32 research outputs found
Downy Brome Control on Dryland Winter Wheat with Stubble-Mulch Fallow and Seeding Management
Differences in downy brome (Bromus tectorum L.) control
had been observed under field conditions of eastern
Idaho when dates of stubble-mulch tillage, final rod
weeding, and winter wheat (Triticum aestivum L.) planting
were varied. This field-plot experiment on Tetonia
silt loam (Pachic Cryoboroll-coarse, silty, mixed) tested
the degree of downy brome control obtained with three
initial stubble-mulch tillage dates, two final rod weeding
dates, and three winter wheat planting dates.
Downy brome was best controlled with a combination
of initial tilling early in the spring and a final rod weeding
just before the late (15 September) wheat planting
date. The early tillage killed downy brome before they
produced seed. This also resulted in sufficient soil moisture
retention in the seed zone for fall germination of
other downy brome seeds, which were then killed by the
final rod weeding just before the late wheat planting.
A reduction in natural downy brome emergence was
observed at later fall dates. This was confirmed in a
separate field.plot experiment (Portneuf silt loam, Xerollic
Calciorthid, coarse, silty, mixed) where downy brome
seed was planted at several dates, and helped explain some
of the benefits of the mentioned late rod weeding and
planting treatment.
These procedures incorporating stubble-mulch fallow
are recommended, as normally practiced moldboard plowing
creates an erosion hazard
Convenient Estimation of Soil Organic-N Using the Udy Dye System
A method was developed for conveniently estimating organic-N
in soils using Udy dye, which is bound on the positive sites of
the soil organic matter complex. The quantity bound is associated
with the quantity of organic-N. These amounts can be determined
by initially adding an excess of dye and, after equilibrium,
colorimetrically measuring the amount remaining in solution. A
soil pretreatment wash with water and oxalic acid is used to remove
soil solution coloration, buffer the soil pH, and precipitate
soluble soil calcium. High amounts of soil free iron oxides or
carbonates interfered with the test
Simulated erosion and fertilizer effects on winter wheat cropping Intermountain dryland area
Topsoil loss from erosion in the intermountain dry-farming area
reduces crop yields. This study tested the hypothesis that the effects
of erosion on water storage and wheat (Triticum aestivum L.) yield
could be partially alleviated by applying appropriate fertilizers. Two
sites were used, one on Rexburg silt loam, a coarse-silty, mixed,
frigid Calcic Haploxeroll, and the other on Newdale silt loam, a
coarse-silty, mixed frigid Calciorthidic Haploxeroll. Topsoil-depth
treatments were + 15, 0, —15, or —30 cm changes relative to the
original surface. After making the soil depth changes, 54 kg P ha-1
were incorporated on one half of each topsoil depth plot and the
other half received no P. These P or no P plots were split for applications
of 0, 34 or 68 kg N ha-1. Phosphorus had no effect on
wheat yield. Without fertilizer N, yields on —15 and —30-cm plots
were reduced 46 and 55%, respectively, but increased 69% from the
addition of 15 cm of topsoil, compared with the 0-cm plot. Removing
15 and 30 cm of topsoil also reduced the upper limit of N-fertilized
production to 80 and 65%, respectively, of production on undisturbed
N-fertilized plots. Three kilograms fertilizer N ha-1 each crop year
offset each centimeter of soil removed, but only to the new lower
production limit. All plots had similar amounts of stored, available
soil water in the spring, but a large fraction of this water remained
unused at harvest on plots with 15 and 30 cm of topsoil removed
because the low-yielding wheat did not use as much water. Profile
water differences at harvest were no longer apparent by the next
spring, following winter recharge. Unused water at harvest, which
partially filled the soil profile, reduced winter infiltration and contributed
to subsequent runoff from precipitation on those plots. Adding
N fertilizer was only a partial solution to topsoil deficiencies
Potential for Reducing Evaporation During Summer Fallow
INITIAL attempts by farmers to settle
the dryland areas of the United
States failed when they tried farming
methods used in more humid areas.
A stable agriculture developed only
after summer fallowing was introduced.
Even with modern tillage methods,
no more than 30 percent of all precipitation
is stored in most dryland soils
during an entire fallow period—from
fall, at harvest, through the summer
fallow year, to the spring of the crop
year. Evaporation accounts for most
of the precipitation lost. Methods to
suppress evaporation are thus needed
Using yield and protein history from dryland fields to improve nitrogen fertilizer recommendations
Typical of dryland, where fallowed wheat yields range from 15 to 45
Bu/A, neither yield nor protein responses to nitrogen (N) fertilizer are
consistent (2, 3, 4, 8). Workers at the Tetonia and Aberdeen Branch
Stations in Intermountain Idaho began trials as early as the 1940's, but
there were no unifying concepts that would allow projection of trial
results to individual farm fields. Therefore, few reports have been
published, although trials have continued to date (1, 5, 8, 9).
The purpose of this paper is to summarize and interpret the data
collected over the entire period. We identified the two following goals:
1. The summary should be based on established agronomic relations,
and
2. The results of the analysis should improve predictions of yield
and protein responses to N fertilizer
Productivity Losses from Soil Erosion on Dry Cropland in the Intermountain Area
Soil erosion substantially reduces the productivity of deep, loessial soils on
dry cropland in the intermountain region. The eroded areas usually coincide with steeper
slopes where runoff is a problem. Reduced soil moisture limits crop growth, although the
eroded soils also have fertility limitations. Where erosion was simulated by removing
various amounts of topsoil from more level land, similar stored soil moisture readings
were obtained on all plots. On those plots, however, added fertilizer did not fully replace
lost topsoil for maintaining production. Also, poor soil profile moisture extraction by
crops led to reduced infiltration and increased runoff during fallow. Erosion thus seems
to be somewhat self-perpetuating, and there is no simple remedy once it has occurred
Downy Brome (Cheatgrass) Control in a Dryland Winter Wheat-Fallow Rotation
The similar growth cycles of
downy brome and winter wheat
make weed control difficult. Each
downy brome plant growing in a
square foot area decreases wheat
yield about 4 percent. Downy
brome may be effectively controlled
by combining three practices:
(1) Tilling fallow early enough in
the spring to retain good seedbed
moisture and thereby increase
early fall downy brome
germination;
(2) Rodweed just before planting
winter wheat;
(3) Plant wheat after mid-September
Fall Chiseling for Annual Cropping of Spring Wheat in the Intermountain Dryland Region
Comparisons were made among annual cropping, annual
cropping with fall chiseling, and a spring wheat-fallow
rotation with chiseling after harvest under a climate
with near uniform monthly precipitation of 23
cm. Because cropping season precipitation averaged only
9.1 cm, soil water storage before planting was necessary
to ensure crop production. "Annually cropped" plots
averaged 15.0 cm stored available water per 180-cm
depth at planting, whereas "annually cropped-fall chiseled,"
and "cropped-fall chiseled-fallowed" plots averaged
21.3 and 22.9 cm, respectively.
Soil water storage from the spring of the summerfallow
year until the spring of the crop year was dependent
upon the previous over-winter storage (r² = 0.65). When
this initial storage was less than 23.9 cm per 180-cm depth,
water in storage was increased by summer-fallowing.
However when the initial storage exceeded 23.9 cm,
summer-fallowing resulted in a soil water loss. As crop
yields were dependent on soil water storage at planting
time (r² = 0.68), it was possible to estimate in the spring
what yields would be with annual cropping, and also
what extra water might be stored by fallowing as an
alternative practice.
Nonfertilized, "annually cropped" and "annually
cropped-fall chiseled" plots contained approximately the
same amount of soil NO?-N at planting, but only the
chiseled plots with their extra stored water produced
a yield response from fertilizer N. In comparison, nonfertilized
followed plots contained 1½ times as much
NO?-N, and no yield response was obtained with fertilizer
N
Evaluation of bravo for disease control in alfalfa cultivars grown for hay, 1983
EVALUATION OF BRAVO FOR DISEASE CONTROL IN ALFALFA CULTIVARS GROWN FOR HAY, 1983: The alfalfa cultivars, having Turkish
and/or Flemish parentage and which were adapted to the northern and central U.S., were established under irrigated culture in late spring, 1981, on a
productive Portneuf silt loam. Plots were randomized block with 4 replications, each split for Bravo, and were 5 x 25 ft. Following the establishment
year, Bravo was applied to the stubble prior to regrowth in an attempt to control inoculum. The tractor-mounted spray rig, which had a 25-ft boom (T-jet
6503 nozzles, 40 psi, 35 gpm) was driven across only the Bravo-treated plots in 1982, but across all plots in 1983 to eliminate the wheel compaction
variable
Evaluation of bravo for disease control in seed alfalfa, 1982
EVALUATION OF BRAVO FOR DISEASE CONTROL IN SEED ALFALFA, 1982: A field with a 3-yr-old stand under irrigation on Portneuf very fine
loam was used for this test. It was typical of seed fields in this area in that lower leaves were lost from shading and disease during the growing season.
Different Bravo rates were applied to field length strips with a tractor mounted sprayed (boom width = 28.5 ft, PTO pump, T-jet 6503 nozzles, 28 psi).
Three consecutive applications were made at, "full bloom" on Jun 27, and then Aug 4, and finally on Aug 27. The treatments were randomized and replicated
4 times. Seed pollinization was enhanced with adequate alfalfa leafcutting bees (Megachile rotundata), taken to the field on Jul 6. Field observations
and a preharvest plant sampling were made to compare leaf loss. Also, the bee activity and flower set were observed on treatments. The seed crop
was harvested by cutting a 15-ft swath from the middle of the strip with a self propelled combine