An Econometric Analysis on the Effect of Climate Change on Wheat Cropping Area in China

[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.

Crop area and leaf area index simultaneous retrieval based on spatial scaling transformation

Accurate estimation of crop yields is crucial for ensuring food security. However, crops are distributed so fragmentally in China that mixed pixels account for a large proportion in moderate and coarse resolution remote sensing images. As a result, unmixing of mixed pixel becomes a major problem to estimate crop yield by means of remote sensing method. Aimed at mixed pixels, we developed a new method to introduce additional information contained in the spatial scaling transformation equation to the canopy reflectance model. The crop area and LAI can be retrieved simultaneously. On the basis of a precise and simple canopy reflectance model, directional second derivative method was chosen to retrieve LAI from optimal bands of hyper-spectral data; this method can reduce the impact of the canopy non-isotropic features and soil background. To evaluate the performance of the method, Yingke Oasis, Zhangye City, Gansu Province, was chosen as the validation area. This area was covered mainly by maize and wheat. A Hyperion/EO-1 image with the 30 m spatial resolution was acquired on July 15, 2008. Images of 180 m and 1080 m resolutions were generated by linearly interpolating the original Hyperion image to coarser resolutions. Then a multi-scale image serial was obtained. Using the proposed method, we calculated crop area and the average LAI of every 1080 m pixel. A SPOT-5 classification figure serves as the validation data of crop area proportion. Results show that the pattern of crop distribution accords with the classification figure. The errors are restrained mainly to -0.1-0.1, and approximate a Normal Distribution. Meanwhile, 85 LAI values obtained using LAI-2000 Plant Canopy Analyzer, equipped with GPS, were taken as the ground reference. Results show that the standard deviation of the errors is 0.340. The method proposed in the paper is reliable.

Inter-provincial Differences in Rice Multi-cropping Changes in Main Double-cropping Rice Area in China: Evidence from Provinces and Households

Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring challenges to food security in China because rice is the staple food for more than 60% of the Chinese population. It has been generally recognized that rapidly rising labor costs due to economic growth and urbanization in China is the key driving force of the ‘double-to-single' rice cropping system adaption. However, not all provinces have shown a dramatic decline in DCR area, and labor costs alone cannot explain this difference. To elucidate the reasons for these inter-provincial distinctions and the dynamics of rice cropping system adaption, we evaluated the influencing factors using provincial panel data from 1980 to 2015. We also used household survey data for empirical analysis to explore the mechanisms driving differences in rice multi-cropping changes. Our results indicated that the eight provinces in the study can be divided into three spatial groups based on the extent of DCR area decline, the rapidly-declining marginal, core, and stable zones. Increasing labor cost due to rapid urbanization was the key driving force of rice cropping system adaption, but the land use dynamic vary hugely among different provinces. These differences between zones were due to the interaction between labor price and accumulated temperature conditions. Therefore, increasing labor costs had the greatest impact in Zhejiang, Anhui, and Hubei, where the accumulated temperature is relatively low and rice multi-cropping index declined dramaticly. However, labor costs had little impact in Guangdong and Guangxi. Differences in accumulated temperature conditions resulted in spatially different labor demands and pressure on households during the busy season. As a result, there have been different profits and rice multi-cropping changes between provinces and zones. Because of these spatial differences, regionally appropriate policies that provide appropriate subsidies for early rice in rapidly-declining marginal zone such as Zhejiang and Hubei should be implemented. In addition, agricultural mechanization and the number of agricultural workers have facilitated double-cropping; therefore, small machinery and agricultural infrastructure construction should be further supported.

Distribution of Surface Ozone Concentration in the Clean Areas of China and Its Possible Impact on Crop Yields

From August 1994 to July 1995, ozone and its precursors were measured in the clean areas of China. The results show that in the period of crop growth, hourly mean ozone concentration, ozone concentration averaged in seven hours of daytime and accumulated ozone concentration in long period have approached or overpassed the harmful level in environmental and health standard of U. S. A. and Canada.

Effects of Inorganic-organic Incorporation on Productivity and Soil Fertility of Rice Cropping System in Red Soil Area of China

Results from ten-year (1990 - 1999) field experiments indicated that the productivity and the soil fertility of rice cropping system were significantly influenced by the fertilization system adopted in red soil area of China. Contrasting with no-fertili/er treatment (CK), yield-increase rate of organic matter cycling, chemical NPK and inorganic-organic fertilizer incorporation treatments were 56.5% , 62.5% and 80.7% , respectively. In the case of optimum fertilization system, the largest contribution of inorganic fertilizer to the yield was 38.5% while that of inorganic-organic fertilizer incorporation was 44.7%. The content of soil organic matter changed in tendency from decrease to equilibrium with heightened the extent of N, P and K incorporation while that of inorganic-organic fertilizer incorporation could be enhanced further. After N, P and K entered into the rice cropping system and maintained organic matter cycling in the system, the pools of total N, P and K could be strengthened.

Heavy Metal Contaminated Food Crops Irrigated with Wastewater in Peri Urban Areas, Zambia

Studies on peri urban farming in Zambia have not adequately tackled the issues pertaining to heavy metal contaminated wastewater irrigation farming. The study investigated heavy metal contamination of water, soils and crops at two peri urban areas in Zambia. Two study sites were New Farm Extension in Mufulira Town in the Copperbelt Province and Chilumba Gardens in Kafue Town in Lusaka Province. The heavy metals investigated were lead, copper, cobalt, nickel and chromium. These heavy metals were found to be higher than acceptable limits in wastewater used to irrigate crops and there are potential human health risks associated with consumption of heavy metal contaminated food crops which have implications on the livelihoods of people. Samples of water, soil and crops were collected and analysed for lead (Pb), copper (Cu), chromium (Cr), cobalt (Co) and nickel (Ni) using the Atomic Absorption Spectrometer (AAS). The data on heavy metals was analysed using mean, standard error and T-test. The results indicated that the levels of heavy metals in wastewater, soil and food crops were above acceptable limits at two study sites. It can be concluded that there was heavy metal contamination of wastewater, soil and food crops at the two peri-urban areas in Zambia. The study highlighted the actual levels of heavy metal contaminant uptake in food crops consumed by the peri urban population. The information from this study can be used by the relevant authorities to develop appropriate measures for monitoring and control of heavy metal contamination in wastewater irrigation farming systems in peri urban areas inZambia.

Analysis of the Impact of the Growing Area of Food Crops on Farmers' Income in Yunnan Province

As a major agricultural province,Yunnan has always attached great importance to food production,and the proportion of the growing area of food crops to the growing area of total crops is more than one half in Yunnan Province,but the grain production efficiency has been low in recent years.Therefore,under the guidance of stabilizing food production and adjusting structure proposed by Yunnan provincial government,we analyze the impact of the growing area of food crops on farmers' income,based on the recent trends of the growing area of food crops.Finally we put forth the following recommendations:developing the food production based on market; rationally making overall arrangement of planting structure; paying attention to the agricultural science and technology progress.

Water Consumption and Use Efficiency of Main Crops on Semi-drought Area of Western Liaoning Province

The laws of water consumption in corn,peanuts and millet on the semi-drought area of western Liaoning Province were studied through the FAO-Penman Monteith method and the water balance method.Among three corps,the amount of the day water demand,the whole growth period water demand and the soil water deficit of corn were all the largest.At the same time,its degree of agreement between the water demand and the level of precipitation was the worst,and its average in crop coefficient was larger.The amount of th...

Land Resource Areas and Spatial Analysis of Potential Location of Bioenergy Crops Production in Mississippi

Mississippi State is renowned for its land resource areas (LRA) and production of bioenergy crops which generate both agricultural and economic benefits. Agricultural commodities play a key role in economic growth, therefore the ability to produce more would enhance development. This paper offers an analysis of the production of bioenergy crops in Mississippi. Relative measures, time series graphs and descriptive statistics coupled with geographic information systems (GIS) mapping using ArcMap were employed to generate the outcome of this research. The outcome of the statistical analysis indicated that corn and soybeans were the most produced crops in Agricultural Districts 10 and 40. These districts produced more bioenergy crops than the other districts. GIS mapping results also showed that the potential area for bioenergy crops is in zone 131 of the Mississippi Land Resource Area (MLRA). This zone has an absolute advantage in the production of these crops which includes the diversity of biomass production such as corn, cotton, soybeans, wheat, rice, barley, grain sorghum, canola, camelina, algae, hardwoods, and softwood. The paper recommends a constant GIS mapping and land management systems for each agricultural district in Mississippi to enable researchers and farmers to determine the factors which contribute towards the increasing and decreasing trends in the production of the bioenergy crops.

Natural conditions and cropping regionalization of rice area in China

The formation of rice distribution is based on certain natural ecological conditions and social economic environments. In China, rice cropping is distributed in a vast area extending across 5 tempera ture belts, the northernmost of rice growing area in the world being in China. Distribution of rice cropping is characterized by a gradual decrease from south to north, from large and concentrated regions in Southeast to small and separated areas in Northwest. Natural conditions in rice regions differ in China with a varied topography, high in the west and low in the east. Rice fields in the west are mostly distributed on flatlands on plains, valleys among mountains, tablelands in river valleys, yellow-soil plains and basins in low valleys, alluvial plains, plains in river valleys, while those in the east are mainly distributed on alluvial plains, hilly areas among low mountains, coastal plains, along rivers and lakes and in basins among mountains.

Analysis on Change Tendency of the Precipitation Resource during Growth Period of the Conventional Crops in Plain Area before Taihang Mountains

[Objective] The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [ Method] Based on daily precipitation data at Shijiazhuang meteorological station in recent 51 years, average rainfall dudng growth periods of the 9 kinds of conventional crops was obtained. Precipitation tendency dudng growth periods of the 9 kinds of conventional crops in plain area before Taihang Mountains was analyzed by Mann-Kendall nonparametric test. [ Result] Seen from rainfall during growth pedods of the different crops, rainfall was the least during the growth period of winter wheat, followed by summer corn. Rainfall during growth peri- ods of the cotton, oil plant, vegetable, fruit tree, potato, rice and legumes was more. Under different guaranteed rates, precipitation change also had difference. Rainfall change during growth periods of the wheat and corn was bigger, and rainfall change during growth period of the rice was smaller. Change degree of the precipitation during growth periods of the cotton, oil plant, vegetable, fruit tree and legumes was equivalent, while precipitation change during growth period of the potato was the biggest. Seen from change tendency of the precipitation during growth periods of the different crops, precipitation in the growth period of winter wheat was increasing at a speed of 0.62 mm/a. However, precipitation in growth periods of the other crops had a decreasing tendency. Precipitation in the growth periods of summer corn and legumes decreased at the same speed which was 2.11 mm/a, while precipitation in growth periods of the cotton, oil plant, vegetable, fruit tree, potato and rice decreased insignificantly. [ Con dusion] The study laid foundation for determination of the agricultural irrigation water and provided theoretical reference for regional agricultural water-saving.

基于AquaCrop模型的玉米需水和降水匹配度变化特征研究

雨热同期为我国大部分地区农业生产提供了充足的水热资源,但从需水机理的角度评估作物生长和降水过程匹配度的变化特征还有待深入。基于AquaCrop模型模拟了关中地区1978-2017年夏玉米生育期内需水量、灌溉需水量、有效降水量和产量的变化特征,并在充分考虑玉米不同生育阶段对水分需求程度差异的基础上,分析了作物需水与降水匹配度的变化特征。结果表明:关中地区玉米生育期内累积降雨量变化幅度相对较小,但降水过程明显后移,且更多的以暴雨的形式发生;玉米生育期内需水量和灌溉需水量均呈现明显的增加趋势,增加幅度分别为4.10 mm/10a和13.38 mm/10a,而有效降水量则以-10.28 mm/10a的速率减小;玉米生育期内需水与降水的平均匹配度为58%,且整体以-2.7%/10a的速率下降。上述结果表明关中地区降水模式越来越难以满足夏玉米的水分需求,延迟播种可作为提高作物需水与降水匹配度的应对措施之一。

Estimation of Wheat Area in Córdoba, Argentina, with Multitemporal NDVI Data of SPOT-Vegetation

Determining the area occupied by a crop is a prerequisite for estimating agricultural production in a region, and such information at present can be generated from satellite remote sensing systems. This study uses multitemporal NDVI images of SPOT-VEGETATION with a 1 km spatial resolution to estimate the wheat area in Córdoba Province, Argentina, and to assess 2 generic digital classification procedures based on crop phenological behavior. The Characteristic Phenology Behavior Method (CPBM) uses the contrast each year between typical values of NDVI variation in the wheat crop season and those of the area not occupied by active vegetation;while the other procedure, the Reference Curve Method (RCM), assesses the correspondence in each pixel between the observed sequence of NDVI from seeding to physiological maturity, compared with 4 curves of reference. The CPBM 2 procedure, which uses the amplitude of NDVI between sowing and heading (ampsh), produces estimates that correlate better with the observed record, with approximately 70% (P s the state reports at about 5%. On the other hand, RCM using Curve 1 explains 50% (P sh in the model with the minimum NDVI during physiological maturity stage (minpm) produced a deterioration of estimation, with R2 reduced to 0.37 (P 2 of 0.61 (P ed the linear relationship between observed and estimated with a slope that did not approach 1. RCM classification models reach a predictive performance similar to that shown in Río Segundo, with R2 values close to 0.50

Effects of Crop Growth and Development on Land Surface Fluxes

In this study, the Crop Estimation through Resource and Environment Synthesis model （CERES3.0） was coupled into the Biosphere-Atmosphere Transfer Scheme （BATS）, which is called BATS CERES, to represent interactions between the land surface and crop growth processes. The effects of crop growth and development on land surface processes were then studied based on numerical simulations using the land surface models. Six sensitivity experiments by BATS show that the land surface fluxes underwent substantial changes when the leaf area index was changed from 0 to 6 m2 m-2. Numerical experiments for Yucheng and Taoyuan stations reveal that the coupled model could capture not only the responses of crop growth and development to environmental conditions, but also the feedbacks to land surface processes. For quantitative evaluation of the effects of crop growth and development on surface fluxes in China, two numerical experiments were conducted over continental China： one by BATS CERES and one by the original BATS. Comparison of the two runs shows decreases of leaf area index and fractional vegetation cover when incorporating dynamic crops in land surface simulation, which lead to less canopy interception, vegetation transpiration, total evapotranspiration, top soil moisture, and more soil evaporation, surface runoff, and root zone soil moisture. These changes are accompanied by decreasing latent heat flux and increasing sensible heat flux in the cropland region. In addition, the comparison between the simulations and observations proved that incorporating the crop growth and development process into the land surface model could reduce the systematic biases of the simulated leaf area index and top soil moisture, hence improve the simulation of land surface fluxes.

Assimilation of Remote Sensing and Crop Model for LAI Estimation Based on Ensemble Kalman Filter

Data assimilation in agricultural remote sensing research is of great significance to integrate with remote sensing observations and model simulations for parameters estimation. The present investigation not only designed and realized the Ensemble Kalman Filtering algorithm （EnKF） assimilation by combing the crop growth model （CERES-Wheat） with remote sensing data, but also optimized and updated the key parameters （LAI） of winter wheat by using remote sensing data. Results showed that the assimilation LAI and the observation ones agreed with each other, and the R2 reached 0.8315. So assimilation remote sensing and crop model could provide reference data for the agricultural production.

拱架送/回风方式对日光温室冬季作物冠层区热环境的影响

传统日光温室被动的热环境调控模式难以满足温室作物冠层区空气温度和速度调控需求,且能源利用效率低下。为了改进日光温室热环境精准调控方法和提高温室能源利用效率,该研究结合日光温室围护结构特点,提出了一种日光温室拱架的送/回风方法,并基于温室作物多孔介质模型,建立了拱架送/回风系统温室的数值传热模型。采用空气温度与速度不均匀系数、气流速度适宜区面积比、能量利用系数以及累计有效积温等评价参数,研究了下送上回、中间回风和上送下回等3种温室拱架送/回风方式对日光温室冬季作物冠层区热环境的影响。结果表明,与中间回风和上送下回通风方式相比,下送上回通风方式对不同作物冠层高度处的空气温度和速度调控的结果最优,且不同作物冠层高度处气流速度适宜区面积比和累计有效积温都最大。当采用下送上回通风方式时,与送风干管风速为9、11和12 m/s相比,送风干管风速为10 m/s的能量利用系数最大,在作物冠层高度0.4、0.6、0.8和1.0 m处的能量利用系数分别为0.976、0.982、0.985和0.987,并且不同作物冠层高度处的空气温度不均匀系数和速度不均匀系数也都最小。因此,下送上回通风方式的推荐送风干管风速为10 m/s。该研究可为日光温室热环境的精准调控提供参考。

Assimilation of temporal-spatial leaf area index into the CERES-Wheat model with ensemble Kalman filter and uncertainty assessment for improving winter wheat yield estimation

To accurately estimate winter wheat yields and analyze the uncertainty in crop model data assimilations, winter wheat yield estimates were obtained by assimilating measured or remotely sensed leaf area index （LAI） values. The performances of the calibrated crop environment resource synthesis for wheat （CERES-Wheat） model for two different assimilation scenarios were compared by employing ensemble Kalman filter （EnKF）-based strategies. The uncertainty factors of the crop model data assimilation was analyzed by considering the observation errors, assimilation stages and temporal-spatial scales. Overalll the results indicated a better yield estimate performance when the EnKF-based strategy was used to comprehen- sively consider several factors in the initial conditions and observations. When using this strategy, an adjusted coefficients of determination （R2） of 0.84, a root mean square error （RMSE） of 323 kg ha-1, and a relative errors （RE） of 4.15% were obtained at the field plot scale and an R2 of 0.81, an RMSE of 362 kg ha-1, and an RE of 4.52% were obtained at the pixel scale of 30 mx30 m. With increasing observation errors, the accuracy of the yield estimates obviously decreased, but an acceptable estimate was observed when the observation errors were within 20%. Winter wheat yield estimates could be improved significantly by assimilating observations from the middle to the end of the crop growing seasons. With decreasing assimilation frequency and pixel resolution, the accuracy of the crop yield estimates decreased; however, the computation time decreased. It is important to consider reasonable temporal-spatial scales and assimilation stages to obtain tradeoffs between accuracy and computation time, especially in operational systems used for regional crop yield estimates.

粮食主产区农业社会化服务发展水平的时空演变与影响因素

确保粮食等重要农产品的有效供给是乡村振兴的首要任务,而农业社会化服务作为对接传统小农户和现代农业的关键抓手,对保障粮食供给安全、推进乡村振兴具有重要意义。为了更好地促进农业社会化服务发展,在系统分析农业社会化服务发展逻辑的基础上,基于2008—2021年中国省级面板数据,运用熵值法、空间自相关和地理探测器等方法,测度粮食主产区农业社会化服务发展水平,探究其时空演变特征,并对其影响因素进行识别。结果表明:1)研究期间,粮食主产区农业社会化服务整体水平呈持续增长态势,形成了以技术信息服务和公共设施服务为核心支撑的发展结构;2)三大主产区农业社会化服务水平均有提高,发展水平按从高到低排列,依次为黄淮海主产区、长江流域主产区、东北主产区,但由于各维度发展水平参差不齐,各主产区分别形成了不同的结构特征;3)粮食主产区农业社会化服务水平在空间上呈现南高北低的分布特征,各省发展差距较大但协调发展态势良好,且空间正向集聚效应增强;4)多方因素均对农业社会化服务发展造成影响且程度大小不一,从位居前两位的影响因子看,经济社会发展层面为经济发展水平和农业发展规模,农村生产生活层面为土地规模经营水平和农村居民收入水平。据此,提出如下建议:兼顾总体建设和结构优化,在扬长补短中加快发展;充分发挥自身禀赋优势并把握外界机遇,针对性解决突出问题和促进发展;加快资源跨区共享联动,促进区域协调发展;推进经济社会有序运行和农村生产生活环境持续改善,为农业社会化服务发展创造更多有利条件。

实际灌溉面积遥感监测技术及其在江苏省灌区示范应用分析

总结实际灌溉面积监测技术研究进展,分析了江苏省灌区监测实际灌溉面积面临的问题及难点;介绍了一种灌区多尺度实际灌溉面积遥感监测关键技术方法,并以宿迁灌区、船行灌区为例阐述了这一方法的合理性、适用性,提出应用该方法提高江苏省各地灌区实际灌溉面积监测精度与效率的建议,可为江苏灌区管理提供关键技术支撑。

宁夏灌区不同牧草复种模式综合效益分析

针对宁夏引黄灌区饲草产量低、栽培技术落后、季节性青饲料极其短缺导致草畜矛盾尖锐等现状,本研究设置了秋播饲用小黑麦(×Triticosecale Wittmack)+高丹草(Sorghum bicolor×S.sudanense)(T-SS)、饲用小黑麦+饲用高粱(S.bicolor)(T-FS)、饲用小黑麦+饲用谷子(Setaria italica)(T-FM)和饲用小黑麦+青贮玉米(Zea mays)(T-SM)4个复种模式处理,通过检测分析不同处理的生长指标、草产量、营养品质(粗蛋白、酸性洗涤纤维、中性洗涤纤维)、经济效益及土壤养分含量,旨在探明4种不同饲草复种模式的生产性能和综合效益,为该区牧草复种技术提供理论依据。结果表明:4种复种牧草的株高、茎粗和SPAD差异极显著,不同复种系统对牧草鲜草、干草产量、枝条数、粗蛋白产量、品质、土壤理化性状和经济效益均有极显著影响。高丹草复种系统草产量最高、枝条数最多、粗蛋白产量最高,饲用谷子粗蛋白含量最大,青贮玉米酸性和中性洗涤纤维含量最低,而相对饲用价值最大;对土壤有机质、全盐和pH的影响不显著,对速效钾和碱解氮含量的影响显著,对速效磷影响极显著;高丹草复种系统的产投比最高。综合评价筛选出饲用小黑麦复种饲用谷子和高丹草的种植模式可推广为宁夏引黄灌区牧草周年栽培模式。