A comparative description of two farmer-managed irrigation systems in Nepal     

Edward D. Martin  Robert Yoder 《Irrigation and Drainage Systems》1988,2(2):147-172

The organization of two farmer-managed irrigation systems in the western hills of Nepal is described by examining the ways in which the activities of water allocation, water distribution, maintenance, and resource mobilization are performed. Due to the topography and environment, these two organizations are structured primarily to mobilize the large amount of labor required for maintenance of the intake and canal. Both organizations precisely define each member's water allocation. In one system, water is allocated in proportion to the area of an individual's land holding, while in the other water allocation is by purchased shares. These two cases were used to analyze the importance of the principle of water allocation for expansion of area irrigated and equity of access to irrigation. Evidence from the two systems shows that in this hill environment water allocation by purchased shares provides the individual incentive and an organizational mechanism for efficient development of irrigation resources. Expansion of area irrigated and equity of access to irrigation were found to be greater in the system which allocates water by purchased shares than where water was allocated in proportion to area irrigated.  相似文献   

The impact of increasing farm size and mechanization on rural income and rice production in Zhejiang province,China   总被引：1，自引：0，他引：1  

M. Marrit Van den Berg  Huib Hengsdijk  Joost Wolf  Martin K. Van Ittersum  Wang Guanghuo  Reimund P. Roetter 《Agricultural Systems》2007

Economic growth in China’s agricultural sector lags behind growth in industry and services, creating an ever widening rural–urban income gap. Development of the non-agricultural sectors offers new opportunities for farmers in China’s more advanced provinces such as Zhejiang. Increased income in the urban sector creates markets for new products, and migrating farmers rent their land to those staying. Until now, the prevailing rice-based systems have been managed mainly using manual labour and animal traction, but the larger farms resulting from migration may facilitate, or even require mechanization. In this study, we use a simulation model of the farm household to analyse the effects of increasing farm size and the transition from rice to vegetable production, while also studying the effects of mechanization.  相似文献   

The effect of breed,sex, and oral meloxicam administration on pain biomarkers following hot-iron branding in Hereford and Angus calves     

Miriam S Martin  Michael D Kleinhenz  Lily N Edwards-Callaway  Terry E Engle  Octavio Guimaraes  David W Schafer  Shawnee R Montgomery  Andrew K Curtis  Mikaela M Weeder  Devin R Jacobs  Johann F Coetzee 《Journal of animal science》2022,100(3)

Hot-iron branding uses thermal injury to permanently identify cattle causing painful tissue damage. The primary objective was to examine the physiological and behavioral effects of oral meloxicam (MEL), compared to a control, administered at the time of hot-iron branding in Angus and Hereford steers and heifers. The secondary objectives were to investigate breed and sex effects on pain biomarkers. A total of 70 yearlings, consisting of 35 heifers and 35 steers (Angus, Hereford, or Angus × Hereford), were enrolled in the study. Animals were blocked by sex, randomized across weight, and assigned to receive MEL (1 mg/kg) or a placebo (CON). Biomarkers were assessed for 48 h after branding and included infrared thermography (IRT), mechanical nociceptive threshold (MNT), accelerometry and a visual analog scale (VAS), and serum cortisol and prostaglandin E₂ metabolites (PGEM). Wound healing was assessed for 12 wk. Hair samples to quantify cortisol levels were taken prior to and 30 d post-branding. Responses were analyzed using repeated measures with calf nested in treatment as a random effect, and treatment, time, treatment by time interaction, breed, and sex as fixed effects. There was a treatment by time interaction for PGEM (P < 0.01) with MEL having lower values than CON at 6, 24, and 48 h (MEL: 18.34 ± 3.52, 19.61 ± 3.48, and 22.24 ± 3.48 pg/mL, respectively; CON: 32.57 ± 3.58, 37.00 ± 3.52, and 33.07 ± 3.48 pg/mL; P < 0.01). MEL showed less of a difference in maximum IRT values between the branded (2.27 ± 0.29 °C) and control site (3.15 ± 0.29 °C; P < 0.01). MEL took fewer lying bouts at 0–12 h (4.91 bouts ± 0.56) compared with CON (6.87 bouts ± 0.55; P < 0.01). Compared with Hereford calves, Angus calves exhibited greater serum but lower hair cortisol, greater PGEM, more lying bouts, and less healed wound scores at 3, 4, and 5 wk. Compared with heifers, steers exhibited lower PGEM, lower branding site and ocular IRT, higher MNT, and lower plasma meloxicam levels. Steers spent more time lying, took more lying bouts and had greater VAS pain, and more healed wound scores at 5 wk than heifers. Meloxicam administration at branding reduced branding and control site temperature differences and reduced lying bouts for the first 12 h. Breed and sex effects were observed across many biomarkers. Changes from baseline values for IRT, MNT, lying time, step count, VAS pain, and wound scoring all support that branding cattle is painful.  相似文献   

Short‐term degradation of semiarid grasslands—results from a controlled‐grazing experiment in Northern China     

Martin Wiesmeier  Olivia Kreyling  Markus Steffens  Philipp Schoenbach  Hongwei Wan  Martin Gierus  Friedhelm Taube  Angelika Kölbl  Ingrid Kögel‐Knabner 《植物养料与土壤学杂志》2012,175(3):434-442

The assessment of grassland degradation due to overgrazing is a global challenge in semiarid environments. In particular, investigations of beginning steppe degradation after a change or intensification of the land use are needed in order to detect and adjust detrimental land‐use management rapidly and thus prevent severe damages in these sensitive ecosystems. A controlled‐grazing experiment was established in Inner Mongolia (China) in 2005 that included ungrazed (UG) and heavily grazed plots with grazing intensities of 4.5 (HG4.5) and 7.5 (HG7.5) sheep per hectare. Several soil and vegetation parameters were investigated at all sites before the start of the experiment. Topsoil samples were analyzed for soil organic C (SOC), total N (N_tot), total S (S_tot), and bulk density (BD). As vegetation parameters, aboveground net primary productivity (ANPP), tiller density (TD), and leaf‐area index (LAI) were determined. After 3 y of the grazing experiment, BD increased and SOC, N_tot, S_tot, ANPP, and LAI significantly decreased with increasing grazing intensity. These sensitive parameters can be regarded as early‐warning indicators for degradation of semiarid grasslands. Vegetation parameters were, however, more sensitive not only to grazing but also to temporal variation of precipitation between 2006 and 2008. Contrary, soil parameters were primarily affected by grazing and resistant against climatic variations. The assessment of starting conditions in the study area and the application of defined grazing intensities is essential for the investigation of short‐term degradation in semiarid environments.  相似文献   

Identification and quantification of cyclolinopeptides in five flaxseed cultivars     

B Gui  YY Shim  RS Datla  PS Covello  SL Stone  MJ Reaney 《Journal of agricultural and food chemistry》2012,60(35):8571-8579

Cyclolinopeptides are a group of naturally occurring hydrophobic cyclic peptides found in flaxseed and flax oil that have immunosuppressive activity. This study describes the measurement of flaxseed cyclolinopeptide concentrations using an internal standard HPLC method. In addition, the concentration of cyclolinopeptides in the seed of Canadian flax cultivars grown at two locations over two years is reported. The data are consistent with the formation of flaxseed cyclolinopeptides from two ribosome-derived precursors. Each precursor protein includes the sequences corresponding to three cyclolinopeptides from which those cyclolinopeptides are presumably derived by precursor processing. The concentrations of cyclolinopeptides C and E, which are encoded by the same gene sequence, are highly correlated, and the concentrations of cyclolinopeptides D, F, and G, which are encoded by a second gene sequence, are also highly correlated. The strong correlation between the cyclolinopeptides arising from the same gene may prove to be important in understanding how peptide concentration is controlled. Additional research may lead to approaches to improve flax either as a platform for peptide production or as a source of oil with improved drying properties and flavor.  相似文献   

Roughness of biopores and cracks in Bt‐horizons assessed by confocal laser scanning microscopy          下载免费PDF全文

Martin Leue  Horst H. Gerke 《植物养料与土壤学杂志》2016,179(4):529-536

In structured soils, water and reactive solutes can preferentially move through larger inter‐aggregate pores, cracks, and biopores. The surface roughness of such macropores is crucial for describing microbial habitats and the exchange of water and solutes between macropores and the soil matrix together with other properties. The objective of this study was to compare the roughness of intact structural surfaces from the Bt‐horizons of five Luvisols developed on loess and glacial till and to test the applicability of confocal laser scanning microscopy. Samples of 5 to 10 cm edge length with intact structural surfaces including cracks with and without clay‐organic coatings, earthworm burrow walls, and root channels were prepared manually. The surface roughness of these structures was determined with a confocal laser scanning microscope of the type Keyence VK‐X100K. The root‐mean‐squared roughness (R_q) the curvature (R_cu) and the ratio between surface area and base area (R_A) were calculated from selected surface regions of interest of 0.342 mm² with an elevation resolution of 0.02 µm. The roughness was smaller for coated as compared to uncoated cracks and earthworm burrows of the Bt‐horizons. This reduction of roughness by the illuviation of clayey material was similar for the structural surfaces of the coarser textured till‐Bt and the finer‐textured loess‐Bt. This similarity suggested a dominant effect of pedogenesis and a minor effect of the parent material on the roughness levels of structural surfaces in the Bt‐horizons. An expected “smoothing” effect of burrow wall surfaces by earthworm activity was not reflected in the roughness values compared to those of uncoated cracks at the chosen spatial scale. However, for root channel walls from one loess‐Bt, the roughness was reduced as compared to that of other structures. These results suggest that the surface roughness of the structural surface types should separately be considered when describing preferential flow and macropore‐matrix exchange or analysing root growth, microbial habitats, and colloidal transport in structured soils. The confocal laser scanning microscopy technique was found useful for characterizing the roughness of intact structural surfaces.  相似文献   

The use of lysimeter data for the test of two soil–water balance models: A case study     

Martin Wegehenkel  Yongqian Zhang  Thomas Zenker  Heiko Diestel 《植物养料与土壤学杂志》2008,171(5):762-776

Two soil–water balance models were tested by a comparison of simulated with measured daily rates of actual evapotranspiration, soil water storage, groundwater recharge, and capillary rise. These rates were obtained from twelve weighable lysimeters with three different soils and two different lower boundary conditions for the time period from January 1, 1996 to December 31, 1998. In that period, grass vegetation was grown on all lysimeters. These lysimeters are located in Berlin‐Dahlem, Germany. One model calculated the soil water balance using the Richards equation. The other one used a capacitance approach. Both models used the same modified Penman formula for the estimation of potential evapotranspiration and the same simple empirical vegetation model for the calculation of transpiration, interception, and evaporation. The comparisons of simulated with measured model outputs were analyzed using the modeling‐efficiency index IA and the root mean squared error RMSE. At some lysimeters, the uncalibrated application of both models led to an underestimation of cumulative and annual rates of groundwater recharge and capillary rise, despite a good simulation quality in terms of IA and RMSE. A calibration of soil‐hydraulic and vegetation parameters such as maximum rooting depth resulted in a better fit between simulated and observed cumulative and annual rates of groundwater recharge and capillary rise, but in some cases also decreased the simulation quality of both models in terms of IA and RMSE. The results of this calibration indicated that, in addition to a precise determination of the soil water‐retention functions, vegetation parameters such as rooting depth should also be observed. Without such information, the rooting depth is a calibration parameter. However, in some cases, the uncalibrated application of both models also led to an acceptable fit between measured and simulated model outputs.  相似文献   

Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of alternative management practices on water quality and quantity   总被引：10，自引：0，他引：10  

Antje Ullrich  Martin Volk 《Agricultural Water Management》2009,96(8):1207-1217

Alternative land management practices such as conservation or no-tillage, contour farming, terraces, and buffer strips are increasingly used to reduce nonpoint source and water pollution resulting from agricultural activities. Models are useful tools to investigate effects of such management practice alternatives on the watershed level. However, there is a lack of knowledge about the sensitivity of such models to parameters used to represent these conservation practices. Knowledge about the sensitivity to these parameters would help models better simulate the effects of land management. Hence, this paper presents in the first step a sensitivity analysis for conservation management parameters (specifically tillage depth, mechanical soil mixing efficiency, biological soil mixing efficiency, curve number, Manning's roughness coefficient for overland flow, USLE support practice factor, and filter strip width) in the Soil and Water Assessment Tool (SWAT). With this analysis we aimed to improve model parameterisation and calibration efficiency. In contrast to less sensitive parameters such as tillage depth and mixing efficiency we parameterised sensitive parameters such as curve number values in detail.In the second step the analysis consisted of varying management practices (conventional tillage, conservation tillage, and no-tillage) for different crops (spring barley, winter barley, and sugar beet) and varying operation dates. Results showed that the model is very sensitive to applied crop rotations and in some cases even to small variations of management practices. But the different settings do not have the same sensitivity. Duration of vegetation period and soil cover over time was most sensitive followed by soil cover characteristics of applied crops.  相似文献   

Renumbering the S-RNase alleles of European pears (Pyrus communis L.) and cloning the S109 RNase allele     

Martin Goldway  Takashi Takasaki-Yasuda  Javier Sanzol  Mariana Mota  Annat Zisovich  Raphael A. Stern  Silviero Sansavini 《Scientia Horticulturae》2009

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Combining agent-based and stock-flow modelling approaches in a participative analysis of the integrated land system in Reichraming, Austria   总被引：1，自引：0，他引：1  

Veronika Gaube  Christina Kaiser  Martin Wildenberg  Heidi Adensam  Peter Fleissner  Johannes Kobler  Juliana Lutz  Andreas Schaumberger  Jakob Schaumberger  Barbara Smetschka  Angelika Wolf  Andreas Richter  Helmut Haberl 《Landscape Ecology》2009,24(9):1149-1165

The integrated modelling of coupled socio-ecological systems in land-change science requires innovative model concepts capable of grasping the interrelations between socioeconomic and natural components. Here, we discuss the integrated socio-ecological model SERD (Simulation of Ecological Compatibility of Regional Development) that was developed for the municipality of Reichraming in Upper Austria in a participative 2-year process involving local stakeholders. SERD includes three main components: (1) an agent-based actors module that simulates decisions of farmsteads, the municipal administration and other important actors; (2) a spatially explicit (GIS based) land-use module that simulates land-use change at the level of individual parcels of land and (3) an integrated socio-ecological stock-flow module that simulates carbon and nitrogen flows through both socioeconomic and ecological system compartments. We report on outcomes of a scenario analysis that outlines possible future trajectories depending on both external (e.g. agricultural subsidies and prices) and internal (e.g. innovation, willingness to co-operate) factors. We find that both external and internal factors can affect the behaviour of the integrated system considerably. Local and regional policies are found to be able to counteract adverse global socioeconomic conditions to some extent, but not to reverse the trend altogether. We also find strong interdependencies between socioeconomic and ecological components of the system. Fully evaluating these interdependencies is, however, not possible at the local scale alone and will require explicit consideration of higher-level effects in future research.  相似文献