STEEP - Integrated conservation spring cropping systems

2001 Table of Contents

2001 STEEP III Final Report

PROJECT TITLE: Integrated conservation spring cropping systems for the arid and semiarid wheat-fallow region of the PNW.

Determine residue management, straw decomposition rates, and soil cloddiness for the four cropping systems.
Quantify the incidence and impact of weeds, diseases, and insects in the no-till spring cropping systems and compare to traditional winter-wheat fallow.
Use standard crop production budgets to estimate the cost of production for each cropping system and rank each system by average profitability and income stability (risk).
Accelerate grower evaluation and adaptation of profitable conservation farming systems and conduct field days and presentations to disseminate information.

KEY WORDS: no-till cropping systems, weed population dynamics, chem fallow, wheat.

STATEMENT OF PROBLEM: The major farming practice in the arid and semiarid regions of the PNW is a winter wheat-fallow rotation. This system is characterized by soil erosion, reduced soil quality, high incidence of winter annual grass weeds and diseases. It is thought that continuous no-till spring cropping of cereals will reduce the number of fallow fields, increase residue cover on fields in the summer and fall, increase soil quality, and reduce the potential of wind blown dust. However, there are no current established best management practices for continuous, no-till spring cropping systems. Little information is known on nutrient management strategies, crop varieties, crop planting date and rate, and pest problems associated with dryland spring cropping systems. Weed species shifts and dynamics must be evaluated in these new systems.

ZONE OF INTEREST: Arid and semiarid region (low and intermediate rainfall) of the PNW.

ABSTRACT OF RESEARCH FINDINGS: The no-till spring cropping project of the wheat fallow region completed Phase I (5 yrs) in September 2000. Final analysis for weed populations and weed seeds in the soil are still being conducted. The reduced tillage winter wheat -fallow system was the most economical and surprisingly decreased wind erosion an estimated 55%. Winter wheat yield averaged 62 bu/A compared to the long-term farm average of 55 bu/A. The soft white spring wheat-chem fallow system was not efficient in storing soil moisture even with the second winter of fallow. Best management practices for no-till spring cereal production have initially been developed. These systems were successful environmentally and agronomically. In regards to economics, none of the spring cereal cropping systems were economically viable. For the past three growing seasons, no-till hard red spring wheat made protein (> 14%). Downy brome continues to be a problem in the winter wheat-fallow system and Russian thistle, Hessian fly, and Rhizoctonia root rot are the major pests encountered in continuous no-till cereals.

RESULTS AND INTERPRETATION: The 1999-2000 crop year concluded the 5-yr Phase I study of the Ralston Project. This harvest year also concluded a complete crop rotation cycle in which 'Scarlet' hard red spring wheat and 'Rely' club winter wheat were planted.

Objective 1. Residue management, straw decomposition, and soil cloddiness: The dust-mulch fallow phase of winter wheat production in low-rainfall areas leaves the soil surface loose-structured and exposed to erosion during high winds common to the region, and is a source of airborne particulate (PM). During a 3-yr transition period from winter wheat-fallow, surface residue cover (SRC), random roughness (RR), and crop canopy coverage (CC) were measured in three no-till spring cereal systems. These measurements were used to calculate soil loss ratios as indices to wind erosion potential. No-till spring cereal rotations reduced erosion potential compared with winter wheat-fallow by maintaining soil cover during spring and fall when erosion potential is high. Crop canopy reduced erosion potential after fall seeding in winter wheat-fallow and after spring seeding in the no-till rotations.

Objective 2. Quantify pest incidence in no-till spring cropping systems and the traditional winter-wheat fallow:
Winter wheat/fallow rotation. Winter wheat seedlings were damaged each year by a root disease complex including Rhizoctonia root rot, take-all, and Fusarium foot rot. Rhizoctonia root rot generally occurred on a high percentage of plants but mean severity ratings were generally low to intermediate. Survival of this pathogen was definitely perpetuated but damage to plants was usually minor in the winter wheat/fallow rotation. An exception occurred when Rhizoctonia root rot caused distinct patches of stunted plants during 1998. Take-all was generally insignificant in winter wheat but was found extensively during 1999. Fusarium foot rot occurred in most years but damage differed from year to year. Crown rot damage was especially important during 1999 and subcrown internode damage was important each year except 1998. Strawbreaker foot rot was generally inconsequential although highly damaging during 1998.

No-till annual spring wheat. Two diseases were of continual importance in no-till annual spring wheat. Until year 5, the incidence (percentage of infected plants) of both Rhizoctonia root rot and take-all had always been highest in the experimental section lying east of Marcellus Road, and lowest in the section located west of Marcellus Road. It was assumed that this difference, due to plot location, was associated with the cropping history for these fields before the experiment was established. The eastside had four cereal crops during the 5 years preceding this experiment whereas one cereal crop was grown on the west side. Although disease incidence was always higher on the east side, this difference from crop history was not always apparent for disease severity ratings. During 1999, the amount of root cortex disintegration, supposedly due to root lesion nematode, was also higher on the east than on the west side of the experiment.

No-till spring wheat/ spring barley. Spring wheat and spring barley were swapped back and forth between the west side and east side plots during consecutive years. A distinct positional effect occurred for Rhizoctonia root rot during years two, three, four, and five. In spring barley, 95% of the plants or tillers were infected with Rhizoctonia root rot with a disease severity rating of 2.4 (on a scale of 4.0) in 2000. Patches of depressed plant growth and grain yield were not as prevalent as in 1999. Disease was more severe on the east side than the west side, regardless of whether wheat or barley was planted. Damage from this disease is usually more severe on barley than wheat. The positional effect for plots in this experiment was, therefore, more important than genetic susceptibility of the crop species. This presumptive observation was based on differences in crop history before the experiment began.

During year four, take-all was more severe on the east than west side, but the pattern of prevalence was reversed during year five. During the last 2 years, the prevalence of take-all has been higher on spring wheat than spring barley. This pattern has indicated that differential susceptibilities of these plant species have become more important than field history at this stage in the maturation of this continuous no-till annual cereal rotation.

There were no aphids (English, Russian, etc.) detected in winter wheat. In spring cereals, aphid populations exceeded 1998-99 levels but remained below economic levels. Aphid densities peaked at early dough development, with English grain aphid (EGA) ranging from 5.5 to 7.5% infested tillers and Russian wheat aphid (RWA) densities from 0.5 to 1.25% infested tillers. Spring barley supported no EGA and few RWA (0.5% infested tillers). There were moderate numbers of Coccinellid predators detected in spring wheat, with highest populations on July 7. A substantial number of parasitized aphids (8 to 29%) also were found in spring wheat on this date. Fifteen to 47% of winter wheat and spring wheat tillers, respectively, were infested with Hessian fly (HF) larvae and puparia. The economic injury level was "estimated" to be 15 to 20% infested tillers. 'Baronesse' spring barley was resistant to HF attack. HF mortality between egg and larvae/puparia stages in spring wheat and spring barley ranged from 85 to 97%. The number of HF infested tillers has increased dramatically over the last three seasons with the highest populations consistently detected in continuous hard red spring wheat. Infestations in hard red spring wheat in rotation with barley exceeded the economic injury level in 2000, although levels were considerably lower than in continuous hard red spring wheat. Infestation levels in winter wheat were extremely low prior to 2000 but reached 23% infested tillers in 2000. This may reflect the natural phenomenon of year-to-year variability in populations of pest insects, or the close proximity of winter wheat to no-till spring wheat plots and competition from host plants. Results from this 5-yr study and satellite studies indicate that the deployment of HF-resistant genes in wheat cultivars can prevent economic losses.

Russian thistle is still the primary weed in spring cereals. As in 1999, a post-harvest herbicide application was not applied to spring barley or hard red spring wheat plots. In-crop herbicides for the control of Russian thistle were rotated for the fifth consecutive year to prevent herbicide resistance to the sulfonylurea herbicides. After 5 years, no other major weed species shift has occurred in the continuous no-till spring cereals.

Downy brome continues to plague the winter wheat/fallow rotation. Initial weed populations (downy brome) were much higher on the east side of the road compared to the west side of the road. A very aggressive management program was established to manage downy brome on the east side of the road. This program included post harvest disking to increase fall germination, split applications of metribuzin, at maximum-labeled herbicide rate. In contrast, the downy brome population on the west side escalated to near catastrophic proportion by the spring-fall of 2000. On this side of the road, a single light rate of herbicide was used and stubble was disked only once after harvest. Basically downy brome has almost been eliminated in the two no-till continuous spring cropping systems.

Objective 3. Cropping systems profitability and risk: The purpose of the economic analysis of the Ralston Project is to assess the profitability of no-till cropping systems in comparison to the traditional winter wheat-fallow system. In the case of this study, the winter wheat-fallow system entails a conservation tillage regime that does not include severe fall tillage with several subsequent rodweedings in the summer. Economic analysis of the first 5-year data set has been conducted.

Average net returns over total costs are negative for all four cropping systems for the period 1996-2000. Grain farmers have received substantial government payments from 1998-2000 but they were not figured into the Ralston profitability results. The traditional winter wheat/fallow system dominated the 1996-2000 average profitability. Winter wheat after fallow has yielded exceptionally well for the region averaging 69bu/ac (5-yr average). Relatively low production costs of the wheat/fallow system contributed to its profit advantage. When comparing net returns over total costs (best long-run measure of profitability) the spring wheat/chemical fallow system ranked second, followed by no-till hard red spring wheat/spring barley, and the least profitable was the continuous no-till hard red spring wheat. This system was ranked last because of the higher fixed costs as well as the declining price premium for protein in hard red spring wheat (1995 to 1999 compared to 1993 to 1997). It is quite possible that growers may be able to trim the cost of hard red spring wheat production by further reducing fertility and herbicide costs. Additional research has indicated the public values higher levels of air quality which continuous cropping systems provide. The public may be willing to cost share for growers to profitably adopt soil conserving annual spring cropping systems. Crop yields for the 1999-00 growing season (Table1) were slightly higher compared to the yield in 1999.

Table 1. Five year yields for the 1999-00 spring cropping project at Ralston, WA.^a

Table 1

Table 2. Precipitation (inches) at Ralston, WA from 1995-2001.^a

Table 2

Average precipitation during the first five years of the Ralston project was 1 inch per year more than the cooperator's farm average of 11.5 inches per year (Table 2). The last two years of the study, however, was dry or normal. The 1998-99 growing season was 2 inches of precipitation less than average.

Winter wheat in the reduced tillage wheat fallow system yielded very well. The five year average was 62 bu/A compared to the long-term farm field average of 55 bu/A (Table 1). Low yields (58 bu and 52 bu) were indicative of soil crusting and replanting (1996-97) and dry weather (1998-99). No-till spring wheat following chem fallow averaged 14 bu/A less than winter wheat in this study (Table 1). The only time yields were similar was in 1996-97 when winter wheat was replanted. The spring wheat/chem fallow system was inefficient and not profitable. A major problem encountered was reducing herbicide costs and timely applications during the fallow year. Continuous no-till hard red spring wheat was successful agronomically. Yields ranged from 30 to 50 bu/A and 14% protein was obtained each of the last 3 years with minimal nitrogen carry-over. Normally fertilizer (N) was split-applied with approximately 60 to 75% of the season-long N requirement applied in the fall. The remainder would be applied at planting which provided sufficient N throughout the soil profile for the wheat roots during the growing season. For the first 3 years, hard red spring wheat grown after spring barley yielded similarly to continuous hard red spring wheat. By the fifth year, wheat after barley produced 5 bu/A more than continuous hard red spring wheat. At the present time, researchers speculate that this 5 bu increase was because of a 15 to 20% reduction in Hessian fly infestation in the wheat/barley rotation compared to winter wheat. On the average, no-till spring barley yielded almost 1.25 tons/A, however, yields were extremely variable ranging from less than 0.75 tons/A to almost 1.75 tons/A. Rhizoctonia incidence was extremely high every year and coupled with frost injury that occurred in 1999, yield was less 0.75 tons/A. The variety 'Baronesse' is resistant to Hessian fly, which helped reduce the damage on the following year's hard red spring wheat crop.

Objective 4. Accelerate grower evaluation and adaptation of profitable conservation farming systems and conduct field days and presentations to disseminate information:
During the 5 years of this project, three formal field days were held (1996,1998, 2000) in which over 550 people attended. Numerous tours were given to groups such as the Washington Wheat Commission, National Air Quality Task Force, growers and extension personnel from Oregon, individual growers from Nebraska and California, and simply interested neighbors and scientists.

INTERACTION (COOPERATION) WITH OTHER SCIENTISTS CONDUCTING RELATED ACTIVITY: Scientists on this project routinely interacted with University and ARS researchers from ID, WA, and OR. This interaction included single component research as well as multi-interdisciplinary projects. These projects include cropping systems research in the low, intermediate, and high rainfall areas of WA as well as OR.

PUBLICATIONS AND PRESENTATIONS: Four Washington State University, Crop and Soil Science Technical Bulletins have been published since 1998. Tow manuscripts are currently in University review to be submitted to professional journals for publication. Numerous other manuscripts are in various stages of writing representing the disciplines of agronomy, economics, weed science, and entomology.

Since the conception of this project, the following presentations have been made: National Direct Seed Conference (STEEP III), American Society of Agronomy (Minneapolis, MN and North Carolina), Pacific Northwest Insect Management Conference (Portland, OR in 1998, 1999, 2000), and numerous regional fertilizer conferences.

Contact us: Hans Kok, (208)885-5971 | Accessibility | Copyright | Policies | WebStats | STEEP Acknowledgement
Hans Kok, WSU/UI Extension Conservation Tillage Specialist, UI Ag Science 231, PO Box 442339, Moscow, ID 83844 USA Redesigned by Leila Styer, CAHE Computer Resource Unit; Maintained by Debbie Marsh, Dept. of Crop & Soil Sciences, WSU