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1.
N. Tremblay M. Y. Bouroubi B. Panneton S. Guillaume P. Vigneault C. Bélec 《Precision Agriculture》2010,11(6):621-635
A fuzzy inference system (FIS) was developed to generate recommendations for spatially variable applications of N fertilizer.
Key soil and plant properties were identified based on experiments with rates ranging from 0 to 250 kg N ha−1 conducted over three seasons (2005, 2006 and 2007) on fields with contrasting apparent soil electrical conductivity (ECa), elevation (ELE) and slope (SLP) features. Mid-season growth was assessed from remotely sensed imagery at 1-m2 resolution. Optimization of N rate by the FIS was defined against maximum corn growth in the weeks following in-season N
application. The best mid-season growth was in areas of low ECa, high ELE and low SLP. Under favourable soil conditions, maximum mid-season growth was obtained with low in-season N. Responses
to N fertilizer application were better where soil conditions were naturally unfavourable to growth. The N sufficiency index
(NSI) was used to judge plant N status just prior to in-season N application. Expert knowledge was formalized as a set of
rules involving ECa, ELE, SLP and NSI levels to deliver economically optimal N rates (EONRs). The resulting FIS was tested on an independent
set of data (2008). A simulation revealed that using the FIS would have led to an average N saving of 41 kg N ha−1 compared to the recommended uniform rate of 170 kg N ha−1, without a loss of yield. The FIS therefore appears to be useful for incorporating expert knowledge into spatially variable
N recommendations. 相似文献
2.
Recent studies have demonstrated the potential importance of using soil texture to modify fertilizer N recommendations. The
objective of this study was to determine (i) if surface clay content can be used as an auxiliary variable for estimating spatial
variability of soil NO3–N, and (ii) if this information is useful for variable rate N fertilization of non-irrigated corn [Zea mays (L.)] in south central Texas, USA across years. A 64 ha corn field with variable soil type and N fertility level was used
for this study during 2004–2007. Plant and surface and sub-surface soil samples were collected at different grid points and
analyzed for yield, soil N parameters and texture. A uniform rate (UR) of 120 kg N ha−1 in 2004 and variable rates (VAR) of 0, 60, 120, and 180 kg N ha−1 in 2005 through 2007 were applied to different sites in the field. Distinct yield variation was observed over this time period.
Yield and soil surface clay content and soil N parameters were strongly spatially structured. Corn grain yield was positively
related to residual NO3–N with depth and either negatively or positively related to clay content depending on precipitation. Residual NO3–N to 0.60 and 0.90 m depths was more related to corn yield than from shallower depths. The relationship of clay content with
soil NO3–N was weak and not temporally stable. Yield response to N rate also varied temporally. Supply of available N with depth,
soil texture and growing season precipitation determined proper N management for this field. 相似文献
3.
Mohammad Monirul Islam Eef Meerschman Timothy Saey Philippe De Smedt Ellen Van De Vijver Marc Van Meirvenne 《Precision Agriculture》2012,13(3):384-392
Every growing season, paddy fields are kept both flooded and drained for a significant period of time. As a consequence, these
soils develop distinct physico-chemical characteristics. For practical reasons, these soils are mostly sampled under dry conditions,
but the question arises how representative the results are for the wet growing conditions. Therefore, the apparent electrical
conductivity (ECa) of a 1.4 ha alluvial paddy field located in the Brahmaputra floodplain of Bangladesh was measured in both dry and wet conditions
by a sensing system using the electromagnetic induction sensor EM38, which does not require physical contact with the soil,
and compared both surveys. Due to the smooth water surface under wet conditions which ensured increased stability of the sensing
platform, the results of the survey showed considerably reduced micro-scale variability of ECa. Furthermore, the wet survey results more reliably furnished soil-related information mainly due to the absence of soil moisture
dynamics. The differences between ECa under wet and dry conditions were attributed to differences in soil texture, mainly the sand content variation having considerable
effect on soil moisture differences when flooded following drainage. Accordingly, the largest differences between ECa under wet and dry conditions were found in those parts of the field with a large sand content. Hence, the conclusion was
that an ECa survey on flooded fields has an added value to precision soil management. 相似文献
4.
The general objectives of this study were to evaluate (i) the specificity of the spatial and temporal dynamics of apparent soil electrical conductivity (ECa) measured by a electromagnetic induction (EMI) sensor, over 7 years, in variable conditions (of soil moisture content (SMC), soil vegetation cover and grazing management) and, consequently, (ii) the potential for implementing site-specific management (SSM). The DUALEM 1S sensor was used to measure the ECa in a 6 ha pasture experimental field four times between June 2007 and February of 2013. Soil spatial variability was characterized by 76 samples, geo-referenced with the global positioning system (GPS). The soil was characterized in terms of texture, moisture content, pH, organic matter content, nitrogen, phosphorus and potassium. This study shows a significant temporal stability of the ECa patterns under several conditions, behavior that is an excellent indicator of reliability of this tool to survey spatial soil variability and to delineate potential site-specific management zones (SSMZ). Significant correlations were obtained in this work between the ECa and relative field elevation, pH, silt and soil moisture content. These results open perspectives for using the EMI sensor as an indicator of SMC in irrigation management and of needs of limestone correction in Mediterranean pastures. However, it is interesting to extend the findings to other types of soil to verify the origin of the lack of correlation between the ECa data measured by DUALEM sensor and properties such as the clay, organic matter or phosphorus soil content, fundamental parameters for establishment of pasture SSM projects. 相似文献
5.
Machado S. Bynum E. D. Archer T. L. Lascano R. J. Wilson L. T Bordovsky J. Segarra E. Bronson K. Nesmith D. M. Xu W. 《Precision Agriculture》2000,2(4):359-376
Inadequate information on factors affecting crop yield variability has contributed to the slow adoption of site-specific farming (SSF). This study was conducted to determine the effects of biotic and abiotic factors on the spatial and temporal variability of irrigated corn grain yields and to derive information useful for SSF. The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil index (SI)(texture), soil NO3–N, arthropods, and diseases on corn grain yield were investigated at Halfway, TX on geo-referenced locations. Grain yields were influenced by interrelationships among biotic and abiotic factors. Grain yields were consistently high under high water treatment, at higher elevations, and on soils with high SI (high clay and silt). Soil NO3–N increased grain yields when water was adequate. Management zones for variable rate fertilizer and water application should, therefore, be based on information on elevation, SI, and soil NO3–N. The effects of arthropods, diseases, and crop stress (due to drought and N) on corn grain yield were unpredictable. Spider mite (Oligonychus pratensis) and common smut (Ustilago zeae) damage occurred under hot and dry conditions in 1998. Spider mite infestations were high in areas with high soil NO3–N. Moderate air temperatures and high relative humidity in 1999 favored southwestern corn borer (Diatraea grandiosella) and common rust (Puccinia maydis) incidences. Knowledge of conditions that favor arthropods and diseases outbreak and crop stress can improve the efficiency of scouting and in-season management of SSF. Management of SSF can be improved when effects of biotic and abiotic factors on grain yield are integrated and evaluated as a system. 相似文献
6.
7.
By accounting for spatial variation in soil N levels, variable-rate fertilizer application may improve crop yield and quality, and N use efficiency within fields. The main purpose of this study was to demonstrate how site-specific wheat yield and protein data, and a geographic information system may be used in developing precision N-recommendations for spring wheat. The three steps in the procedure include: (1) estimate the amount of N-removed in wheat in the year in which the crop is harvested, (2) estimate the N-deficit, defined as the amount of additional N needed for raising protein concentration in a future crop to a specified target level, and (3) estimate the total N-recommendation by summing the mapped values of the N-removed and the N-deficit. A map for variable-rate application of fertilizer is derived by specifying cutoff values to divide the range in the total N-recommendation into classes representing N management zones.A field experiment was conducted within an annually cropped wheat field (101 ha) in northern Montana to determine whether the proposed method could improve grain yields and protein levels. The N-removal and N-deficit were estimated from site-specific wheat yield and protein data that were acquired during harvest of 1996. In 1997, which was a dry year, an experiment was conducted in the same field that consisted of a randomized complete block design arranged as pairs of strip plots. Variable- or uniform-rate N treatments were randomly assigned to each pair of strips. Both treatments received nearly the same amount of fertilizer, however, N in the variable treatment was varied to match patterns in grain yield and protein levels that previously existed in 1996. Yields were not significantly different between management systems, but proteins were significantly enhanced by spatially variable N application. In addition, variability in protein levels was reduced within the whole field. Field areas deficient in N fertility could be identified without having to sample for soil profile N. 相似文献
8.
Stefan Patzold Franz Michael Mertens Ludger Bornemann Britta Koleczek Jonas Franke Hannes Feilhauer Gerhard Welp 《Precision Agriculture》2008,9(6):367-390
Crop protection seldom takes into account soil heterogeneity at the field scale. Yet, variable site characteristics affect
the incidence of pests as well as the efficacy and fate of pesticides in soil. This article reviews crucial starting points
for incorporating soil information into precision crop protection (PCP). At present, the lack of adequate field maps is a
major drawback. Conventional soil analyses are too expensive to capture soil heterogeneity at the field scale with the required
spatial resolution. Therefore, we discuss alternative procedures exemplified by our own results concerning (i) minimally and
non-invasive sensor techniques for the estimation of soil properties, (ii) the evidence of soil heterogeneity with respect
to PCP, and (iii) current possibilities for incorporation of high resolution soil information into crop protection decisions.
Soil organic carbon (SOC) and soil texture are extremely interesting for PCP. Their determination with minimally invasive
techniques requires the sampling of soils, because the sensors must be used in the laboratory. However, this technique delivers
precise information at low cost. We accurately determined SOC in the near-infrared. In the mid-infrared, texture and lime
content were also exactly quantified. Non-invasive sensors require less effort. The airborne HyMap sensor was suitable for
the detection of variability in SOC at high resolution, thus promising further progress regarding SOC data acquisition from
bare soil. The apparent electrical conductivity as measured by an EM38 sensor was shown to be a suitable proxy for soil texture
and layering. A survey of arable fields near Bonn (Germany) revealed widespread within-field heterogeneity of texture-related
ECa, SOC and other characteristics. Maps of herbicide sorption and application rate were derived from sensor data, showing
that optimal herbicide dosage is strongly governed by soil variability. A phytoassay with isoproturon confirmed the reliability
of spatially varied herbicide application rates. Mapping areas with an enhanced leaching risk within fields allows them to
be kept free of pesticides with related regulatory restrictions. We conclude that the use of information on soil heterogeneity
within the concept of PCP is beneficial, both economically and ecologically. 相似文献
9.
M. C. Gregoret M. Díaz Zorita J. Dardanelli R. G. Bongiovanni 《Precision Agriculture》2011,12(6):831-849
In semi-arid regions, soil water and nitrogen (N) are generally limiting factors for corn (Zea mays L.) production; hence, implementation of appropriate N fertilization strategies is needed. The use of precision agriculture
practices based on specific site and crop properties may contribute to a better allocation of fertilizer among management
zones (MZ). The aim of this study was to develop a model for diagnosis of N availability and recommendation of N fertilizer
rates adjusted to MZ for dryland corn crops growing in Haplustolls. The model considered variability between MZ by including
site-specific variables [soil available water content at sowing (SAW) and Available Nitrogen (soil available N-NO3 at planting + applied N, Nd)] using spatial statistical analysis. The study was conducted in Córdoba, Argentina in Haplustolls
and consisted in four field trials of N fertilizer (range 0–161 kg N ha−1) in each MZ. The MZ were selected based on elevation maps analysis. Grain yields varied between MZ and increased with larger
SAW and Nd at sowing. Grain responses to Nd and SAW in any MZ were not different between sites, allowing to fit a regional
model whose parameters (Nd, Nd2, SAW, SAW2) contributed significantly (p < 0.001) to yield prediction. Agronomical and economically optimum N rates varied among MZs. However, the spatial variability
of optimum N rates among MZs within sites was not enough to recommend variable N fertilizer rates instead of a uniform rate.
Variable N fertilizer rates should be recommended only if variability in SAW and soil N among MZ is greater than that found
in this work. 相似文献
10.
以浙江省为例,探讨了南方河谷平原水田土壤肥力状况及其空间变化特点。因成土物质来自周围高度风化土壤及其质地偏砂,河谷平原水田土壤酸化明显,酸性及强酸性土壤的比例高达58.75%。土壤质地是导致河谷平原水田土壤肥力空间差异的关键因素,位于河流下游的泥质田和泥筋田质地较重,保肥性较强,土壤有机质、全氮积累明显,供钾能力较高,土壤酸化相对较弱;相反,位于河流上游及河沿的洪积泥砂田、泥砂田和培泥砂田土壤质地偏砂,其保肥性较弱,有机质、全氮较低,供钾能力较弱,土壤酸化明显。土壤有效磷空间异质明显,同时存在过度积磷与严重缺磷的现象。分析认为,在河谷平原水田土壤管理与施肥策略上应考虑土壤性状的空间差异,并重视磷和钾的测土配方施肥。 相似文献
11.
Soil electrical conductivity as a function of soil water content and implications for soil mapping 总被引：1，自引：2，他引：1
Apparent soil electrical conductivity (ECa) has shown promise as a soil survey tool in the Midwestern United States, with a share of this interest coming from the precision agriculture community. To fully utilize the potential of ECa to map soils, a better understanding of temporal changes in ECa is needed. Therefore, this study was undertaken to compare temporal changes in soil ECa between different soils, to investigate the influence of changes in soil water content on soil ECa, and to explore the impacts these ECa changes might have on soil mapping applications. To this end, a 90 m long transect was established. Soil ECa readings were taken in the vertical and horizontal dipoles at five points once every one to two weeks from June until October in 1999 and 2000. At the same time, soil samples were collected to a depth of 0.9 m for volumetric soil water content analysis. Soil ECa readings were compared to soil water content. At four of the five sites linear regression analysis yielded r
2 values of 0.70 or higher. Regression line slopes tended to be greater in lower landscape positions indicating greater ECa changes with a given change in soil water content. Two of the soils had an ECa relationship that changed as the soils became dry. This is an item of concern if ECa is to be used in soil mapping. Results indicated that soil water content has a strong influence on the ECa of these soils, and that ECa has its greatest potential to differentiate between soils when the soils are moist. Soil water content is an important variable to know when conducting ECa surveys and should be recorded as a part of any report on ECa studies. 相似文献
12.
Innovations in precision agriculture (PA) have created opportunities to achieve a greater understanding of within-field variability. However, PA adoption has been hindered by uncertainty about field-specific performance and return on investment. Uncertainty could be better addressed by using innovative analyses that provide insights into variability among fields and across a region. The objectives of this research were to: (1) generate a within-field soil clay-content variability index (VIc), (2) create a regional-scale growing-season precipitation variability index (VIp), and (3) integrate the soil and weather indices with the USDA NRCS soil erosion vulnerability index (SVI) to produce a final index that incorporated both variability and vulnerability (VVI). The interpretation of the outcomes represented by each objective supports unique decisions that land managers may consider for reducing uncertainty about implementing PA. All indices were derived using publically available information for Missouri, USA. The VIc was the ratio between the maximum and minimum clay content within fields. The VIp was calculated as the standard deviation of the total growing-season precipitation from 2006 to 2015. Significant clustering of VIc and VIp were observed along the Missouri River corridor, northeast and northwest Missouri. Fields with high VVI were mostly in the claypan soil region of northeast Missouri, and along a portion of the Missouri River dominated by loess soils on steep slopes. Southeast Missouri displayed the greatest diversity in soil and weather variability, but had low vulnerability. This research could be used as a decision-support tool to aid producers and PA service and product providers in determining where PA opportunities exist. 相似文献
13.
Thompson A. N. Shaw J. N. Mask P. L. Touchton J. T. Rickman D. 《Precision Agriculture》2004,5(4):345-358
Characterizing the spatial variability of nutrients facilitates precision soil sampling. Questions exist regarding the best technique for directed soil sampling based on a priori knowledge of soil and crop patterns. The objective of this study was to evaluate zone delineation techniques for Alabama grain fields to determine which method best minimized the soil test variability. Site one (25.8 ha) and site three (20.0 ha) were located in the Tennessee Valley region, and site two (24.2 ha) was located in the Coastal Plain region of Alabama. Tennessee Valley soils ranged from well drained Rhodic and Typic Paleudults to somewhat poorly drained Aquic Paleudults and Fluventic Dystrudepts. Coastal Plain soils ranged from coarse-loamy Rhodic Kandiudults to loamy Arenic Kandiudults. Soils were sampled by grid soil sampling methods (grid sizes of 0.40 ha and 1 ha) consisting of: (1) twenty composited cores collected randomly throughout each grid (grid-cell sampling) and, (2) six composited cores collected randomly from a 3×3m area at the center of each grid (grid-point sampling). Zones were established from (1) an Order 1 Soil Survey, (2) corn (Zea mays L.) yield maps, and (3) airborne remote sensing images. All soil properties were moderately to strongly spatially dependent as per semivariogram analyses. Differences in grid-point and grid-cell soil test values suggested grid-point sampling does not accurately represent grid values. Zones created by soil survey, yield data, and remote sensing images displayed lower coefficient of variations (%CV) for soil test values than overall field values, suggesting these techniques group soil test variability. However, few differences were observed between the three zone delineation techniques. Results suggest directed sampling using zone delineation techniques outlined in this paper would result in more efficient soil sampling for these Alabama grain fields. 相似文献
14.
为了研究土壤外源铬（Cr）对不同作物毒性和有效性的差异，本研究选用生菜、小麦和玉米作为受试植物，分别采用K2CrO4溶液和某化工厂Cr污染土壤作为土壤外源Cr污染来源开展了作物根伸长实验和田间试验。结果表明：两种外源Cr处理土壤中，小麦根伸长的EC10和EC50值（10%和50%效应浓度）分别为生菜相应值的2.22~2.35倍和1.45~1.87倍，说明生菜对土壤Cr污染更为敏感。外源添加化工厂Cr污染土壤的处理中EC10值大约为外源添加K2CrO4处理土壤中的14~15倍，而对于EC50值该倍数为4~5倍。田间试验中，与对照处理相比，两种外源Cr处理均显著增加了土壤中乙二胺四乙酸提取态Cr（EDTA-Cr）含量。生菜-小麦-玉米轮作过程中，在生菜种植的3个月内，土壤中EDTA-Cr含量下降迅速，不同外源Cr处理中下降了75.2%~89.4%。在小麦和玉米种植期间，EDTA-Cr含量下降速率变慢，到玉米收获后EDTA-Cr含量共下降了89.0%~94.9%，并且外源添加K2CrO4处理的土壤中EDTA-Cr含量的下降速率高于添加化工厂Cr污染土壤的处理。三种作物可食用部分Cr含量均低于国家食品安全标准，但生菜对Cr的富集显著大于小麦和玉米的。 相似文献
15.
土壤盐渍化问题是制约干旱半干旱区植被生长最主要的生态环境地质问题,也是影响绿洲农业生产的障碍性问题。而将遥感与近感技术相结合,是当前评价、监测及预报土壤盐渍化程度的先进方法。以新疆塔里木盆地北缘的渭干河-库车河三角洲绿洲为例,以遥感数据和解译后的电磁感应数据为基础数据源,利用解译后的数据结合GIS和地统计学知识以及野外实测所得到的土壤电导率和盐分资料,分别采用泛克里格(Universal Kriging)、光谱指数回归(Spectral Index Regression)和回归残差泛克里格(Regression-Universal Kriging)3种方法研究了该地区两个关键季节(干季和湿季)土壤盐分的空间变异特征。研究结果表明:研究区的土壤浸提液电导率EC1:5和土壤盐分呈现显著相关,可以用EC1:5来代替土壤的全盐量进行分析;电磁感应仪(EM38)所测各季节土壤表观电导率与EC1:5的相关系数均达到1%显著水平,以表观电导率垂直读数(EMV) 和水平读数(EMH)为自变量的多元回归模型拟合效果较好;研究区各季节的表层土壤电导率的空间分布均表现为强相关性,说明土壤采样点间的内部结构性良好,采用能够充分考虑到干旱区表层土壤电导率空间变异的尺度依赖性的球状套合模型,能够更好的拟合土壤表观电导率的空间结构;经过精度比较,回归残差泛克里格法为最优预测方法,这表明将遥感和电磁感应技术相结合,能够有效的提高预测与评估土壤盐分空间分布的精度,为精确地进行土壤盐分预测以及土壤次生盐渍化的防控提供了一定的依据。 相似文献
16.
Johnson Cinthia K. Wienhold Brian J. Doran John W. Drijber Rhae A. Wright Sara F. 《Precision Agriculture》2004,5(4):311-328
Soil biological response to management is best evaluated in field-scale experiments within the context of the soil environment and crop; however, cost-effective methods are lacking to relate these data which span multiple spatial scales. We hypothesized that zones of apparent electrical conductivity (ECa) could be used to integrate soil properties (sampling-site scale), microbial-scale measures of vesicular-arbuscular mycorrhizal (VAM) fungi, and field-scale wheat yields from yield maps. An on-farm dryland experiment (250 ha) was established wherein two (32-ha) fields were assigned to each phase of a winter wheat (Triticum aestivum L.) – corn (Zea mays L.) – proso millet (Panicum miliaceum L.) – fallow rotation. Each field was mapped and classified into four zones (ranges) of ECa. Soil samples were collected from geo-referenced sites within ECa zones and analyzed for multiple soil properties associated with productivity (0–7.5 and/or 0–30 cm). Additionally, VAM fungi were assessed using C16:1(cis)11 fatty acid methyl ester biomarker (C16vam), glomalin immunoassay, and wet-aggregate stability (WAS) techniques (1–2mm aggregates from 0- to 7.5-cm soil samples). Concentrations of C16vam and WAS increased among cropping treatments as: fallow < wheat < corn < millet. Glomalin across crops and replicates, C16vam and WAS in fallow (crop effect removed), soil properties associated with productivity, and wheat yields were negatively correlated with ECa and different among ECa zones (P 0.05). Zones of ECa provide a point of reference for relating data collected at different scales. Monitoring cropping system parameters and profitability, over time, may allow linkage of microbial-scale processes to farm-scale economic and ecological outcomes. 相似文献
17.
Mohammad Monirul Islam Liesbet Cockx Eef Meerschman Philippe De Smedt Fun Meeuws Marc Van Meirvenne 《Precision Agriculture》2011,12(6):850-859
Continuous paddy rice cultivation requires fields to be flooded most of the time limiting seriously the collection of detailed
soil information. So far, no appropriate soil sensor technology for identifying soil variability of flooded fields has been
reported. Therefore, the primary objective was the development of a sensing system that can float, acquire and process detailed
geo-referenced soil information within flooded fields. An additional objective was to determine whether the collected apparent
electrical conductivity (ECa) information could be used to support soil management at a within-field level. A floating sensing system (FloSSy) was built
to record ECa using the electromagnetic induction sensor EM38, which does not require physical contact with the soil. Its feasibility was
tested in an alluvial paddy field of 2.7 ha located in the Brahmaputra floodplain of Bangladesh. The high-resolution (1 × 1 m)
ECa data were classified into three classes using the fuzzy k-means classification method. The variation among the classes could be attributed to differences in subsoil (0.15–0.30 m below
soil surface) bulk density, with the smallest ECa values representing the lowest bulk density. This effect was attributed to differences in compaction of the plough pan due
to differential puddling. There was also a significant difference in rice yield among the ECa classes, with the smallest ECa values representing the lowest yield. It was concluded that the floating sensing system allowed the collection of relevant
soil information, opening potential for precision agriculture practices in flooded crop fields. 相似文献
18.
Better understanding of within-field spatial variability of crop quality parameters and yield are needed for precision management
of crops. This study was conducted to determine the magnitude of within-field variability in soil properties, corn (Zea mays L.) quality parameters and yield and to characterize their spatial structures. Another objective was to compare the effects
of hybrid on corn quality, yield, and the spatial structure of grain quality. Four Pioneer hybrids were planted side-by-side,
two in each of the two study fields in eastern Illinois, USA. Coefficients of variation (CV%) for soil properties varied from
6.3 (pH) to 56.8% (soil test P). All the soil properties (except pH at Site 2) displayed well-defined spatial structures,
with either strong or moderate spatial dependence. Variability in corn quality and yield (CVs < 10%) was smaller than variability
in soil properties. Most quality parameters examined at Site 1 exhibited either moderate or strong spatial dependence, except
that corn oil (both hybrids), kernel roundness and weight (hybrid 33Y18) did not show any spatial correlation. Hybrid 33G26
had significantly higher yield and quality for most quality parameters than 33Y18 at Site 1. At Site 2, hybrid 34W67 was significantly
lower in oil and protein content, length, roundness and vitreousness than 34K77, but higher in other quality parameters. Significant
differences in spatial structures were also observed across hybrids for some corn quality parameters. We conclude that hybrid
selection is an important strategy for precision management of corn for optimum yield and quality. 相似文献
19.
A Geostatistical Analysis of the Spatial Variation of Soil Mineral Nitrogen and Potentially Available Nitrogen Within an Arable Field 总被引：1，自引：0，他引：1
The technology for site-specific applications of nitrogen (N) fertilizer has exposed a gap in our knowledge about the spatial variation of soil mineral N, and that which will become available during the growing season within arable fields. Spring mineral N and potentially available N were measured in an arable field together with gravimetric water content, loss on ignition, crop yield, percentages of sand, silt, and clay, and elevation to describe their spatial variation geostatistically. The areas with a larger clay content had larger values of mineral N, potentially available N, loss on ignition and gravimetric water content, and the converse was true for the areas with more sandy soil. The results suggest that the spatial relations between mineral N and loss on ignition, gravimetric water content, soil texture, elevation and crop yield, and between potentially available N and loss on ignition and silt content could be used to indicate their spatial patterns. Variable-rate nitrogen fertilizer application would be feasible in this field because of the spatial structure and the magnitude of variation of mineral N and potentially available N. 相似文献