Do Land Characteristics Affect Farmers' Soil Fertility Management?

Soil fertility management （SFM） has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.

Simulation analysis on characteristics of land surface over western Qinghai-Xizang Plateau during freez-ing-thawing period

Using the Global Energy and Water Cycle Experiment-Asian Monsoon-Tibet Plateau Experiment (GAME-Tibet) observa-tional data-from October 2002 through September 2003-of Gaize in the western Qinghai-Xizang Plateau (QXP),the land-surface characteristics of the Qinghai-Xizang Plateau are simulated by the improved land-surface model Common Land Model (CoLM).The results show that CoLM can reproduce the land-surface characteristics of plateau areas well.In the sur-face-energy balance of the western QXP in the winter half year,the sensible heat (SH) flux constituted the dominant energy,and the latent heat (LH,here and after) flux is very small.Although the LH flux nearly equals zero in freezing season,it cannot be ig-nored during the period of freezing-thawing in QXP.In the transition season from midto late-May,the frequent phase change of soil water that is caused by the freezing-thawing process leads to the increase of LH flux and decrease of the Bowen ratio.The simulation results also indicate that the changes of surface effective heat fluxes (SH and LH flux) are associated with precipitation and the frequent change between freezing and thawing processes in soil surface.

DYNAMIC CHARACTERISTICS OF PRESENT PRODUCTIVITY FOR CULTIVATED LAND IN THE FARNMING-PASTORAL ZONE OF INNER MONGOLIA

In this article, the distribution of cultivated land, the changes ofcultivated land productivity, and regional differentiation of the Change forpresent productivity in the Farming-Pastoral Zone, Inner Mongolia arediscussed. Then, the close relationship between dynamic characterlsticsdivision and atmospheric circulation systems is revealed. Finally, based ondynamic characteristics, four regions are divided, including thenortheastem area, the eastern area, the western area, and the middle area.

Land Use Characteristics of Areas Around the Metro Station in the Old City of Chengdu: A Case Study of Sichuan Gymnasium Station

Taking Sichuan Gymnasium Station as the research object, we explore land use characteristics over time of areas around Sichuan Gymnasium Station in terms of time. We extract the basic information of land use in areas around Sichuan Gymnasium Station in 2005, 2011, and 2016 through Google Earth in order to draw the map of land use status in three time nodes. We then analyze the degree of mixing and equilibrium, intensity of development of land, and land use patterns of areas around Sichuan Gymnasium Station with indexes including the area proportion of land use patterns, information entropy, and degree of equilibrium within a 1,000-m radius centered on the station, so as to reveal the spatial distribution characteristics of land around the station in different time nodes. Through comparative analysis, it is found that the development of rail transit has not significantly contributed to the boom of commerce and the development of the old city of Chengdu. We also analyze land use changes in areas around Sichuan Gymnasium Station in terms of space, and find that land use patterns in areas around commuter stations seem to be more complicated than that of the average station, and land use patterns in areas around Huaxiba Station and Nijiaqiao Station on Line 1, which opened first, are more complicated than that of Moziqiao Station and Yiguanmiao Station on Line 3. The original land use patterns formed in the old city often determine the selection of rail transit routes and rail transit stations. Adaptive stations do not play a decisive role in land use patterns in their surrounding areas, but have some impact on the plot ratio and building height of land for commercial use within the core area of the stations.

Impacts of precipitation variation and soil and water conservation measures on runoff and sediment yield in the Loess Plateau Gully Region, China

The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation analyses were performed on hydrological data(1981–2012) from the Yanwachuan watershed in the Loess Plateau Gully Region to study the evolution characteristics of runoff and sediment yield. A time-series contrasting method also was used to evaluate the effects of precipitation and soil and water conservation(SWC) on runoff and sediment yield. Annual sediment yield declined markedly from 1981 to 2012 although there was no significant change in annual precipitation and annual runoff. Change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively. Compared with that in the baseline period(1981–1996), annual runoff and annual sediment yield in the change period(1997–2012)decreased by 17.0% and 76.0%, respectively, but annual precipitation increased by 6.3%. Runoff decreased in the flood season and normal season, but increased in the dry season, while sediment yield significantly declined in the whole study period. The SWC measures contributed significantly to the reduction of annual runoff(137.9%) and annual sediment yield(135%) and were more important than precipitation. Biological measures(forestland and grassland) accounted for 61.04% of total runoff reduction, while engineering measures(terraces and dams) accounted for 102.84% of total sediment yield reduction. Furthermore, SWC measures had positive ecological effects. This study provides a scientific basis for soil erosion control on the Loess Plateau.

Estimations of Land Surface Characteristic Parameters and Turbulent Heat Fluxes over the Tibetan Plateau Based on FY-4A/AGRI Data

Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationary Radiation Imager (AGRI) satellite data and the China Land Data Assimilation System (CLDAS) meteorological forcing dataset CLDAS-V2.0 were applied for the retrieval of broadband albedo, land surface temperature (LST), radiation flux components, and turbulent heat fluxes over the Tibetan Plateau (TP). The FY-4A/AGRI and CLDAS-V2.0 data from 12 March 2018 to 30 April 2018 were first used to estimate the hourly turbulent heat fluxes over the TP. The time series data of in-situ measurements from the Tibetan Observation and Research Platform were divided into two halves-one for developing retrieval algorithms for broadband albedo and LST based on FY-4A, and the other for the cross validation. Results show the root-mean-square errors (RMSEs) of the FY-4A retrieved broadband albedo and LST were 0.0309 and 3.85 K, respectively, which verifies the applicability of the retrieval method. The RMSEs of the downwelling/upwelling shortwave radiation flux and downwelling/upwelling longwave radiation flux were 138.87/32.78 W m^(−2) and 51.55/17.92 W m^(−2), respectively, and the RMSEs of net radiation flux, sensible heat flux, and latent heat flux were 58.88 W m^(−2), 82.56 W m^(−2) and 72.46 W m^(−2), respectively. The spatial distributions and diurnal variations of LST and turbulent heat fluxes were further analyzed in detail.

The dual choice of geodetic horizontal reference systems for Ukraine

Almost all European countries use at least two horizontal reference systems, which allow them to minimize all risks when changing the coordinate system. The first system is used for the needs of the national survey in general, and also for technical applications in engineering surveys. A brief description of this system can be written by the formula: Geocentric Ellipsoid(GRS80) + Projection(UTM). More than half of the European countries for the second national systems use the GRS80 geocentric ellipsoid together with a projection other than UTM, some of them continue to use the projection of the old coordinate systems. The rest of the countries, excluding Ukraine, adapted the existing national coordinate systems to modern requirements, removing deformations from them concerning the ETRS89. A small number of European countries have implemented the GRS80 geocentric ellipsoid together with the UTM projection for cadastral surveys and topographic maps with a scale of 1:5000 and larger. Only one country, Ukraine, chose a variant for the new coordinate system(UCS2000), which is briefly written by the formula: Old Not Geocentric Ellipsoid + New Projection. The analysis of modern coordinate systems of Europe made it possible to formulate two variants of the future coordinate system of Ukraine based on a geocentric ellipsoid. It is shown that the transition to a geocentric ellipsoid will change the coordinates and heights of the points, but practically will not change the distance between the points and the area of the parcels.

Expert System Land Evaluation for Oil Palm Cultivation （ESLEOP）

Land evaluation assesses the suitability of land for specified land uses. The FAO Framework for Land Evaluation provides guidance for land suitability assessment. An Expert System Land Evaluation for Oil Palm Cultivation （ESLEOP） software was developed using climate, land qualities and land characteristics as diagnostic criteria in order to speed up the process of land assessment for oil palm cultivation in tropical regions. The results showed that ESLEOP evaluated land suitability for oil palm cultivation faster than the conventional method.

Relationship between Land Indices and Yield of Oil Palm in Peninsular Malaysia

Twenty four soils of Peninsular Malaysia derived from a varied geology and providing a range of particle size classes as well as different profile development stages were chosen for the study. Land characteristics and land qualities were used to determine the land suitability for oil palm cultivation. The results show that land characteristics have stronger influence on the yield of oil palm compared to land qualities. The use of the Framework for Land Evaluation together with the combined limitation-parametric approach enabled a more meaningful interpretation of the land units. Results demonstrated that land characteristics are recommended for land evaluation for oil palm cultivation.