Study On The Utilization Strategies Of Major Crops From Neolithic To Historical Periods In The Western Loess Plateau

The history of the origin and spread of agriculture,as well as its complex relationship with the development of human society is a critical issue in academia worldwide.The western region of the Chinese Loess Plateau is a key center of origin of dry-land agriculture in northern China,with a long history of both Neolithic cultures and a well-understood sequence of historical cultures.In addition,there are a large number of Neolithic and historical sites in the region,making it an ideal area to study the origin and developmental history of early agriculture and its interactions with human society.With the flourishing of archaeobotanical research in China in the past two decades,agricultural research on the western Loess Plateau has made signifigant progress,but there remain some weaknesses.First,many archaeobotanical studies focus on the prehistoric period,with little attention paid to historic periods.Further there is a lack of research on the development of agricultural systems between Neolithic and historical periods.Second,much research focuses on the temporal and spatial changes of crop proportions,while the investigation of the selective selection and management strategies of ancient crop remain insufficient.Here we present the results of plant remain identification,grain size measurement and the stable isotope analysis of crop seeds from the western Loess Plateau.35104 and 25424 charred seeds were identified from fifty investigated sites in Zhuanglang country as well as the Dadiwan site in the western Loess Plateau,respectively.A total of 5176 charred crop seeds were selected for morphological measurements of length,width and thickness.In addition,131 stable carbon isotope samples of modern bristlegrass seeds and 297 stable carbon and nitrogen isotope samples of charred crop seeds were analyzed along with 70 direct dating samples of crop seeds.Combined with published data from the study area,we systematically review the utilization and selective evolution history of major crops in the western Loess Plateau from the Neolithic to historical periods.We also explore crop management behavior of principle crop species(foxtail millet,broomcorn millet,wheat and barley)by ancient humans.The main conclusions of this work are listed below:(1)Four stages of human utilization of major crops(foxtail millet,broomcorn millet,wheat and barley)in the western Loess Plateau from the Neolithic to historic periods have been explored:Firstly,from the first phase of Dadiwan culture(5800～5300 BC)to early Yangshao culture(4500～4000 BC),humans primarily cultivated broomcorn millet,with a secondary reliance on cultivated foxtail millet;Secondly,from the middle Yangshao culture(4000～3500 BC)to Qijia culture(2600～1500 BC),humans cultivated primarily foxtail millet,with secondary broomcorn millet cultivation;Thirdly,from the Siwa culture(1500～300 BC)to the Tang dynasty(618～907AD),people mainly cultivated foxtail millet and broomcorn millet,with secondary cultivated wheat and barley;Fourthly,from Song dynasty(960～1279 AD)to Qing dynasty(1636～1932 AD),people mainly cultivated wheat and barley,with secondary cultivated foxtail millet,broomcorn millet,oats,buckwheat and soybean etc.(2)From the middle Yangshao(4000～3500 BC)to the Qing dynasy(1636～1912 AD),humans have optimized the cultivation of foxtail millet and broomcorn millet,focusing on optimizing the yields of foxtail millet,followed by broomcorn millet in the western Loess Plateau;From the Qijia period(2600～1500BC)to the Song dynasty(960～1279 AD),wheat and barley were selectively evolved by human at the same time.However,from the Song Dynasty on,only wheat was cultivated and selectively evolved by human beings.(3)From the middle Yangshao Culture to Qing Dynasty,a "rain-fed" strategy was adopted to manage millet-based agriculture in the western Loess Plateau.However,from the Qijia culture to Qing Dynasty,people adopted a variety of water resources management strategies for wheat and barley.Wheat was cultivated primarily in areas at low altitudes in valleys and plains where water resources were abundant.Barley however was cultivated on hilly and gentle slopes at higher altitudes,in areas where water resources are scarce.From the Neolithic to historical periods,people consistently carried out medium levels of manuring on foxtail millet,broomcorn millet,wheat and barley regardless of time period.(4)The utilization,selective evolution and management of major crop species by humans on the western Loess Plateau are significantly affected by climatic and population changes.Since the middle Yangshao period,suitable climate conditions led to cultivated foxtail millet and secondarily cultivated broomcorn millet on the western Loess Plateau.Climate change led humans to grow wheat and barley from the Qijia culture.In addition,population growth has prompted humans to manage and selectively evolve foxtail millet,broomcorn millet,wheat and barley,in order to increase their yields.This paper provides important research data for understanding the selection and utilization of main crops from the Neolithic to historical periods in the western Loess Plateau,and provides key evidence for the historical study of dry-land agriculture.At the same time,this paper has made an exploration and attempt in the comprehensive application of archaeobotanical research methods,providing important research cases and new perspectives for understanding the history of human utilization of major crops from the Neolithic to historic periods on the western Loess Plateau.