Remote sensing of soil surface characteristics from a multiscale classification approach

Due to their significant influence on infiltration/runoff partitioning and soil erosion, hydrological soil surface characteristics (SSC) have to be known in a spatially distributed manner. This paper proposes a new approach based on radiometric and spatial remotely sensed information, for the mapping of hydrological SSC classes according to a predefined typology based on infiltration rates. Traditional remote sensing approaches usually focus on single SSC attributes only, where the latter correspond to key structural properties such as micro topography, surface crusting and soil cover. The originality of the method proposed here is considering the composite nature of SSC classes, by combining the aforementioned single attributes. This method makes use of a multiscale image segmentation that allows extracting image objects at two spatial scales of interest. At the fine scale, each Homogeneous Unit (HU) is assigned to an SSC attribute. At the coarse scale, SSC classes are identified by combining HU of SSC attributes assigned at the fine scale. The method was applied on airborne images collected over a Mediterranean vineyard by a small Pixy drone, and validated using intensive ground-based observations. The results showed acceptable performances with an overall accuracy ranging from 63 to 84%, depending on SSC classes and surface conditions. However, unsystematic confusions still remained between SSC classes which significantly differ in terms of hydrological behaviours. Improvements are expected considering richer spectral information, and ancillary information about SSC evolution in the case of intensive temporal monitoring.     

葡萄枝条堆肥化过程中的生物化学变化和物质转化特征

以葡萄枝条为原料,采用好氧静态堆肥箱法(体积为0.25 m3),分别在添加无机N素和不添加无机N素条件 下进行为期122 d的堆肥实验,结合常规化学分析、感应耦合等离子体发射光谱分析(ICPAES)和傅里叶变换红外光 谱(FTIR)分析技术研究了其堆肥化进程中的生物化学变化和物质转化特征。结果表明:添加无机N素和不加无机N 素处理的材料最高温度分别在堆肥后3 d和4 d达到76℃和65℃,堆肥高温(≥50℃)持续时间分别为21 d和7 d。干 物质变化明显分为初期(0-30 d)的快速分解阶段和中后期(30-122 d)的缓慢分解阶段,添加无机N素处理的分解速 度快于不加无机N素的。全C、全N及C/N不断下降,但全N相对含量上升,以添加无机N素处理最为明显。在整个 堆肥过程中,OH、CH3和CH2基化合物相对减少,CO基化合物相对增加,COO化合物以羧酸盐、PO化合物以磷酸盐 的形式出现。标志着脂肪族化合物减少,芳香族化合物增加以及有机物发生了明显的矿化作用。添加无机N素比不 加无机N素能更快地获得成熟稳定和富含作物所需营养的优质生态有机肥或土壤改良剂。     

木质素降解菌筛选及葡萄枝条木质素降解研究

从腐烂的葡萄枝条中,分离筛选出产木质素降解酶活高及对葡萄枝条木质素降解能力强的微生物.经分离纯化,获得24株在愈创木酚培养基平板上产生变色圈的真菌.通过PDA-愈创木酚平板显色和PDA-苯胺蓝平板退色反应,筛选出5株产木质素降解酶较高的菌株.对上述5菌株进行液态产酶和固态降解试验.结果表明,A-51-1的木质素降解酶活性较高,其Lac和MnP酶活分别达9.20和21.6 U·mL-1;葡萄枝条经A-51-1处理30 d后,木质素的降解率为32.53%.     

Comparison of three evapotranspiration models to Bowen ratio-energy balance method for a vineyard in an arid desert region of northwest China

The accurate determination of vineyard evapotranspiration (ET) in the arid desert region of northwest China is important for allocating irrigation water and improving water use efficiency. Taken a vineyard at the Shiyang river basin of the Hexi corridor of Gansu Province as an example, this study evaluated the applicability of the Bowen ratio-energy balance (BREB) method in the arid desert region of northwest China, simulated the variation of vineyard ET by Penman–Monteith (P–M), Shuttle–Wallace (S–W) and Clumping (C) models in this region and compared the estimated ET by the three models with the measured ET by the BREB. Results indicated that the BREB could provide the accurate measurement of vineyard ET from the arid desert region when the Bowen ratio instrument with higher accuracy was correctly installed. Generally, the variation of the estimated ET from P–M, S–W and C models were similar to that of the measured ET by the BREB method. However, the P–M model overestimated the ET significantly; the estimated ET from the S–W and C models, especially from the C model was approximately equal to the measured ET by the BREB. After a rainfall, the performances of the S–W and C models were also good. Therefore, among the three models, the C model was the optimal model in simulating the vineyard ET in the arid region of northwest China. However, after a frost, the C model significantly overestimated the evapotranspiration because the canopy resistance did not fully reflect the dramatic decrease of grapevine transpiration.     

Alley cropping of maize with calliandra and leucaena in the subhumid highlands of Kenya: Part 2. Soil-fertility changes and maize yield

Although N-rich leaf biomass of multipurpose trees is known to be a good source of N to crops, integrating such trees into crop production systems is a major challenge in the development of viable agroforestry systems. An approach to integrating calliandra (Calliandra calothyrsus Meissner) and leucaena (Leucaena leucocephala (Lam.) de Wit), two promising agroforestry tree species, into maize (Zea mays L.) production system was investigated in the subhumid highlands of central Kenya during four maize-growing seasons from 1994 to 1996. The experiment consisted of maize plots to which tree prunings obtained from hedgerows grown either in situ (alley cropping) or ex situ (biomass transfer from outside) were applied. When alley-cropped with leucaena, maize produced significantly higher yields compared to maize monoculture (both non-fertilized and fertilized) treatments, but when alley-cropped with calliandra, the yield of maize was less than that of the monocropped unfertilized control. Application of ex situ grown calliandra and leucaena prunings with or without fertilizer resulted in higher maize grain yield than in the nonfertilized and fertilized treatments. Yields of calliandra alley- cropped maize were 11% to 51% lower than those of nonalley-cropped treatments receiving calliandra prunings from ex situ grown trees; the decrease was 2% to 17% with leucaena, indicating that calliandra hedges were more competitive than leucaena hedges. The alley-cropped prunings-removed treatments produced the lowest maize yields. The study showed that, in the subhumid tropical highlands of Kenya, inclusion of calliandra hedges on cropland adversely affected maize yields. On the other hand, alley cropping with leucaena was advantageous. This revised version was published online in June 2006 with corrections to the Cover Date.     

A regional-scale study of multi-decennial erosion of vineyard fields using vine-stock unearthing–burying measurements

Erosion and deposition rates were quantified in a vineyard context (Languedoc, France) using a method based on vine-stock bio-markers. The within-field spatial structure of erosion (Field Erosive State) was described based on maps of “unearthing” height of vine-stock.     

An evapotranspiration model for sparsely vegetated canopies under partial root-zone irrigation

An evapotranspiration (E^T) model for sparsely vegetated canopies under partial root-zone irrigation (PRI) was developed and tested using measurements from a vineyard in the arid region of northwest China. This model (PRI-ET) was mainly based on the Shuttleworth–Wallace (S-W) model and took into consideration the differences in soil water content between furrow-irrigation ditch and ridge under the PRI scheme and variable canopy shading over the surface. Estimates of E^T and its components (plant transpiration and soil evaporation) by the PRI-ET and S-W models were compared to E^T, plant transpiration and soil evaporation measured by Bowen ratio–energy balance, heat-pulse sap flow sensor and micro-lysimeter, respectively. The PRI-ET model can estimate the vineyard E^T and its components more accurately than the S-W model, indicating that the PRI-ET model is suitable for estimating vineyard E^T under PRI.     

Invertebrates and nutrients in a Mediterranean vineyard mulched with subterranean clover (Trifolium subterraneum L.)

Summary In the 25-year-old vineyard of a farm near the Maremma National Park (Central Italy), replicate plots were established with a mulch of Trifolium subterraneum L. or cultivation and two levels of fertilizer. The mai objective of this research was to analyse responses by soil invertebrates and nutrients after introducing a herbaceous component into the system; the yield was also considered. The greater availability of organic substrate and the reduced cultivation as a result of green mulching increased the soil mesofauna biomass, especially detritivores. With time, a significant difference became evident between the populations of invertebrates present in the mulched plots and those in the cultivated plots. Over 2 years, most nutrients (Ca, K, P, and N) were significantly increased in the mulched plots compared to the cultivated plots. Grape yields were consistently higher in the bare plots. No significant differences were found in fertilizer effects.     

椪柑“三疏一改”和贮藏監始际跫捌湫Ч

针对衢县椪柑生产中果形偏小、品质欠佳和商品率低等问题 ,经大面积推广疏株、疏大枝、疏果、增施有机肥改良土壤 (三疏一改 )和果品贮藏保鲜技术后表明 :实施以“三疏一改”为核心的低改技术 ,基地平均产量超过 45t·hm-2 ,特级和一级果率由实施前的 30 %提高到 78% ,增加 1 60 % ,二级和三级果明显减小 ;年增收 0 2 6万～ 1 88万元·hm-2 ,投产比达 1∶4～ 6。推广万利得贮藏保鲜技术 ,果品保鲜时间达 3～ 4个月 ,好果率提高 3 4% ,衢县柑有 95 %果品实施贮藏保鲜 ,减少了损耗。推广“三疏一改”和保鲜技术 ,经济效益十分显著。表 5参 5     

世界葡萄园文化遗产的地理分布特征及其成因分析

葡萄园文化遗产是《世界遗产名录》中数量最多的一类农业文化遗产.基于《世界遗产名录》中葡萄园文化遗产的有关信息,对世界葡萄园文化遗产的地理分布特征及其成因进行研究.结果表明:葡萄园文化遗产的入选时间跨度较小,其数量随着时间的变化呈阶段性递增趋势,2000-2005年是葡萄园文化景观入选《世界遗产名录》最为集中的阶段;葡萄园文化遗产的空间分布呈组团状,但分布不均衡,主要以欧洲国家居多;葡萄园文化遗产的地理分布受生态因子、国家经济发展水平和对遗产的重视与保护程度、世界遗产评选的政策导向和行动等因素的影响.中国传统生态农业模式类型多样,潜在的文化价值巨大,借助“全球重要农业文化遗产”保护项目的平台,我国应该在全国范围内加快开展农业文化遗产的普查与价值挖掘工作,促进农业文化遗产地的生物-文化多样性的保护和经济社会的可持续发展,为申报世界遗产做好必要的准备工作.