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Clarifying the matching degree and the trade-offs and synergies between supply and demand of ecosystem services is of significance for scientific division of management zoning and sustainable urban development. We calculated the supply and demand of ecosystem services at the sub-district (town) scale of Taiyuan based on multi-source data, explored the coldspots and hotspots area of the supply-demand ratio and the trade-offs and synergies of six ecosystem services using the Getis-Ord Gi * tool and correlation analysis, and proposed strategies based on the regional characteristics of natural-resource and socio-economy. Results showed the distribution of the supply and demand of ecosystem services had a spatial heterogeneity. In terms of supply, the area with high supply of carbon storage, air purification, thermal environment regulation and recreation service were located in the east and west parts, that of soil conservation in the west and water yield in the south part. In terms of demand, the demand distribution of carbon storage, thermal environment regulation, water yield and recreation service were characterized by high in the central and east-south area, and low in the periphery, and high demand of air purification in south and north parts, soil conservation in west part. There were substantial mismatches between the demand and supply of ecosystem services. The risk levels of the supply and demand of six ecosystem services showed a decreasing pattern from the Fenhe River to the eastern and western mountains. There were trade-offs between water yield and other five ecosystem services in their supply, while air purification and soil conservation had trade-offs with other four ecosystem services in demand. Based on the regional ecological management framework, we divided the study area into three primary zones and eight secondary zones, and proposed differentiated ecological management strategies to provide theoretical support for ecological zoning. The results could provide a basis for balancing the relationship of supply and demand of ecosystem services and promoting the sustainable development of the city.

It is of great practical significance to identify service blind area, scientifically select park construction areas, and clarify the priority of parks' construction based on the co-ordination of supply-demand evaluation. With the urban parks within the Taiyuan Ring Expressway as the research subjects, we estimated the accessibility range and the service pressure of each park by using the application programming interface of Gaode map route planning and point of interest data to characterize their supply and demand levels. We identified the service blind areas of parks by overlay analysis, and used the location-allocation (LA) model to purposefully supply park green space. Results showed that the accessibility coverage rates of the parks by walking and bicycling within 15 minutes were 35.6% and 71.7%, respectively, indicating insufficient supply capacity of parks. The areas with large potential demand for park green space in Taiyuan were mainly concentrated in the business district of Qinxian-Changfeng Street and the Shuangta business district within Dongzhong ring road, which existed the obviously invisible blind areas. Finally, we proposed new park green space site selection proposal based on LA model. Optimization results indicated that the coverage rates of walking and bicycling within 15 minutes increased to 46.7% and 81.0%, respectively, and that the service pressure of parks was relieved. We combined the leisure demands of urban residents and the distribution of urban parks by utilizing network big data, which could promote the scientific nature and accuracy of the optimizing site selection and provide scientific method and theory basis for urban park construction.

To reveal the variation of leaf nutrient utilization strategies with altitude gradient in subtropical mountain broadleaved trees, 44 species of broadleaved trees at different altitudes (1400, 1600 and 1800 m) in Wuyi Mountains were selected to measure nutrient content, stoichiometric ratio, and nutrient resorption efficiency of green and senescent leaves, and analyzed their allometric growth relationships. The results showed that nitrogen (N) and phosphorus (P) contents in green leaves were significantly higher than those in senescent leaves, which increased with the increases of altitude. The average values of phosphorus resorption efficiency (PRE) and nitrogen resorption efficiency (NRE) were 48.3% and 34.9%, respectively. PRE was significantly higher than NRE. There was no significant difference in nutrient resorption efficiency with altitude. NRE had positive isokinetic growth with and mature leaf N content at low altitude (1400 m) and negative allometry growth with senescent leaf N content at high altitude (1800 m). PRE and N and P contents of senescent leaves had negative isokinetic growth at low altitude (1400 m) and negative allometry growth at high altitudes (1600 and 1800 m). PRE-NRE allometric growth index was 0.95 at each altitude. The nutrient contents of green and senescent leaves increased with the increases of altitude, but altitude did not affect nutrient resorption efficiency. Plants preferred to re-absorbed P from senescent leaves. Nutrient resorption efficiency of leaves at high altitude affected the nutrient status of senescent leaves.

We explored the impacts of nitrogen (N) inputs and the rhizosphere effect on the properties of rhizosphere and bulk soils in a salinized grassland in Northern Shanxi under N addition rates of 0, 1, 2, 4, 8, 16, 24 and 32 g N·m -2 ·a -1 . The results showed that N addition significantly decreased soil pH, but significantly increased Ca 2+ , NO 3 - -N and inorganic nitrogen contents in rhizosphere and bulk soil. With the increases of N addition rates, the contents of Ca 2+ , NO 3 - -N, inorganic nitrogen in rhizosphere and bulk soils and total nitrogen in rhizosphere soil increased gradually, whereas the contents of Na + , K + , Mg 2+ , NH 4 + -N and amino acid in rhizosphere soil, and total nitrogen in bulk soil first increased and then decreased. Results of the principal component analysis showed that the responses of soil properties to low (≤8 g·m -2 ·a -1 ) and high nitrogen addition rates (>8 g·m -2 ·a -1 ) were significantly different. Compared with bulk soil, soil pH, the contents of organic acids and amino acids in rhizosphere soil were significantly lower by 0.71 units, 44.3% and 9.8%, respectively, while the contents of K + , Ca 2+ , Mg 2+ , NH 4 + -N, inorganic nitrogen, total carbon and total nitrogen in rhizosphere soil were significantly higher by 51.0%, 47.6%, 20.8%, 215.5%, 139.3%, 31.7% and 65.3%, respectively. These results indicated that rhizosphere effect on soil properties was stronger than that of nitrogen addition.

Grazing is the dominant land use way for natural grasslands. Different grazing intensities could affect soil stoichiometry in grasslands by influencing the selective feeding by livestock, litter input, and microbial community structure. In this study, a grazing experiment was carried out in a grassland of agro-pastoral ecotone in Northern China for three years (2017-2019). The concentrations of total carbon (TC), total nitrogen (TN), dissolved organic carbon (DOC), dissolved nitrogen (DN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) in soils were measured. We analyzed the stoichiometric characteristics of those parameters. The results showed that different grazing intensities (1, 2, 4 sheep·0.2 hm -2 ) had no significant effect on soil TC after three years. The moderate grazing intensity significantly reduced soil TN in 10-20 cm layer in 2019. The light, moderate, and heavy grazing intensities significantly increased soil C/N at 10-20 cm layer, while grazing intensities did not affect soil DOC, DN and DOC/DN. The soil DOC and DN content showed a decreasing trend with the increase of grazing intensity in 2019. It indicated that continuous high intensity grazing might reduce soil dissolved nutrients. The light grazing inten-sity increased soil MBC, while heavy grazing intensity reduced soil MBC significantly, with the increase of grazing year. Different grazing intensities did not affect soil MBN and MBC/MBN.

Nutrient resorption is an important strategy of nutrient conservation, which reflecting the ability of plants to conserve and utilize nutrients and adapt to environment. To explore the relationship between nutrient content and nutrient resorption of broadleaved woody species of different life forms ( i.e ., evergreen vs. deciduous), we sampled 30 broadleaved woody species in subtropical region of China located in Yangjifeng National Nature Reserve, Jiangxi Province. The nitrogen (N) and phosphorus (P) concentrations in green and senescent leaves of each species were measured to calculate nutrient resorption efficiency. Furthermore, we analyzed the relationship of leaf nutrient concentration and resorption efficiency for the different life forms. The results showed that N and P concentrations in green leaves were significantly higher in deciduous trees than those in evergreen trees. The P concentrations of senescent leaves in deciduous woody species was significantly higher than that in evergreen woody species. There was no significant difference of N concentration in senescent leaves between evergreen and deciduous species. Nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) of the 30 broadleaved woody species were 49.6% and 50.9%, respectively. There were no significant differences between the NRE and PRE of evergreen and deciduous species. NRE and PRE negatively correlated with N and P concentrations in senescent leaves, respectively. Additionally, evergreen and deciduous species showed similar relationships between nutrient resorption efficiency and nutrient concentration in senescent leaves. The sca-ling exponent of allometric relationship between NRE and PRE was 1.18 across all the species. The nutrient resorption efficiency of all the species were affected by the nutrient status of the senesced leaves. Plants examined in this study generally re-absorbed P from senescing leaves than N.

To investigate the effects of stem configuration on leaf biomass allocation in different organs of the current-year shoots at different canopy heights, relationships of biomass in different organs (i.e., leaves, stems, and twigs) and stem configuration (i.e., stem diameter, length, width/length, stem volume and stem density) were analyzed using the data of 69 woody species from the Yangjifeng Natural Reserve, Jiangxi Provence. Standardized major axis (SMA) was used to explore the regression between biomass and stem configuration. The results showed that there was no significant difference in leaf biomass, stem biomass, twig biomass, stem diameter, stem length, stem width/length and stem volume of current year shoots from upper and lower canopy heights and life forms (i.e., evergreen and deciduous woody plants). Stem density differed significantly in the current year shoots at different heights for both evergreen and deciduous woody species. There were isometric relationships among leaf, stem and total biomass of shoots in different canopy heights and in different life forms. Leaf biomass scaled allometrically with stem diameter and volume, with the scaling exponents being not different significantly among different canopy heights. With respect to the stem configuration of the twigs, stem length, stem width/length and stem density contributed less than 24% to the leaf biomass variation in the current-year shoots. On the contrary, stem diameter and volume had greater effects on leaf biomass of the current-year shoots than stem length, stem width/length and stem density. Canopy heights did not significantly affect the allometric scaling relationships between the stem configuration and leaf biomass of the current-year shoots.

To investigate the trade-off between the twig size and leaf size, we measured the total leaf mass, stem mass, individual leaf mass and leafing intensity of typical bamboo’s (Phyllostachys edulis, Indocalamus tessellatus, Oligostachyum oedogonatume, Yushania hirticaulis and Yushania wuyishanensis) twigs at different altitudes in Wuyi Mountain. The results showed that the exponents of the scaling between total leaf mass and stem mass on twigs significantly decreased with increasing altitude for all the five bamboo species. The common scaling exponents of total leaf mass vs. stem mass for P. edulis, I. tessellatus and O. oedogonatum were 0.94, 0.85 and 0.84, respectively. A common slope of 0.79 was observed in total leaf mass vs. stem mass in Y. hirticaulis and Y. wuyishanensis. There was significant negative correlation between individual leaf mass and leafing intensity among bamboo species, except Y. wuyishanensis. A common slope of -1.12 existed between individual leaf mass and leafing intensity for five bamboo species. In conclusion, bamboos at low altitudes tended to support more leaf biomass while preferring to invest more to stem biomass at high altitudes. Although the stem mass investment of different bamboo’s twig increased with altitude, the leafing intensity strategies based on stem mass were determined by the leaf size construction rather than altitude.

Using the eddy covariance technique, the Bowen-ratio meteorological and soil monitoring system, we analyzed the CO 2 flux dynamics and its responses to temperature and moisture over a meadow wetland in the Horqin during the growing season (from May to September) in 2016. The results showed that the accumulated net ecosystem CO 2 exchange (NEE) was -766.18 g CO 2 ·m -2 during the growing season. The gross primary productivity (GPP) and ecosystem respiration (R e ) were 3379.89 and 2613.71 g CO 2 ·m -2 , respectively. The ratio of R e to GPP was 77.3%, indicating that this ecosystem was an obvious carbon sink. The average diurnal variation of NEE exhibited a single peak U-shaped curve with an absorption of CO 2 from May to mid August and a release of CO 2 from late August to September. Daytime NEE well fitted with the photosynthetically active radiation (PAR) by a rectangular hyperbolic function. Meanwhile, the relationship was affected by the environmental factors, including vapor pressure deficit (VPD), soil water content (SWC) and air temperature (T a ). Regression analysis showed that the VPD and SWC for the maximum daytime NEE were 1.75 kPa and 35.5%, respectively. Daytime NEE increased with T a , and with no inhibitory effect on the daytime NEE when it reached the maximum. Nighttime NEE had an exponential relationship with soil temperature (T s ). During the entire growing season, the temperature sensitivity of the ecosystem respiration (Q 10 ) was 2.4, which was negatively related to SWC. The nighttime NEE was controlled by both T s and SWC.

Large-scale ecological patches play an important role in regional biodiversity conservation. However, with the rapid progress of China's urbanization, human disturbance on the environment is becoming stronger. Large-scale ecological patches will degrade not only in quantity, but also in quality, threatening the connections among them due to isolation and seriously affecting the biodiversity protection. Taking Poyang Lake Eco-economic Zone as a case, this paper established the potential ecological corridors by minimum cost model and GIS technique taking the impacts of landscape types, slope and human disturbance into consideration. Then, based on gravity quantitative model, we analyzed the intensity of ecological interactions between patches, and the potential ecological corridors were divided into two classes for sake of protection. Finally, the important ecological nodes and breaking points were identified, and the structure of the potential ecological network was analyzed. The results showed that forest and cropland were the main landscape types of ecological corridor composition, interaction between ecological patches differed obviously and the structure of the composed regional ecological network was complex with high connectivity and closure. It might provide a scientific basis for the protection of biodiversity and ecological network optimization in Poyang Lake Eco-economic Zone.

Green roof has a significant influence on reducing runoff volume, delaying runoff-yielding time, reducing the peak flow and improving runoff quality. This paper addressed the related research around the world and concluded from several aspects, i.e., the definition of green roof of different types, the mechanism how green roof manages runoff quantity and quality, the ability how green roof controls roof runoff, and the influence factors of green roof toward runoff quantity and quality. Afterwards, there was a need for more future work on research of green roof toward roof runoff, i.e., vegetation selection of green roof, efficient construction model selection of green roof, the regulating characteristics of green roof on roof runoff, the value assessment of green roof on roof runoff, analysis of source-sink function of green roof on the water pollutants of roof runoff and the research on the mitigation measures of roof runoff pollution. This paper provided a guideline to develop green roofs aiming to regulating roof runoff.

Based on the literature data, the N20 emission, N leaching, N runoff and NH3 volatilization were compared from different rice production regions and their effective factors were evaluated. The results showed that N2 0 emission, N leaching and N runoff in single rice in Yangtze River basin were higher than in other rice production regions, with N loss of 1.89, 6.4 and 10.4 kg N · hm(-2), and N loss rate of 0.8%, 3.8% and 5.3%, respectively. The high N20 emission, N leaching and N runoff in these regions might be attributed to high-rate N application and dry-wet alternation. The NH3 volatilization was the highest in late rice in southern China, with N loss of 54.9 kg N · hm(-2) and N loss rate of 35.2% due to higher temperature at late rice growing stage. In the field, the practice often decreased one reactive N loss but increased another one, indicating that intergated practical management is necessary to reduce reactive N loss. Reactive N loss often increase with increasing grian yield, which is associed with the high-rate N application. The N20 emission, N leaching and N runoff decreased with increasing the partial factor productivity of applied N (PFP). Therefore, reducing N losses per unit of yield is necessary for integrating higher yield with minimum environmental pollution.

Studies on ecosystem service from landscape scale aspect have received increasing attention from researchers all over the world. Compared with ecosystem scale, it should be more suitable to explore the influence of human activities on land use and land cover change (LUCC), and to interpret the mechanisms and processes of sustainable landscape dynamics on landscape scale. Based on comprehensive and systematic analysis of researches on landscape service, this paper firstly discussed basic concepts and classification of landscape service. Then, methods of evaluation, mapping and modeling of landscape service were analyzed and concluded. Finally, future trends for the research on landscape service were proposed. It was put forward that, exploring further connotation and classification system of landscape service, improving methods and quantitative indicators for evaluation, mapping and modelling of landscape service, carrying out long-term integrated researches on landscape pattern-process-service-scale relationships and enhancing the applications of theories and methods on landscape economics and landscape ecology are very important fields of the research on landscape service in future.

Semiochemicals released by plants or insects play an important role in the communication among plants, phytophagous insects and their natural enemies. They thus form a chemical information network which regulates intra- and inter-specific behaviors and sustains the composition and structure of plant and insect communities. The application of insect-resistant genetically modified (IRGM) crops may affect the chemical communication within and among the tritrophic levels, and thus cause disturbances to the biotic community structure and the stability of the farmland ecosystem. This has raised concerns about the environmental safety of IRGM crops and triggered research worldwide. In the current article we provided a brief summary of the chemical communication among plants, herbivores and natural enemies; analyzed the potential of IRGM crops to affect the chemical communication between plants and arthropods and the related mechanisms; and discussed the current research progress and the future prospects in this field. We hope that this will promote the research in this field by Chinese scientists and increase our understanding of the potential effects of growing of IRGM crops on the arthropod community structure.

Effects of four controlled release nitrogen (N) fertilizers, including two kinds of polyester coated urea (Ncau, CRU) and phosphate (NhnP) and humic acid (NhnF) coated urea on assimilates accumulation and nitrogen balance of summer maize were investigated in a mode of one-time fertilization at the regional N recommended rate. The results showed that the N release curves of the two controlled release fertilizers CRU and Ncau matched well with the summer maize N uptake. Compared with the regional N recommendation rate, CRU could increase maize yield by 4.2% and Ncau could maintain the same yield level. CRU significantly increased the dry matter accumulation rate after anthesis of summer maize, but Ncau markedly increased the dry matter accumulated ratio before anthesis. Meanwhile, CRU could reduce the apparent N losses by 19 kg N x hm(-2) in the case of large precipitation. However, NhnF and NhnP caused the yield losses by 0.1%-8.9%, and enhanced the apparent N losses. Therefore, both CRU and Ncau with one-time fertilization could be a simplified alternative to the "total control, staging regulation" fertilization technique at the regional N recommended rate for summer maize production.

Understanding the impacts of climate change on agriculture production and the underlying mechanism in North China Plain is important to take effective adaptations for national food security. Using Hybrid-Maize model, this paper investigated the impacts of climate change on summer maize yield potential and famers' adaptation by changing varieties with longer growth periods from 1981 to 2010 in Xingtai County, Hebei Province. Results showed a significant warming trend with the average temperature increasing by 0.49 degrees C x 10 a(-1) since the 1980s. Both solar radiation and sunshine hours decreased significantly since the 1980s. The sunshine hours decreased by 0.56 h x d(-1) x 10 a(-1) and the solar radiation decreased by 265.1 MJ x m(-2) x 10 a(-1), while the precipitation kept constant with large variation among years since 1981. Yield potentials of both irrigated and rainfed maize were simulated to decrease by 0.63-0.64 Mg x hm(-2) x 10 a(-1) since 1981 if varieties were assumed fixed with the 1980s. This was mainly due to the decrease of solar radiation during the maize growth season and the shortened growth stage by warming, and around 60% of grain yield decrease was attributed to the decreased solar radiation. In practice, by changing varieties with longer growth periods, the growing degree days of varieties adopted by local farmers since the 2000s increased by 19% (280 degrees C) compared to the 1980s, and consequently the yield potential was simulated to increase by 34%-40% (2.73-3.40 Mg x hm(-2)) for both irrigated and rainfed maize.

A 2-year field experiment was conducted in 2011 and 2012 to investigate the effects of phosphorus (P) fertilization on the leaf area index (LAI), dry matter accumulation (DMA), and P use efficiency (PUE) of maize in wheat/maize/soybean intercropping system. Five P fertilization rates were installed, i.e., 0, 45, 90, 135, and 180 kg P2O5 x hm(-2) for wheat, marked as WP0, WP1, WP2, WP3, and WP4, respectively, and 0, 37.5, 75, 112.5, and 150 kg P2O5 x hm(-2) for maize, marked as MP0, MP1, MP2, MP3, and MP4, respectively. During the coexisted growth periods of wheat and maize, P fertilization increased the LAI, leaf area duration (LAD), and stem and leaf DMA of maize significantly. After the jointing stage of maize, the maize LAI, LAD, DMA, and crop growth rate (CGR) all decreased after an initial increase with the increasing P rate, with the maximum growth in treatment MP2 or MP3. During the reproductive stage of maize, the maize dry mass translocation from vegetative to reproductive organ increased with increasing P fertilization rate, and the grain yield of both maize and whole cropping system increased firstly and decreased then, with the maximum grain yield of maize and whole cropping system being 6588 and 11955 kg x hm(-2) in treatment P3, respectively. The P apparent recovery efficiency of maize was the highest (26.3%) in treatment MP2, being 82.6%, 38.4%, and 152.9% higher than that in MP1 (14.4%), MP3 (19.0%), and MP4 (10.4%), respectively. In sum, for the wheat/maize/soybean intercropping system, applying appropriate amount of P fertilizer could promote maize growth, alleviate the impact of wheat on maize, and consequently, increase the P apparent recovery efficiency of maize. In this study, the appropriate P fertilization rate was 75-112.5 kg P2O5 x hm(-2).

A total of 120 recombinant inbred lines (RIL) derived from Chinese winter wheat cultivars Longjian 19xQ9086 and the two parents were taken as test materials to study the quantitative genetics characteristics of their plant height at different development stages, thousand-grain mass, as well as the correlations between the two traits under rainfed (drought stress) and well-watered conditions, and evaluate the genetic variation of the RIL. Under the two water conditions, the target traits of the RIL showed substantial transgressive segregation and great sensitivity to water condition. The drought stress coefficient of the plant height was higher at jointing stage, being up to 0.851. There was a significant positive correlation between the plant height at different development stages and the thousand-grain mass, and comparing with that at other growth stages, the plant height at jointing stage had a higher correlation coefficient with the thousand-grain mass (R2DS = 0.32, R2WW = 0.28). The plant height at both jointing and flowering stages had significant positive and direct effect but negative and indirect gross effect on the thousand-grain mass, while the plant height at heading and maturing stages was in adverse. The target traits showed a lower heritability ranged from 0.27 to 0.60. The numbers of the gene pairs controlling the thousand-grain mass were 10 under rainfed and 13 under well-watered conditions, while those of the gene pairs controlling the plant height at different development stages were 3-7 under rainfed and 4-14 under well-watered conditions, respectively. According to the clustering of the drought stress coefficient of plant height, the RIL could be classified into five subgroups, showing the abundant variation of the RIL in their phe- notypes and in the sensitivity to water condition. It was considered that the test RIL were appropriate for the study of the quantitative genetics of wheat drought resistance.

In this paper, silkworm excrement was harmless-treated via controlled fermentation to prepare silkworm excrement organic fertilizer (SEOF). The nutrient properties of the SEOF were determined, and a pot experiment was conducted to examine the application effect of the fertilizer. After fermentation, the total N, P, and K contents in the SEOF had a significant increase, being 58.0%, 84.4% , and 29.7% higher than those in the raw material, respectively. The addition of microbial inoculants shortened the fermentation period, and decreased the carbon and nitrogen losses during fermentation. With the application of SEOF, the seed germination index of cabbage and tomato was higher than 80% , suggesting that the fertilizer had no inhibitory effect on the seed germination. The application of SEOF not only increased the Chinese cabbage yield and its nutrients and Vc contents, decreased the plant nitrate content, but also improved the soil pH value, and increased the soil available nutrients and organic matter contents and soil enzyme activities, with better effect than applying composted goat feces.

Based on the ideology of macro environmental economics, a function of environmental pressure represented by pollutant emission was built, and the relative importance of the driving factors in the dynamic changes of the relationships between economic growth and environmental pressure in Gansu Province in 1990 - 2005 was analyzed by using structural decomposition analysis (SDA) model combining with 'refined Laspeyres' method. In the study period, the environmental pressure in the Province was mainly caused by the emission of waste gases and solids in the process of economic growth, and showed a rapid increasing trend at the late stage of the period. Population factor had less impact on the increase of this environmental pressure, while economic growth factor had obvious impact on it. Technological progress did mitigate, but could not offset the impact of economic growth factor, and the impacts of economic growth and technological factors on the environmental pressure differed with the kinds of pollutants.

Different from the large scale farm management in Europe and America, the scattered farmland management in China made the spatial variability of soil nutrients at county scale in this country more challenging. Taking soil Olsen-P in Wuhu County as an example, the influence of interpolation method and sampling number on the spatial prediction accuracy of soil nutrients was evaluated systematically. The results showed that local polynomial method, ordinary kriging, simple kriging, and disjunctive kriging had higher spatial prediction accuracy than the other interpolation methods. Considering of its simplicity, ordinary kriging was recommended to evaluate the spatial variability of soil Olsen-P within a county. The spatial prediction accuracy would increase with increasing soil sampling number. Taking the spatial prediction accuracy and soil sampling cost into consideration, the optimal sampling number should be from 500 to 1000 to evaluate the spatial variability of soil Olsen-P at county scale.

A field experiment with 12-level N fertilization in winter wheat growth season and zero-N in summer maize growth season was conducted to study the appropriate soil nitrate N content for a winter wheat/summer maize rotation system in North China Plain. The results showed that when the soil mineral N content before sowing was higher, a split application of 150 kg N x hm(-2) in winter wheat growth season could meet the N demand of both winter wheat and summer maize in the rotation system. The N use efficiency of winter wheat in different N treatments was only from 11% to 23%, while the residual N use efficiency of summer maize ranged from 30% to 52%. When the nitrate N content in top 90 cm soil layer before maize sowing was up to 82 and 151 kg x hm(-2), respectively, the N demand of summer maize at its ten-leaf stage and in its whole growth season could be met with no N application. However, when the nitrate N content in top 90 cm soil layer was less than 46 and 65 kg x hm(-2) at maize ten-leaf stage and after harvest, respectively, no N application could impact maize growth, and decrease its grain yield. With the maize yield and environmental protection considered comprehensively, the nitrate N content in top 90 cm soil layer should be maintained at an appropriate level from 65 to 151 kg x hm(-2) during maize growth season.