Potato yield gaps across the rainfed Yin-mountain Hilly Area of China

Yin-mountain Hilly Area is one of the ideal regions for potato （Solanum tuberosum） production in China. However, potato yield is severely limited as a result of rain-fed crop mode due to water deficiency, as well as an inadequate farming practices. In this study, yield gaps were determined by using attainable yield （Ya） as a benchmark under optimized management practices, i.e., micro-ridge and side planting with plastic-mulching （MS）, and flat planting with plastic-mulching （PM）. The yields under MS and PM modes are defined as Yal and Ya2, respectively. Under the same field with MS and PM modes but different densities and fertilizer usages and so on, it was defined as simulated farmers＇ practices. The yield of simulated farmers＇ practices （Yfl） reached 57.3 and 69.6% of Yal and Ya2, respectively, while the average yield of 298 randomly surveyed farmers （Yf2） reached only 37.0 and 47.8% of Yal and Ya2 for rain-fed potato, respectively. The gaps of water use efficiency exhibited similar pattern. Further analysis shows that improper measures in rainwater conservation and accumulation, and other management practices contributed to 18.5, 18.2, and 42.6% of yield gap between Yal and Yf2. Improper nutrition management, including overuse of nitrogen and the deficiency of phosphorus andpotassium supplication, was one of the important reasons of yield gap. The results indicate the possibilities of increasing rain-fed potato yields by optimized water and fertilizermanagements in the Yin-mountain Hilly Area.

Effects of Land Use Change on Eco-environment in Hilly Area of Central Sichuan Basin——A Case Study of Yanting County, Sichuan Province

With the artificial alder and cypress mixed forest being planted, there has been a marked land use change since 1970s' in Hilly Area of Central Sichuan Basin, China. Data from meteorological observations or posts operated over long time, measurement and calculation of NPP (net primary production) and biomass of biological community, and analysis of soil organic matter content show that the artificial alder and cypress mixed forest has outstanding eco-environmental effect: adjusting local climate, raising soil fertility, alleviating menace of drought, and raising NPP and biomass of biological community. It is very beneficial for improving ecological environment to afforest artificial alder and cypress mixed forest in populous Hilly Area of Central Sichuan Basin, China. Key Words: land use/land cover change (LUCC); eco-environmental effect; Hilly Area of Central Sichuan Basin; the artificial alder and cypress mixed forest

Spatial and Temporal Distributions of Soil Organic Matter in the Mixed Plantations of Alder and Cypress in the Hilly Areas of Central Sichuan Basin

The investigation was conducted on the spatial and temporal distributions of soil organic mater （SOM） in the mixed plantations of alder （Aluns crernastogyne） and cypress （Cupressus funebris ） （MPAC）, which distributed in the hilly areas of central Sichuan Basin （HACSB）. The results show that： （1） the spatial distribution of SOM among different sites at the same age are not significant before 15-year-old, but significant at 20-year-old, and not significant again after 25-year-old; （2） the SOM contents in 0-15 cm and 15-30 cm layers increase sharply from 10- to 15-year-old, and decline gradually from 15- to 30- year-old; the SOM contents of the 30-year-old PCP were 80. 38% and 78.42% higher than that of the 10-year-old, but 29.16% and 53.37% lower than that of 15-year-old in the 0-15 cm and 15-30 cm layers, respectively. The decrease of SOM contents would lead to the degradation of soil fertility and the decline of forest productivity.

Characteristics of Soil Seed Banks of Typical Plant Communities in Hilly Area of Funiu Mountain

[Objectives]The purpose was to investigate the characteristics of soil seed bank of typical plant communities in hilly area of Funiu Mountain.[Methods]The seed density,number of species and species composition of the soil seed bank of typical plant communities such as Themeda japonica,Imperata cylindrica,Vitex negundo,Quercus acutissima,Robinia pseudoacacia,Platycladus orientalis and Populus canadensis in the surface,top 0-5 and top 5-10 cm soil were studied.[Results]The seed reserves of plant communities at different succession stages were(220.00±95.39)–(2650.00±1064.52)seeds/m2.A total of 48 species were counted in the seed bank,belonging to 45 genera in 22 families.Total 27 species were identified in the above-ground vegetation,belonging to 25 genera in 14 families.In the shallow soil where the seeds gathered,the seed densities of Imperata cylindrica and Themeda japonica were relatively low.The reserves of plant communities with different naturalness degrees were(403.33±64.29)-(2110.00±356.79)seeds/m2.A total of 67 species were counted in the seed bank,belonging to 64 genera in 37 families.A total of 45 species were identified in the above-ground vegetation,belonging to 43 genera in 28 families.In the soil layers of 0-5 and 5-10 cm,the seed density of natural secondary Q.acutissima was higher than those of planted P.canadensis,P.orientalis and R.pseudoacacia.In each soil layer,the species number of natural secondary Q.acutissima forest was slightly smaller than those of planted P.canadensis,P.orientalis and R.pseudoacacia forests.[Conclusions]The seeds in the soil seed bank may not completely come from existing above-ground vegetation.Manual assistance is required for vegetation restoration or reconstruction relying on soil seed bank,to ensure the direction of community succession.

Path for the “Interaction between Industrialization and Urbanization” in Low Hilly Areas of Sichuan Against the Background of New Urbanization: A Case Study of Overall Planning of Lianjie Town in Weiyuan County

Taking the practical experience of Lianjie Town, Weiyuan County for example, this paper analyzed regional characteristics of the low hilly areas in Sichuan and interaction mechanism of "industrialization and urbanization", explored the path for the interaction between industrialization and urbanization from 5 perspectives, namely accelerating industrial upgrading, optimizing industrial structure, breaking through the dual system, industry back-feeding town, and protecting ecological background.

Moderate scale and realization potential of new citrus-planting business entities in hilly and mountainous areas in China

The natural and economic conditions of agricultural resources vary greatly in China,especially in hilly and mountainous areas.The phenomenon of land fragmentation has become increasingly prominent,so that large-scale operations cannot be fully achieved in a short period of time,and the centralized and continuous scale of operations cannot be realized in China.In addition,with increasingly strict farmland protection and agricultural land use control systems,the issues of nongrain production and nonagricultural cultivated land use have become increasingly restricted.Thus,it is quite necessary to determine the appropriate scale of operations and the means to achieve moderately scaled operations for the new business entities.On the basis of microsurvey data for 108 new citrus-planting business entities in the modern agricultural park in the Chongqing's Jiangjin District,an area with long citrus-planting history,we measured the moderate scale of new citrus-planting business entities to maximize profit using a translog growth model.According to the projection pursuit model,we evaluated the suitability conditions of citrus planting in garden land,woodland,grassland,and general cultivated land in the study area.We then explored the potential for new moderate-scale business entities within different farming radii.The results showed that large-scale planting conditions of citrus in garden land,forest land,grassland,and general cultivated land in the study area were suitable,and the proportion of high-suitable and mediumsuitable land was 73.42%.Under the existing social and economic conditions,the moderate scale of new citrus-planting business entities in the study area was 1.8–2.7 hm^(2).In particular,its rankings from large to small were agricultural enterprises(17.19–25.78 hm^(2)),farmer cooperatives(16.88–25.33 hm^(2)),big growers and breeders(6.39–9.59 hm^(2)),and family farms(5.02–7.53 hm^(2)).In the sample of 108 households,only 47.22%of the entities achieved moderate-scale operation,of which 25%of the entities achieved a scale greater than moderate operation.However,52.78%of the entities achieved a scale of less than moderate operation.These entities would have to transfer the surrounding adjacent garden land,forest land,grassland,or general cultivated land to achieve largescale land management.The land area of the adjacent gardens in a 1000 m farming radius could meet the moderate-scale operation demand of the vast majority of new business entities.For the vast majority of new business entities,the land area of the adjacent woodland,grassland,and general cultivated land could supplement the garden land to achieve moderate-scale operation in a 500 m farming radius.If the land area with moderate suitability and high suitability is prioritized,the land area in the adjacent gardens in the 1000 m farming radius could meet the moderate-scale operation demand for the vast majority of new business entities.Within the 500 m farming radius,the vast majority of new business entities have achieved moderate-scale operations if the land area adjacent to forest land,grassland,and general arable land was supplemented by gardens;however,a few entities could not achieve moderate-scale operations.From the village perspective,gardens were prioritized.Sixteen villages had planting areas and planting suitability that exceeded the average level of the study area,accounting for 23.53%.If combined with the reserve potential of the garden land,eight villages could improve their potential,accounting for 11.76%.Therefore,the conditions of large-scale citrus planting in the study area should be further improved,and the scale expansion of new citrus-planting business entities should receive additional scientific guidance.

Structure and governance model of rural social space quality:A case study of Longxi County in the Loess Hilly Area of China

The rural social space quality is an important indicator to measure the living standard and thinking ideas and so forth of rural residents in a certain region.In this paper,213 administrative villages in Longxi County of the Loess Hilly Area,China are taken as evaluation units to construct the evaluation model of the rural social space quality.This paper deeply analyzed the variation patterns and their formation mechanism of the rural social space quality at a village scale,and proposed a governance model based on the rural social space quality.The results show that:(1)the social space quality levels of individual administrative villages show a gradually decreasing trend from the township seats to outward.The eastern part of Longxi County has a relatively high education level and living standard,and the western part has a relatively high population stability level and income level.(2)The rural social space quality is mainly in a ring structure,supplemented by the interlaced structure.The core area is the towns and their surrounding areas,while the transition area,marginal area,and other areas are expanded around the core area.(3)Social forces and spatial effects jointly shape the variation of the rural social space quality.Social organizations provide a driving force for the allocation of elements,and interweaving with the spatial effects lead to the differences in the social space quality.(4)The governance models of the rural social space quality are constructed based on the principles of retaining the rural“people”,optimizing the rural“land”,and developing the rural“industry”,so as to improve the rural centripetal force,core force,inner thrust,and source power.

Temporal variation of soil water and its influencing factors in hilly area of Chongqing,China

The paper studied the temporal variation of soil water content and its influencing factors in hilly area of Chongqing by the yearly data of 2006 and 2007.According to precipitation anomaly percentage,the year 2006 was a dry year and 2007 a normal year.In the dry year 2006,the variations of soil moisture in all three layers(0-10 cm,10-20 cm,20-40 cm)were medium(10%<CV<30%);in the normal year 2007,the variation in the layer of 0-10 cm was strong(CV>30%),and those of the two deeper layers were weak(CV<10%).Hence,the seasonal variation of soil moisture in the humid area was large in the dry year and small in the wet year.The probability distributions of soil moisture in all three layers in both dry and normal years showed single-peak shapes.However,peak locations and values varied with different layers and years.Among factors affecting the temporal variation of soil moisture in the 0-10 cm layer,during March to May,the meteorological factors including temperature,sunshine and precipitation were all inversely correlated with soil water content variation.The correlations with average temperature and accumulated temperature were both highly significant P<0.01(P=0.00).The inverse correlations with sunshine and precipitation were significant P<0.05(P=0.01).Among soil physical properties,except for bulk density which was inversely correlated with soil moisture,all other properties were positively correlated.Organic material was positively correlated with soil moisture,which suggested that organics had the sponge effect and contributed to soil water storage and movement.During the period of June to September,there was no significant correlation between soil water content and total storage.The meteorological factors of temperature,accumulated temperature and sunshine were all inversely and highly significantly correlated with soil water content P<0.01(P=0.00).

Design and experiment analysis of the small maize harvester with attitude adjustment in the hilly and mountainous areas of China

To solve the problem of small planting plots and large sloping land for mechanized maize harvesting in China hilly and mountainous areas,a small maize harvester with attitude adjustment was designed to realize maize snapping,peeling,straw crushing and attitude adjusting at on time in this study.The basic structure and working principle of the small maize harvester were described,and the key components were designed as follows.The maize snapping device adopted the combination form of maize snapping plates and straw pulling rollers,and the gap of the straw pulling rollers can be adjusted to adapt to different maize varieties.Two pairs of peeling rollers formed a groove arrangement to improve peeling rate and reduced ear grain loss.The pressure feeding device mainly comprised drive chain and three grade pressure feeding rollers to increase the friction between ears and the peeling rollers,and help ears slide.The attitude adjustment advice was designed according to the high point stationary pursuit leveling method.When the attitude angle of the rack approached 0,the small maize harvester reached the level state.The actual range of attitude adjustment was obtained and the accuracy of static attitude adjustment was verified through attitude adjustment test.The influencing factors of ear loss rate and bract peeling rate were determined by orthogonal test,including the rotational speed of straw pulling rollers,peeling rollers and pressure feeding rollers.The mathematical regression model between the experimental factors and indicators was established by using Design Expert,and through the analysis variance to verify the significance of the evaluation indicators,the best combination of operation parameters was determined that the rotational speed of straw pulling rollers,peeling rollers and pressure feeding rollers were 1440 r/min,1535 r/min and 406 r/min.Under the optimal combination of the operation parameters,the ear loss rate and bract peeling rate were 1.33%and 93.98%.The design indicators of the small maize harvester can meet the relevant national standards,and can satisfy the need of maize mechanized harvesting in China hilly and mountainous areas.

Two New Species of Fire-Bellied Newts (Caudata, Salamandridae, Cynops) from Southeastern China

The fire-bellied newt genus Cynops contains ten known species distributed in China and Japan in East Asia.In this work,two new Cynops species are described,namely Cynops jiaoren sp.nov.distributed in northern Guangdong and Cynops maguae sp.nov.distributed in eastern Jiangxi.The two new species can be distinctly distinguished from their congeners by the independent phylogenetic placements and a combination of morphological characteristics.The discovery of these two new species in the Southeast Chinese Hilly Area,where half of congeners occur,increases the known diversity of Cynops,and indicates unresolved relationships among the species in southeastern China.Further discussions on the taxonomic status of Cynops cyanurus are also provided.

The effects of land use and its patterns on soil properties in a small catchment of the Loess Plateau

Due to relatively strong human activities in the hilly area of Loess Plateau, the natural vegetation has been destroyed, and landscape pattern based on agricultural land matrix was land use mosaic composing of shrub land, grassland, woodland and orchard. This pattern has an important effect on soil moisture and soil nutrients. The Danangou catchment, a typical small catchment, was selected to study the effects of land use and its patterns on soil moisture and nutrients in this paper. The results are as follows: The comparisons of soil moisture among seven land uses for wet year and dry year were performed: (1) the average of soil moisture content for whole catchment was 12.11% in wet year, while it was 9.37% in dry year; (2) soil moisture among seven land uses was significantly different in dry year, but not in wet year; (3) from wet year to dry year, the profile type of soil moisture changed from decreasing type to fluctuation-type and from fluctuant type to increasing type; (4) the increasing trend in soil moisture from the top to foot of hillslope occurred in simple land use along slope, while complicated distribution of soil moisture was observed in multiple land uses along slope. The relationships between soil nutrients and land uses and landscape positions were analysed: (1) five nutrient contents of soil organic matter (SOM), total N (TN), available N (AN), total P (TP) and available P (AP) in hilly area were lower than that in other areas. SOM content was less than 1%, TN content less than 0.07%, and TP content between 0.05% and 0.06%; (2) SOM and TN contents in woodland, shrub land and grassland were significantly higher than that in fallow land and cropland, and higher level in soil fertility was found in crop-fruit intercropping land among croplands; (3) soil nutrient distribution and responses to landscape positions were variable depending on slope and the location of land use types.

Seasonal Variation and Meteorological Control of CO_2 Flux in a Hilly Plantation in the Mountain Areas of North China

The carbon cycle of terrestrial ecosystems is an important scientific issue in global climate change research.Plantation forest plays an important role in terrestrial carbon budget in China.In this study,eddy covariance flux data measured at Xiaolangdi forest ecosystem research station（XLD） in 2007 and 2008 are used to analyze the seasonal variation and meteorological control of CO2 flux in a 30-yr-old mixed plantation.The plantation forest mainly consists of Quercus variabilis,Platycladus orientalis,and Robinia pseudoacacia.The results show that the seasonal variations of net ecosystem exchange of CO2（NEE）,gross primary production（GPP）,and ecosystem respiration（Re） display single-peak curves.The maximum of carbon sequestration appears during May and June each year.The relative contribution of carbon release from ecosystem respiration to GPP varied slightly between 2007 and 2008.The relationship between NEE and photosynthetic active radiation（Qp） accords with the rectangular hyperbola model on diurnal scale,and shows a good linear correlation on monthly scale.The ecosystem photosynthetic parameters：the maximum photosynthetic rate（Pmax）,the ecosystem photosynthetic photonyield（α）,and the daytime ecosystem respiration（Rd） exhibit seasonal variations.Pmax reaches the maximum in August each year,with small interannual difference.The interannual differences of α and Rd are obvious,which is attributed to the changes of meteorological factors,such as solar radiation,vapor pressure deficit（D）,precipitation,etc.Parameters Re,GPP,and NEP（net ecosystem production） have obvious exponential relations with temperature on monthly scale.There is a hysteresis in the response of GPP and NEP to temperature,i.e.,the carbon sequestration is not the maximum when the temperature reaches the peak value.The Q10 values were 1.37 and 1.45 in 2007 and 2008,respectively.On monthly scale,Re,GPP,and NEE increase as D increases,but rise slowly and even decrease when D is higher than 1.5 kPa.

Restoration technologies of damaged paddy in hilly post-mining and subsidence-stable area of Southwest China

The paddy fields and water storage facilities are seriously damaged by the coal mine subsiding in the hilly post-mining and subsidence-stable areas in China,which make the farmers there being suffered greatly from the lack of water for traditional rice cultivation and daily life.The purpose of this paper is to find a method to restore the damaged paddy fields,thereby promoting sustainable development of land resources,and alleviating the contradiction between people and land,as well as creating a more inhabitable environment.The research methodology included field experiments,cultivated observation,and field investigation.This paper selected the Songzao Mining Area as the research area,and focused on the restoration technologies of damaged paddy fields,through the following four different measures at three experimental fields:(1)Traditional repeated cattle plowing(CK);(2)Water retention agent with repeated cattle plowing(W&C);(3)Film without holes under tilth depth(FO);and(4)Film with holes under tilth depth(FW).At last,a contrastive analysis of the four measures was made according to the results of the experiments.The results show that the use of water retaining agent with repeated cattle plowing(W&C)can be the most appropriate method to restore the damaged paddy field in the hilly post-mining and subsidence-stable area in southwest China.Compared with the other three measures,its water productivity is the maximum(0.81 kg/m3),and the net income is the highest(1403$/hm^(2)).What’s more,it is simple,short time-consuming,and low cost,which is benefit to generalize the use of this restoration technology.

Planning Method of Ecological Embedded Industrial Parks

Exploration of the gentle slopes of low mountains and hills has already become a new topic in the development of urban land resources in hilly areas. For the high ecological sensitivity, tremendous cost of urban construction, as well as complicate utilization technology, planning and design of gentle slopes of low mountains and hills are faced with serious challenges. This paper took the planning of Yidu High-tech Industrial Park for example, to explore the design concepts and rational methods of planning "ecological embedded" industrial parks in hilly areas.

An applied research on remote sensing classification in the Loess Plateau

Dae to complex terrain of the Loess Plateau, the classification accuracy is unsatisfactory when a single supervised classification is used in die remote sensing investigation of the sloping field. Taking the loess hill and gully area of northern Shaanxi Province as a test area, a research was conducted to extract sloping field and other land use categories by applying an integrated classification. Based on an integration of supervised classification aad unsupervised classification, sampling method is remarkably unproved. The results show that the classification accuracy is satisfactory by the method and is of critical significance in obtaining up-to-date information of the sloping field, which should be helpful in the state key project of converting farmland to forest and grassland on slope land in this area. This research sought to improve the application accuracy of image classification in complex terrain areas.

Problems and prospects of fish farming in the Chattogram Hill Tracts of Bangladesh:Community-based aquaculture might be a right choice

The study was carried out in Matiranga Upazila,Bandarban district,which is considered one of Bangladesh’s major hill tract regions.The study aimed to identify present farming conditions,prospects,and problems and suitable solutions to the problems of fish farming.Different participatory rapid appraisal tools such as focus group discussion,field visits,and farmers’interviews were used to collect relevant fish farming information in the study area.The polyculture method was the most practised aquaculture method.Among the selected farms,eleven fish species were identified as culture species.The transportation cost for seeds purchased from remote areas was high(11%of total seed cost).The average transportation-related mortality of fish fry and fingerlings was 7.2%and 2.8%.Feed cost was found as the major cost(58.4%)in aquaculture.Costs and revenue for fish production per decimal varied from BDT 311 to 3528 and BDT 23 to 1268.Utilization of vacant lake,youth and women engagement,integrated aquaculture,the desire of people to engage in aquaculture,and available human resources were found as significant prospects.The major problems identified were lack of hatchery,high feed cost,lack of stakeholder linkage,lack of capital for fish farming,and lack of proper knowledge,guidelines,and consultancy for fish culture.A community-based aquaculture model was proposed to overcome the present challenges and problems in the study area.The model may help to expand aquaculture and thus improve the livelihood and socio-economic status of the people of the hilly areas of Bangladesh.

Hydrological cycle research by D&^(18)O tracing in small watershed in the loess hilly region

The objective of this study was to determine the mechanisms of the hydrologic cycle in the loess area in China.Sixty eight water samples from precipitation,soil water of the 0-4 m layer,surface water in the valley,ground water(spring and well)were collected and the Deuterium(D)and Oxygen-18(^(18)O)of these water samples were analyzed to interpret the relationship among those waters in the watershed in the loess hilly region during 2005-2009.The results show that:the D&^(18)O of precipitation in Yangou was consistent with that of Xi,an,apparently the north migration of water vapor in Xi^an;according to the correlations among the differential waters in D&^(18)O,confirmed that precipitation recharge could account for most of the sources of valley flow,with part of the recharge water going to soil water recharge.The D&^(18)O of groundwater were very close to that of precipitation,likely the soil preferential flow was dominant in groundwater recharge although the infiltration had a certain lag.Under the influence of rainfall and evaporation,the response of the soil moisture profile,and its D&^(18)O profile were different.The soil moisture had the strong influenced layer in the 60-160 cm range,a weak impacted layer in 60 l60 cm,and a stable layer below l60 cm.It was shown that the soil evaporation depth could be up to l60 cm because the D&^(18)O changed in that depth.The study could increase our understanding of the magnitude and pattern of the hydrologic cycle,which should improve water resources management in the watershed scale.

湘闽赣山区劳动力转移差异对梯田荒决策和规模的影响

In recent years,the phenomenon of abandonment of cultivated land in mountainous areas has occurred frequently,and the problem of abandonment has become a focus of attention of government agricultural departments and academic circles.However,few studies have paid attention to the impact of differences in labor transfer on the abandonment behavior of farmers’terraced fields.Based on this,this paper takes the terraced fields of Hunan,Fujian and Jiangxi provinces as the research area,combined with data from 1438 farmer households,and uses the Probit and Tobit models to analyzed the impact of the difference in the quantity,distance and quality of labor off-farm transfer on the decision-making and scale of terraced field abandonment of farmer households.The results show that:(1)The greater the quantity of labor transfer,the farther the transfer distance and the higher the quality of non-agricultural employment,can promote the decision of farmers to abandon terraced fields;(2)With the deepening of the degree of non-agricultural transfer,the scale of abandoned terraced fields by farmers in hilly and mountainous areas will also expand;(3)The distance and quality of labor transfer can strengthen the impact of labor transfer quantity on farmers’decision to abandon land.To alleviate the phenomenon of abandoned terraced fields,the government should pay attention to the labor substitution role of agricultural service outsourcing and mechanization in mountainous areas.The government should actively promote the transformation of terraced fields into mechanized farming,improve the cultivated land transfer market,and encourage farmers to transfer terraced fields.

Integrated rice management simultaneously improves rice yield and nitrogen use efficiency in various paddy fields

The hilly area of Southwest China is a typical rice production area which is limited by seasonal droughts and low temperature in the early rice growth period.A field experiment was conducted on three typical paddy fields(low-lying paddy field,medium-elevation paddy field,and upland paddy field)in this region.Nitrogen(N)treatment(180 kg N ha-1 year-1)was compared to a control treatment(0 kg N ha-1 year-1)to evaluate the effects of integrated rice management(IRM)on rice growth,grain yield,and N utilization.Integrated rice management integrated raised beds containing plastic mulch,furrow irrigation,and triangular transplanting.In comparison to traditional rice management(TRM),IRM promoted rice tiller development,with 7–13 more tillers per cluster at the maximum tillering stage and 1–6 more tillers per cluster at the end of tillering stage.Integrated rice management significantly increased the rice aboveground biomass by 34.4%–109.0%in different growth periods and the aboveground N uptake by 25.3%–159.0%.Number of productive tillers significantly increased by 33.0%,resulting in a 33.0%increase in grain yield and 8.0%improvement of N use efficiency(NUE).Grain yields were significantly increased in all three paddy fields assessed,with IRM being the most important factor for grain yield and productive tiller development.Effects of paddy field type and N level on N uptake by aboveground plants were reflected in the rice reproductive growth period,with the effects of IRM more striking due to the dry climate conditions.In conclusion,IRM simultaneously improved rice yield and NUE,presenting a valuable rice management technique in the paddy fields assessed.

Spatiotemporal variation of agricultural patterns in different geomorphologic and climatic environments in the eastern Loess Plateau,north-central China during the late Neolithic and Bronze Ages

Human settlement and agricultural development are closely linked to local geomorphological and climatic environments.However,the variation in agricultural systems in different environmental and prehistoric contexts remains unknown.We report new archaeobotanical and radiocarbon dates from 34 Neolithic and Bronze Age sites in the Hutuo River Valley(HTRV)in north-central China and compare them with updated archaeobotanical studies in the Sushui River Valley(SSRV)and Henan Province(HNP),to explore the similarities and differences of agricultural patterns under different geomorphologic and climatic environments in north-central China.Our results reveal that humans consistently cultivated foxtail and broomcorn millet in the HTRV from the Miaodigou(6000–5700 cal.a BP)to the Shang-Zhou(3600–2256 cal.a BP)period,despite the introduction of wheat and barley into the area around 4000 a BP.Climate conditions and hilly landforms in the HTRV,SSRV and some parts of the HNP led people to develop foxtail and broomcorn millet dry land farming practices between 7000 and 3000 a BP.Alternatively,in other areas of the HNP,the climate conditions and alluvial plains enabled people to develop a mixed agriculture of millets,soybeans,and rice from 7000 to 4000 a BP,with the addition of wheat between 4000 and 3000 a BP.Farmers’different agricultural technologies and interactions with foreign cultures may have also influenced the formation of different agricultural patterns in the three regions between 7000 and 3000 a BP.Population growth during 7000–3000 a BP can explain the overall propensity of the higher-yield foxtail millet rather than broomcorn millet as the main cultivated crop.In the HTRV,however,higher proportions of broomcorn millet(as compared to the SSRV and HNP),may reflect the greater drought and heat tolerance of broomcorn millet,representing an adaptive agricultural strategy in the river valley.