Dry or Wet? Evaluating the Initial Rice Cultivation Environment on the Korean Peninsula

Shinya Shoda,Kohei Yamazaki,Hiroo Nasu,Minoru Yoneda,Natsuki Murakami,Geon-Ju Na,Sung-Mo Ahn

doi:10.3390/agronomy11050929

Abstract

The origins and development of rice cultivation are one of the most important aspects in studying agricultural and socio-economic innovations, as well as environmental change, in East Asian prehistory. In particular, whether wet or dry rice cultivation was conducted is an important consideration of its impact on societies and the environment across different periods and places. In this study, carbon and nitrogen stable isotope analysis of charred crop remains from archaeological sites dating from the Early Bronze Age (ca. 1.1 k BC) to the Proto-Three Kingdoms (ca. 0.4 k AD) was conducted to clarify: (1) if there were any shifts from dry to wet cultivation around 1500 years after rice adoption as previously hypothesized and (2) the difference in stable carbon and nitrogen isotope values between rice and dry fields crops excavated from the same archaeological context to understand the cultivation environment. The result show that stable isotope values of charred rice grains have not changed significantly for around 1500 years. Moreover, rice possessed higher nitrogen stable isotope values than dry crops across all periods. While other potential factors could have influenced the 15N-enrichment of soils and crops, the most reasonable explanation is bacteriologic denitrification in anaerobic paddy soil where the rice was grown.

Highlights

Rice (Oryza sativa L.) is undoubtedly one of the most important crops in modern societies
The significance of studying the origins and development of rice cultivation is widely recognized because it has played a crucial role in the development of early agricultural societies and environmental change in East Asia [1,2]
Since rice is the only crop that could have been cultivated in a wet environment among the major East Asian crops, we investigated whether there is a significant difference in plant nitrogen stable isotope values (δ15N) between rice and these other crops—which can be explained by bacteriologic denitrification in anaerobic paddy soil, which could affect δ15N values [8]

Summary

Introduction

Rice (Oryza sativa L.) is undoubtedly one of the most important crops in modern societies. Since rice is the only crop that could have been cultivated in a wet environment among the major East Asian crops, we investigated whether there is a significant difference in plant nitrogen stable isotope values (δ15N) between rice and these other crops—which can be explained by bacteriologic denitrification in anaerobic paddy soil, which could affect δ15N values [8]. To date, this has not been previously investigated for plant remains recovered from Korean archaeological sites. Other charred plant remains, including C3 crops (wheat), C4 crops (foxtail millet), and N2-fixing legumes (azuki bean) were sampled to estimate the impact of diagenesis and reconstruct the prehistoric plant management

Objectives

Methods

Findings

Discussion

Conclusion