Impact of Spatial Variability on Transport of Pesticides From Soil Surface to Pumping Well

1993 ◽  
pp. 441-444
Author(s):  
W. H. J. Beltman ◽  
J. J. T. I. Boesten ◽  
S. E. A. T. M. Zee
Keyword(s):  
Spatial Variability ◽  
Soil Surface

scholarly journals Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

2020 ◽  
Vol 17 (3) ◽  
pp. 771-780 ◽  
Author(s):  
Stephanie C. Pennington ◽  
Nate G. McDowell ◽  
J. Patrick Megonigal ◽  
James C. Stegen ◽  
Ben Bond-Lamberty
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Spatial Variability ◽  
Temperature Sensitivity ◽  
Large Scale ◽  
Deciduous Forest ◽  
Basal Area ◽  
Soil Surface ◽  
Study Sites ◽  
Positive Effect

Abstract. Soil respiration (Rs), the flow of CO2 from the soil surface to the atmosphere, is one of the largest carbon fluxes in the terrestrial biosphere. The spatial variability of Rs is both large and poorly understood, limiting our ability to robustly scale it in space. One factor in Rs spatial variability is the autotrophic contribution from plant roots, but it is uncertain how the presence of plants affects the magnitude and temperature sensitivity of Rs. This study used 1 year of Rs measurements to examine the effect of localized basal area on Rs in the growing and dormant seasons, as well as during moisture-limited times, in a temperate, coastal, deciduous forest in eastern Maryland, USA. In a linear mixed-effects model, tree basal area within a 5 m radius (BA5) exerted a significant positive effect on the temperature sensitivity of soil respiration. Soil moisture was the dominant control on Rs during the dry portions of the year, while soil moisture, temperature, and BA5 all exerted significant effects on Rs in wetter periods. Our results suggest that autotrophic respiration is more sensitive to temperature than heterotrophic respiration at these sites, although we did not measure these source fluxes directly, and that soil respiration is highly moisture sensitive, even in a record-rainfall year. The Rs flux magnitudes (0.46–15.0 µmol m−2 s−1) and variability (coefficient of variability 10 %–23 % across plots) observed in this study were comparable to values observed in similar forests. Six Rs observations would be required in order to estimate the mean across all study sites to within 50 %, and 518 would be required in order to estimate it to within 5 %, with 95 % confidence. A better understanding of the spatial interactions between plants and microbes, as well as the strength and speed of above- and belowground coupling, is necessary to link these processes with large-scale soil-to-atmosphere C fluxes.

DETERMINATION OF VARIABILITY IN SOIL PHYSICAL PROPERTIES AND MICROBIAL BIOMASS UNDER CONTINUOUS DIRECT-PLANTED CORN

1986 ◽  
Vol 66 (4) ◽  
pp. 747-750 ◽  
Author(s):  
M. R. CARTER ◽  
R. P. WHITE
Keyword(s):  
Zea Mays ◽  
Microbial Biomass ◽  
Spatial Variability ◽  
Prince Edward Island ◽  
Zea Mays L ◽  
Soil Surface ◽  
Soil Bulk Density ◽  
Soil Strength ◽  
Microbial Biomass C ◽  
Winter Period

The spatial variability of soil strength, porosity, and microbial biomass was determined under 4-yr continuous direct-planted silage corn (Zea mays L.) on Prince Edward Island. All soil properties changed relative to the row position. Microbial biomass C and N were lower in the in-row compared to the between-row position. Positional and depth differences for soil bulk density and volume of macropores (EPD > 50 μm) were only evident at the soil surface (0–8 cm). Temporal and spatial variations in soil strength indicated the extent of the rooting potential within the soil profile, the depth to compacted soil layers, and the degree of soil structure regeneration during the winter period. Key words: Spatial variability, soil strength, soil porosity, microbial biomass, direct-planted corn, Zea mays L.

scholarly journals DISTRIBUIÇÃO DA EVAPORAÇÃO NO INTERIOR DE UM AMBIENTE PROTEGIDO.

Irriga ◽  
2006 ◽  
Vol 11 (2) ◽  
pp. 246-256
Author(s):  
Cleber Junior Jadoski ◽  
Antonio Evaldo Klar ◽  
Marcio Furlan Maggi ◽  
Juliana Ramiro Alexandre Barreto Almeida dos Santos ◽  
Samuel Rodrigues Fulan
Keyword(s):  
Energy Distribution ◽  
Spatial Variability ◽  
Soil Surface ◽  
Longitudinal Axis ◽  
Class A ◽  
Set Up ◽  
Equidistant Points ◽  
Class A Pan

DISTRIBUIÇÃO DA EVAPORAÇÃO NO INTERIOR DE UM AMBIENTE PROTEGIDO.  Cleber Junior Jadoski1; Antonio Evaldo Klar1; Marcio Furlan Maggi2; Juliana Ramiro1 Alexandre Barreto Almeida  dos Santos1;  Samuel Rodrigues Fulan11Departamento de Engenharia Rural, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, SP,  [email protected]  2Universidade Estadual do Centro Oeste, UNICENTRO, Guarapuava, PR   1 RESUMO. Este trabalho teve por objetivo estudar a distribuição da evaporação no interior de um ambiente protegido. O experimento foi instalado em uma estufa de polietileno na Fazenda Experimental Lageado da Faculdade de Ciências Agronômicas (FCA), no período do inverno de 2005. Para analisar a distribuição espacial da energia, foram utilizados microevaporímetros plásticos de 500 ml (13,7 cmde diâmetro) com o que foram obtidos os valores respectivos de evaporação que integram os elementos meteorológicos envolvidos. Foram instalados 132 microevaporímetros distribuídos em três alturas, 0,40, 0,80 e1,20 m, a partir da superfície do solo, perfazendo 44 pontos uniformemente distribuídos. A estufa plástica é do tipo túnel com 7,5m de largura por 27,5m de comprimento, 3,20m de altura no centro e 2,00m nas paredes laterais fechadas com tela do tipo “sombrite”. A orientação noroeste/sudeste, com base no norte verdadeiro, foi adotada para o eixo longitudinal da estufa. Para a comparação das variáveis, foram utilizados princípios de geoestatística com auxílio do programa GS+. Os dados obtidos permitiram chegar às seguintes conclusões: ocorreu variabilidade espacial nas diferentes regiões e alturas de instalação dos microevaporímetros, com maior evaporação na altura mais próxima do solo no mês de julho; o tanque Classe “A” não difere significativamente em relação aos microevaporímetros; pode-se estimar a evaporação interna do ambiente protegido através de medições em um tanque Classe “A” instalado fora do ambiente protegido. UNITERMOS: Geoestatística, microevaporímetro, tanque Classe “A”,  Jadoski, c. j.; KLAR, A. E.; MAGGI, M. F.; RAMIRO, J.; Santos,  a. b. a. dos;  Fulan S. R. EVAPORATION DISTRIBUTION IN A PROTECTED ENVIRONMENT  2 ABSTRACT             This work aimed to study evaporation distribution in a protected environment.  The experiment was set up in polyethylene greenhouse at the Lageado Experimental Farm in theSchoolofAgronomic Sciences(FCA, UNESP-Botucatu) in the  winter of  2005. 132  500-ml plastic micro evaporimeters  (13.7 diameter) were used used to obtain evaporation values and analyze spatial energy distribution. These micro evaporimeters were distributed in 44 equidistant points, at three different heights from the soil surface: 0.40, 0.80 and 1.20cm The tunnel-type greenhouse was7.5 mwide,27.5 mlong and  3.20 mhigh at the center, and was covered with black shadow screen (sombrite) on the sides.  Southeast /northwest orientation, based on true north, was used foro othe greenhouse longitudinal axis.  For variable comparison,  a geostatistics  was used through the  GS+ program. From obtained data, it was concluded that: there was spatial variability at different points and heights of the microevaporimeters and higher evaporation values for the height near to  soil surface in July; evaporation values   obtained from micro evaporimeters were not statistically different from those obtained from Class “A” Pan installed in the center of  the greenhouse; the Class “A” Pan installed outside the greenhouse can be used to evaluate the internal evaporation. KEYWORDS: Geostatistics, microevaporimeter, Class “A” Pan.. 

scholarly journals Spatial variability of soil hydraulic properties on a steep slope in the loess plateau of China

2008 ◽  
Vol 65 (3) ◽  
pp. 268-276 ◽  
Author(s):  
Wei Hu ◽  
Ming An Shao ◽  
Quan Jiu Wang ◽  
Jun Fan ◽  
Klaus Reichardt
Keyword(s):  
Spatial Structure ◽  
Spatial Variability ◽  
Loess Plateau ◽  
Spatial Dependence ◽  
Hydraulic Properties ◽  
Applied Pressure ◽  
Soil Surface ◽  
Pressure Head ◽  
Steep Slope ◽  
The Loess Plateau

The understanding of the structure of the spatial variability of soil surface hydraulic properties on steep slopes is important for modeling infiltration and runoff processes. The objective of this study was to investigate the spatial variability of these properties on a steep slope of the Loess Plateau in northwest China. A 9600 m² area was systematically sampled in a grid of 106 points spaced 10 m x 10 m. Hydraulic properties were determined with a disc infiltrometer under multiple pressure heads (-15, -9, -6, -3, 0 cm) at each sample point. Classical and geo-statistical methods were used for data analysis. The results indicated that the variation of Gardner's a and hydraulic conductivities at all applied pressure heads was moderate and the heterogeneity for hydraulic conductivities increased as the applied pressure head increased. Along the slope, hydraulic conductivities generally decreased downwards, while the Gardner's a fluctuated slightly. The Gardner's a of the shaded aspect of the slope was greater than that of the sunny aspect. The hydraulic conductivities of the shaded aspect were greater at higher pressure heads as compared to the sunny aspect, but lower than those of the sunny aspect at lower pressure heads. Correlation analysis showed a negative correlation between hydraulic conductivity and soil organic matter and clay (<0.01 mm) contents. Hydraulic conductivities at pressure heads of -3, -6, -9, -15 cm varied across the slope and their spatial dependence increased as the pressure head declined. The heterogeneity and spatial dependence of hydraulic properties were larger for the areas with shaded aspect as compared to the sunny aspect, however, as pressure decreased they showed a progressively increasing spatial structure, and their spatial structure behaved increasingly similar in both the shaded and sunny aspects.

Spatial variability of physical soil properties influencing the temperature of the soil surface

1983 ◽  
Vol 6 (2-3) ◽  
pp. 213-226 ◽  
Author(s):  
H.F.M. ten Berge ◽  
L. Stroosnijder ◽  
P.A. Burrough ◽  
A.K. Bregt ◽  
M.J. de Heus
Keyword(s):  
Spatial Variability ◽  
Soil Properties ◽  
Soil Surface

scholarly journals Neutron probe measurement of soil water content close to soil surface

1993 ◽  
Vol 50 (3) ◽  
pp. 333-337 ◽  
Author(s):  
M.C. Falleiros ◽  
A. Ravelo Sanchez ◽  
M.Dornelas de Souza ◽  
O.O.S. Bacchi ◽  
J.E. Pilotto ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Surface ◽  
Slow Neutron ◽  
Neutron Probe ◽  
Points Of View ◽  
Red Latosol ◽  
Sphere Of Influence

The problem of neutron probe soil water content measurements close to soil surface is analysed from the spatial variability and also from the slow neutron "loss" to the atmosphere points of view. Results obtained on a dark red latosol of the county of Piracicaba,SP, indicate the possibility of precisely measuring the neutron "sphere of influence" when different media are used on soil surface.

scholarly journals Soil Physical Properties Spatial Variability under Long-Term No-Tillage Corn

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 750 ◽  
Author(s):  
Ripendra Awal ◽  
Mohammad Safeeq ◽  
Farhat Abbas ◽  
Samira Fares ◽  
Sanjit K. Deb ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Organic Carbon ◽  
Spatial Variability ◽  
Physical Properties ◽  
Soil Surface ◽  
Soil Physical Properties ◽  
No Tillage ◽  
Tillage Practices ◽  
Soil Surface Temperature

Spatial variability of soil physical and hydrological properties within or among agricultural fields could be intrinsically induced due to geologic and pedologic soil forming factors, but some of the variability may be induced by anthropogenic activities such as tillage practices. No-tillage has been gaining ground as a successful conservation practice, and quantifying spatial variability of soil physical properties induced by no-tillage practices is a prerequisite for making appropriate site-specific agricultural management decisions and/or reformulating some management practices. In particular, there remains very limited information on the spatial variability of soil physical properties under long-term no-tillage corn and tropical soil conditions. Therefore, the main objective of this study was to quantify the spatial variability of some selected soil physical properties (soil surface temperature (ST), volumetric water content (θv), soil resistance (TIP), total porosity (θt), bulk density (ρb), organic carbon, and saturated hydraulic conductivity (Ksat)) using classical and geostatistical methods. The study site was a 2 ha field cropped no-tillage sweet corn for nearly 10 years on Oahu, Hawaii. The field was divided into 10 × 10 and 20 × 20 m grids. Soil samples were collected at each grid for measuring ρb, θt, and soil organic carbon (SOC) in the laboratory following standard methods. Saturated hydraulic conductivity, TIP at 10 and 20 cm depths, soil surface temperature, and θv were also measured. Porosity and ρb have low and low to moderate variability, respectively based on the relative ranking of the magnitude of variability drawn from the coefficient of variation. Variability of the SOC, TIP, and Ksat ranges from moderate to high. Based on the best-fitted semivariogram model for finer grid data, 9.8 m and 142.2 m are the cut off beyond which the measured parameter does not show any spatial correlation for SOC, and TIP at 10 cm depth, respectively. Bulk density shows the highest spatial dependence (range = 226.8 m) among all measured properties. Spatial distribution of the soil properties based on kriging shows a high level of variability even though the sampled field is relatively small.

scholarly journals Estimating Non-Sustainable Soil Erosion Rates in the Tierra de Barros Vineyards (Extremadura, Spain) Using an ISUM Update

2019 ◽  
Vol 9 (16) ◽  
pp. 3317 ◽  
Author(s):  
Jesús Rodrigo-Comino ◽  
Jesús Barrena-González ◽  
Manuel Pulido-Fernández ◽  
Artemi Cerdá
Keyword(s):  
Soil Erosion ◽  
Spatial Variability ◽  
Management System ◽  
Soil Management ◽  
Soil Surface ◽  
Surface Level ◽  
Erosion Rates ◽  
Erosion Processes ◽  
Sampling Points ◽  
Soil Erosion Rates

Monitoring soil erosion processes and measuring soil and water yields allow supplying key information to achieve land degradation neutrality challenges. Vineyards are one of the most affected agricultural territories by soil erosion due to human and natural factors. However, the spatial variability of soil erosion, the number of sampling points, and plot size necessary to estimate accurate soil erosion rates remains unclear. In this research, we determine how many inter-rows should be surveyed to estimate the soil mobilization rates in the viticulture area of Tierra de Barros (Extremadura, SW Spain) using the Improved Stock Unearthing Method (ISUM). This method uses the graft union of the vines as a passive biomarker of the soil surface level changes since the time of plantation and inter-row measures. ISUM was applied to three inter-row and four rows of vines (5904 sampling points) in order to determine how many surfaces and transects must be surveyed as all the previous surveys were done with only one inter-row. The results showed average values of soil depletion reaching −11.4, −11.8, and −11.5 cm for the inter-rows 1, 2, and 3, respectively. The current soil surface level descended 11.6 cm in 20 years. The inter-rows 1, 2, and 3 with a total area of 302.4 m2 each one (2016 points) recorded 71.4, 70.8, and 74.0 Mg ha−1 yr−1, respectively. With the maximum number of sampling points (5904), 71.2 Mg ha−1 yr−1 were obtained. The spatial variability of the soil erosion was shown to be very small, with no statistically significant differences among inter-rows. This could be due to the effect of the soil profile homogenization as a consequence of the intense tillage. This research shows the potential predictability of ISUM in order to give an overall overview of the soil erosion process for vineyards that follow the same soil management system. We conclude that measuring one inter-row is enough to get an overview of soil erosion processes in vineyards when the vines are under the same intense tillage management and topographical conditions. Moreover, we demonstrated the high erosion rates in a vineyard within the viticultural region of the Tierra de Barros, which could be representative for similar vineyards with similar topographical conditions, soil properties, and a possible non-sustainable soil management system.

Sign in / Sign up

Export Citation Format

Share Document