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