Title: Integrated Residue Management Systems for Sustained Seed Yield of Kentucky Bluegrass
Without Burning - Phase I (Year three of a three year proposal)
Duration: 3 years (2002-2005)
Research Areas: 1A. Crop Management; 1B. Weed, Insect, Disease Control; 1C. Plant
Nutrition; 1D. Straw and Stubble Removal Systems; 2B Economic and Social Analysis of
Residue Handling Methods On- and Off- Farm
Investigators: Donn Thill, Prof. Weed Sci. (0.2 FTE); Jodi Johnson-Maynard, Assist. Prof. Soil
Sci. (0.2 FTE); Joe McCaffrey, Prof. Entom. (0.1 FTE); Larry VanTassell, Head Dept. of Agric.
Econ. & Rural Soc. (0.1 FTE); Bob Smathers, Agric. Econ. Spec. (0.1 FTE); and J. D.
Wulfhorst, Assist. Prof. Rural Soc. (0.1 FTE); John Holman, Ext. Support Scientist. (0.1 FTE).
Cooperators: Growers: David Mosman, Craigmont, ID; Chris Ramsey, Rockford, WA;
Industry Rep.: Lawrence Lampert, Dye Seed Co.; Steve Bateman and Tom Pyle, Jacklin Seed
Div.; Dave Tellesson, Seeds Inc.; EPA: Mike Silverman, grant coordinator; Coeur d' Alene
Tribe: Alfred Nomee, Liaison to UI; Nez Perce Tribe: Julie Simpson, Envir. Spec. and Paul
Brusvan, Agronomist; Idaho DEQ: Raylan Roetman, Air Qual. Sci. Officer; Ken Hart, Ext.
Educ., Lewis Co.; David Clark, Ext. Educ., Benewah and Kootenai Co., ID; Statistical Analysis:
Bahman Shafii, Dir. Statistical Programs CALS, UI; Wes Chun, Assoc. Prof. Plant Path.
Statement of Problem: Alternative management systems must be developed that eliminate or
substantially reduce the need to burn Kentucky bluegrass residue yet sustains productivity and
economical seed yield. Sustained bluegrass seed productivity historically has relied on openfield burning of post-harvest residues that has been associated with significant air quality issues
and public health impacts. To sustain the future of bluegrass seed production, an important
source of income for farmers in northern ID and eastern WA, the goal must be to encourage in
situ decomposition and/or removal of straw residue. In the absence of burning and without
enhanced straw decomposition or efficient removal methods, bluegrass acreage in this area will
decrease dramatically.
Justification: Approximately 70 to 80% of the nation’s Kentucky bluegrass seed is produced in
northern Idaho and eastern Washington (Mahler and Ensign 1989). Established bluegrass stands
prevent erosion and nutrient loss to surface water, protecting soil and water quality (Ghidey and
Alberts 1997, Painter et al 1995).
Non-thermal Kentucky bluegrass seed production reduces the economical seed crops from ten
or more to about three (Chastain et al 1998; Murray 1996; Murray and Johnston 1995) due to
increased weed, disease, and insect damage and longer floral induction periods from the
accumulation of straw residue. Increased stand density also contributes to decreased seed yield
as stands age. Baling and mowing are less effective than more thorough residue removal
treatments, especially in older stands, and are more expensive than burning. Seed yield of
aggressive, elite cultivars, with long floral induction requirements usually decline more rapidly
than yields of common non-aggressive cultivars (Murray et al 1997a, 1997b). Due to shorter
stand life, more frequent bluegrass establishment decreases economic opportunities for sustained
bluegrass seed production, increases the potential for soil erosion and may impact the social and
political dynamics of growers in local communities of this region.
Grass seed growers in northern ID usually burn bluegrass residues, while growers in eastern
WA use non-thermal residue removal methods. Mandatory regulations that restrict or eliminate
burning of bluegrass fields in Idaho are anticipated. Effective and economical non-thermal and
reduced thermal management practices must be developed and tested before restrictions are
imposed; otherwise the viability of this economically and environmentally sound industry will be
threatened severely. Residue management systems must be developed and tested in long-term,
large-scale, on-farm trials that represent typical grower field conditions to properly assess
treatment effectiveness on residue levels and impacts on grass seed production. This includes
appropriate agronomic, ecological, environmental, economic and sociological studies and
analyses.
Kentucky bluegrass production areas in northern ID include the Camas and Palouse Prairies
and parts of Benewah and Kootenai Co. Baling may allow development of non-thermal (bale
and mow) and reduced thermal (bale and burn) residue management systems. However, the
adoption of bale and burn practices depend on a market for the straw and if any burning will be
allowed in the future. On the Camas and Palouse Prairies, there is limited local market for baled
straw and transportation costs limit the practicality of baling. Alternative non-thermal residue
management systems, such as in situ straw decomposition during a fallow year, need to be
developed for these production regions.
This project focuses on understanding and managing processes and reactions controlling
decomposition of bluegrass straw. The effect of herbicides, used to suppress bluegrass growth in
chemical fallow systems, on the decomposition rate is unknown. Application of glyphosate
(Roundup) increased, decreased, or did not affect the decomposition rate of various residues
(Grossbard and Wingfield 1978, Grossbard and Harris 1979, Pollard 1979, Hendrix and
Parmelee 1985). Decreased decomposition rates most often are reported when herbicides are
applied to plant residues, while enhanced decomposition rates result from treatment of living
vegetation. There are no reported studies of herbicide effects on bluegrass decomposition rates
or processes. A detailed study of decomposition processes in untreated and herbicide-treated
residue will result in information that can be used to develop more efficient nutrient management
plans accounting for nutrient fluxes from the decomposing residues; establish new management
techniques such as the addition of N or microbial consortiums to increase decomposition by
enhancing natural processes; and develop profitable and environmentally acceptable practices
that will increase acreage of bluegrass.
Kentucky bluegrass requires a high N application rate that is often applied based on potential
yields and precipitation (Mahler and Ensign 1989). Over application of N may result in nitrate
contamination of groundwater and decreased seed yields due to lodging. Detailed N budgets
must be calculated. Leaving residues to decompose in the field may reduce the need for N
fertilizers. In situ residue removal resembles natural systems where litter decomposition is a
major source of nutrients to the soil (Schlesinger 1991). Where bluegrass is grown for turf,
leaving clippings resulted in equivalent quality turf compared to twice as much N fertilizer when
clippings were removed (Heckman et al. 2000). Integrated approaches to residue and N-fertilizer
management in grass seed production systems have not been fully evaluated.
Objective: Design and test economically sustainable Kentucky bluegrass management systems
that minimize or eliminate the need for open-field burning of residues, thereby substantially
improving regional air, soil, and water quality.
1. Develop non-thermal or reduced thermal systems that optimize straw decomposition and
maintain or increase Kentucky bluegrass seed yield.
2. Compare nutrient cycling efficiency and soil quality factors in burned, reduced thermal, and
non-thermal Kentucky bluegrass systems.
3. Investigate the aboveground insect pest and predator relationships in bluegrass systems.
4. Examine the economic efficiency of each bluegrass production system including the
associated production, price and financial risk.
5. Identify potential key social and economic costs and benefits of in situ decomposition and/or
“bale and burn” management practices versus current open-burning practices.
6. Disseminate information to growers, field consultants, extension educators, and scientific
audiences.
Procedures: General (Thill): Large-scale, long-term, on-farm experiments have been
established. Each experiment contains two to four main treatments replicated four times. Each
plot is 25 to 70-ft wide by 300-ft long. All production operations are performed using field scale
equipment. One half of each plot contains only main treatments (see below), while the other half
is used for smaller plot experiments (fertility trials, pest control and monitoring, etc.). Main
plots are managed using agronomic practices typical to the area. Weather stations at each
location record air and soil temperatures, precipitation, and total solar radiation. Panicle number,
grass seed yield, 100 seed weight, and percent seed germination are determined for each main
plot treatment. Post-harvest residue biomass is measured immediately after grass seed harvest
and periodically thereafter in each plot. Phase I is the first 3 yr of the experiment. Phase II will
be years four through six. At least three cycles of a system are necessary to determine the longterm effects of treatment on grass seed production, macro and micro fauna, and residue
decomposition.
Kootenai Co. Site: 'Alene' bluegrass was seeded during spring 2001 and the first seed harvest
was summer 2002. Treatments are full-load burn; bale + burn; bale + mow + harrow; and bale +
mow + harrow yr 1, bale + burn yr 2, full-load burn yr 3 with the same sequence of treatments
repeated in years 4, 5, and 6. Grass seed is harvested every year in each treatment. Straw is
baled and removed immediately after harvest and specific plots mowed and harrowed. Plots will
be burned when the grower burns the rest of the field to achieve a "typical" burn. The non-burn
plots will be protected from fire.
Lewis Co. Site: 'Quantum Leap' was seeded in spring of 2000 and the first seed crop was
harvested during summer 2001. Main treatments are grass seed harvest in 2002, 2004, 2006, and
2008 followed by non-thermal residue management during a fallow year (no grass seed harvest)
in 2003, 2005 and 2007; and non-thermal residue management during a fallow year in 2002,
2004 and 2006 followed by grass seed harvest in 2003, 2005 and 2007. Plots are mowed
immediately after seed harvest. Sub-plot fallow year treatments are mowing or glufosinate
(Liberty) applied about 2 to 3 weeks after bluegrass growth resumes in the spring, followed by
mowing about 3 to 5 weeks after spraying.
Objective 1 (Johnson-Maynard and McCaffrey): Following mechanical treatment to reduce
residue particle size and increase surface area available for microbial attack, chemical and
biological treatments are applied to determine viable methods of enhancing in situ
decomposition. Nitrogen Treatments: Decomposition rate is measured in mechanically and
mechanically + N-treated sub-subplots within subplots at the Lewis Co. site to determine if N
applications will increase residue decomposition and seed yield. N fertilizer treatments is
applied based on the C:N ratio of the residues. Straw biomass following harvest is collected in
each plot, dried, weighed, and the total elemental composition determined. The C and N content
is determined by dry combustion. The residue decomposition rate is determined by periodic
sampling (Stott et al.1990). Biological study: Changes in the decomposer communities, in both
untreated and herbicide treated straw is monitored at the Lewis County site. Decomposition of
the residues is monitored as described above in the N experiment. Fauna is considered in terms
of their functional ecology. Surface-active macro fauna are collected in pitfall traps placed at the
soil surface of control (no herbicide) and herbicide treated plots. Mesofauna (micro arthropods)
is extracted from decomposing residues in Tullgren funnels and separated into springtails, mites,
and others.
Objective 2 (Johnson-Maynard and McCaffrey): N cycling in each treatment at both sites is
studied using both static and dynamic methods. N in soil solution sampled at 10 to 100 cm is
measured to determine dynamic processes occurring and the potential risk of NO3- contamination
to ground water throughout a season using porous cup suction lysimeters. Soil solution is
sampled every 2 wk until the soil dries to levels where soil water can no longer be extracted.
Total N is determined by dry combustion. Inorganic forms (NH4+ and NO3-) are determined
using an auto analyzer. Soil samples are taken to 1 m within each treatment during the first fall
of the experiment to establish baseline N data. Samples are taken in the fall of each year to track
changes in N availability.
Indicators of soil quality include chemical, physical, and biological parameters. N status and
availability (described above) are used to assess soil quality in terms of chemical properties.
Physical properties important to water movement and storage, and aeration are studied using
bulk samples and intact cores. Bulk density is determined using the mass and volume of intact
cores (Blake and Hartge 1986). Water retention is determined using a pressure plate apparatus
and plant available water is calculated as the difference between water content at field capacity
and permanent wilting point. Aggregate stability is determined by wet sieving (Kemper and
Rosenau 1986). Saturated hydraulic conductivity is determined on intact cores using a constant
head method (Klute and Dirksen 1986). Biological indicators include microbial biomass C and
N that are determined using the fumigation extraction method (Joergensen 1995). Mesofauna are
extracted periodically during the season from 15 cm deep core samples (Southwood 1978).
Springtails, mites, and other arthropods are separated into families and suborders and classified
as to their ecological function with regard to nutrient cycling. Earthworm numbers, species, and
ecological niches are determined by removing a known volume of soil and hand sorting.
Objective 3 (McCaffrey): Arthropods, including spiders, harvestman, carabid and rove
beetles, and Collops spp. are sampled periodically during the season using pitfall traps and
sweep-net samples in each plot at both locations. Carabids are well known predators of slugs in
cereal systems in Europe (Ayre and Port 1996) and could be significant biological control agents
for slugs commonly found in grass seed fields (David Mosman, personal comm.). Slugs are
sampled periodically during the season using refuge traps (Bolton et al. 1996) to estimate their
relative abundance across treatments. This periodic survey of predators will help to explain the
relationships of the predators and slugs in time and space.
Objective 4 (Van Tassell and Smathers): The economic analysis will assess the production,
price and financial risk associated with each of the six bluegrass production systems. Cost and
return (CAR) estimates will be developed for each system. Ownership costs will be allocated
over the productive live of the assets required for each system using established capital recovery
methods (AAEA, 1998). A deterministic comparison of the profitability of the production
systems will be conducted using the CAR estimates, actual bluegrass seed and straw yields and
actual output prices. To quantify production, price, and financial risk, a stochastic simulation
model will be developed using @RISK (Palisade, 2000). The base model will be the sixbluegrass enterprise budgets obtained from the CAR estimates. Empirical probability
distributions for seed and straw yields will be incorporated into the model to account for
production risk. Historical bluegrass seed prices have been obtained, and cyclical and long-term
trends will be modeled using harmonic regression techniques tools (Van Tassell et al., 1989).
Residuals from these trends will be modeled and simulated to account for price risk. A planning
horizon covering the bluegrass stand life will be used in the stochastic simulation. Random
draws from each price and yield distribution will be obtained each year of the simulation while
maintaining historical correlations (Palisade, 2000). The appropriate yields from each system,
along with input and output prices, will be used to determine yearly income and cash flow. For
iteration, the net present value of each system will be determined by summing the present values
of the yearly income streams. Net present values will be compared using stochastic dominance
techniques (Hardaker et al., 1997). Differences in net present values and other key economic
indicators will also be examined using appropriate t-statistics and chi-square statistics.
Objective 5 (Wulfhorst and Smathers): Change in management and/or production may result in
socioeconomic impacts to growers related to land tenure and community well being (Salamon
1993). Bluegrass growers currently face a traditional information-subsidy-technical assistance
approach (Napier 2000) to developing economically and socially viable alternatives to open-field
burning. Growers will be contacted through purposive sampling techniques at each study site to
participate in key-informant interviews to describe ecological, economical, and sociological risk
perceptions related to bluegrass production options. Data will be analyzed within a conservation
risk model to determine overall likelihood patterns of adaptation and decision-making regarding
changes to bluegrass burning policy in Idaho, including special attention to Indian sovereignty
relating to the two study areas (Wunder 1996).
Objective 6 (Holman): Information will be disseminated to growers and the general public by
field consultants, county extension educators and scientists. Activities include annual field tours
at each site and presentations (GSCSSA annual meeting and winter extension meetings put on by
field consultants and/or county extension educators). Publications will include popular news
articles and extension bulletins (preliminary data will be published in the PNW Conservation
Tillage Handbook Series and/or UI CIS at the end of phase I and an extension bulletin will be
published at the end of phase II). Findings will be presented to scientific audiences in refereed
publications (Weed Technology, Soil Science, Journal of Applied Seed Production, etc.) and
presentations (regional and national professional meetings).
Timeline: Summer 2001 - determine plot locations and establish plots, collect residue and soil
samples, applied residue management treatments (Lewis Co. only); Fall 2001 - install weather
station, collect additional samples; Spring 2002 - applied residue management treatments and
herbicide, collect residue and soil samples; Summer 2002 - field tours, harvest plots (year 1),
collect samples, apply residue management treatments; Fall 2002 (both locations) - collect
residue and soil samples; Spring 2003 through summer 2005 - same sequence of events as
previously stated, except grass seed harvest will occur at both locations. This will complete
phase I of the study. Phase two will be fall 2006 through summer 2008 with a similar sequence
of activities.
References:
American Agricultural Economics Association (AAEA). 1989. Commodity costs and returns
estimation handbook. Ames, Iowa.
Ayre, K. and G.R. Port. 1996. Carabid beetles recorded feeding on slugs in arable fields using
ELISA. p. 411-418, In 1996 BCPC Symposium Proc. 66 Slug and snail pest in agriculture.
Blake, G.R., and P. Germann. 1986. Particle density. p. 377-382. In Methods of soil analysis.
Part 1. 2nd Ed. A. Klute (ed.). Agron. Monogr. 9. ASA and SSSA, Madison, WI.
Bolton, A., L.D. Incoll, S.G. Compton, and C. Wright. 1996. The effects of management of
rotational set-aside on abundance and dispersion of slugs. p. 109-116, In 1996 BCPC
Symposium Proc. 66 Slug and snail pest in agriculture.
Chastain, T.G., G.L. Keimnec, G.H. Cook, C.J. Garbacik, B.M. Quebbeman, and F.J. Crowe.
1997. Residue management strategies for Kentucky bluegrass seed production. Crop Sci.
37:1836-1840.
Ghidey, F., and E.E. Alberts. 1997. Plant root effects on soil erodbility, splash detachment, soil
strength, and aggregate stability. Transactions of the ASAE 40:129-135.
Grossbard, E., and G.I. Wingfield. 1978. Effects of paraquat, aminotriazole and glyphosate on
cellulose decomposition. Weed Research 18:347-353.
Grossbard, E., and D. Harris. 1979. Effects of herbicides on the decay of straw, p. 167-176, In E.
Grossbard, ed. Straw decay and its effect on disposal and utilization. Wiley, Chichester.
Hardaker, J.B., R.B.M. Huirne, and J.R. Anderson. 1997. Coping with risk in agriculture. CAB
International. New York, NY.
Heckman, J.R., H. Liu, W. Hill, M. DeMilia, and W.L. Anastasia. 2000. Kentucky bluegrass
responses to mowing practice and nitrogen fertility management. Journal of Sustainable
Agriculture 15:25-31.
Hendrix, P.F., and R.W. Parmelee. 1985. Decomposition, nutrient loss and microarthropod
densities in herbicide-treated grass litter in a Georgia piedmont agroecosystem. Soil Biol.
Biochem. 17:421-428.
Kemper, W.D., and R.C. Rosenau. 1986. Aggregate stability and size distribution. p. 425-442. In
A. Klute (ed.) Methods of soil analysis. Part 1. 2nd ed. Agron. Monogr. 9. ASA and SSSA,
Madison, WI.
Klute, A., and C. Dirksen. 1986. Hydraulic conductivity and diffusivity: Laboratory methods. p.
687-734. In Methods of soil analysis. A. Klute (ed.) Part 1. 2nd Ed. Agron. Monogr. 9. ASA and
SSSA, Madison, WI.
Mahler, R.L., and R.D. Ensign. 1989. Evaluation of N, P, S and B fertilization of Kentucky
Bluegrass see in northern Idaho. Commun. in Soil Sci. Plant Anal. 20:989-1009.
Murray, G.A. 1996. Bluegrass seed production without open-field burning. STEEP II Prog. Rep.
Murray, G.A., and J.B. Swensen. 1997a. Kentucky bluegrass floral induction and cultivar
response to mechanical removal of harvest residue. International Grassland Congress
Proceedings. Session 7. Plant Physiol. and Growth. p. 13-14.
Murray, G.A., J.D. Griffin, V.J. Parker-Clark, and J. B. Swensen. 1997b. Floral induction and
seed yield relationships in perennial turfgrasses. Perennial Cool Season Turfgrasses Seed
Production Symposium. Amer. Soc. Agron. Abstracts. p.120. Oct 26-31, Anaheim CA.
Murray, G.A. and W.J. Johnston. 1995. Cultivar identification and on farm technology for
sustained Kentucky bluegrass seed production. Grass Seed Prod. Systems for Sust. Agr. Prog.
Rep. p. 37-40
Napier, T.L. 2000. Use of Soil and Water Protection Practices Among Farmers in the North
Central Region of the United States. Journal of the Amer. Water Res. Assoc. 36(4):723-735.
Painter, K.M., D.L. Young, D.M. Granatstein, and D.J. Mulla. 1995. Combining alternative and
conventional systems for environmental gains. Am. J. Alt. Agric. 10:88-96.
Palisade. 2000. @RISK, advance risk analysis for spreadsheets. Palisade Corporation,
Newfield, NY.
Pollard, F. 1979. The decay of straw on the surface of undisturbed soil in the field and the effects
of herbicides, p. 177-184, In E. Grossbard, ed. Straw decay and its effect on disposal and
utilization. Wiley, Chichester.
Salamon, S. 1993. Culture and Agricultural Land Tenure. Rural Sociology 58(4):580-598.
Schlesinger, W.H. 1991. Biogeochemistry: An Analysis of Global Change. 2nd ed. Academic
Press, San Diego.
Southwood, T.R.E. 1978. Ecological methods, with particular reference of the study of insect
populations. 2nd Edition. John Wiley & Sons, New York.
Stott, D.E., H.F. Stroo, L.F. Elliott, R.I. Papendick, and P.W. Unger. 1990. Wheat residue loss
from fields under no-till management. Soil Sci. Soc. Am. J. 54:92-98.
VanTassell, L.W., J.R. Conner, and J.W. Richardson. 1989. The impact of range improvements
on the success and survivability of producers in the Eastern Rolling Plains of Texas. Texas
Agricultural Experiment Station Bulletin No. 1618, July.
Wunder, J.R., ed. 1996. Native American Sovereignty. Garland Publishing, Inc., New York.