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The University of Arizona
Department of Soil, Water,
and Environmental Science

IK 2010 Phase I Field Study Installation
Materials and Methods

In April 2010 the eastern half of the impoundment was selected for establishment of four years worth of field studies. Two areas were surveyed; one which would encompass study years 1 and 2 (1.71 ac; 0.69 ha) and a second for study years 3 and 4 (2.28 ac; 0.92ha).

Phase I and II area prior to land prep in 2010
aerial image field study location and layout

Each block was ripped and cross ripped to a depth of 15 in. (38 cm) with a John Deer 410 track dozer to break up the hard pan occurring between 10 and 12". Ripping was followed with an agricultural disk to breakup large clods and even out the surface [Fig.3]. Initially a small tractor and light weight disk was used, but it proved to be ineffective at breaking up the large clods created during ripping. As a result a heavier track dozer and larger/heavier disk was needed to create a surface suitable for planting.
Study area was ripped and cross ripped to 15" surface after ripping
attempting to disk field with too small and disk bigger disk, BIGGER TRACTOR
effective disking surface following disking

In May 2010 plot borders were staked out for the year 1 study. Twenty four plots (31.7ft x 50ft; 7.6m x 15.2m) were laid out in a randomized complete block design, with 6 treatments of varying compost and seeding rates [Table 1 and 2], and 4 replications blocked against a previously surveyed pH gradient [Figure 4] (Hayes etal, 2009).

Table 1. Field Study Treatments
Treatment #
Treatments (replicated four times)
% Compost w/w
seeded *
seeded *
seeded **
* all selected species used. ** only buffalo grass and mesquite species used

Table 2. . Species and Seeding rates for Seeded Treatments

Seeding Rates
common scientific
Arizona Fescue Festuca arizonica
Buffalo Grass Buchloe dactyloides

Quail bush Atriplex lentiformas
Mountain Mahogany Cercocarpus montanus

Catclaw Acacia Acacia greggii
Mesquite Prosopis juliflora

Figure 4. Site Selection pH survey

Composted dairy manure (Arizona Dairy Compost, LLC) (Table 3 and 4) was applied to plots according to treatment designations using a John Deere 210 front end loader. The applied compost mass was weighed out by the bucket load using truck scales prior to applying to the plots. The compost was spread on out the plots with the front end loader [Fig 5] and then rototilled into the tailings with an 80 inch pto-driven rototiller. Following treatment applications, three soil cores (1.25" diameter, 3 ft deep) per plot were collected to establish initial chemical parameters.

compost delivery
Compost applied by the bucket load

Small seed species were hand broadcasted over the plots according to treatment designations. Seed was mixed into the tailings using a 80" spiked toothed harrow and chain link drag. Following seeding Straw was scattered over the plot surfaces at a rate of 150 lbs/plot (2 bales). The hay was then crimped 4 inches deep into the tailing surface with a bank of four 18" agricultural disk blades. Seed and hay applications were conducted at night as high winds during the day made these operations difficult.

night time broadcast seeding
hay applied and crimped

Large seeded species (mesquite and acacia) were sewn by hand post hay application. Each specie was planted to to two seed lines across the length of the plot, 1.0 inch deep and 12" apart. Seed lines were were spaced 3 foot apart and species were alternated between the seed lines.

Once treatments were complete plot borders were completed with an 80" border disk. The finished plot size after completion of the borders was 25ft x 43ft. A sprinkler system was then installed to provide irrigation and fence was erected around the study area to to inhibit wildlife grazing.

In June 2010 an onsite weather station was erected with allowed for real time web access monitoring of weather parameters, estimated reference ET, and representative soil moisture status.

Plots were irrigated every 7 to 10 days in the absence of rainfall. Due to limited water availability the amount of water applied was limited to about 0.5" per application representing about 25 to 40 % of the estimated ET.

sprinkler irrigation

A photolog of the field status was recorded with each irrigation event .

In Sept. 2010 plant canopy cover and specie composition were surveyed using Duabenmire methods to make treatment comparisons. No plant biomass was collected so as to minimize disturbance to established plants and thus minimize affect on evaluation of over winter survival. [2010 canopy survey]

pvc frames used for estimated canopy cover of a 1 sq. m area
pvc frames used for estimated canopy cover of a 1 sq. m area
Irrigation was suspended in November when signs of winter senescence were observed. Irrigation system was winterized to prevent frost damage.
Quail bush and grass entering winter senescence
buffalo grass entering winter senescence
In April 2011, irrigation was restarted as spring sprouting was noted and the Phase II study was established.

Arizona Crop Information Site
Arizona Crop Information Site

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