Unintended effects of urbanization in China: Land use spillovers and soil carbon loss

This paper uses a national-level geographic information system database on land use, weather conditions, land quality, soil organic carbon (SOC), topographic features, and economic variables to analyze the major drivers of land use change and the resulting impact on soil carbon storage in China. The framework developed in this study includes two main components. One is a spatial panel multinomial logit land use model that takes into account the spatial and temporal dependence of land use choices explicitly. The other is a statistical causal evaluation model that estimates the effect of land use change on SOC density. Results indicate that local economic growth, as measured by county-level gross domestic product, was a major cause of urban development and grassland conversions. Rapid expansion of road networks, promoted by massive public investment, increased the conversion of forests, grassland, and unused land to crop production and urban development. Urbanization had significant secondary ripple effects in terms of both indirect land use change and soil carbon loss. Some of the soil carbon loss may be irreversible, at least in the short run.Land use, propensity score-matching, road density, soil organic carbon, spatial panel,

Empirical Analysis of Land-use Change and Soil Carbon Sequestration Cost in China

This project examines the driving forces behind the land-use change and evaluates the effects of land-use transition on soil organic carbon density and sequestration cost in China. It contributes to the literature in three aspects. First, it applies a discrete choice method to model multiple land-use options with a unique set of high-quality data. Second, it conducts a comprehensive analysis of biophysical characteristics and changes in soil carbon storage caused by land-use change. Third, it examines the economic efficiency of alternative land use policies as instruments for carbon sequestration in China.carbon sequestration, land-use, soil organic carbon density, China, Environmental Economics and Policy, Land Economics/Use,

Uncovering the economic value of natural enemies and true costs of chemical insecticides to cotton farmers in China

Little empirical evidence on economic value of biological control of pests at farm level is available to improve economic decision-making by farmers and policy makers. Using insect sampling and household survey in an integrated bio-economic analysis framework, this paper studies farmers' crop management practices in cotton in the North China Plain, and estimates the marginal value of natural enemies and costs of chemical insecticides to farmers. Ladybeetles (mainly Harmonia axyridis, Propylea japonica, and Coccinella septempunctata), the dominant natural enemy group that controls the primary pest (aphid) in cotton in our study area, provide a significant economic benefit that is unknown to the farmers. Even at the current high levels of insecticide use, additional ladybeetle provides an economic benefit of 0.05 CNY (USD 0.01) to farmers. The use of broad-spectrum insecticides by farmers is alarmingly excessive, not only undermining farmers' profitability but also inducing social costs as well as disruption of the natural pest suppression system. Doubling current ladybeetle density in cotton field could gain an estimated USD 300 million for cotton farmers in China, providing a strong economic case for policies to move the pest control system toward a more ecologically-based regime, with positive consequences for farm income and environmental health. With rising use of biological control service provided by natural enemies in cotton fields, significant falls in farmers' insecticide use would be expected, which could raise the value of ladybeetles and other natural enemies even further. The results indicate that there is an urgent need to rationalize inputs and move forward to improved agro-ecosystem management in smallholder farming system. Raising knowledge and awareness on the costs and value of biological pest control versus insecticides among farmers and policy makers and having effective extension service are priorities toward achieving a more ecologically-based approach to crop protection on smallholder farms

Spatial Pattern of Water Footprints for Crop Production in Northeast China

Water is an important resource for crop production; identifying the spatial pattern of the crop water footprint (WF) is of great significance for the optimization of water resource consumption and management in agricultural production. This study quantified the green, blue and grey water footprints (GWF, BWF and GRWF) and water consumption (GWC, BWC and GRWC) of rice, maize and soybean at the 1 km grid level and city level in Northeast China in 2019 based on the CROPWAT 8.0 model. The results showed that the average total water footprints of rice (TWFr), maize (TWFm) and soybean (TWFs) were 624.31 m3·ton−1, 527.26 m3·ton−1 and 1298.21 m3·ton−1, respectively. The spatial differences in the WF of each crop were obvious in Northeast China, with the highest values of TWFr mainly occurring in Baicheng, Dalian and Qitaihe; the highest TWFm values were mainly found in Baicheng, Yingkou and Hulundao, and the highest TWFs were mainly found in Baicheng, Chifeng and Tongliao. The total water consumption of all three crops (TWCc) in Northeast China was 94 billion m3·yr−1 (42% green, 26% blue and 32% grey), in which the total water consumption of maize production (TWCm) accounted for 60%. The production of rice, maize and soybean in Northeast China mainly depends on green water, grey water and blue water, respectively. Combining the results of the spatial patterns of crop TWF and TWC, the study revealed that the planting pattern of crops in Northeast China was relatively reasonable for sustainable water use. Meanwhile, cities that have the potential to enhance crop production and cities that should improve their water use efficiency and reduce fertilizer application were also identified

Land use change and soil carbon sequestration in China: Where does it pay to conserve?

This paper estimates the impact of land use change on soil organic carbon (SOC) sequestration in China from 1985 to 2005 using a nationwide, georeferenced database on land use, soil, and climate. The method presented here is capable of incorporating site-specific information on soil, climate, and land use change into a national-level analysis. We find that grassland restoration contributed to the largest increase in SOC in China from 1985 to 2005, while grassland degradation caused the largest decrease. Overall, land use change resulted in only a small net increase in SOC, by 7.5 TgC (0.02 %), which is statistically insignificant at the 95 % confidence level. A cost-effectiveness analysis indicates that it is important to consider SOC when assessing land conservation programs. Restoring degraded grassland is more cost-effective than returning dry farmland to grassland. Inner Mongolia is a key region for dense grassland restoration

Empirical Analysis of Land-use Change and Soil Carbon Sequestration Cost in China

This project examines the driving forces behind the land-use change and evaluates the effects of land-use transition on soil organic carbon density and sequestration cost in China. It contributes to the literature in three aspects. First, it applies a discrete choice method to model multiple land-use options with a unique set of high-quality data. Second, it conducts a comprehensive analysis of biophysical characteristics and changes in soil carbon storage caused by land-use change. Third, it examines the economic efficiency of alternative land use policies as instruments for carbon sequestration in China