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The aim of this paper is to assess the loss of grain production caused by agrometeorological disasters in the Inner Mongolia Autonomous Region (IMAR), which is an important grain production base of China. The disaster-yield assessment model was formed and verified using grain production, yield, planting area and agrometeorological disaster conditions data of the IMAR from 1981 to 2020, and the loss of grain yield caused by meteorological disasters was assessed by this model. The results showed that grain production, yield and planting area observed an escalating trend from 1981 to 2020, and the rate of increase was 78.85×104t·y-1, 100.97kg·ha-1·y-1 and 74.48×10³ha-1·y-1. The covered and affected area of agrometeorological disasters for the IMAR and National both increased and then decreased during the 1981-2020 period. Drought was the most important agrometeorological disaster in the IMAR, and the covered and affected area was 64.10% and 62.45%, respectively, accounting the total covered and affected area of all kinds of disasters in 1981-2020. The grey correlation analysis showed that drought had the highest correlation with grain yield at the level of disaster covered and affected rate, and hail had the highest correlation with grain yield at the level of disaster destory rate. The disaster-yield assessment model constructed by this study was of high simulation accuracy, and the linear regression coefficients (R²) and the slop between the simulated and measured grain yield was 0.99 and 0.98, respectively (P < 0.01). The average relative simulation yield was 0.20% and relative simulation error of the following year grain yield was 2.49%. Grain yield loss rate due to disaster in the IMAR decreased (R²=0.77，P<0.01) from 1981 to 2020 with a rate of 0.48 percentage points·y-1, and average grain yield loss rate was 14.79% and there were 68.42% of years which grain yield loss rate above 10%. The disaster-yield assessment model of the IMAR formulated in this study can simulate and predict grain yield, and assess the loss of grain yield due to disasters, which can meet the needs of agrometeorological services. [ABSTRACT FROM AUTHOR]

【Objective】The agro-pastoral ecotone at Inner Mongolia and Liaoning border is an important part of the farming-pastoral ecotone in northern China, and it is also the ecological barrier of the commodity grain base and heavy industry production base in Liaoning. 【Method】Maize was the main crop in this area and play an important role in grain production. In this paper, the maize in the agro-pastoral ecotone at Inner Mongolia and Liaoning border was used as the research object, and the differences of C and N contents in various organs of maize under the two methods of irrigating and mulching were analyzed. 【Result】Under the two planting methods, the C content of the stem was the highest and the C content of the root was the lowest; The N content of leaves and ears was higher, the N content of roots was lower; the C/N of roots and stems was higher, and the C/N of leaves was lower. Compared the two planting methods: The C content of leaf in the irrigated land was significantly higher than that in the mulched land; the N content of the stem was significantly lower than that in the mulched land; The C/N of stem and leaf was significantly higher than that in the mulched land; The soil organic matter was significantly lower than that in the mulched land. 【Conclusion】Comparing with irrigated land, the mulching method can more effectively maintain soil nutrients, reduce water waste and also improve maize quality and yield. [ABSTRACT FROM AUTHOR]

In China, ultra-small-scale agricultural production remains low agricultural income which cannot afford adequate livelihood and as well meet their basic needs of rural households. Smallholder production systems have seriously hindered the sustainable development of China’s agriculture. Family farms with a moderate land scale is a way to develop China's agriculture. Moderate land scale of China's agriculture is affected by multiple factors like average social income level, grain production income, etc. So moderate land scale is a dynamic value. This paper aimed to assess moderate land scales of grain family farms at the municipal level in China based on the method of income equalization. The research findings are as follows. The moderate land scale of grain family farms was 13-14 hm2 in 2016-2017, equivalent to the local household contracted area of 30 times. According to the policy formulated by China’s central government in 2014, the moderate scale of one family farm should be 10-15 times of average household contracted area. That is, the current standard of moderate scale is low. Mainland China can be divided into 9 districts and 38 sub districts according to the different types of land scale management. The moderate scale of the Northeast Region and the Inner Mongolia Plateau Region are 15-17 hm2, the North China Plain Region is about 10 hm2, the Lower Yangtze River Region and the Southeast Coastal Region are 7-9 hm2, the Southwest Mountainous Region is 6 hm2, the Loess Plateau Region is 18 hm2, and the Northwest Arid Region is 25 hm2 . The scale of the Qinghai-Tibet Plateau Region is the highest, 30 hm2 . The ratio of the moderate scale to the average cultivated land area per household in the Inner Mongolia Plateau Region is 8, and the ratio in the North China Plain Region and the Lower Yangtze River Region is about 35. It is difficult for China to achieve scale management on the whole, and the difficulty gradually decreases from the southeast coast to the northwest inland. The boundary line extends from Beijing to Nujiang Lisu Nationality Autonomous region, Yunnan. The moderate scales of grain family farms in the southeast region of the line are mostly 6-10 hm2, and it is difficult to achieve. In contrast, the moderate scales in the northwest region of the line are mostly above 15 hm2, and it is easy to achieve. China's scale management reform is at the initial stage. The promotion speed of scale management should not be fast to avoid social unrest. It is recommended to raise the standard of moderate management scale to the range of 15-20 times, and the standard can be adjusted according to the actual situation in different regions. The government should also promote institutional innovation to reduce high land transfer transaction costs. System reform can be carried out in three aspects. Firstly, the government should promote farmers who do not rely on agriculture to actively release land resources; Secondly, the local governments should actively play a coordinating role to promote land centralization and scale management; Finally, a unified and perfect land circulation market should be established [ABSTRACT FROM AUTHOR]