Effects of irrigation on geochemical processes in a paddy soil and in ground waters in Camargue (France)

In waterlogged soils, dynamics of water influence the redox conditions and thus the mobility of elements. Irrigation of rice in Camargue (South eastern France) induces yearly dynamics of water. In order to determine the impact of irrigation on the geochemical properties of ground waters, a continuously in situ record of physico-chemical parameters (pH, Eh, temperature and electric conductivity) is performed during 1 year in an irrigated rice field. Seasonal dynamics show large Eh and pH variations. An annual irrigation cycle generates fast precipitations of Ca–Mg carbonates and Fe oxides between 50 and 110 cm depth when the soil is waterlogged. The dissolution of these minerals is initiated during a year without irrigation.     

多时相Radarsat数据在广东肇庆地区稻田分类中的应用

将1996年获取的4个时相的Radarsat图像用于广东肇庆地区的稻田分类试验,结果表明,多时相Radarsat数据对水稻类型的识别精度较高,而且稻田的轮作规律容易推测出来。本文系统地介绍了这一试验研究的最新进展,探讨了神经网络分类方法在SAR图像处理中的应用潜力和Radarsat数据在中国南方水稻监测中的最佳时相选择和有效分辨率问题。     

全球稻谷主产国遥感估产可行性研究

利用NOAA气象卫星的序列资料,对全球稻谷遥感估产的可行性进行了探讨。并以泰国、美国、越南为例,分别对NDVI植被指数与产量进行相关分析,取得良好的应用效果。此外,还应用数理统计方法对全球稻谷的历史产量进行数学模拟,达到较高的拟合精度。     

Global rain-fed,irrigated, and paddy croplands: A new high resolution map derived from remote sensing,crop inventories and climate data

Irrigation accounts for 70% of global water use by humans and 33–40% of global food production comes from irrigated croplands. Accurate and timely information related to global irrigation is therefore needed to manage increasingly scarce water resources and to improve food security in the face of yield gaps, climate change and extreme events such as droughts, floods, and heat waves. Unfortunately, this information is not available for many regions of the world. This study aims to improve characterization of global rain-fed, irrigated and paddy croplands by integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets. To achieve this goal, we used supervised classification of remote sensing, climate, and agricultural inventory data to generate a global map of irrigated, rain-fed, and paddy croplands. We estimate that 314 million hectares (Mha) worldwide were irrigated circa 2005. This includes 66 Mha of irrigated paddy cropland and 249 Mha of irrigated non-paddy cropland. Additionally, we estimate that 1047 Mha of cropland are managed under rain-fed conditions, including 63 Mha of rain-fed paddy cropland and 985 Mha of rain-fed non-paddy cropland. More generally, our results show that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. However, regions with rapidly changing irrigation or complex mixtures of irrigated and non-irrigated crops present significant challenges and require more and better data to support high quality mapping of irrigation.     

水稻覆膜节水种植对NO排放的影响

为保障粮食安全和节约水资源,水稻覆膜节水技术正越来越多地被农业生产部门运用到水稻生产中。但是,与传统种植模式(采用淹水与烤田相结合的间歇灌溉)相比,水稻覆膜节水种植模式通过改变土壤条件,引起稻田生物地球化学过程变化,进而使得大气环境污染性气体一氧化氮(NO)的排放发生变化。为了定量研究两种种植模式的NO排放差异及其关键控制因子,采用静态暗箱—化学发光法,对不同种植模式下两种施肥条件(常规施肥与无氮肥对照)的水稻—休耕系统NO排放通量及其环境因子进行了原位周年观测。结果表明,水稻生长季NO排放主要发生在中期烤田阶段,覆膜节水种植模式的NO通量多高于常规淹水种植模式,水稻生长季NO排放系数分别为0.12%和0.016%,主要原因是覆膜节水种植模式提高了土壤温度和氧化还原电位。在休耕季,两种种植模式的NO排放都与土壤湿度呈显著负相关。覆膜节水种植模式全年NO排放有大于传统种植模式的趋势,其排放系数分别为0.15%和0.032%,但需时间更长地点更多的试验研究加以证实。     

控制水稻分蘖角度对群体生态特性的影响

控制分蘖角度对群体温度、群体相对湿度、群体CO2浓度和光合有效辐射均会产生一定影响。选用2006年水稻有关研究数据,分析水稻分蘖角度对群体生态特征的影响。结果表明：各生育时期群体温度在07:00－19:00处理大于CK。分蘖高峰期到孕穗期CK白天群体相对湿度大于处理,齐穗期到灌浆期处理群体相对湿度大于CK。群体CO2浓度在拔节期和孕穗期均为处理大于CK,其他生育期差异不显著。光合有效辐射垂直分布是处理前期和后期上层截获的光能均小于CK,群体内消光系数小。控制分蘖角度形成了有较高温度、较低湿度、高CO2浓度和适宜光分布的群体,可为获得高产奠定基础。     

Production of Levulinic Acid from Bagasse and Paddy Straw by Liquefaction in the Presence of Hydrochloride Acid

A method of levulinic acid production from bagasse and paddy straw is presented. Biomass waste was mixed with hydrochloride acid and water, and then liquefied at about 200°C in a pressurized reactor. Both the mass of the biomass and the amount of hydrochloride acid were kept as constants, and the effects of temperature, reaction time, and acid concentration on the levulinic acid yield were studied. It was found that the yield of levulinic acid was maximum when the reaction temperature was carried out for 45 min at 220°C using 4.45% concentration of hydrochloride acid, and the maximum yields of levulinic acid were 22.8 and 23.7% for bagasse and paddy straw, respectively. The products were analyzed using NMR, HPLC, and GC/MS.     

高产水稻理想株型的灰色关联度分析

应用灰色关联分析方法 ,分析了 6个水稻品种 2 1个株型性状对单株产量的影响。结果表明 :单株产量与 2 1个株型性状的关联序依次为 :剑叶厚 >倒二叶厚 >剑叶宽 >倒二叶宽 >倒二叶鞘长 >剑叶鞘长 >倒二叶弦长 >倒三叶宽 >倒三叶厚 >倒三叶鞘长 >剑叶长 >倒二叶长 >倒三叶长 >剑叶弦长 >倒三叶弦长 >倒三叶基夹角 >倒三叶叶开角 >剑叶叶开角 >剑叶基夹角 >倒二叶基夹角 >倒二叶叶开角。     

Application of geostatistics and GIS technique to characterize spatial variabilities of bioavailable micronutrients in paddy soils

To understand the spatial dependency of bioavailable micronutrients in paddy soils, 134 soil samples were taken from Pinghu County, Zhejiang Province, south-east China to characterize the spatial variabilities of bioavailable Cu, Zn, Fe, and Mn. The geostatistics and geographic information system (GIS) techniques were applied. Bioavailable Zn and Mn were fitted to an exponential model with a range of 4.4 km and 2.97 km, respectively. Bioavailable Fe was fitted to the linear model with the longest range of 23.48 km. Bioavailable Cu did not show any spatial correlation with the fitted pure nugget effect model. Bioavailable Zn and Mn had strong spatial dependence due to the effects of intrinsic factors such as parent material, relief and soil types. Bioavailable Fe had moderate spatial dependence over a long distance. The spatial distribution of the four bioavailable micronutrients were significantly correlated to the soil formation factors. Human activity, such as application of fertilizer and pesticide, emission of waste gas and industrial pollution also had significant effects on the spatial distributions of the bioavailable micronutrients.     

对广西水稻气候区划的探讨

根据广西88个气象站的气候资料,以水稻安全生长季为指标,采用网格距为0.1×0.1经纬度的小网格气候分析方法,将广西稻作区划分为4个适宜气候区:晚熟双季稻适宜气候区、中晚熟双季稻适宜气候区、早中熟双季稻适宜气候区和单季稻再生稻适宜气候区。