福建耕地土壤硫肥效应及其临界指标研究

硫是作物生长发育所需的营养元素。根据多年多点田间试验和土壤有效硫测定,研究福建主要粮经作物的硫肥效应、土壤有效硫临界指标和耕地土壤硫肥力状况。64个田间试验表明,福建主要农作物施用硫肥平均增产10.5%,增产幅度是旱作物>水稻>香蕉;水田土壤和旱地土壤有效硫临界指标分别为23mgkg-1和25mgkg-1。根据全省372个耕层土样有效硫测定结果,土壤有效硫含量平均为27.6mgkg-1,低于土壤有效硫临界值的样品数占57.0%,其中,闽东南地区耕地土壤有效硫缺乏程度比闽西北地区高;在土地不同利用类型中,旱地土壤有效硫总体比水田匮乏,旱地土壤有效硫平均含量是茶果园>菜园>农地,其中,农地土壤有效硫低于临界指标的样品占75.3%;水田中不同土种的土壤有效硫含量以埭田最高,灰沙泥田为最低,旱地则以灰赤土最高而风沙土最低。     

棕壤地区玉米和水稻施用聚合物包膜尿素效应初报

通过一年田间小区试验,研究了棕壤地区施用MEISTER热塑性树脂包膜尿素对玉米和水稻生物性状、产量以及田间土壤NH 4-N和NO-3-N一直保4-N和NO-3-N的影响。结果表明,施用MEISTER包膜尿素能使土壤NH 持在较高水平,并且使玉米和水稻产量分别增加了5.1%和15.1%。当MEISTER包膜尿素施用量减少20%时,玉米和水稻产量与尿素追施处理相当,但玉米根和叶中氮的含量以及水稻秸杆和根中氮含量明显降低。MEISTER包膜尿素配施DCD没有进一步增加玉米和水稻的产量,DCD抑制土壤硝化作用的效果不稳定。     

稻草还田与施氮水平对土壤氮素供应和水稻产量的影响

比较研究了3年定位试验后稻草还田和施N水平对红壤双季稻作系统土壤供N能力、水稻吸N特征和水稻生产的影响。结果表明:头年晚稻草秋季还田对来年早稻土壤NH4 -N和作物吸N量的提高具有促进作用,而早稻新鲜稻草还田使晚稻土壤NH4 -N和作物吸N量均略低于移走稻草处理。稻草还田处理3年后,土壤可矿化N与移走稻草处理相比提高了35.4%~53.9%,且水稻各生育期干物质生产量均高于移走稻草处理,稻谷增产率达4.0%~4.7%。施用N肥可以显著增加土壤NH4 -N和可矿化N含量,且随着N肥用量的增加,水稻植株的累积吸N量和系统生产力(地上干物质量和产量)均显著的增加,建议N(全年施N量185 kg hm-2)和习惯N(全年施N量265 kg hm-2)处理相对于无N处理的增产率分别为35.2%和45.3%,而N肥的吸收利用效率分别为27%和25%,农学产量效益分别为每公斤纯N增产谷粒12.7 kg和11.4 kg。     

氮肥深施对作物产量和氮肥利用率的影响

应用盆栽试验和15N示踪技术，研究了辽宁省两种主要耕作土壤氮肥施用方法对玉米、水稻产量和肥料利用率影响。结果表明，氮肥深施能显著提高作物产量和肥料利用率。玉米以硫铵深施10或15m，尿素深施10cm时增产效果明显；水稻施硫铵和尿素均以深施15m增产效果最好。两种氮肥表施和施5cm效果不好。旱田流铵和尿素均以深施10或15cm利用率最高，平均达到52.62％；水田施硫铵以深施10或15cm利用率最高，平均达到57．48％，尿素则以深施10cm；。利用率较高。氮肥深施能增加土壤肥料氮残留率，减少氮素损失。     

硫肥对小麦蛋白质组分及产量的影响

试验在高肥力而硫素极缺的土壤上进行了试验,在施用常规氮磷钾肥料的基础上,比较不同小麦品种施硫肥与不施硫肥对小麦蛋白质组分及产量的影响。结果表明:在常规肥料措施下增施硫肥,提高了小麦营养体及籽粒中的含氮量,显著提高了籽粒中醇溶蛋白及总蛋白含量,而且不同蛋白质含量的小麦对硫肥的反应存在差异.施用硫肥极显著降低了千粒重和容重,产量也有所下降,但未达显著水平。     

碱性水田土壤施用硅肥的效应

选取碱性水田土壤,采用盆栽试验的方法,研究了施用硅肥后水稻生育期土壤溶液pH、Eh、硅浓度及对水稻产量的影响。结果表明,各处理pH经历了一个迅速降低,趋于中性的过程。单施硅肥对pH影响不大;施用葡萄糖或葡萄糖与高炉渣配施可明显降低水稻生育前期土壤溶液pH。各处理Eh的变化基本呈现为近似“W”形。淹水初期,施肥各处理土壤Eh均低于对照;后期施硅处理的Eh高于对照,而单施葡萄糖和高炉渣与葡萄糖配施处理Eh低于对照。各处理土壤溶液硅的浓度都经历了一个先上升达到高峰,然后逐渐下降,最终趋于稳定的过程。与对照相比,施用硅肥可不同程度地提高水稻生育期土壤溶液硅的浓度和不同生育期水稻植株含硅量;施用葡萄糖可提高水稻营养生长期土壤溶液中硅的浓度,但对提高水稻植株硅含量的作用不大;施用硅肥可以显著提高水稻产量,施用葡萄糖没有增产作用。     

外源钾对三种不同土壤钾转化影响的研究

采用盆栽试验,在黄棕壤,砖红壤,黑土三种土壤上种植烟草,研究了外源钾对土壤中钾转化的影响,结果表明:在黄棕壤,黑土上,0.0-0.8 g kg-1施肥范围内,随着施钾量的增加,土壤中速效钾和缓效钾的总增量、作物的含钾量均在增加,尤其是在0.8 g kg-1施肥水平时,二者超出了施肥的增加量,说明施钾促进了其它钾的释放;三种土壤中粘土矿物含量为:黑土>黄棕壤>砖红壤。     

长期定位施肥残留养分对作物产量及土壤化学性质的影响

棕壤肥料长期定位试验结果表明,连续15年培肥后,磷肥、有机肥残留养分对粮豆作物的增产效果至少在三年以上,低量有机肥与磷钾肥配施残留养分的增产率最高,为119.46%。长期施用有机肥既能增加土壤有机质,还能促进土壤磷有效性的发挥;棕壤条件下,土壤速效磷与有机质有明显的正相关关系(r=0.841,α=0.01,n=36)。在投入磷素相等的情况下,土壤中残留的全磷含量则主要受作物吸磷量的制约。有机—无机结合培肥是实现农业可持续发展的重要措施。     

辽宁大豆主产区土壤硫素状况及不同硫肥肥效研究

本文通过对辽宁省大豆主要产区(8个县)土壤全硫及有效硫含量进行测定与分析,阐述了不同类型、不同肥力土壤硫素状况。在不同地区开展的硫肥肥效试验结果表明,在有效硫含量很低的土壤上施用硫肥增产效果都很明显,而有效硫含量较高的土壤上施用硫铵增产效果较好,石膏和硫磺的增产效果不稳。     

施用白云石对酸性黄红壤作物产量及化学性质的影响

白云石改良酸性黄红壤三年定位试验结果表明:酸性黄红壤施用白云石可以降低土壤交换性铝的含量,提高土壤pH值和交换性钙、镁的含量,显著提高作物产量,且有明显的后效。第1—6季作物分别增产10.8%~13.4%、21.5%~48.6%、9.4%~16.2%、10.9%~44.6%、7.9%~22.0%和6.6%~29.8%。白云石施用量为600kg hm-2时,降酸作用可维持3季作物以上;白云石施用量为2500 kg hm-2时,降酸作用可维持6季作物以上。     

Soil loss predictions with three erosion simulation models

Quantification of soil loss is one of the greatest challenges in natural resources and environmental planning. Computer simulation models are becoming increasingly popular in predicting soil loss for various land use and management practices. In this study, three soil erosion prediction models — the Water Erosion Prediction Project (WEPP), the Erosion Productivity Impact Calculator (EPIC), and the Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS) were used for simulating soil loss and testing the capability of the models in predicting soil losses for three different tillage systems (ridge-till, chisel-plow, and no-till). For each model, the most sensitive model parameters were calibrated using measured soil erosion data. After calibration, models were run and predicted soil loss values were compared with the measured soil loss values. The measured soil erosion data were collected from an erosion experiment field of Kansas State University at Ottawa (Kansas), USA. Field experiments were conducted from 1995 to 1997 on small plots to measure runoff and soil losses under all three tillage systems. All three models were evaluated on the basis of individual event, total yearly, and mean event-based soil loss predictions. Results showed that all the three models performed reasonably well and the predicted soil looses were within the range of measured values. For ridge-till and chisel-plow systems, WEPP and ANSWERS gave better predictions than those by EPIC model. For no-till system, WEPP and EPIC predictions were better than those by ANSWERS. The overall results indicate that WEPP predictions were better than those by the other two models in most of the cases, and it can be used with reasonable degree of confidence for soil loss quantification for all the three tillage systems.     

Interference of salt and moisture on soil reflectance spectra

This article portrays the effects of salt and moisture on soil reflectance spectra and their consequent influences on the estimation of soil salinity and soil moisture contents (SMC). It is amid to demonstrate and discuss how the interference of salt and moisture, as soil constituents, on soil spectra can affect the estimation of either soil salinity or SMC when spectral variabilities are used as predictive variables. To achieve this objective, a data set was obtained from a test area where soil salinity and SMC were largely varied. Furthermore, the Inverted Gaussian (IG) modelling approach, which has been successfully used for the estimation of soil salinity under laboratory conditions and for the estimation of SMC for non-saline soil, is used in this study. Using the IG function, the near-infrared (NIR) and the shortwave infrared (SWIR) regions of the salt-affected soil spectra, with various amount of moisture, were fitted to an IG curve. Parameters of the fitted curve such as functional depth, distance to the inflection point and area under the curve were then used as predictors in a multi-regression analysis to quantify the effect of soil salinity and SMC on soil spectra. The results suggest that a combination of salt and moisture in soil causes anomalies and therefore variations in neither salt nor moisture contents can be modelled accurately on the basis of quantification of soil reflectance. These results suggest that further studies are required to determine a set of calibrating coefficients that can be used to eliminate the background spectral effects caused by either soil salinity or SMC.     

土壤养分遥感监测研究现状及展望

土壤肥力状况信息可以为精准农田管理提供响应依据,对近年来遥感技术在农田土壤养分监测方面的研究进行了归纳与分析,总结为直接监测方法和间接监测方法。直接监测方法主要利用土壤光谱特征监测土壤养分含量,而间接监测方法则通过不同土壤养分水平下的作物表现特征来估算土壤养分状况。在全面比较两种方法各自优缺点的基础上,指出两种方法各有优势并可互为补充,通过结合可以有效提高监测的精度与全面性,并对土壤养分遥感监测的发展进行了展望。     

Soil spectral effects on 4-space vegetation discrimination

The influence of soil background on vegetation discrimination in four-band reflectance space was examined. Dry and wet reflectance data were obtained for 20 soils covering a wide range in spectral properties with a hand-held radiometer. Principal components analysis was used to study the distribution of soil spectra in 4-space and to define a mean soil line. Soil-specific background lines were similarly derived and used to examine the overall cloud of soil spectra in individual soil form. Reflectance data from a full-canopy wheat plot were used to compute unit vector coefficients in the greenness direction from the mean soil line and from the individual soil lines. Analysis of the mean soil line showed that it was not possible to discriminate bare soil from low vegetation densities. Greenness measurements were shown to be sensitive to both soil type and soil moisture condition. In contrast, the use of individual soil lines as a base to measure greenness minimized soil background influence and improved vegetation assessment, particularly at low green plant canopy covers.     

SOILPSI: a potential-driven three-dimensional soil water redistribution model—description and comparative evaluation

ECOPHYS, an individual-based process model for poplar, requires a three-dimensional soil water redistribution model to simulate soil water dynamics, plant uptake, and root growth. SOILPSI is a potential-driven water redistribution model based on the RHIZOS rhizosphere simulator. It expands on RHIZOS by calculating water flux based on water potential, and has a macropore flow mode to allow rapid drainage of the soil. SOILPSI simulates water flux in three dimensions and accounts for slope. SOILPSI was evaluated by comparing model output to soil moisture data collected under bare soil conditions. AMMI analysis of a date×depth matrix of differences between simulated and observed soil moisture content showed that excluding the two shallowest soil layers resulted in a difference matrix that conformed to an additive model. The grand mean predicted values were within 2% of the observed values, and 50 of 56 predicted values were within 5% of the observed values. Better agreements between simulated and observed soil moisture content were observed deeper in the soil profile and later in the season. Agreement between SOILPSI and field conditions was consistently more accurate than RHIZOS. Improving simulation of evaporative flux at the soil surface would improve simulation accuracy in the upper horizons.     

微波遥感监测土壤水分的研究初探

在GPS定位的基础上，同步测量土攘水分、土壤后向散射系数，和同步获取的X波段、HH机化SAR图像进行了土攘水分监N.]的徽波遥感试验研究。结果表明，X波段SAR图像的灰度与表层土壤(0~10cm)水分有较好的相关性，35OHH极化的土峨后向散射系数与SAR图像灰度和土攘水分也有较好的相关性，由SAR图像及土攘的后向散射系数估算的土峨水分精度相近，相对误差均为12%左右，因而利用X波段、HH极化的机载SAR图像监浏土壤水分是可行的。雷达图像的穿透力一般在10cm以内，因此探讨了由表层土壤水分推求剖面土壤水分的可能性，并提出以土攘水分计法在浏童精度和速度上改进传统土壤水分测量的方法。     

Thermal microwave emission depth and soil moisture remote sensing

This paper presents some additional theoretical and experimental results on the problem of estimating the soil depth to which soil moisture can be directly measured by VHF radiometers. The experimental work was implemented in August 1992 at the Research Farm of the Institute of Hydrotechnique and Amelioration, Sofia, Bulgaria. The soil thermal microwave emission was measured by an L-band Dicke-type radiometer at 1.65GHz at off-nadir angle from 20 to 60. It was found that the value obtained for the effective penetration depth depends on the definition used in the analysis: the definition of penetration depth is based on soil thermal emissivity or soil reflectivity. Further it was found that the depth to which the soil moisture can be directly measured exhibits a negligible dependence on polarization (horizontal, vertical) as well as on off-nadir observation angle. For the purpose of soil brightness temperature and soil reflectivity computing, a fast and robust method and algorithm were proposed which are based on Kong's coherent soil model. The experimental measurements were used to verify the model fitting to experimental conditions and results.     

基于3S技术的土壤采集信息处理系统的设计与实现*

土壤采样质量的高低对精准农业施肥决策制定正确与否有重要的影响,高效、优化的土壤样品采集方案和基于GPS的准确采样是精准农业的基本重要问题之一.运用系统工程的方法,初步构建了土壤采集信息处理系统的通用设计和开发框架,并在此基础上,利用组件技术开发了车载土壤采集信息处理系统.该系统解决了GIS、GPS和RS之间的逻辑链接,实现了基于GIS和GPS的土壤样品采集方案优化设计与取样点导航定位功能;实现了采样点坐标和土壤化验结果的统一管理,与专用传感器相连可实现土壤理化指标的实时快速分析.     

A model for retrieving soil moisture saturation with Landsat remotely sensed data

Soil moisture saturation indicates the capability of the vegetation humus layer and the soil layer to reabsorb and drain water in an area; it is crucial in predicting natural disasters, such as landslides and droughts. In this article, a model was created to retrieve soil moisture saturation based on multispectral remotely sensed data. Soil brightness and soil wetness, calculated from the tasseled cap transformation, were utilized to obtain soil moisture saturation. With the above model, a soil moisture saturation map of Maoergai District, which is located on the upper Minjiang River in northern Sichuan Province in the south-west of China, was created from a Landsat Enhanced Thematic Mapper Plus (ETM+) image in July 2002. Then, the soil type data and the vegetation distribution data of the year 2000 were used to evaluate the model. The result shows that the model for soil moisture saturation is viable and that the vegetation type, vegetation distribution and soil type have strong correlation with soil moisture saturation.     

A new index for mapping lichen-dominated biological soil crusts in desert areas

Tracking the presence, distribution and disappearance of biological soil crusts is important for ecosystem management of desert regions and provides highly valuable information on desertification and climate change studies in arid environments. Based on the analysis of the spectral features of biological soil crusts, we propose a new biological soil crust index (BSCI) for biological soil crusts mapping. Using both a radiative transfer simulation and an analysis of a Landsat Enhanced Thematic Mapper Plus (ETM+) image, we examined the ability of satellite remote sensing to detect and map biological soil crusts. Our simulation indicated that Landsat ETM+ data could be used, after atmospheric correction, to detect biological soil crusts if 33% or more of any pixel was accounted for by biological soil crusts. When the proposed BSCI was applied to the detection of biological soil crusts in the Gurbantonggut Desert, Xingjiang, China, a Kappa coefficient of 0.82 and an overall accuracy of 94.7% were achieved. These experimental results indicate that the new index is applicable to identification of lichen-dominated biological soil crusts, and therefore has good potential for biological soil crust detection and mapping in cool and cold deserts.