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Evaluation of experimental sugar beet hybrids for resistance to curly top in Malheur County, OR, 2005
Get PDFTwenty-five experimental sugarbeet hybrids submitted to the official variety trials were evaluated for resistance to Beet curly top virus (BCTV). Hybrids were planted in a commercial sprinkler-irrigated sugarbeet field and exposed to a natural epiphytotic of BCTV. Experimental units were arranged in a randomized complete block design with seven replications. Plots were evaluated for BCTV based on a Disease Index (DI) scale of 0 to 9 (no symptoms to dead) on Sept 14, 2004 by three raters. The moderately severe epiphytotic resulted in uniform disease pressure and significant differences between hybrids for DI, root yield, sugar content, and estimated recoverable sugar. Our disease ratings were positively correlated with (r = 0.632, P < 0.0001) ratings from the 2004 Curly Top Nursery. There was no correlation between DI and estimated recoverable sugar which was probably due to field or genetic variation influencing yield
Evaluation of commercial sugar beet hybrids for resistance to curly top in Malheur County, OR, 2005
Get PDFCommercial sugar beet hybrids were evaluated for resistance to Beet severe curly top virus in a furrow-irrigated sugar
beet field near Ontario, OR where curly top had been a problem in previous years. The field trial relied on natural infection
and was planted on 6 Apr. Plots were planted to a density of 285,120 seeds/A, and thinned to 40,731 plants/A. Plots were
four rows wide (22 in. between rows) and 23 ft long. The experimental design was a randomized complete block with eight
replications. The crop was managed according to standard cultural practices. The weather during the growing season was
normal except for above average temperatures in Mar and Aug and above average precipitation in Apr and May. Disease
pressure was uniform and moderately severe. Disease data were recorded on 16 Sep by three individual raters separately
using a disease index of 0 to 9 (0 = no symptoms; 9 = dead plant). The three ratings per plot were averaged prior to analysis.
The center two rows were harvested on 13 and 14 Oct using a small plot harvester. Yield data were reduced by 10% to
account for tare. Sugar content of the beets was determined by the Amalgamated Sugar Co. laboratory using a polarimeter,
and recoverable sugar was estimated based on percent sugar and conductivity. Data were analyzed using the general linear
models procedure (Proc GLM-SAS), and Fisher's protected LSD was used for mean comparisons.
Yields were typical for this site and above average for growers. The commercial hybrids response to Beet severe curly top
virus ranged from acceptable (slight leaf curl = 2 to most leaves with moderate curling = 4) to severe (most larger leaves
becoming prostrate = 6). Analysis of variance indicated there were significant differences among hybrids for disease index,
root yield, sugar content, and estimated recoverable sugar. Based on Spearman's coefficient of rank correlation, our disease
ratings positively correlated (r s = 0.82, P < 0.0001) with those from the 2005 Curly Top Nursery in Kimberly, ID. There was
an inverse relationship (rs = -0.63, P = 0.0005) between estimated recoverable sugar and disease index
An assessment of the hypervariable domains of the 16S rRNA genes for their value in determining microbial community diversity: The paradox of traditional ecological indices
Get PDFAmplicon length heterogeneity PCR (LH-PCR) was investigated for its ability to
distinguish between microbial community patterns from the same soil type under
different land management practices. Natural sagebrush and irrigated mouldboard-ploughed
soils from Idaho were queried as to which hypervariable domains,
or combinations of 16S rRNA gene domains, were the best molecular markers.
Using standard ecological indices to measure richness, diversity and evenness, the
combination of three domains, V1, V3 and V1 +V2, or the combined V1 and V3
domains were the markers that could best distinguish the undisturbed natural
sagebrush communities from the mouldboard-ploughed microbial communities.
Bray–Curtis similarity and multidimensional scaling were found to be better
metrics to ordinate and cluster the LH-PCR community profiling data. The use/
misuse of traditional ecological indices such as diversity and evenness to study
microbial community profiles will remain a major point to consider when
performing metagenomic studies
An ecoinformatics tool for microbial community studies: Supervised classification of amplicon length heterogeneity (ALH) profiles of 16S rRNA
Get PDFSupport vector machines (SVM) and K-nearest neighbors (KNN) are two computational machine learning tools that
perform supervised classification. This paper presents a novel application of such supervised analytical tools for microbial
community profiling and to distinguish patterning among ecosystems. Amplicon length heterogeneity (ALH) profiles from
several hypervariable regions of 16S rRNA gene of eubacterial communities from Idaho agricultural soil samples and from
Chesapeake Bay marsh sediments were separately analyzed. The profiles from all available hypervariable regions were
concatenated to obtain a combined profile, which was then provided to the SVM and KNN classifiers. Each profile was
labeled with information about the location or time of its sampling. We hypothesized that after a learning phase using
feature vectors from labeled ALH profiles, both these classifiers would have the capacity to predict the labels of previously
unseen samples. The resulting classifiers were able to predict the labels of the Idaho soil samples with high accuracy. The
classifiers were less accurate for the classification of the Chesapeake Bay sediments suggesting greater similarity within the
Bay's microbial community patterns in the sampled sites. The profiles obtained from the VI +V2 region were more
informative than that obtained from any other single region. However, combining them with profiles from the V1 region
(with or without the profiles from the V3 region) resulted in the most accurate classification of the samples. The addition
of profiles from the V9 region appeared to confound the classifiers. Our results show that SVM and KNN classifiers can
be effectively applied to distinguish between eubacterial community patterns from different ecosystems based only on their
ALH profiles
Nitrate accumulation and movement under deficit irrigation in soil receiving cattle manure and commercial fertilizer
Get PDFNitrate leaching from agricultural soils can increase groundwater nitrate concentrations.
The objectives of the study were to assess the accumulation and movement of nitrate in the
soil profile over a 2-year period under deficit irrigation conditions following a one time
application of N in cattle feedlot manure and commercial fertilizer to corn at rates to achieve
yield goals expected under conditions of full irrigation. Cattle manure and ammonium
nitrate were applied in 2002 at the University of Nebraska recommended rate (1M and 1F ;
respectively) and cattle manure was applied at twice the recommended rate (2M) for N for
the 2002 corn (Zea mays L.) crop. The recommended rate was based on expected yields under
full irrigation. The manure N treatments were applied to percolation lysimeters and
adjacent plots on a Cozad silt loam soil. Ammonium nitrate was applied only to the
percolation lysimeters. Leachate from the lysimeters was extracted from a depth of
2.1 m and soil samples were collected from field plots in 0.3 m depth increments to
2.1 m on a periodic basis. Water available to the crop was sufficient to meet 89 and 79%
of the potential crop ET in 2002 and 2003, respectively. When averaged over the manure N
treatments, reduced ET resulted in grain yields that were approximately 2.1 and 2.7 Mg ha- 1
less than expected in 2002 and 2003. Under deficit water inputs there was leachate movement
below the root zone. Leachate depths averaged over N treatments were, however,
reduced by 15% (33 mm) in 2002 and 47% (102 mm) in 2003 compared with those reported
under full irrigation. The average nitrate-N (NO3-N) concentrations in leachate were higher
under the 2M treatment (41 mg L- 1) compared to the 1M treatment (17 mg L- 1). The average
NO3-N concentrations in leachate from the 1F treatment (28 mg L- 1) was not different than
the 1 or 2M treatments. There were trends for greater NO3-N mass losses in leachate
averaged over all treatments in 2003 compared to 2002, indicating that NO3-N derived from
the 2002 application leached to at least 2.4 m below the soil surface. There were no mass loss
differences in leachate due to the 2001 crop in 2002. In 2003, mass of NO3-N in lysimeters
cropped to soybean in 2001 were significantly higher (144 kg NO3-N ha 1) than the mass in lysimeters cropped to corn in 2001 (51 kg NO3-N ha-1). Nitrate-N mass increased in the 0.9-
2.1 m soil depth 12-13 months after manure N treatment applications. The 2M treatment had
greater soil NO3-N mass than the 1M treatment for most sampling dates in the surface
0.9 m. This research shows that there can be significant nitrate losses under deficit irrigation
when manure N is over applied. These losses are likely related to water initially stored below
the root zone and preferential flow of water from irrigation and precipitation. Determining
accurate yield expectations under deficit irrigation conditions, correct scheduling of irrigation,
and the use current best management practices for N management can help minimize
nitrate losses in leachate
Soil management practices
Get PDFSoil management practices affect soil resources
obviously, but those practices also affect water
and air resources and the plants and animals that
depend upon those resources. Good soil management
builds soil quality, maintains or improves
water and air quality, and supports plant, animal,
and human life (NRCS, 1996a). Minimizing soil
erosion, increasing water infiltration, and promoting
biological activity through good management
ultimately produces a soil with physical and
chemical characteristics consistent with parent
material, topography, and climat
Mineral concentrations in soil extracts, forages, and blood sera of cattle grazing on reclaimed uranium-mined land in southeastern Wyoming
Get PDFThe Pathfinder Uranium Mine which is located in southeastern Wyoming,
was actively mined during the 1960's-1980's. Reclamation involved returning the
spoil/overburden and replacing the salvaged topsoil. The area was revegetated in
1974-1977, but was not grazed until 1980-85. A grazing experiment was then
conducted to determine solubility of mineral elements in soil, uptake by plants and
absorption by grazing animals. Blood sera were collected at 28-30 day intervals
during the three grazing/growing seasons in 1980-1982. Blood sera samples were
frozen and later analyzed by ICP. When compared to published data, plants on the
reclaimed site contained lower concentrations of Ca, Mg, Mn, P, and Zn; but higher
concentrations of Cd, Cr and Ni than plants on adjacent undisturbed sites. When
compared to expected blood sera data, animals grazing on the reclaimed site had
lower concentrations of B. Ca, Cu, Mg, and Na; but higher concentrations of Cr and
Fe than would be expected for most grazing animals. Livestock producers are
advised to provide supplements of Ca, Mg, Mn, P, and Zn to minimize deficiency of
these elements in livestock nutrition when grazing these reclaimed lands
Influence of subsoiling on direct-seeded cereals in southeastern Idaho
Get PDFThe influence of shallow (20 cm deep) subsoil tillage on cereals planted with a no-till planter was investigated
for 3 years at two locations in southeastern Idaho. Among Fusarium spp., F. culmomm was the primary fungus isolated
from diffuse brown—black root lesions in the wetter location (Ririe), while F. semitectum, F. reticulatum, F. equiseti, and
F acuminatum were the dominant species isolated at the drier location (Arbon Valley). Increased yields resulting from
methyl bromide fumigation indicated that biological factors were limiting the yield. However, subsoiling did not
influence nematode populations or fungal root rots. The primary parasitic nematode found at both locations was
Pratylenchus neglecms. Subsoiling had a tendency to increase soil moisture at depths between 61 and 90 cm, to increase
organic matter, and to decrease nitrogen. Yield increased by 8% or more with subsoil tillage at both locations the first
year. Yield increases were not significant in other years, when moisture was particularly limiting or abundant. Subsoiling
may prove favorable for cereals planted in a soil-conservation tillage system, but the risk of fungal root rots may increase
with such a practice. Additional study is warranted, as subsoil—tillage practices may increase yield and desirable soil
parameters without compromising the benefits associated with cereal production in a soil—conservation tillage system
Drought risk management for irrigated potato production in Idaho
Get PDFStreamflow in much of the western United States originates as snowfall that has
accumulated in the mountains during the winter and early spring. During periods
of drought, the water supply for a large portion of irrigated cropland in Idaho is at
risk of depletion before the growing season ends. In the case of irrigated potato
production, early depletion or limited availability of irrigation water can result in
substantial financial loss to a producer due to reduced yield and quality and
difficulty in harvesting, handling and storing the raw product. Basin wide
estimates of available water supply are provided by Federal and State agencies,
however, a given producer's irrigation water supply can be vastly different due to
water rights based on the Doctrine of Prior Appropriation, which allocates water
according to a priority date. To minimize financial risk under drought conditions,
potato producers need realistic estimates of available water supply well in
advance of the growing season and production management guidelines for
economical potato production under limited water supply. To address this need, a
methodology for estimating the probability of a water supply shortage that
incorporates water right based allocation was developed to assist producers with
drought risk management planning. Additionally, the drought tolerance of six
commercial potato varieties was evaluated for four widely varying seasonal
drought management patterns simulated by irrigation management. The
methodology developed to estimate probability of a water shortage on an
irrigation district basis is described and results of an economic risk analysis for
the six potato varieties subjected to the four drought management patterns is
presented. The results show that the probability of a water shortage can vary
widely among irrigation districts due to differences in water priority dates. The
results of the economic risk analysis show that potato variety selection and
irrigation management strategy can substantially reduce economic loss in potato
production systems during drought
Water balance for a predominantly surface irrigated district in southern Idaho
Get PDFWater quantity and quality are being measured in an 82,000 ha irrigation district in
southern Idaho to determine the effects of conservation practices, primarily
conversion from furrow to sprinkler irrigation, for the Conservation Effects
Assessment Project (CEAP). The percentage of sprinkler irrigated land has steadily
increased from about 10% in 1990 to more than 30% in 2005. The objective of this
study was to calculate a preliminary water and soluble salt balance for April through
November, 2005. The water balance was calculated by subtracting measured outflow
and estimated crop water use from measured inflow and precipitation. Precipitation
was about 250% of normal in April and May, which delayed irrigation for many
crops and probably increased the amount of return flow during these months. Water
diverted for irrigation was 82% of the total water input to the irrigation district
(inflow plus precipitation). Precipitation contributed 16% of the total input. Thirty-six
percent of the diverted water left the irrigation district as surface return flow from
April through November. This percentage will increase on an annual basis because
return flow continues through the winter months after irrigation diversions have
ceased. The irrigation district was a source of suspended sediment and a sink for
soluble salts. April through November 2005 monitoring showed a net gain of 1620 kg
ha-1 of soluble salts in the irrigation district, which could be a long-term concern if
these salts accumulate in the root zone. Net sediment loss was 102 kg ha -1 , which is
less than the 461 kg ha-1 measured during a similar study in 1971. These preliminary
results indicate that converting to sprinkler irrigation, along with other conservation
practices, has reduced sediment loss from this irrigation district. However, solid
conclusions cannot be made until at least one year of monitoring is complete to
adequately characterize annual trends, particularly the quantity and quality of non-irrigation
season return flows