Western Oregon Grass Seed Crop Rotation and Straw Residue Effects on Soil Quality

Abstract

Understanding the impact of crop rotation and residue management in grass seed production systems on soil quality and, in particular soil C dynamics, is critical in making long-term soil management decisions supporting farm sustainability. Th e eff ects of a 6-yr rotation and residue management (high vs. low residue) on soil quality were investigated at three locations in Oregon, each contrasting in soil drainage classifi cation. Th e crop rotations were continuous perennial grass seed production, grass/legume seed production, and grass/legume/cereal seed production. Th e grass species grown at each location were diff erent and represented those most commonly produced in each environment; perennial ryegrass (Lolium perenne L.), tall fescue [Schedonorus phoenix (Scop.) Holub], and creeping red fescue (Festuca rubra L.). All three grass seed crop rotations and residue methods maintained high soil quality in conventional or direct seeded soils, but under some situations, soil quality was higher with continuous grass rotation and high residue. Data suggest that straw removal for value-added use, like bioenergy production, can be accomplished in the Pacifi c Northwest Marine climate without appreciably aff ecting soil quality. Furthermore, grass seed cropping systems play an important role in soil C storage and enhancement, a valuable ecosystem service in this region where grass seed is produced on land that is not suitable for production of conventional crops that require better-drained soil. We conclude that by nature perennial grass seed crops promote high soil fertility and enriched soil C pools and consequently contribute to the tolerance of these systems to the use of less conservation-oriented crop management methods at times when crop loss could be potentially high. Th is attribute provides producers greater latitude in selecting soil and crop management options to address issues of soil fertility, pest, weed, or seed certifi cation to minimize economic crop yield losses. Perennial ryegrass-Linn CountyGrass (G P ): perennial ryegrass (3 yr/3 yr); CT Grass/Legume (GL P ): white clover (2 yr)/meadowfoam (1 yr)/perennial ryegrass (3 yr); CT Grass/Legume/Cereal (GLC P ): white clover (2yrs)/perennial ryegrass (3 yr)/wheat (1 yr); CT Tall fescue-Benton County Grass (G T ): tall fescue (3 yr/3yrs); CT Grass/Legume (GL T ): red clover (2 yr)/meadowfoam m(1 yr)/tall fescue (3 yr); CT Grass/Legume/Cereal (GLC T ): tall fescue (3 yr)/red clover (2 yr)/wheat (1 yr); CT Creeping red fescue-Marion County Grass (G F ): creeping red fescue (3 yr)/creeping red fescue (3 yr); DS Grass/Legume (GL F ): creeping red fescue (2 yr)/creeping red fescue (3yrs)/red clover (1 yr); DS Grass/Legume/Cereal (GLC F ): fi ne fescue (3 yr)/wheat/red clover (2 yr)/fi ne fescue (1 yr); DS

Spatial methods for deriving crop rotation history

“…Indeed, such fields sometimes posed challenges to trained personnel during drive-by, roadside collection of groundtruth data. Transitions needing correction matched some of the more common classification errors detected in the original 11-years of landuse data(Mueller-Warrant et al, 2011 and2015).The end products of corrections made to crops in the transition period into new grass seed stands in general duplicated cropping sequences already present at high frequency (data not shown). A total of 36 PR and 116 TF fields had to be omitted from further analysis because their cropping sequences were too ambiguous.…”

“…This research was conducted over 25,303 km 2 of the Willamette River basin and nearby drainages in north-western Oregon and south-western Washington from 2004 to 2014 as previously described in detail (Mueller-Warrant et al, 2011, 2015, 2016a, and 2016b. Groundtruth data of crop kind and stand establishment phase were collected during drive-by, roadside surveys of 3000 to 7000 fields per year, simplified into 57 landuse categories representing ~99% of the area.…”

“…First, links from one grass seed stand to the next would produce knowledge of the number of years growers use to change their seed crops, a key variable for interrupting pest cycles and reducing populations of weeds, diseases, and invertebrates. Second, frequencies at which specific rotational crops appear in the years between two grass seed stands could determine whether growers choose certain crops for their anticipated benefits or merely randomly select them (Griffith et al, 2011;Mueller-Warrant et al, 2016b).…”

Detecting and correcting logically inconsistent crop rotations and other land-use sequences

“…Counts of allowed transitions between general category groups and each row's specific class, both from a specific class the previous year into a general class group and from a general class group the previous year into a specific class 2002a, 2002b, 2005Steiner et al 2006;Mueller-Warrant, Whittaker, and Young III 2008;Griffith et al 2011;Hoag et al 2012;. Strict landuse laws and regulations in Oregon governing both forest management and urban development served as the basis for prohibiting most transitions into new urban development or out of forest.…”

Yield and Quality of Straw of Italian and Perennial Ryegrass Cultivated for Seed Production

“…This method was advantageous for farmers as it was cheap and solved sanitary problems with diseases, pests and weeds, recycled mineral nutrients and supported autumn tillering of the grasses (Stamm, 1992). Due to air pollution, risk of traffic accidents (low visibility along fields) and a hazard of fires spreading to nature, this management is banned (Griffith et al, 2011). American farmers had to find another way of straw disposal and they bale it and offer for erosion control during grassing of slope areas (e.g.…”