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Sustainable agricultural development is a topic of global concern aiming at satisfying food demand of the growing population while reducing impact on environment. Circular agriculture has become a promising development pattern with the advantages of complementing environmental resources, replacing feedback from outside system, and processing waste of bottom of system, etc. This study combined economic analysis, life cycle assessment and emergy accounting to evaluate sustainability of an integrated maize-pig system (IS) driven by indigenous microbes in Northeast China, compared with separated maize and pig system (SS). IS reduced input of concentrate feed, coal, vaccines, disinfectants, fertilizer and labor by 14.35%, 100%, 46.11%, 100%, 60.1% and 60.8% driven by indigenous microbes. Economic analysis results showed that IS has 82.88% higher profit than that of SS. The sum of potential environmental impacts of IS was lower than SS for 80.65% according to lifecycle assessment. The emergy results revealed that IS performed better sustainability. Internal feedback emergy for fertilizer and local resources for maize straw increasing of IS significantly improved emergy efficiency. The reduction resulted in nonrenewable resources decreased 33.01% than that of SS, and increased renewable resources by 67.81%, which reduced environmental load ratio of IS by 60.08% of IS. Meanwhile, these factors were the primary factors generating higher sustainability of IS. Overall, the integrated maize-pig system driven by indigenous microbes in this study can effectively alleviate the problems caused by agricultural waste and promote sustainable agricultural development. [ABSTRACT FROM AUTHOR]

The winter wheat–summer maize double cropping system caused overexploitation of groundwater in the North China Plain; it is unsustainable and threatens food security and the overall wellbeing of humankind in the region. Finding water-saving cropping systems without compromising food security is a more likely solution. In this study, six alternative cropping systems' water conservation and food supply capacity were compared simultaneously. A combined water footprint method was applied to analyze the cropping systems' water consumption. The winter wheat–summer maize system had the largest water consumption (16,585 m3/ha on average), followed by the potato/spring maize, spinach–spring maize, rye–spring maize, vetch–spring maize, pea/spring maize, soybean||spring maize and mono-spring maize cropping systems. For the groundwater, the spinach–spring maize, pea/spring maize, soybean||spring maize systems showed a higher degree of synchronization between crop growth period and rainfall, which could reduce use of groundwater by 36.8%, 54.4% and 57.6%, respectively. For food supply capacity, the values for spinach–spring maize, pea/spring maize, soybean||spring maize systems were 73.0%, 60.8% and 48.4% of winter wheat–summer maize, respectively, but they showed a better feeding efficiency than the winter wheat–summer maize system. On the whole, spinach–spring maize may be a good option to prevent further decline in groundwater level and to ensure food security in a sustainable way. [ABSTRACT FROM AUTHOR]

The maize sole cropping system solves problems related to ground water resource shortages and guarantees food security in the North China Plain. Using optimal sowing dates is an effective management practice for increasing maize yield. The goal of this study was to explore an optimum sowing date for high-yield maize. Six sowing dates (SDs) from early April to late June with intervals of 10 to 20 days between SD—SD1 (early April), SD2 (mid to late April), SD3 (early May), SD4 (mid to late May), SD5 (early June), SD6 (late June)—were applied from 2012 to 2017. The results showed that yield was correlated with the sowing date based on the thermal time before sowing (r = 0.62**), which was defined as the pre-thermal time (PTt), and that the yield was steadily maintained at a high level (>10,500 kg ha−1) when PTt was greater than 479 °C. To satisfy the growing degree-days required for maturity, maize needs to be sown before a PTt of 750 °C. Data analysis of the results from 2014, 2015, and 2017 revealed the following: i) Most of the grain-filling parameters of late-sown dates (SD4, SD5 and SD6) were better than those in early-sown dates (SD1, SD2, and SD3) in all years, because of the high daily maximum temperature (Tmax) and wide diurnal temperature (Td) from silking to blister (R1–R2) of early-sown dates. The weight of maximum grain-filling rate (Wmax) of SD3 decreased compare with SD4 by the narrow Td from blister to physiological maturity (R2–R6) in all years (−5, −12, and −33 mg kernel−1 in 2014, 2015, and 2017, respectively). ii) In 2017, the pollination failure rates of early-sown dates were 8.4~14.5%, which was caused by the high Tmax and Td of R1–R2. The apical kernel abortion rates were 28.6 (SD2) and 38.7% (SD3), which were affected by Tmax and Td during R2–R6. iii) Compared with late-sown dates, the wide Td of early-sown dates in R1–R2 was caused by higher Tmax, but the narrow Td in R2-R6 was caused by higher Tmin. Our results indicate that high-yielding maize can be obtained by postponing the sowing date with a PTt of 480~750 °C, which can prevent the negative effects of the high Tmax of R1–R2 and high Tmin of R2–R6 on kernel number and weight formation. Moreover, these above-mentioned traits should be considered for heat tolerance breeding to further increase the maize yield. [ABSTRACT FROM AUTHOR]

Water, energy, and food, which are closely related to human beings, have been proposed by the Sustainable Development Goals, and there are closely related but contradictory relationships among the three. As one of China's main grain-producing regions, the North China Plain (NCP) with dominant grain-oriented cropping system is faced with severe challenges for agricultural sustainable development, such as water and energy shortages, as well as grain safeguard. In this study, a "TKL-WEFN" model combining Tapio decoupling, Kaya, and LMDI was used to evaluate the synergistic relationship from the water-energy-food (WEF) and determine the key drivers taking Wuqiao County in the NCP as a case. The results showed as follows: the synergistic relationship between water-food, as well as energy-food, showed a "M" shaped fluctuation trend from 2009 to 2018 in Wuqiao County. The best performance was achieved in 2011 and 2016, with the state of high yield and low resource consumption. Food increased by 9.43% and 3.52%, while water resources decreased by 5.95% and 8.91%, and energy decreased by 5.36% and 2.15% in 2011 and 2016, respectively. The changes in water consumption for irrigation and fossil energy consumption per unit area of maize and cotton, as well as the adjustment of planting structure, are the main factors affecting the sustainability of crop systems from 2009 to 2018. Water-saving irrigation, no-tillage, and cropping system transformation can improve resources supply and demand, saving 4.61%–50.27% (with an average of 19.47%) of water consumption and 1.91%–13.08% (with an average of 6.45%) of energy consumption by scenarios analysis. Therefore, changing grain-oriented cropping system while maintaining food security and developing water-saving irrigation technology can accelerate the realization of green agriculture. [Display omitted] • Water, energy shortage, and food security are the challenges in North China Plain. • Water-food and energy-food showed a wave trend in 2009–2018 of Wuqiao County. • The high state was 2011 and 2016, with high yield and low resource consumption. • Water-saving irrigation and cropping system change can be considered in study area. [ABSTRACT FROM AUTHOR]

Intercropping of maize and soybean has proven to be a sustainable cropping system all over the world. In recent years, as imports of maize and soybean have increased, the Chinese government has strongly promoted the maize -soybeans intercropping to prevent a decline in maize production and to obtain an extra soybean harvest. It is not clear what the coupling relationship is between the intercropping model and the change in yield of maize and soybean across China. The research searched for articles that fulfilled the criteria related to maize-soybean intercropping in China since 2000. It investigated the yield change through meta-analysis, and analyzed the allocation path of yield increase based on the field configuration level using single factor analysis, multilevel model analysis and random forest analysis. Compared to monoculture, the total yield of intercropping maize and soybean increased by approximately 12%, while the equivalent yield decreased by 8% and 40%, respectively. The proportion of maize area was crucial for the maize intercrop yield. The shading effect of maize on soybean was a key factor in soybean yield reduction. Increasing the distance between the maize and soybean strips lead to an elevation of soybean intercropping yields without compromising maize yield or the total yield. Huang-Huai-Hai Plain Summer Sowing region and Southwest Mountain region were more suitable for promotion. The yield of intercropping was beneficial in this suitable integrated region when the soybean strip width did not exceed 78 cm (soybean row spacing ≤3) and the distance between the maize and soybean strips ≥ 77 cm. Maize-soybean intercropping had great potential for yield improvement, the overall LER was 1.6. In the Huang-Huai-Hai Plain Summer Sowing and Southwest Mountain regions, the yield-advantaged field configurations were: (soybean strip-width ≤61 cm or soybean rows ≤3, distance between strips ≥65 cm) and (soybean strip-width ≤76 cm or soybean rows ≤3, distance between strips ≥73 cm), respectively. Each plantation regions still need to select the optimal distance based on the local farming facilities and traditional farming habits. The research demonstrates the yield changes of maize-soybean intercropping in China, providing a methodology with certain reference value for intercropping yield improvement based on field configuration level. [ABSTRACT FROM AUTHOR]

• A water-energy-food relative index for cropping systems at the field scale is proposed. • Synergy among water, energy and food in the North China Plain is evaluated. • Sustainable systems can balance crop production while reducing resource depletion. Extreme climate change, rapid population growth and economic development drive a growing demand for resources, which lead to energy, food, water and their intertwined nexus becoming increasingly important. Agricultural decisions considering the interconnections among water, energy, and food are critical. The consumption of large amounts groundwater and non-renewable energy by the predominant traditional wheat-maize cropping system has caused a serious water shortage in the North China Plain (NCP), which is a large food production region in China. This situation has strained the relationship between water/energy consumption and food production. It is important to seek synergy in the water-energy-food nexus. This paper proposed a relative index of water-energy-food (WEF RI) based on different values of resource consumption and use efficiency between treatment systems and control system to analyze the synergy between water utilization, energy consumption and food supply in different cropping systems at the field scale. The goal is to seek a sustainable cropping system to balance crop production while reducing energy consumption and water depletion. In this case, different systems including monocropped maize (Zea mays) (MM), intercropped maize and soybean (Glycine max) (MS), relay cropped of maize with pea (Pisum sativum) (MP) and potato (Solanum tuberosum) (MO), rotation of maize with spinach (Spinacia oleracea) (MI) and ryegrass (Secale cereale) (MR), and using traditional wheat-maize (Triticum aestivum) (MW) as a control. MM, MS, MP and MO were the best systems within a particular range of food supply reduction. The WEF RI of the MM/MS system was the highest (2.96/2.78). Compared to the MW system, the groundwater consumption of MM/MS was reduced by 73.84%/73.84%, and non-renewable energy inputs were reduced by 48.01%/48.30%; however, the food supply decreased by 48.05%/51.70%. The WEF RI of the MP system was 1.98. In comparison with the MW system, the groundwater consumption of the MP system was reduced by 28.46%, and the non-renewable energy inputs were reduced by 42.68%. However, the food supply decreased by 37.13%. The WEF RI of MO system was 1.92. Compared to the MW system, the groundwater consumption of MO was reduced by 11.47%, non-renewable energy inputs were reduced by 32.14%, and the food supply only decreased by 26.27%. In conclusion, we theoretically proposed the following references for cropping systems in the NCP: MM and MS are implemented when the areas has extreme water shortages, MO is implemented when a less than 30% reduction in the food supply capacity is acceptable, and MP is recommended if a 30%–40% reduction in the food supply is acceptable. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) yield and yield variation are both affected by climate and cultivation management. Changing the sowing date (SD) is one of the most commonly used cultivation managements for achieving high yield of maize in North China Plain (NCP). Climate is one of the most important factors in maize yield variation under different SDs. But the yield variation under different SDs and the contribution of each climatic variable remain unclear. In this study, a 7-year field experiment of SDs was used to assess the changing trends of climatic variables under different SDs, and the relative contribution of climatic variables on yield and yield variation of maize were also evaluated. The experiment was conducted at Wuqiao Experimental Station in NCP, with 35 SDs in 7 years from 2013 to 2018, and 2021, totally. Through analyzing the historical meteorological data, our results showed that more photosynthetically active radiation (PAR) distributed in August and September, minimum temperature was increased from April to September, and high temperature days (HTDs) in a year was significantly advanced from 1990 to 2021. These changes in climate caused the optimum SD with both high yield and yield stability was in early- to mid-June, mainly because of the reduction of HTDs in 5 d pre-silking to 5 d post-silking (SS) and increased PAR in SS and silking to harvest (SH). Through variance partitioning analysis, the climatic variables in SS, SH and the whole growth stage (WS) contributed 56 %, 44 %, and 18 % of maize yield variation, respectively. In SS, 7 %, 28 % and 5 % of maize yield variation were explained by HTDs, PAR, and temperature independently. And this contribution was 18 % and 15 % of the PAR and temperature in SH. While in WS, only temperature explained 20 % of the yield variation. Our results highlight the importance of focusing on the yield stability of maize, and for the first time to clarify the differences in maize yield stability under different SDs in NCP. Meanwhile, the relative contribution of climate on yield variation was quantified. This study also proposed and predicted the optimal SDs for high and stable maize yield in NCP. These results will help to study the regional maize production under climate change in the future. [ABSTRACT FROM AUTHOR]