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The diurnal cycling of sugars in grasses impact strip-graze management plans
Get PDFSoluble sugar concentrations increase in forage plants during the day and decrease at
night. The objective of this study was to quantify the sugar concentrations in the upper
and lower parts of the grass canopy at the end of a light and subsequent dark period and
relate these changes in animal grazing behavior and production responses. Tall fescue
(Festuca arundinacea) grown in controlled-environment chambers was cut after a 15-h
light and a subsequent 9-h dark period, and tillers were separated into leaves and stems.
Leaves, but not stems, demonstrated diurnal fluctuation in sugars. Leaf sugars
concentrations, after 15-h of light, were 1.6 times greater than those in leaves following
the 9-h dark period. It is suggested that animal production may benefit from afternoon
vs. morning turnout onto fresh pastures because of the extra sugars accumulating in the
leaves during the day
Polyacrylamide + aluminum sulfate and polyacrylamide + calcium oxide remove coliform bacteria and nutrients from swine wastewater
Get PDFAnimal wastes are a major contributor of nutrients and enteric microorganisms to surface water and ground water. Polyacrylamide
(PAM) mixtures are an effective flocculent, and we hypothesized that they would reduce transport of microorganisms in
flowing water. After waste water running at 60.0 1 min-1 flowed over PAM + Al2(SO4)3, or PAM + Ca0 in furrows, total coliform
bacteria (TC) and fecal coliform bacteria (FC) were reduced by 30-50% at 1 and 50 m downstream of the treatments compared to
the control. In a column study, PAM + Al 2 (SO4)3 , and PAM + Ca0 applied to sandy, sandy loam, loam, and clay soils reduced
NH4 and ortho-P concentrations in leachate compared to the source waste water and the control. PAM + Al 2 (SO4)3 and
PAM + CaO applied to sandy, sandy loam and loam soils reduced both total and ortho-P, concentrations in leachate compared to
the source wastewater and control treatment. In a field study, PAM + Al 2(SO4)3 , or PAM + CaO treatments did not consistently
reduce NH4, ortho-P, and total P concentrations in wastewater flowing over any soil compared to inflow wastewater or the
control treatment. With proper application PAM + Al 2 (SO4)3 and PAM + CaO may be able to reduce the numbers of enteric bacteria
in slowly flowing wastewater running off animal confinement areas, reducing the amount of pollutants entering surface water
and groundwater
Performance of high-magnesium cultivars of three cool-season grasses grown in nutrient solution culture
Get PDFBreeding for high magnesium (Mg) concentrations pas been conducted
for several forage species. Mgwell, Magnet, and HiMag are the first
experimental strains, bred for increased Mg concentrations of orchardgrass,
Italian ryegrass, and tall fescue, respectively. This experiment
compared the performance and genetic variability of these high-Mg
cultivars grown in solution culture with other cultivars in each species.
Three mineral absorption experiments were carried, out with one month
aged seedlings. Seedlings were evaluated for shoot dry weight, uptake and
concentration of Mg, calcium (Ca), and potassium (K), and also the
density of these minerals in the shoot. The cultivars of different species
behaved differently among the experiments even though the over all
environmental condition was kept similar. The high-Mg cultivars showed
higher Mg uptake per plant, but the differences were not so distinct.
However, the trend in Mg concentration among the cultivars of different
species was similar, and the difference between high-Mg cultivars and
control cultivars was distinct. The Mg density in the shoot of these
cultivars was significantly high. Also the high-Mg cultivars showed lower
equivalent ratio, K/(Ca+Mg). Genotypic differences in high-Mg cultivars
with others could be distinctly explained by differences in Mg
concentration and Mg density in the shoot, which coupled with low
K/(Ca + Mg) ratio. These common properties of high-Mg cultivars might
be considered as a good parameter for screening
Irrigated water, polymer application in
Get PDFIn the past decade, water-soluble polyacrylamide (PAM)
was identified as an environmentally safe and highly
effective erosion preventing and infiltration enhancing
polymer when applied in furrow irrigation water at
1 mg L-1 - 10 mg L-1 , i.e., 1 ppm- 10 ppm.[1-9] Various
polymers and biopolymers have long been recognized as
viable soil conditioners because they stabilize soil surface
structure and pore continuity. The new strategy of adding
the conditioner, high molecular weight anionic PAM, to
irrigation water in the first several hours of irrigation
implies a significant costs savings over traditional
application methods, in which hundreds of kilograms per
hectare of soil additives are tilled into the entire (15 cm
deep) soil surface layer. By adding PAM to the irrigation
water, soil structure is improved in the important 1-5 mm
thick layer at the soil/water interface of the 25%-30% of
field surface contacted by flowing water.
In 1995, the U.S. Natural Resource Conservation
Service (NRCS) published a PAM-use conservation
practice standard for PAM-use in irrigation water." 01 A
3-year study[21 applying these standards showed that PAM
at dosage rates of 1 kg ha-1 -2 kg ha-1 per irrigation
eliminated 94% (80%-99% range) of sediment loss in
furrow irrigation runoff, while increasing infiltration
15%-50%. Seasonal application rates using the NRCS
standard typically total 3 kg ha -1 -5 kg ha-1 .
As PAM-use is one of the most effective and
economical technologies for reducing soil-runoff, it has
branched into stabilization of construction sites and road
cuts, with formal statewide application standards set in
Wisconsin and several southern states. Recent studies with
biopolymers such as charged polysaccharides,[11-143
whey," 51 and industrial cellulose derivatives[11.141 introduce
potential biopolymer alternatives to PAM
Irrigated agriculture and tillage practices impact microbial community structure
Get PDFIrrigation increases carbon (C) input to soils via increased litter and root production.
Intensively managed crop or pastureland has potential for C gain through the use of improved grazing
regimes, fertilisation practices and irrigation management. Soil microbial diversity is important
because it is often regarded as an index of soil health. Loss of biodiversity leads to loss of ecosystem
resistance and resilience to anthropogenic as well as natural stresses. Organic C and microbial
structural diversity present in Southern Idaho soils having long term cropping histories was measured.
The sites sampled were native sagebrush vegetation (NSB); irrigated mouldboard ploughed 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>1P 0-30 cm = ICT 0-15 cm>IMP 0-30
cm>NSB 5-15 cm = NSB 15-30 cm. Amplicon length heterogeneity (ALH) LH-PCR, a DNA profiling
method, was used to profile the eubacterial structural diversity in all soils sampled at the different
depths. LH-PCR interrogates the variable domains of the ribosomal small subunit genes (SSU rRNA),
and separates these variable domains on high-resolution genetic analysers. ALH assays are based on
the natural variation in sequence lengths of the 16S rRNA genes and are independent of restriction
enzyme recognition sites. The application of the ALH technique as a monitoring tool for microbial
ecology has been shown to enhance and extend the current understanding of the structural dynamics of
microbial communities in their specific environments.
Using the profiling data from four hypervariable regions of the 16S rRNA (VI, VI +V2, V3 and V9), it
was shown that native sagebrush soil communities differed in bacterial richness (i.e. different
phylotypes) within the top 30 cm when compared to the irrigated agricultural soils. Between the
agricultural management systems (in the top 30 cm) the bacterial richness of conservation-tilled soils
was greater than irrigated mouldboard ploughed soils but less than irrigated pastures. Soil C
concentrations also correlated with eubacterial diversity indices for the four variable regions (r2 = 0.91,
0.92, 0.68, 0.70, respectively), evenness indices (r2 = 0.72, 0.68, 0.93, 0.80, respectively) and the
active bacterial biomass (r 2 = 0.75, 0.75, 0.79, 0.79 respectively). Since 1CT and IP increase C
sequestration and appear to support higher eubacterial diversity in soils compared to IMP, producers
can use these management practices on their lands to sequester organic C, improve soil microbial
diversity and enhance soil biological processes
The phosphorus composition of temperate pasture soils determined by NaOH-EDTA extraction and solution 31P NMR spectroscopy
Get PDFInformation on the composition and dynamics of soil phosphorus (P) remains limited, but is integral to
understanding soil biogeochemical cycles. We used solution 31P nuclear magnetic resonance (NMR) spectroscopy
to characterise NaOH—EDTA extractable P in 29 permanent pasture soils from England and Wales (total carbon
29-80 g kg- 1 soil, clay 219-681 g kg- 1 soil, pH 4.4-6.8). Total P ranged between 376 and 1981 mg P kg- 1 soil,
of which between 45 and 88% was extracted with NaOH—EDTA. The extracts were dominated by orthophosphate
monoesters (29-60% extracted P) and inorganic orthophosphate (21-55% extracted P), with smaller concentrations
of orthophosphate diesters (2-10% extracted P), pyrophosphate (1-7% extracted P), phosphonates (0 -
3% extracted P), and traces of polyphosphates. Orthophosphate diesters were subclassified into phospholipids (1-
7% extracted P) and DNA (1-6% extracted P). Signals slightly downfield of inorganic orthophosphate were tentatively
assigned to aromatic orthophosphate diesters similar in structure to R-(—)-1,1'-binaphthyl-2,2'-diyl hydrogen
phosphate. Such signals are rarely detected in soil extracts, but were present in relatively large concentrations in the
samples analysed here (2-5% extracted P). Relationships between functional P groups and soil properties suggested
that the various functional groups are involved in the soil P cycle to different extents. In particular, concentrations of
orthophosphate monoesters appeared to be controlled by the potential for chemical stabilisation in soil, whereas DNA
and pyrophosphate were strongly correlated with the microbial biomass, suggesting an active involvement in biological
nutrient turnove
Inhibiting water infiltration with polyacrylamide and surfactants: Applications for irrigated agriculture
Get PDFEfficiencies of surface irrigation systems are often limited by infiltration conditions.
Treatments that decrease infiltration into unlined canals, reservoirs, and the inflow end of
furrows relative to outflow ends would reduce seepage losses and improve application
uniformity. Several laboratory studies evaluated effects of high molecular weight (10 to 15 Mg
mol-1), water-soluble, anionic polyacrylamide (PAM), alone and combined with anionic
surfactants, on the hydraulic conductivity (KSAT) of soils. Dry soils were treated with one or two
treatment solutions and subjected to conditions that simulated those in an irrigation furrow or
pond. The KSAT of soil packed in columns was measured with a constant head apparatus for 19
hours. PAM treatment concentrations> 125 mg L" applied to dry soils preceding flooding
reduced KSAT by 25%, and a 10 mg-L-1 PAM + 29 k-mg-L-1 sodium-lauryl-sulfate surfactant
application reduced KSAT by 70%, relative to controls. Miniflume tests then applied the
treatments only to the inflow end of the mini-furrows. The 125 and 250 mg L.t PAM treatments
significantly improved water application uniformity: Cumulative infiltration was reduced in the
upper half of miniflume furrows and increased in the lower, relative to controls. When applied to
dry soils and allowed to dry overnight, as may be done when treating irrigation ponds, the 1,000
mg L-1 PAM solution reduced KSAT by 60% to > 90% in silt loam and clay loam soils. Either the
single or combination treatments could potentially be used to increase the uniformity of furrow
water applications and reduce seepage from unlined irrigation ponds and canals
Polyacrylamide and straw residue effects on irrigation furrow erosion and infiltration
Get PDFWater-soluble anionic polyacrylamide (PAM) is a highly effective erosion deterrent
in furrow irrigation, but little is known about the effect of plant residues on PAM efficacy. We
hypothesized that increasing plant residue in irrigation furrows may alter PAM's ability to control
erosion. Furrows with 10 g (485 kg ha-1) on treated area and 3o g m-1 (1490 kg ha-1) wheat
straw applications, irrigated with PAM or untreated water, and conventionally irrigated furrows
(no PAM and no straw) were used. Five irrigations were monitored on a field with 1.5% slope and
silt loam soil (Durinodic Xeric Haplocalcids). PAM was applied as a granular patch at the furrow
inflow end (33 g or 1 kg active ingredient ha 1). Compared to controls, individual straw and
PAM+straw treatments reduced sediment loss in all irrigations by 64% to 100%, but increased
infiltration (1.3x to 2.54 only for irrigation one, when furrows were fresh. Adding more straw to
low straw (with or without PAM) treatments increased average sediment loss reduction from
86% to 94% in the first two irrigations, but provided no extra benefit in subsequent irrigations
(relative to controls). Adding PAM to low and high straw treatments increased average sediment
loss reduction from 80% to 100% in the first two irrigations, and from 94% to 99.8% in
subsequent irrigations. Combining plant residue and PAM in furrows produced greater erosion
control and larger infiltration enhancements than with straw alone. An important additional
benefit of PAM is that it greatly reduced detachment, transport, and redistribution of residue in
furrows, which helped prevent furrow blockage and attendant overflow problems, allowing
farmers to use conservation tillage in furrow irrigated fields
Polyacrylamide for coliform bacteria removal from agricultural wastewater
Get PDFPollution of surface flow and groundwater from animal waste application to soils
has been well documented. Polyacrylamide (PAM) has reduced total coliform (TC) and fecal
coliform (FC) bacteria in animal waste water flowing in irrigation furrows. We measured efficacy
of PAM dissolved in water and as a "patch" application to soil to remove total and fecal coliforms
from: .3.) water flowing over dairy waste in furrow-irrigated, ungrazed forage production systems;
2) soil water after it flowed through i m of soil; and 3) influence of PAM on survival of total and
fecal coliforms in surface flow, soil, and soil water. Total coliforms in surface flow did not differ
when waste was applied to soil, regardless of PAM treatment or days since waste was applied.
Total coliforms in surface flow decreased by tenfold over the 7 days after waste regardless of
PAM treatment. Fecal coliforms in surface flow decreased by tenfold over the 7 days after waste
application and one hundredfold over the 28 days after waste application regardless of PAM
treatment. Total coliforms in soil decreased by tenfold over the 7 days after waste was applied,
one hundredfold over the 28 days after waste was applied and one thousandfold over the 63
days after waste was applied, regardless of PAM treatment or soil depth. Total coliforms did not
differ in control soils and soils receiving waste, regardless of soil depth or PAM treatment over
the 28 and 63 days after dairy waste was applied. Fecal coliforms in soil were greater in the o to
5 and 5 to 15 cm soil depths when waste was applied to soil, regardless of soil PAM treatment.
Fecal coliforms in all three soil depths decreased as much as one thousandfold over the 28 and
63 days after waste and PAM treatments were applied. In all treatments, except the waste
application x PAM patch treatment, total coliforms in soil water showed a tenfold decrease over
the 28 and 63 days after waste was applied. PAM may not provide additional protection to
surface water from waste applied to ungrazed forage production systems, but the compound
does not enhance survival of total or fecal coliforms in soils or water
Soil organic matter biochemistry and potential susceptibility to climatic change across the forest-tundra ecotone in the Fennoscandian mountains
Get PDFWe studied soil organic carbon (C) chemistry at the mountain birch forest-tundra ecotone
in three regions of the Fennoscandian mountain range with comparable vegetation cover
but contrasting degrees of continentality and latitude. The aim of the study was to
identify functional compound classes and their relationships to decomposition and
spatial variation across the ecotone and latitudinal gradient. Solid-state 13C nuclear
magnetic resonance (CPMAS 13C NMR) was used to identify seven functional groups
of soil organic C: alkyls, N-alkyls, 0-alkyls, acetals, aromatics, phenolics and carboxyls.
N-alkyls, 0-alkyls and acetals are generally considered labile substrates for a large
number of saprotrophic fungi and bacteria, whilst phenolics and aromatics are mainly
decomposed by lignolytic organisms and contribute to the formation of soil organic
matter together with aliphatic alkyls and carboxyls. All soils contained a similar proportional
distribution of functional groups, although relatively high amounts of N-alkyls,
0-alkyls and acetals were present in comparison to earlier published studies, suggesting
that large amounts of soil C were potentially vulnerable to microbial degradation. Soil
organic matter composition was different at the most southerly site (Dovrefjell, Norway),
compared with the two more northerly sites (Abisko, Sweden, and Joatka, Norway), with
higher concentrations of aromatics and phenolics, as well as pronounced differences in
alkyl concentrations between forest and tundra soils. Clear differences between mountain
birch forest and tundra heath soil was noted, with generally higher concentrations of
labile carbon present in tundra soils. We conclude that, although mesic soils around the
forest-tundra ecotone in Fennoscandia are a potential source of C to the atmosphere in a
changing environment, the response is likely to vary between comparable ecosystems in
relation to latitude and continentality as well as soil properties especially soil nitrogen
content and pH