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Progress Report: Rustand Pasture Imprinting project
Several substantial rains in Dec 97 delayed the imprinter seeding until 7 Jan 98. The 6-foot demonstration imprinter, fully weighted, accomplished the seeding and imprinting in a once-over operation. The soil was still moist from the December rains and was thus soft enough to not require ripping before imprinting. The silty soil area on the east side was the hardest, whereas the sandy soil in the extreme northwest corner was the softest. In fact the sandy soil area was imprinted last, at which time all weight was removed from the imprinter to prevent the imprinting roller from bogging down into the soft sand.
A diverse seed mixture of a number of different plant species was dropped on top of the imprinting roller, carried forward by the roller, and then imbedded in the faces of the imprints. The mix contained an equal volume of red flaky wheat bran to prevent seed segregation in the seed hopper. Without the bran, the smooth dense seeds tend to settle downward and the fluffy light seeds rise to the top like the shaking of a bowl of partially popped corn.
The seed-mix given in the Table included early mid and late seral species to accelerate the secondary succession toward the establishment of a desirable plant community of perennial forage species. Seeding rates in pounds of pure live seeds (PLS) per acre are also tabulated along with the seral stage of each species--early, mid and late. Season of germination and growth are included in the Table.
After imprinter seeding, the remainder of January was dry except for one small shower. A series of good rains occurring on 5, 9, 15, 17, 20 and 24 Feb totaling about 3 inches germinated many of the seeds of the cool season species. The resulting seedlings along with annual seedlings from the soil seed bank are now greening the pastures ( see photos ). Many soil bank seeds germinated after the December rains thereby giving the resulting seedlings a head start on the February-germinated seedlings. Soil bank seedlings include such species as wild mustard, stork's beak, red brome, cheeseweed, fiddlehead, etc. These species perform the beneficial roles of early seral species, however when they get a head start, copious growth may provide excessive competition for moisture and light with the seeded species. Mowing these plants using a garden tractor with the blade set as high as possible will let light reach the seeded species that are too short to be harmed by the mower. Larger tractors, generally, should not be used for the mowing operation, as they will smash the seeded seedlings along with the imprints.
March turned dry again like January until a total of nearly 1-1/2 inches of rain fell in two rains occurring on the 26 th and 29 th . This rain was preceded by some unseasonably warm weather that may have germinated some seeds of warm season species. Warm season species in the soil bank and those that were seeded will germinate mostly after adequate summer monsoonal rain occurs. Dead winter annuals will help the warm season species become established by providing protective cover and mulch.
Prior to imprinting, several low east-west trending soil ridges were formed using a 3-point border disk. These ridges act like terraces, shortening the land slope length for water runoff and erosion control. These ridges were seeded with the main mix and also with a mix of southwestern flowers (see list). Some of the flower mix was also scattered along the bramble barrier. Also some commercial birdseed was added to the flower mix to increase its diversity even more. The birdseed contained grain sorghum pearl millet, sunflower and wheat.
LIST: SOUTHWEST WILDFLOWER SEED MIX
Desert Marigold African Daisy
Rock Daisy Palmer Penstemon
Firecracker Penstemon Arizona Lupine
Desert Senna Mexican Gold Poppy
White Mexican Primrose Arroya Lupine
Upright Prairie Coneflower Scarlet Flax
Desert Lupine Firewheel
Desert Globemallow Lance-Leaf Coreopsis
Purple Verbena Blanket Flower
California Bluebells California Poppy
Tidy Tips Annual Sunflower
Notes: Most of these wildflowers germinate in the fall or early
winter if rainfall is adequate and then bloom in the
spring. Next fall this mix will again be scattered along
pasture ridges and the bramble barrier.
Future expectations and maintenance includes:
1) The lush growth of annual plants will die a natural death in May as the weather dries.
2) Saltbush that germinated during the cool season will emerge through the layer of dead annuals.
3) Warm season species will germinate when and if adequate monsoonal rain occurs usually during
the last half of July, August and the first half of September.
4) Some thick patches of tumbleweed may require mowing in mid to late summer.
5) Some areas with thin stands may require reseeding, but probably not before 1999.
6) Initially, the pastures will have a somewhat ragged appearance as perennial species are replacing
the soil bank and seeded annuals.
TABLE : FORAGE SEED MIX
SPECIES SEEDING RATE SUCCESSION SEASONALITY LONGEVITY TYPE
Common (latin) #PLS/ Acre Seral Stage Cool/Warm Annual/Perennial S/G/F
Quailbush (Atriplex lentiformis) 1 late C/W P S
Fourwing Saltbush (Atriplex canescens) 1 late C/W P S
Desert Saltbush (Atriplex polycarpa) 1 mid C/W P S
Wilman lovegrass (Eragrostis superba) ½ mid C/W P G
Cochise lovegrass (Eragrostis lehmann x ather) ½ mid C/W P G
Lehmann lovegrass (Eragrosis lehmanniana) ½ mid C/W P G
Plains bristlegrass (Setaria macrostachya) ½ late W P G
Sand dropseed (sporobolus cryptandrus) ½ late W P G
Sideoats grama, Vaughn (Bouteloua curtipendula) ½ late W P G
Arizona cottontop (Tricachne californica) ½ late W P G
Bermudagrass (Cynodon dactylon) ½ mid W P G
Perennial ryegrass (Lolium perenne) 2 early C A G
Indianwheat (Plantago insularis) 1 early C A F
Brittlebush (Encelia forinesa) ¼ mid C/W P F/S
Notes:
1) Early cool season species will be the first plants to appear, followed by mid-seral species. Ultimately the plant community will consist primarily of late
seral forage shrubs and grasses .
2) Legend: PLS = pure live seed, C = cool , W = warm , S lash ( / ) = both , A = annual , P = perennial , F = forb , G = grass , S = shrub
APPENDIX: Pasture Project Photos
Photos 1 & 2. Thawing of a deep snowpack in the upper tributaries of the Tanque Verde Wash has maintained a rapid flowing stream for the last several months. Fortunately a late spring has prevented serious flooding so far.
Photos 5 & 6. The two photos in a northwesterly view, taken from the south central part of the pasture, show the considerable greening that resulted from a series of February rains. Saltbush seedlings are coming up beneath the winter annuals in foreground.
Photos 9 & 10. Views from above individual imprints revealing how they work to germinate seeds and establish seedlings. Resources such as seeds, rainwater and plant litter are concentrated in the bottom of imprints to accelerate revegetation processes.
Photo 11. With help from the Rustand Family, a lush growth of soil bank annuals was mowed in early April to allow the seeded species more light and soil moisture. They were mowed several inches high to not damage the relatively short saltbush seedlings. The head start of the soil bank seedlings, combined with above normal rainfall, made the mowing necessary. The mown plants will serve as a beneficial mulch to help warm season plants become established during the summer monsoon.
Photos 7 & 8. A nine-week response to the imprinter seeding treatment in the eastern part of the pasture. Wildflowers seeded along the terrace/dike in the foreground were beginning to bloom by income tax day.
Photos 3 & 4.
The first step in pasture establishment was to form east-west trending dikes or terraces to shorten the length of slope to aid the imprints in controlling runoff and erosion. The imprints in photo 2 show that some of the seedbank seedlings survived the imprinting operation. The shade in the bottom of imprints helps seeds to germinate and seedlings to survive with minimal rainfall. The V-shaped imprints funnel vital resources together to establish the seeded vegetation.
The Imprinting Foundation
1616 E. Lind Road
Tucson, Arizona 85719