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Effects of a new polysaccharide-based amendment on furrow irrigation infiltration and erosion
Get PDFControlling soil erosion on furrow‐irrigated fields is essential to maintain productivity and reduce off‐site impacts.
Identifying effective alternatives to polyacrylamide (PAM) is desired for continued, affordable irrigation erosion control. We
compared the effectiveness of a new polysaccharide/PAM amendment with water‐soluble, high molecular weight, anionic
PAM in two furrow‐irrigated field tests in southern Idaho. Test 1 evaluated three rates of the polysaccharide/PAM amendment
(6, 12, and 18 mg L-1 of polysaccharide/PAM), two rates of PAM (2 and 10 mg L-1 of PAM), 10 mg L-1 polysaccharide, and
a control during two irrigations in a fallow field. Treatments were applied as a solution with furrow inflow water during
irrigation advance. Test 1 results indicated that polysaccharide/PAM amendment could improve infiltration and reduce
sediment loss compared to untreated furrows, but its effectiveness seemed to diminish when amendment application stopped.
Polysaccharide alone did not significantly effect infiltration, runoff, or sediment loss compared to the control for either
irrigation, whereas the polysaccharide/PAM amendment significantly increased infiltration and reduced sediment loss for
one irrigation. Test 2 compared polysaccharide/PAM amendment and PAM, both applied at either 2 mg L-1 (active ingredient)
continually during irrigation (dissolved treatments) or as a 20 g per furrow of dry material near the furrow inflow point (patch
treatments), during four irrigations on a dry bean field. Both amendments significantly increased cumulative infiltration and
decreased cumulative runoff and sediment loss compared to untreated furrows. Dissolved polysaccharide/PAM increased
cumulative infiltration 19% compared to the control, while dissolved PAM, patch polysaccharide/PAM, and patch PAM
treatments increased cumulative infiltration 13%, 11%, and 7%, respectively, compared to the control. Dissolved and patch
PAM and dissolved and patch polysaccharide/PAM treatments significantly reduced cumulative sediment loss 98%, 90%,
65%, and 49%, respectively, compared to the untreated furrows. These test results indicate that the polysaccharide/PAM
amendment can be used as an alternative, albeit less effective, to PAM for reducing sediment loss from furrow‐irrigated fields
Influence of beet necrotic yellow vein virus on sugar beet storability
Get PDFRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious
sugar beet production problems. To investigate the influence of BNYVV on storability, six sugar
beet cultivars varying for resistance to BNYVV were grown in 2005 and 2006 in southern Idaho
fields with and without BNYVV-infested soil. At harvest, samples from each cultivar were
placed in an outdoor ventilated pile in Twin Falls, ID and were removed at 40-day intervals starting
at the end of October. After 144 and 142 days in storage, sugar reduction across cultivars
averaged 20 and 13% without and 68 and 21% with BNYVV for the 2005 and 2006 roots, respectively.
In the December samplings, frozen root area was 1 and 2% without and 25 and 41%
with BNYVV for the 2005 and 2006 roots, respectively. Root rot was always worse with stored
roots from BYNVV-infested soil in December, January, and February samplings. Root weight
loss was variable in 2005; however, in 2006, an increase in weight reduction always was associated
with BNYVV-infested roots. In order to prevent losses in rhizomania-infested areas, cultivars
should be selected for storability as well as rhizomania resistance
Water treatment residuals and biosolids coapplications affect semiarid rangeland phosphorus cycling
Get PDFLand coapplication of water treatment residuals (WTR) with biosolids has not been extensively researched, but the limited studies performed suggest that WTR sorb excess biosolids-borne P. To understand the long-term effects of a single coapplication and the short-term impacts of a repeated coapplication on soil P inorganic and organic transformations, 7.5- by 15-m plots with treatments of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha-1 and 10 Mg biosolids ha-1) surface coapplied once in 1991 or surface reapplied in 2002 were utilized. Soils from the 0- to 5-cm depth were collected in 2003 and 2004 and were sequentially fractionated for inorganic and organic P (Po). Inorganic P fractionation determined (i) soluble and loosely bound, (ii) Al-bound, (iii) Fe-bound, (iv) occluded, and (v) Ca-bound P, while organic P fractionation determined (i) labile, (ii) biomass, (iii) moderately labile, (iv) fulvic acid, (v) humic acid, and (vi) nonlabile associated Po. Pathway analysis showed that humic, fulvic, and nonlabile Po did not play a role in P transformations. Biomass Po and moderately labile Po contributed to the transitory labile Po pool. Labile Po was a P source for Fe-bound and WTR-bound inorganic phases, with the Fe-bound phase transitory to the occluded P sink. The Al-bound phase additionally contributed to the occluded P sink. The Ca-bound phase weathered and released P to both the Fe-bound and WTR-bound P phases. Overall, the WTR fraction, even 13 yr after the initial application, acted as the major stable P sink
Delinearing site-specific management zones for pH-induced iron chlorosis
Get PDFIron chlorosis can limit crop yield, especially on calcareous soil. Typical management for iron chlorosis includes the use of iron fertilizers or chlorosis tolerant cultivars. Calcareous and non-calcareous soil can be interspersed within fields. If chlorosis-prone areas within fields can be predicted accurately, site-specific use of iron fertilizers and chlorosis-tolerant cultivars might be more profitable than uniform management. In this study, the use of vegetation indices (VI) derived from aerial imagery, on-the-go measurement of soil pH and apparent soil electrical conductivity (ECa) were evaluated for their potential to delineate chlorosis management zones. The study was conducted at six sites in 2004 and 2005. There was a significant statistical relationship between grain yield and selected properties at two sites (sites 1 (2005) and 3), moderate relationships at sites 2 and 4, and weak relationships at site 5. For sites 1 (2005) and 3, and generally across all sites, yield was predicted best with the combination of NDVI and deep ECa. These two properties were used to delineate chlorosis management zones for all sites. Sites 1 and 3 showed a good relationship between delineated zones and the selected properties, and would be good candidates for site-specific chlorosis management. For site 5, differences in the properties between mapped zones were small, and the zones had weak relationships to yield. This site would be a poor candidate for site-specific chlorosis management. Based on this study, the delineation of chlorosis management zones from aerial imagery combined with soil ECa appears to be a useful tool for the site-specific management of iron chlorosis
Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate
Get PDFQuantifying the local crop response to irrigation is important for establishing adequate irrigation management strategies. This study evaluated the effect of irrigation applied with subsurface drip irrigation on field corn (Zea mays L.) evapotranspiration (ETc), yield, water use efficiencies (WUE = yield/ETc, and IWUE = yield/irrigation), and dry matter production in the semiarid climate of west central Nebraska. Eight treatments were imposed with irrigation amounts ranging from 53 to 356 mm in 2005 and from 22 to 226 mm in 2006. A soil water balance approach (based on FAO-56) was used to estimate daily soil water and ETc. Treatments resulted in seasonal ETc of 580–663 mm and 466–656 mm in 2005 and 2006, respectively. Yields among treatments differed by as much as 22% in 2005 and 52% in 2006. In both seasons, irrigation significantly affected yields, which increased with irrigation up to a point where irrigation became excessive. Distinct relationships were obtained each season. Yields increased linearly with seasonal ETc (R2 = 0.89) and ETc/ETp (R2 = 0.87) (ETp = ETc with no water stress). The yield response factor (ky), which indicates the relative reduction in yield to relative reduction in ETc, averaged 1.58 over the two seasons. WUE increased non-linearly with seasonal ETc and with yield. WUE was more sensitive to irrigation during the drier 2006 season, compared with 2005. Both seasons, IWUE decreased sharply with irrigation. Irrigation significantly affected dry matter production and partitioning into the different plant components (grain, cob, and stover). On average, the grain accounted for the majority of the above-ground plant dry mass (≈59%), followed by the stover (≈33%) and the cob (≈8%). The dry mass of the plant and that of each plant component tended to increase with seasonal ETc. The good relationships obtained in the study between crop performance indicators and seasonal ETc demonstrate that accurate estimates of ETc on a daily and seasonal basis can be valuable for making tactical in-season irrigation management decisions and for strategic irrigation planning and management
Irrigation small grain residue management effects on soil properties
Get PDFThe effects of straw removal from fields under irrigated wheat and barley on soil
properties has become a potential concern in Idaho. The demand of straw for animal bedding
and feed, and the potential development of cellulosic ethanol production will likely increase in
the future. This paper reviews published research assessing the effects of wheat and barley straw
removal on soil organic carbon (SOC), and analyzes changes in nutrient cycling within wheat
and barley production systems. Six studies compared SOC changes with time in irrigated
systems in which wheat was removed or retained. These studies indicate that reductions in SOC
due to removal may not be a concern. Soil OC either increased with time or remained constant
when residues were removed. It is possible that belowground biomass is supplying C to soils at a
rate sufficient to maintain or in some cases, slowly increase SOC with time. A separate research
review calculated the minimum aboveground residue required to maintain SOC levels from nine
wheat system studies. Eight of the studies were dryland production systems. The grain yields
required to produce sufficient above ground biomass to maintain SOC levels ranged from 9 to
122 bu acre-1 for wheat and 14 to 185 bu acre-1 for barley. Wheat straw contains approximately
15, 3.4, and 33 lbs nitrogen (N), phosphorus (P2O5), and potassium (K2O) ton-1, respectively.
Barley straw contains approximately 12, 3.9, and 38 lbs N, P2O5, and K2O ton-1, respectively.
The calculated total economic value of the N, P2O5, and K2O in one ton of wheat and barley
straw is 18.18, respectively, based on average nutrient costs in the Pacific
Northwest in 2007. Rotations including wheat and barley in the irrigated agriculture of Idaho
and many other states in the Pacific Northwest are much different than what was reported in the
reported studies. There is very little reported data that can be directly related the irrigated
rotations in Idaho that include wheat or barley. To fully understand the impacts of crop residue
removal from soils in Idaho, research projects need to be conducted on crop rotations that
include wheat and barley under irrigated conditions in Idaho. Otherwise the best data available
for dissemination is from research conducted in different environments and systems
Water treatment residuals and biosolids co-applications affect phosphates in a semi-arid rangeland soil
Get PDFCo‐application of biosolids and water treatment residuals (WTR) land has not been extensively studied but may be beneficial by sorbing excess biosolid‐borne or soil phosphorus (P) onto WTR, reducing the likelihood of off‐site movement. Reduction of excess soil P may affect the role of specific P‐cleaving enzymes. The research objective was to understand the long‐term effects of single co‐applications and the short‐term impacts of repeated co‐applications on soil acid phosphomonoesterase, phosphodiesterase, pyrophosphatase, and phytase enzyme activities. Test plots were 7.5 × 15 m with treatments consisting of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha−1; 10 Mg biosolids ha−1) surface co‐applied once in 1991 or reapplied in 2002. Control plots consisted of those that received no WTR–biosolids co‐applications and plots that received only 10 Mg biosolids ha−1. Plots were sampled to a 5‐cm depth in 2003 and 2004, and soil phosphatases and phytase enzyme activities were measured. Soil phosphodiesterase activity decreased in WTR‐amended plots, and pyrophosphatase activity decreased with increasing WTR application rates. In contrast, acid phosphatase and phytase activity increased with WTR addition, with WTR application possibly triggering a deficiency response causing microorganisms or plants to secrete these enzymes. Biosolids and WTR co‐applications may affect enzymatic strategies for P mineralization in this study site. Reductions in phosphodiesterase activity suggest less P mineralization from biomass sources, including nucleic acids and phospholipids. Increased acid phosphatase and phytase activities indicate that ester‐P and inositol‐P may be important plant‐available P sources in soils amended with WTR
Influence of curly top and Poncho Beta on sugar beet storability
Get PDFSucrose losses during postharvest storage of sugarbeet
(Beta vulgaris L.) maybe exacerbated by field diseases. This
study investigated the influence of curly top (causal agent
Beet severe curly top virus and related viruses) on storability
of sugarbeet roots during the 2005 and 2006 growing seasons.
Three sugarbeet cultivars varying for resistance to
curly top were evaluated both with and without the insecticide
seed treatment Poncho Beta (60 g a.i. clothianidin +
8 g a.i. beta-cyfluthrin/100,000 seed). At harvest, 8-beet
samples from each cultivar were collected and placed inside
an outdoor pile. Samples were removed at 40-day intervals
beginning on 31 October in 2005 and 1 November in 2006.
Sucrose concentration, frozen and discolored root area, and
root weight were evaluated. By mid-September plants from
Poncho Beta treated seed had curly top ratings that were 37
and 31% lower (P < 0.01) than plants from the untreated
seed in 2005 and 2006, respectively. After 124 and 131 days
in storage, roots from Poncho Beta treated seed had 8.5 and
5% more sucrose than roots from untreated seed in 2005
and 2006, respectively. Resistant cultivars and insecticide
seed treatments not only limit losses to curly top in the field,
but also in long term storage
Sugar beet germplasm evaluated for resistance to rhizomania and storability in Idaho, 2007
Get PDFSugar beet germplasm and commercial check cultivars were evaluated in a commercial sprinkler-irrigated sugar beet
field near Rupert, ID where winter wheat was grown in 2006. The field trial relied on natural inoculum for rhizomania
development. The seed was treated with clothianidin (2.1 oz a.i. per 100,000 seed) to limit the influence of pests and curly
top. The plots were planted on 3 Apr to a density of 142,560 seeds/A, and thinned to 47,520 plants/A on 23 May. Plots were
single rows (22-in. row spacing) and 10 ft long. The experimental design was a randomized complete block design with
eight replications per entry. The field was cultivated on 24 May and 15 Jun. The crop was managed by the grower
according to standard cultural practices. The roots were mechanically topped and lifted on 27 Sep. The first ten roots in
each plot were evaluated using a scale of 0-9 (0 = healthy and 9 = dead). The first eight roots were placed in a mesh onion
bag and held in an indoor commercial sugar beet storage facility set to hold 35°F. On 1 Feb 2008, the roots were evaluated
for the percentage of surface area covered by fungal growth (an undescribed Basidiomycete that correlates with sugar loss in
storage). Data were analyzed using the general linear models procedure (Proc GLM-SAS), and Fisher’s protected least
significant difference was used for mean comparison
Influence of irrigated agriculture on soil microbial diversity
Get PDFOrganic carbon (C), bacterial biomass and structural community diversity were measured in Southern Idaho soils with long term cropping histories. The soils tested were native sagebrush vegetation (NSB), irrigated moldboard plowed crops (IMP), irrigated conservation – chisel – tilled crops (ICT) and irrigated pasture systems (IP). Organic C concentration in soils decreased in the order NSB 0–5 cm > IP 0–30 cm = ICT 0–15 cm > IMP 0–30 cm > NSB 5–15 cm = NSB 15–30 cm. Active bacterial, fungal and microbial biomass correlated with soil C as measured by the Walkely Black method in positive curvilinear relationships (r2 = 0.93, 0.80 and 0.76, respectively). Amplicon length heterogeneity (LH-PCR) DNA profiling was used to access the eubacterial diversity in all soils and at all depths. The Shannon–Weaver diversity index was used to measure the differences using the combined data from three hypervariable domains of the eubacterial 16S rRNA genes. Diversity was greatest in NSB 15–30 cm soil and lowest in the IMP soil. With the exception of IMP with the lowest diversity index, the samples highest in C (NSB 0–5 cm, IP 0–30 cm, ICT 0–15 cm) reflected lower diversity indices. However, these indices were not significantly different from each other. ICT and IP increase soil C and to some extent increase diversity relative to IMP. Since soil bacteria respond quickly to environmental changes, monitoring microbial communities may be one way to assess the impact of agricultural practices such as irrigation and tillage regime