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During the Spring and Autumn Period and the Warring States Period, the Yan state attached great importance to the production of grain crops and became a famous dry farming area, where dry crops were mainly planted. Millet, broomcorn and beans were the main grain crops, while wheat, hemp and so on were in a subordinate position. The planting of grain crops had obvious regional differences in the Yan state, which fully reflected the principle of adapting to local conditions. The people of Yan used stone pestle, mortar, grinding disc and grinding rod to peel and husk grains, and stone mills were probably used in the Warring States period. The storage methods of grain in the Yan state were varied and the storage technologies were relatively superior, mainly through castles, cellars and granaries for large-scale storage, and containers were mostly used for temporary storage. Youlin was an important organization for grain storage and management in the Yan state which also had the function of making utensils. Situ was most possibly in charge of agriculture in Yan state, and there were officials under Situ who directly managed granaries. The diversification of grain crops and large-scale grain storage became an important means of preparing for famine and war. [ABSTRACT FROM AUTHOR]

[Objective]In order to select the growth-promoting crops for bio-controlling the soil-borne diseases, soil biological properties and bacterial diversity in rhizospheres among different crops were analyzed and explored whether they could be used as the biological indicators for the selection of the growth-promoting crops.[Method]The present study assessed the Cucurbits, Leguminosae and Convolvulaceae crops as the research subjects, and compared the soil biological characteristics and bacterial community structure in rhizospheres of different crops.[Result] The soil enzyme activities in rhizosphere of Cucurbit involved in soil carbon, nitrogen and phosphorus cycling had no significant difference between each other, without any complementarity.However, soil enzyme activities in rhizosphere between cucurbit crops and sweet potato or legume cowpea showed a significant difference between each other, which indicated that a good complementary effect could be found out in soils between cucurbit crops and sweet potato or legume cowpea.In addition, the results of bacterial diversity showed that the dominant bacterial species in rhizosphere of cucurbit crops tended to be similar.By contrast, specific bacterial species could be found out in rhizospheres of cowpea and sweet potato, respectively.It also indicated that a good complementary effect for bacterial diversity in rhizosphere of cucurbit crops could be implemented by using cowpea or sweet potato for inter-cropping.[Conclusion] Soil enzyme activities, related to carbon, nitrogen and phosphorus cycling, and the indexes of bacterial diversity in rhizosphere, could be used as bio-indicators to identify thecomplementarity effect in rhizosphere among different crops.Meanwhile, it also showed that cowpea and sweet potato, both had the potential in promoting the rhizosphere microenvironment of cucumber, bottle gourd and pumpkin which was according to their biological properties and bacterial diversity. [ABSTRACT FROM AUTHOR]