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While the relationship between crop yields and the environmental impacts of crop agriculture has been well‐documented, research on the relationship between farm size and the sustainability of cereal production is limited. Using survey data on 120 farms with both small‐ and large‐scale fields in Northeast China, this paper combines a life cycle assessment and the carbon‐based sustainability index (SI) algorithm to examine how maize productivity and agricultural inputs vary with farm size and to clarify how increasing farm size is correlated with energy use efficiency (EUE) and the SI. The results indicate that maize grain yield did not vary with farm size. Increasing farm size was shown to lead to reductions in the areal (per ha) rates of agro‐chemical inputs, energy depletion, and greenhouse gas emissions and increased in EUE and SI. Fertilizer‐ and fuel‐related agricultural inputs dominated the variations of EUE and SI. A scenario analysis indicates that, if farmers adopt a comprehensive management strategy (i.e., machines appropriate to farm size and recommended fertilizer application rates and crop management strategies), EUE and SI would increase by 68.5% (from 4.45 to 7.50) and 74.3% (from 10.1 to 17.6), respectively. Although increasing farm size could benefit maize sustainable production when matched with technical innovation and machinery coordination, supporting smallholder farmers to increase their resource use efficiency and sustainability is also key in China and other regions where smallholder farms comprise a large portion of the cropland area. [ABSTRACT FROM AUTHOR]

China is under pressure to improve its agricultural productivity to keep up with the demands of a growing population with increasingly resource-intensive diets. This productivity improvement must occur against a backdrop of carbon intensity reduction targets, and a highly fragmented, nutrient-inefficient farming system. Moreover, the Chinese government increasingly recognizes the need to rationalize the management of the 800 million tonnes of agricultural crop straw that China produces each year, up to 40% of which is burned in-field as a waste. Biochar produced from these residues and applied to land could contribute to China's agricultural productivity, resource use efficiency and carbon reduction goals. However competing uses for China's straw residues are rapidly emerging, particularly from bioenergy generation. Therefore it is important to understand the relative economic viability and carbon abatement potential of directing agricultural residues to biochar rather than bioenergy. Using cost-benefit analysis ( CBA) and life-cycle analysis ( LCA), this paper therefore compares the economic viability and carbon abatement potential of biochar production via pyrolysis, with that of bioenergy production via briquetting and gasification. Straw reincorporation and in-field straw burning are used as baseline scenarios. We find that briquetting straw for heat energy is the most cost-effective carbon abatement technology, requiring a subsidy of $7 MgCO2e−1 abated. However China's current bioelectricity subsidy scheme makes gasification ( NPV $12.6 million) more financially attractive for investors than both briquetting ( NPV $7.34 million), and pyrolysis ($−1.84 million). The direct carbon abatement potential of pyrolysis (1.06 MgCO2e per odt straw) is also lower than that of briquetting (1.35 MgCO2e per odt straw) and gasification (1.16 MgCO2e per odt straw). However indirect carbon abatement processes arising from biochar application could significantly improve the carbon abatement potential of the pyrolysis scenario. Likewise, increasing the agronomic value of biochar is essential for the pyrolysis scenario to compete as an economically viable, cost-effective mitigation technology. [ABSTRACT FROM AUTHOR]

An agricultural production function is estimated using a Chinese county-level dataset along with associated geographic information. County-specific output-input elasticities are computed using the geographically weighted regression (GWR) and mapped with the geographical information system (GIS). A comparison of the ordinary least squares and GWR estimates confirms that allowing spatial variation in the parameters improves model fit of the agricultural production function, and provides valuable insights into the relative importance of inputs in different regions. Moran's indices reveal the spatial dependence of output per unit of land, and four inputs across regions. Mappings of GWR estimates help to detect a few clusters of high output-input elasticities: for labour in the Northeast, North, Southwest and Northwest China, for land in the Central and Southwest, for mechanical power in the North, Northwest and coastal area of the East and South and for fertiliser in the East. The county-specific scale elasticities suggest constant return to scale is likely to hold in the Central, East, Southwest and South. [ABSTRACT FROM AUTHOR]