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Abstract The land system is a crucial factor influencing urban low-carbon sustainable development. However, previous research has paid little attention to the effects and mechanisms of the national land supervision system (NLSS) on urban low-carbon transformation (ULCT). This study uses China’s routine land inspection as a quasi-natural experiment and examines the impact of NLSS on ULCT using panel data from 283 Chinese cities between 2005 and 2016. The study finds that NLSS significantly promotes ULCT, with a series of robustness checks supporting this conclusion, showing a 1.95% improvement in carbon emission performance in cities under supervision. NLSS mainly facilitates ULCT by improving land use efficiency, upgrading the structural of the service sector, and promoting technological progress. Compared to eastern cities, southern cities, large cities, and non-resource-based cities, NLSS more effectively promotes low-carbon transformation in central and western, northern, small- and medium-sized, and resource-based cities. Additionally, in contrast to cities with high environmental awareness, high marketization levels, high financial development levels, and high fiscal pressure, NLSS more strongly promotes ULCT in cities with lower levels of these factors. Furthermore, NLSS exhibits a significant positive spatial spillover effect in promoting ULCT. In advancing ULCT, NLSS can be synergized with smart city pilot policies and innovative city pilot policies but has not shown synergies with low-carbon city pilot policies.

The green and low-carbon transformation of land use (GLTLU) is a pressing global issue that requires urgent attention. The digital economy has emerged as a new driver for the GLTLU. However, current research mainly focuses on the measurement and environmental effects of the digital economy, with less exploration of how the digital economy influences the spatial effects and regulatory mechanisms of GLTLU, particularly regarding the differential impacts and specific mechanisms at the regional level. This study uses panel data from 283 cities in China from 2011 to 2019, employing the spatial Durbin model (SDM) and the panel threshold model to examine the spatial and regulatory mechanisms of the digital economy’s impact on GLTLU. The findings reveal that digital economy promotes GLTLU not only within cities but also in surrounding regions. Robustness analyses support this conclusion. Notably, the digital economy’s positive impact on GLTLU in surrounding areas is confined to the central region of China. In contrast, the Yangtze River Delta urban agglomeration experiences a significant negative impact on GLTLU in nearby regions due to the digital economy. The study also identifies that the positive spatial spillover effect of the digital economy on GLTLU reaches its peak at a distance of 450 km. Additionally, the digital economy’s ability to promote GLTLU is contingent upon financial agglomeration levels exceeding 9.1728. Moreover, the local government’s emphasis on the digital economy and intellectual property protection enhances the digital economy’s impact on GLTLU. The promotion effect is maximized when these factors surpass the thresholds of 27.8054 and 3.5189, respectively. Overall, this study contributes to the understanding of how the digital economy influences sustainable land development, highlighting the critical role of regional factors and regulatory mechanisms in amplifying the digital economy’s positive effects on GLTLU.

A two-year (2020-2021) field experiment was conducted at the National Agricultural Environmental Station for Agricultural Environment in Fuxin. The experiment was conducted in a completely randomized block design, consisting of five sowing dates with three furrow depths each year. Seeds were sown on April 11 (T1), April 18 (T2), April 25 (T3), May 2 (T4) and May 9 (T5), respectively, in 2020, and were sown on April 18 (T2), April 25 (T3), May 2 (T4), May 9 (T5) and May 16 (T6), respectively, in 2021. The furrow depths including 5cm (D0, convention planting as the control), 10cm (D1) and 20cm (D2), respectively. By measuring above-ground dry matter, grain yield and yield components, soil water content on the sowing and harvesting day, and soil water storage and maize water use efficiency were calculated, so as to explore the rule of dry matter accumulation and allocation of spring maize, and the changes in resource utilization efficiency under the influence of sowing dates and furrow depths. Both contribute to optimize the cultivation technology of spring maize by selecting suitable sowing date and furrow depth in semi-arid region. The results showed that the sowing dates from April 18 to May 2 were beneficial to the accumulation of above-ground dry matter. Compared with the average of other sowing dates, the maturity period was increased by 8.0%, and promoted the allocation of dry matter to ear weight, with an average yield 9.9% higher than other sowing dates. The water use efficiency was significantly improved. The production efficiency of solar radiation, growing degree days, and rainfall increased first and then decreased with the delay of sowing date. The above-ground dry matter and panicle ear weight were D2>D1>D0 in different furrow depth treatments at the maturity stage. The grain yield of D2 and D1 treatments was significantly higher than that of D0 (11.1% on average), and there was a significant difference in water use efficiency in 2020. Considering yield, resource utilization efficiency and variation coefficient of yield, authors concluded that suitable sowing dates(April 25-May 2) and 20cm furrow depth were the most beneficial to high yield and resource utilization efficiency of maize in semi-arid area of western Liaoning. [ABSTRACT FROM AUTHOR]

To explore the mechanism of overyielding, improvement of land productivity and water use of maize/soybean intercropping, and optimize the configuration of the intercrop in semi-arid western Liaoning, a 2-year (2018-2019) field experiment was conducted at the National Agricultural Environmental Station for Agricultural Environment at Fuxin. The effects of maize-soybean intercropping on yield, land productivity, spatial distribution of soil water content and water use efficiency were studied. Cropping systems were, (1) 2 rows of maize: 2 rows of soybean (M2S2), (2) 4 rows of maize: 4 rows of soybean (M4S4), (3) 6 rows of maize: 6 rows of soybean (M6S6), (4) sole maize (M) and (5) sole soybean (S). The total yields of the 5 cropping systems were M>M6S6>M4S4> M2S2>S. In intercrops, the contribution of maize for total crop yield was greater than soybean, with 79.0%-87.3% of the contribution rates for intercropped maize, and 12.7%-21.0% for intercropped soybean. The land equivalent ratios (LER) of M6S6 and M4S4 were 1.13-1.19 and 1.06-1.07, respectively, indicating a yield advantage of the intercrop, among which M6S6 showed the highest land productivity. The LER of M2S2 was less than 1, indicating a yield disadvantage. The spatial distribution of soil moisture showed that there was water competition between maize and soybean in 0-50cm soil layer, and was water complementarity between maize and soybean in 60-100cm soil layer in intercrops. On the same land area, all the intercrops improved water use efficiency of maize. M2S2 and M4S4 decreased the water use efficiency of soybean. The water equivalent ratio (WER) of M6S6 and M4S4 were 1.18-1.21 and 1.05-1.06, respectively, indicating the water productivity was increased by 5%-21%. Both of M2S2 and M4S4 had water use advantages, and M6S6 showed the highest water use advantage. The WER of M2S2 was 0.99-1.01, indicating a not significant water use advantage (P>0.05). Overall, M6S6 showed the most significant yield and water use advantage, and would provide opportunity for sustainable agriculture in semi-arid western Liaoning. [ABSTRACT FROM AUTHOR]