Taking the grain-related data of 30 provinces in China from 2002 to 2020 as the research sample, based on the estimation of the flow of virtual cultivated land resources in grain trade, the Dagum Gini coefficient and its decomposition method, Kernel density estimation method and Markov chain analysis method were used to empirically investigate the regional differences and distribution dynamic evolution trend of virtual cultivated land resource flow in China's grain trade. The results show that: (1) the net import of virtual arable land resources in China's grain trade is on the rise, but the development is unbalanced between regions, showing the characteristics of "eastern> western > central"; (2) Inter-regional differences are the main source of regional differences in the net import of virtual arable land resources in China's grain trade, with a contribution share between 60%~70%, and the overall differences between the whole country and the three major regions are large, showing a trend of "rising first and then falling"; (3) The center development trend of net imports of virtual arable land resources in grain trade in the whole country and the three major regions gradually shifted to the right, except for the central region, the phenomenon of right tailing is significant, and the polarization phenomenon is alleviated; (4) When the spatial conditions are not considered, the net import of virtual cultivated land resources is more sustainable, and there will be no state transfer between provinces, but the trend to a high level is obvious. Therefore, it is necessary to clearly understand the spatial imbalance of the net import of virtual cultivated land resources in grain trade, and dynamically adjust the grain import and export trade policy, and at the same time pay attention to avoiding the negative impact of excessive import of virtual cultivated land resources in grain trade on the domestic market.

In this paper, the spatial-temporal characteristics of non-grain cultivated land in Sichuan province from 2000 to 2019 were analyzed by using quantitative model, and the influence of non-grain cultivated land on economic growth was discussed by using Theil index decomposition method. The results showed that: In terms of temporal characteristics, both the non-grain area and the non-grain rate of cultivated land in Sichuan province showed a fluctuating increase in time series, which increased first, then decreased before 2010 and then increased after 2010, and there was a negative correlation between the nongrain conversion of cultivated land and the proportion of cultivated area of food crops in the five economic zones. In terms of spatial characteristics, the non-grain area of 21 cities and prefectures was less in northwest and more in southeast, but the non-grain rate was higher in northwest and lower in southeast, and the spatial difference of the five economic zones was obvious, and the changes of the non-grain area and the non-grain rate of cultivated land were not synchronous. The non-grain area of cultivated land in Sichuan province and its five economic zones was correlated with GDP, and the non-grain conversion of cultivated land had non-absoluteness to regional GDP growth; Although the overall difference of the impact of non-grain cultivation on economic growth had decreased, the regional and spatial difference was significant, and the regional contribution difference was the source of the overall difference of the whole province, which was affected by the regional difference of economic development. And the countermeasures and suggestions of strengthening the control of the use of cultivated land, strengthening the coordinated management of departments, perfecting the compensation system of cultivated land, and strengthening the publicity of cultivated land protection were put forward.

This paper focuses on the processes of water and salt movements in the groundwater-soil-plant-atmosphere continuum (GSPAC) system. First, it analyzes the key driving factors and mutual feedback mechanisms of the groundwater hydrological process and farmland ecosystem and proposes a new conception of groundwater benefit zone (GBZ). Secondly, it elaborates on the formation mechanisms of the groundwater benefit zone and the model development for simulation of the GBZ. Finally, based on the saline farmland water-salt coupling transport mechanism, scale effects, quantitative model of GBZ, and technical parameters of regional groundwater and salt regulation and control, the scientific issues and challenges related to the research framework of GBZ are prospected.

Economic benefit is the first aim of land consolidation, and it is significant to analyze the influence of land consolidation on the profit of planting industry, which can improve the level of project design and agricultural management. In this article the typical project area of land consolidation was selected, the original data was collected by in situ field survey, and all the data were analyzed based on the theory of statistics. Now the preponderant crop in the study area is fruit, and the planting area proportion of grape is above 80%. The profit per unit area of grape is significantly higher than citrus and maize, and the difference are 114.3 k and 193.8 k yuan per ha, respectively. Generally, the new excellent variety reaches higher profit compared with ordinary variety. The average profit in the past three years remained stable, and in the enlargement course of the plot size, the profit per unit area rose at first, then declined dramatically and then rose again, and maintained in high level stably. It is found that the structure of planting industry has changed dramatically with the significant promotion of economic benefit, larger size plot should be designed and built as possible, and new excellent variety of predominant crop should be updated timely in the field management.

Entering the new era of socialism with Chinese characteristics, the strategic position of agricultural science and technology innovation in the development of“agriculture, rural areas and farmers”has been continuously improved, and its supporting and leading role in the development of“agriculture, rural areas and farmers”has been continuously enhanced, which has made important contributions to ensuring national food security and winning the fight against poverty. In the future, agricultural scientific and technological innovation will not only face multiple challenges，such as the increase of international uncertain factors, the prominent domestic agricultural structural contradictions and enhanced resource and environmental constraints, but also face enormous development opportunities brought by the new round of scientific and technological revolution. It is suggested that the investment and support policies for scientific and technological innovation should be strengthened in eight areas: biological breeding, cultivated land conservation, agricultural machinery equipment and intelligence, smart agriculture, digital agriculture, green ecology, new food manufacturing, and prevention and control of major risks and disasters.