1816 research outputs found
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Cross-linked polymers increase nutrient sorption in degraded soils
Full text linkCross-linked polymer hydrogels, such as polyacrylamide co-polymer (XPAM) or polyacrylate (XPAA), can alter soil chemistry and crop nutrient uptake but the persistence of these effects has been little studied. This 9-y, irrigated, outdoor pot study evaluated a single, one-time addition of XPAM or XPAA at 0.25% or 0.5% dry wt. (5.6 or 11.2 Mg ha-1) in a degraded calcareous silt loam. Controls included an unamended degraded soil and an unamended, non-degraded soil (i.e. topsoil). Soils were hand-tilled and planted to crops each year. We measured nutrients in soil and leachate water each year, and in the first 5 y, crop yields and nutrient uptake. Both hydrogels increased average soil pH and electrical conductivity (EC), soil extractable K, Na, and TOC, and decreased soil extractable Mg relative to the control. Unlike XPAM, XPAA produced a greater increase in soil extractable K, increased extractable Fe, Zn, Mn, and Cu, increased Olsen P, and decreased total inorganic C. Neither hydrogel affected crop yields but XPAA increased K and Zn and decreased Mg and Na uptake in crops compared to controls. Relative to the control, both hydrogels decreased cumulative Ca, Mg, and S leaching mass losses and increased mean EC of leachate. Unlike XPAM, XPAA increased cumulative leaching mass losses of K, P, NO3-N, and NH4-N relative to the control. The hydrogels’ soil effects persisted for greater than or equal to 7 years and their effect differed as a function of the quantity of included counterions and the stability of the gel structure after soil placement
Fargo sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2020
Full text linkRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, five Beta vulgaris lines and five check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2020 growing season in a randomized complete block design with 4 replications. At harvest on 13-14 October, roots were dug and evaluated for rhizomania symptoms and then placed in an indoor commercial sugar beet storage building. After 131 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development in the field was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible sugar and red beet checks both had 100% foliar symptoms and a high root disease severity ratings. The resistant check with two resistance genes, Rz1 + Rz2 (check 3), had 1% foliar symptoms and low root rating. The resistant checks with only one resistance gene had foliar symptoms ranging from 7 to 14%, but their root ratings were still within an acceptable range. Foliar symptoms indicate single gene resistance for BNYVV is becoming marginal. Entries 2 and 3 had a level of BNYVV resistance similar to the single gene resistant checks, but the leaves for entry 3 must have been yellowish since it was rated susceptible for foliar symptoms. Entry 3 also had resistance to fungal rots in storage. Entries 2 and 3 should be evaluated again since they may serve as a starting point for identifying additional sources of resistance to BNYVV and storage rots
Ammonia and nitrous oxide emission factors for excreta deposited by livestock and land-applied manure
Full text linkManure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH3) and nitrous oxide (N2O) emissions. Utilizing data on NH3 and N2O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed and effects of mitigation strategies evaluated. The NH3 data represents emissions from cattle and swine manures in temperate wet climates, while the N2O data includes cattle, sheep and swine manure emissions in temperate wet/dry and tropical wet/dry climates. The NH3 EFs for broadcast cattle solid manure and slurry were 0.03 and 0.24 kg NH3-N kg-1 total N (TN), respectively, while broadcast swine slurry was 0.29. Emissions from both cattle and swine slurry were reduced between 46 and 62% with low emissions application methods. Land application of cattle and swine manure in wet climates had EFs of 0.005 and 0.011 kg N2O-N kg-1 TN, respectively, while in dry climates the EF for cattle manure was 0.0031. The N2O EF for cattle urine and dung in wet climates was 0.0095 and 0.002 kg N2O-N kg-1 TN, respectively, which were three times greater than for dry climates. The N2O EFs for sheep urine and dung in wet climates were 0.0043 and 0.0005, respectively. The use of nitrification inhibitors reduced emissions in swine manure, cattle urine/dung and sheep urine by 45 to 63%. These enhanced EFs can improve national inventories; however, more data is needed across multiple livestock species and climates
Antimicrobial resistance in escherichia coli and enterococcal isolates from irrigation return flows in a high-desert watershed
Full text linkIrrigation return flows (IRFs) are of interest because they collect surface runoff and subsurface drainage, causing them to have elevated contaminant and bacterial levels, and making them a potential point source of pollutants. The purpose of this study was to determine antibiotic susceptibility profiles of E. coli and Enterococcus spp. that were collected from IRFs in south-central Idaho. Environmental isolates can be a potentially important source of antibiotic resistance (AR) and IRFs may be one way resistance genes are transported out of agroecosystems. Water samples were collected from nine IRFs and one background site (canal water from Snake River) on a biweekly basis during 2018. Escherichia coli and Enterococcus were enumerated via a Most Probable Number technique, then subsamples were plated on selective media to obtain isolates. About 185 of 800 unique isolates for E. coli and Enterococcus were tested for antimicrobial susceptibility using the Sensititre broth microdilution plates. For E. coli, 11% of the isolates were resistant to tetracycline, with fewer numbers being resistant to the 13 other antibiotics, with none resistant to gentamicin. While 77% of the E. coli isolates were pan-susceptible, 9 MDR patterns with resistance up to 7 drug classes (10 antibiotics) occurred in 11 isolates. For the enterococcal species, only 9% of isolates were pan-susceptible and the single highest resistance was to lincomycin (75%) followed by nitrofurantoin (31%) and tetracycline (11%). In addition, 13 enterococcal isolates were determined to be MDR to up to 5 different drug classes and it was only prevalent among E. faecalis, E. faecium, E. casseliflavus, and E. thailandicus. Due to the potential for human contact, routine monitoring of E. coli and Enterococcus in the IRFs could be a useful tool to understand the long-term trends of AR in this mixed-use watershed
Infiltration and soil water distribution in irrigation furrows treated with polyacrylamide
Full text linkFew if any studies have measured water-soluble anionic polyacrylamide’s (WSPAM) effects on infiltration and soil water distribution in different segments of irrigation furrows. We conducted a three year study on a silt loam soil with 1.5% slopes, planted to corn. Control furrows received no WSPAM and inflows were 15.1 L/min, whereas WSPAM was applied using 8 mg/L a.i. to 45 L/min inflows during furrow advance. After advance, treatments were identical, with inflows of 15.1 L/min. Soil profile water content and net infiltration in upper (inflow-end) and lower (outflow-end) furrow sectors were measured during the growing season. The results indicate mean whole-furrow, net infiltration was the same between treatments in each irrigation. The WSPAM increased lateral wetting from furrow to planted row by as much as 1.3-fold in the lower furrow sector. Mean field-wide soil water content was an average 1.2-fold greater in WSPAM furrows than for the control, but the effect was more significant in lower furrow sectors. This was consistent with infiltration data, which showed that WSPAM decreased the upper-to-lower-sector, net infiltration ratio 33% to 40% relative to control furrows, indicating improved irrigation uniformity. A 62% reduction in furrow advance time afforded by WSPAM accounts for some of the increased uniformity, but opposing changes in infiltration rate between upper and lower furrow sectors suggests that other factors are involved. The WSPAM management approach, while protecting against furrow erosion, provides a means of improving irrigation uniformity, and could potentially reduce associated percolation water and nutrient losses
2020 Idaho soft white spring wheat quick facts
Full text linkThe respective fact sheets list key production recommendations for southern Idaho for the respective crops that ensure growers have easy and timely access to information. Specific recommendations vary depending on the specific type of wheat that is grown. These extension publications include fertilizer recommendation rates, irrigation management and scheduling, pest, disease, and weed management, as well as planting decision recommendations for timing and seeding rate
Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2019
Full text linkRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, eight Beta vulgaris lines and five check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2019 growing season in a randomized complete block design with 6 replications. At harvest on 16 October 2019, roots were dug and evaluated for rhizomania symptoms and then placed in an indoor commercial sugar beet storage building. After 129 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development in the field was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible sugar and red beet checks both had 100% foliar symptoms and a high root disease severity rating. The resistant check with two resistance genes, Rz1 + Rz2 (check 3), had no foliar symptoms and low root rating. The resistant checks with only one resistance gene had foliar symptoms ranging from 14 to 24%, but their root ratings were still within an acceptable range. Foliar symptoms indicate single gene resistance for BNYVV is becoming marginal. Based on foliar ratings, entry 6 (KEMS8) seemed healthy, but root ratings from this entry were significantly worse than the resistant checks. Entry 6 will be investigated further to make sure the root rating was an indication of susceptibility and not just poor root shape. These observations suggest that both foliar and root ratings should be utilized when considering resistance to BNYVV, since relying on just one type of rating may be misleading. Three entries (1, 2, and 6) had resistance to fungal rots in storage, but only entry 6 performed well for both storage and the foliar RZ rating. These three entries will serve as genetic sources for identifying additional resistance to BNYVV and storage rots
Evaluation of a microplate spectrophotometer for soil organic carbon determination in south-central Idaho
Full text linkSoil organic carbon (SOC) is traditionally measured through dry combustion of soil but is inaccurate in soils recently limed or containing carbonates. Soils of south central Idaho contain carbonates therefore 3 alternative methods are typically used. Walkley-Black titration (WBTIT) has an extensive history but generates a large volume of hazardous waste for each sample analyzed. Low temperature loss on ignition (LOI360°C) may be utilized but requires frequent sample manipulation and is therefore prone to human error. A pressure calcimeter (Pcal) may be used, however the sample container may leak leading to inaccurate results. Therefore, a new method of SOC determination (WBSPEC) utilizing a microplate spectrophotometer was compared to LOI360°C, Pcal, and WBTIT in 75 south central Idaho soils and 10 standard soils. First, it was confirmed that soils of south central Idaho contain carbonates leading to inaccurate SOC determination by dry combustion. During the alternative method comparison, the WBSPEC method reduced waste production over the traditional WBTIT method by 89% while reducing sample handling over LOI360°C. The LOI360°C and WBTIT methods were most similar, however, the WBSPEC method performed adequately; the Pcal method often overestimated SOC compared to each other method. As the low SOC soils of south central Idaho were of particular interest, the methods were compared a second time on low SOC (<13.11 g kg-1) soils. Here, SOC determination was challenging however the WBSPEC method followed other methods well. It was determined that WBSPEC allows for accurate SOC determination in low SOC soils containing carbonates while reducing hazardous waste production and sample handling
Soil water extraction patterns and water use efficiency of irrigated sugarbeet under full and limited irrigation in an arid climate
Full text linkThe effects of full and limited irrigation sugarbeet production practices on soil water extraction and evapotranspiration water use efficiency were investigated in 2015, 2016, and 2017 near Kimberly, Idaho. Four irrigation regimes (fully irrigated (FIT), 75% FIT, 50% FIT and 25% FIT) were studied in 2015 and 2017 and three irrigation regimes (fully irrigated, 60% FIT, 30% FIT and rainfed) were studied in 2016. Soil water was extracted from all layers of the 2.25 m soil profile and the pattern of extraction was impacted by irrigation regime. In general, net soil water depleted from the 2.25 m soil profile between emergence and harvest and seasonal average soil water extraction decreased with depth and irrigation amount. For all irrigation treatments and all study years, 70 to 90% of soil water extraction was from the 0 to 1.2 m soil profile and 4 to 10% of soil water extraction was from the 1.8 to 2.25 m soil profile. Water use efficiency increased under limited irrigation. Root yield water use efficiency was greatest for the 50% FIT, 60% FIT and 75% FIT treatments in 2015, 2016, and 2017, respectively. Estimated recoverable sucrose water use efficiency was greatest for the 50% FIT, 60% FIT, and 50% FIT treatments in 2015, 2016, and 2017, respectively. Root yield water use efficiency was greater and estimated recoverable sugar water use efficiency was equal or greater than reported in previous reported studies
Beet curly top resistance in USDA-ARS Kimberly germplasm, 2019
Full text linkCurly top caused by Beet curly top virus (BCTV) is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. In order to identify novel sources of curly top resistance, 8 sugar beet lines produced by the USDA-ARS Kimberly sugar beet program were screened in a disease nursery in 2019. The lines were arranged in a randomized complete block design with six replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the four- to six-leaf growth stage on 3 Jul. Foliar symptoms were evaluated on 22 July using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the susceptible checks. Based on the visual rating, four entries (segregating populations) and two genetic stock line entries were not significantly different from the resistant checks. The resistant segregating populations will be suitable for single trait selection and advancement to breeding lines to enrich the BCTV resistance gene pool in the USDA-ARS sugar beet germplasm