Stable carbon isotope analysis as a direct means of inferring crop water status and water management practices

Abstract

Stable carbon isotope analysis of plant remains is a promising tool for researchers studying palaeoclimate and past agricultural systems. The potential of the technique is clear: it offers a direct measure of the water conditions in which plants grew. In this paper, we assess how reliably stable carbon isotope discrimination can be used to infer water conditions, through the analysis of present-day crop plants grown at multiple locations across the Mediterranean and south-west Asia. The key findings are that: (1) Δ¹³C, as expected, provides an indication of water conditions, (2) even for plants grown in similar conditions there is variation in Δ¹³C and (3) Δ¹³C may reflect crop water status for a period beginning well before the grain filling period. A new framework is presented which increases the robustness with which Δ¹³C values of plant remains can be interpreted in terms of the water conditions in which ancient crops grew.

From Traditional Farming in Morocco to Early Urban Agroecology in Northern Mesopotamia: Combining Present-day Arable Weed Surveys and Crop Isotope Analysis to Reconstruct Past Agrosystems in (Semi-)arid Regions

“…Araus et al 1997;Bogaard et al 2007;Fraser et al 2011;Wallace et al 2013;Fiorentino et al 2015). Thus variation in crop stable isotope values offers a useful way to investigate the ecology of present and past farming systems.…”

“…C values suggest poorly to moderately well-watered conditions ( Figure 13) in comparison with thresholds established for modern barley (Wallace et al 2013). Cereal δ…”

“…C values for inferring water status (Figure 8) (Wallace et al 2013). Application of this 'weed plus isotope' approach to an EBA archaeobotanical assemblage from early urban Tell Brak, Syria identifies low-intensity management of rain-fed fields as the prevailing agrosystem.…”

“…Pulse samples are also few but suggest a range of conditions from poorly to well watered (cf. Wallace et al 2013) (Supplementary Table 4). …”

Crop manuring and intensive land management by Europe’s first farmers

“…Fig. 1 (12,13,(16)(17)(18), experimental work on the effects of charring (19,20), and associated arable weed assemblages (4,5,21,22). The sites mostly date to the earlier Neolithic in their respective regions (Table 1) and were selected on the basis of richness in well-preserved charred crop material (Fig.…”