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A single dominant gene controlling resistance to soil zinc deficiency in common bean
Get PDFCultivated soils often are either deficient or possess toxic concentrations
of one or more mineral elements that adversely affect emergence,
growth, maturity, production potential, and/or nutritional quality
of common bean (Phaseolus vulgaris L.). Our objective was to
study the inheritance of resistance to soil Zn deficiency. The resistant
`Matterhorn' was crossed with the susceptible 'T-39'. The F1 was
backcrossed to Matterhorn (BC1) and T-39 (BC2), and advanced to
the F2. The two parents, F1, F2, BC1 , and BC2 were evaluated in a Zn
deficient field trial at Kimberly, Idaho in 2001. Plants were classified
as tall-healthy or stunted with chlorotic leaves. Leaves were sampled
from the two types of plants at flowering and analyzed for Zn concentration.
The tall plants had an average leaf Zn concentration of 22.5
mg kg- 1 . In contrast, stunted plants had a Zn concentration of 15.0
mg kg- 1. All F1 plants were tall resembling Matterhorn, except that
unlike Matterhorn (white flowers and seeds) they had purple flowers
and black shiny seeds. Thus, the resistance to Zn deficiency was
dominant. A segregation of 45 resistant (R) to 20 susceptible (S)
plants was observed in the F2, giving a good fit to 3 R:1 S (x2 = 1.1538,
P = 0.28). All plants in BC1 were resistant. In BC2, 142 It and 139 S
plants were observed, giving a ratio of 1 R to 1 S (x2 = 0.032, P = 0.86).
This supports a single dominant gene controlling soil Zn deficiency
resistance. The symbol Znd is proposed for the dominant allele controlling
resistance to soil Zn deficiency, and znd for its susceptible
counterpart
Sorption of organic phosphorus compounds in Atlantic Coastal Plain soils
Get PDFOrganic phosphorus (P) can comprise a significant amount of the total
P in animal wastes, yet there is little information on the potential for
organic P to be transferred from soils to watercourses. We examined the
adsorption of organic P compounds to soils typical of the southeastern
United States, i.e., Blanton Sand (loamy, siliceous, thermic, Grossarenic
Paleudult), Cecil sandy clay loam (fine, kaolinitic, thermic, Typic Kanhapludult),
and a Belhaven sandy loam (loamy, mixed, dysic, thermic,
Terric Medisaprist). The behavior of four organic P compounds was
studied: adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate
(ADP), adenosine 5'-monophosphate (AMP), and inositol hexaphosphate
(IHP); while KH2PO4 (ortho-P) was used as an inorganic reference. Laboratory
studies were conducted to determine the effects of concentration
(0-130 p.g P mL-1 ), pH (4.6-7.6), and soil properties on P adsorption. All
the organic P compounds had greater adsorption than KH 2PO4 on the
Blanton and Cecil soils at all concentrations and ranges of pH. In the Belhaven
soil, IHP had the greatest sorption followed by KH 2PO4 and the
nucleotides (ATP, ADP, and AMP, respectively). Adsorption of organic
P was positively correlated with soil organic matter and Fe and Al contents.
The greater sorption of some organic P compounds over that of
ortho-P suggests that these compounds may pose less of a threat to water
quality, although this preferential sorption may increase soluble P in
situations where there is displacement of ortho-P by organic P added in
manures
Soil erosion reduction
Get PDFThe human population may double by midcentury.
Coupled with improved living standards in underdeveloped
nations, this growth will demand unprecedented
increases in agricultural production. The
great threat to meeting these needs is decreased crop
productivity caused by soil erosion. Agricultural productivity
and production value are highest in irrigated
arid areas, which tend to have shallow, highly
erodible soils. Thus, the agricultural systems most
capable of meeting future needs are also the most
threatened by erosion. Developing effective erosion
control methods to protect the sustainability of the
Earth's soil is of utmost importance
Irrigation erosion
Get PDFIrrigation is important to global food production. About
15% of cropland (1) and 5% of food production land, [Fl]
which includes rangeland and permanent cropland (2), are [F2]
irrigated. However, irrigated land produces more than 30%
of the world's food (3), which is 2.5 times as much per unit
area compared with nonirrigated production (1). In the
U.S., approximately 15% of the harvested cropland is
irrigated; however, almost 40% of the total crop value is
produced on irrigated land (4).
Although sprinkler- and drip-irrigated areas are
increasing, most of the world's irrigated land uses surface
or flood irrigation. The countries with the large irrigated
areas are India (59,000,000 ha), China (52,580,000 ha),
U.S. (21,400,000 ha), and Pakistan (18,000,000 ha) (2).
These countries account for 55% of the world's irrigated
land; all other countries have less than 10 million ha each
of irrigated land (2). About 50% of the irrigated land in the
U.S. is surface irrigated (5), although 95-99% of the
irrigated land in India, China, and Pakistan is surface
irrigated (6).
Soil erosion from irrigated fields has been discussed
previously (7, 8); this article focuses on unique aspects
of irrigation-induced soil erosion that are important
when managing and simulating soil erosion on irrigated
lands.
Soil erosion mechanics can be divided into three
components: detachment, transport, and deposition. Water
droplets and flowing water detach soil particles; flowing
water then transports these detached particles downstream;
deposition occurs when flowing water can no
longer transport the soil particles because flow rate
decreases as water infiltrates or as rill slope or roughness
changes. Some particles are deposited within a few meters
although others are transported off the field with runoff
water. These mechanisms are the same for surface
irrigation, sprinkler irrigation and rainfall; however, there
are some systematic differences between irrigation and
rainfall erosion and especially between surface irrigation
and rainfall
The use of PAM -- a linear polyacrylamide for use in irrigation water
Get PDFThis overview will be familiar to anyone who has visited the "PAM page" of the Northwest Irrigation and Soils
Research Laboratory's web site. The reader is encouraged to visit that web site,
, for graphics and photos that were used in this NAICC presentation in
Orlando in January, 2001, as well as for other more detailed technical information.
PAM has been sold in the United States since 1995 for reducing irrigation-induced erosion and enhancing
infiltration. Its soil stabilizing and flocculating properties have also substantially improved runoff water quality by
reducing sediments, N, ortho and total P, COD, pesticides, weed seeds, and microorganisms in runoff. The first
series of practical field tests of PAM for irrigation erosion control was conducted in the U.S. in 1991. PAM used for
erosion control is a large (12-15 megagrams per mole) water soluble (non-crosslinked) anionic molecule, containing
<0.05% acrylamide monomer. In a series of field studies, PAM eliminated an average 94% (80-99% range) of
sediment loss in field runoff from furrow irrigation, with 15-50% relative infiltration increases compared to untreated
controls on medium to fine textured soils. Similar but less dramatic results have been seen with sprinkler irrigation.
In sandy soils infiltration is often unchanged by PAM or can even be slightly reduced. Results are achieved with per
irrigation field PAM application rates of about 1 kg ha-1 for furrow irrigation and about 4 kg ha-1 for sprinkler
irrigation. Often only fractions of these rates are required on subsequent irrigations (if the ground has not been
disturbed between irrigations) to maintain efficacy. Typical seasonal application totals vary from 3 to 7 kg per
hectare. Farmer field sediment control has generally been about 80% or more of test plot results.
Research has shown no adverse effects on soil microbial populations. PAM effects on crop yields have only been
sparsely documented. Initial studies, focused mostly on erosion and runoff water quality effects, conducted largely in
field beans or maize, showed little effect on yields, probably because all treatments were supplied adequate water.
Some evidence exists for PAM-related yield increases where infiltration was crop-limiting, especially in field portions
having irregular slopes, where erosion prevention eliminated deep furrow cutting that deprives shallow roots of
adequate water delivery. PAM's ability to increase lateral spread of water during infiltration is useful for early season
water conservation. Only small amounts of water are needed to germinate seed or sustain small seedlings shortly
after planting. Water conservation is accomplished by not needing to completely fill the soil profile because wetting
patterns of PAM-treated furrows spread further laterally for a given volume of water applied. High effectiveness and
low cost of PAM for erosion control and infiltration management, coupled with relative ease of application compared
to traditional conservation measures, has resulted in rapid technology acceptance in the US, with about 400,000 ha
of irrigated land currently employing PAM for erosion and/or infiltration management.
Water soluble anionic high-purity PAM is a safe environmentally friendly soil conditioner, that when delivered via
irrigation, reduces erosion, prevents sediment and chemical and biological pollutants from entering runoff and greatly
expands management options for all forms of irrigated agriculture because of its soil stabilizing effects and direct
effects on water properties influencing field water management. PAM is economical, typically 12 per
kilogram of active ingredient, effective at low rates (1 to 5 kg per hectare per season) and relatively easy to use
Phosphorus
Get PDFPhosphorus (P) is one of the most important
mineral nutrients for biological systems, yet
it is also one of the most scarce nutrients in
terms of its demand in both terrestrial and
aquatic environments (Moss, 1988). In natural systems, P is tightly cycled through the
plant-soil continuum, but in agricultural
systems soil P is removed in the crop or
animal products and must be replaced if P
deficiency is to be avoided. Therefore, mineral
PO fertilizers and animal manures
are applied to agricultural land to raise soil
P levels and maintain crop yields (Sibbesen
and Sharpley, 1997)
The WEPP model for runoff and erosion prediction under sprinkler irrigation
Get PDFPotential runoff and erosion is a serious problem for some types of sprinkler irrigation systems, particularly
traveling laterals and center pivots on medium– to heavy–textured soils operating on sloping land. Prediction of when runoff
might occur is part of the system design process. The USDA–ARS Water Erosion Prediction Project (WEPP) model was tested
with 3 years of field data under high–rate sprinklers in southern Idaho. Runoff and soil loss were measured on the upper,
middle, and lower portions of a hillslope. The main parameter affecting infiltration and runoff was the effective hydraulic
conductivity. Model predictions for average runoff and soil loss were improved when hydraulic conductivity values were
adjusted to account for soil variability across the field. Runoff amounts were small, and prediction variability for individual
furrows was quite high, but no more than would be expected from previous studies of infiltration variability. Soil loss
predictions were unreliable for the small runoff amounts occurring in this study. The most reasonable use of WEPP for
sprinkler irrigation would be for estimating when potential runoff might occur under center pivots for different soils, slopes,
and crop management practices, and to determine limits on application depths and rates to avoid serious runof
Fate and efficacy of polyacrylamide applied in furrow irrigation: Full-advance and continuous treatments
Get PDFPolyacrylamide (PAM) is applied to 400 000 irrigated hectares
annually in the USA to control irrigation-induced erosion, yet the
fate of dissolved PAM applied in irrigation water is not well documented. We determined the fate of PAM added to furrow streams
under two treatments: Initial-10, 10 mg L-1 PAM product applied
only during the initial hours of the irrigation, and Cont-1, 1.0 mg L—1
PAM product applied continuously during the entire irrigation. The
study measured PAM concentrations in 167-m-long PAM-treated
furrow streams and along a 530-m tail ditch that received this runoff.
Soil was Portneuf silt loam (coarse-silty, mixed, superactive, mesic
Durinodic Xeric Haplocalcid) with 1.5% slope. Samples were taken
at three times during the irrigations, both during and after PAM
application. Polyacrylamide was adsorbed to soil and removed from
solution as the streams traversed the soil-lined channels. The removal
rate increased with stream sediment concentration. Stream sediment
concentrations were higher when PAM concentrations were <2 mg
L-1 a.i., for early irrigations, and when untreated tributary flows combined with the stream. In these cases, PAM concentration decreased
to undetectable levels over the flow lengths used in this study. When
inflows contained >6 mg L-1 PAM a.i., stream sediment concentrations were minimal and PAM concentrations did not change down
the furrow, though they decreased to undetectable levels within 0.5
h after application ceased. One percent of applied PAM was lost in
tail-ditch runoff. This loss could have been eliminated by treating
only the furrow advance or not treating the last two irrigations
Plant tissues suitable for individual selection of Mg in tall fescue
Get PDFEnergy dispersive x-ray microanalyzer (EDX) is an efficient apparatus for forage
screening. It can evaluate only a small amount of sample at a time. On the other hand, for
screening forage mineral concentrations it requires that the sample is a representative of the
whole plant for mineral concentrations. This study was conducted to identify the suitable
tissue in selecting tall fescue populations for high Mg concentration by using MX
Pre-wetting effect on furrow irrigation erosion: A field study
Get PDFFlowing water quickly saturates dry surface soil as water advances in irrigation furrows. Conversely, rain wets
surface soil before runoff occurs. Rapid wetting destroys soil aggregates as water quickly displaces trapped air. Slowly
increasing soil water content prior to saturation increases aggregate stability. We hypothesized that instantaneous wetting
of dry surface soil during furrow irrigation results in greater soil erosion than if furrow soil was pre—wet immediately before
irrigation. We conducted ten irrigation trials on 27—m long furrows in three different fields. Soil was pre—wet by surface drip
irrigation (12 to 14 nun) or by lightly spraying with water (1.3 mm). Pre—wetting with drip irrigation significantly (P < 0.05)
reduced soil loss for 5 of the first 7 irrigations compared to dry soil. The pre—wetting effect on soil loss was not always
dramatic, but cumulative soil loss for the first seven irrigations was significantly different among the three treatments: 16,
30, and 56 Mg ha-1 for drip, spray, and dry treatments, respectively. The dry treatment never had less soil loss than either
pre—wetting treatment. Pre—wetting furrow soil by spraying apparently did not add enough water to stabilize soil aggregates
and decrease soil erosion for most irrigations. This study demonstrated that erosion was greater when water flowed over
initially dry soil, which is typical with furrow irrigation, compared to water flowing over initially wet soil, which occurs during
rain