) were 27% for fababean and 64% for chickpea. (author)