DAIRY MANURE COMPOST EXPERIMENT
Report- 1999

Committee: Dianna Sarich, Denise Guessford, JoAnn Bruenitner, Angelika Schlager, Stephanie Twiford, Dale Anderson, Rochelle Green, Whatcom County WSU Cooperative Extension Master Gardeners

Consultation by: Joyce Jimerson, Master Composter Coordinator and David Simonson, Master Gardener Coordinator at Hovander Park.

Purpose: to utilize scientific methods to measure the benefits of composted dairy manure in vegetable gardening and to conduct the experiment in an area accessible to the public in order to raise awareness and educate the community in the benefits of using composted dairy waste

Hypothesis: Properties of composted dairy manure are beneficial to gardening

Part One: Selection of Specimens

We based the selection of vegetables to grow on ease and speed of growth, ease of quantifying the outcome, popularity of the vegetables in residential gardens in Whatcorn County, and natural resistance to pest and disease. Bush beans, broccoli, and beets met the selected criteria.

Seeds chosen:

Bean -- Lilly Miller brand of Blue Lake Bush Bean
Beets -- Lilly Miller brand of Early Wonder
Broccoli -- Gem Girl, the plants supplied by Dave Simonson
Both beans and beets were direct seeded into the prepared beds.

Part Two: Site Preparation

We selected a site 17ft x 28ft north of and adjacent to the Compost Demonstration Site. To ensure uniformity of the garden area, the entire area was a virgin field which had not been used as a garden area in recent years. Soil samples were analyzed for any needed nutritional amendments.

After tilling, the garden bed was raked, leveled and measured into sections. (Click here to see plot map)

We staked the four corners, as well as corners of the sectioned off plots. Hopefully, these stakes will stay in place during the winter so that when this experiment is repeated next year, it will simplify re-aligning the plots.

We subdivided each third of the garden area into 8 plots or replicates. Results of the soil tests indicated that the soil needed no amending. We worked soil in each replicate equally. We randomly chose replicates to receive dairy compost. To each of these we added 3 five gallon buckets of dairy compost. The compost was worked into the soil 4 inches deep. Control replicates were also reworked to a depth of 4 inches, however no compost was added.

Part Three: Specimen planting and Care

We set out broccoli plants at 4 plants per replicate. To ensure some degree of consistency the two people doing the planting each planted 2 treated and 2 untreated replicates. Deadline slug bait circled the entire broccoli bed. As the broccoli matured, we applied 2 applications of BT to control any problems with cabbage moth.

We planted beets at 3 seeds per hill with hills spaced 7 inches apart in 3 rows running north-south, 5 hills per row.

Beans were planted at 3 seeds per hill, 4 hills per replicate. These were later thinned to 2 plants per hill.

Click here to view site map

One individual person watered the entire garden area on any given day to ensure some degree of consistency. We weeded regularly.

Peacocks and rabbits were creating some problems and it was necessary to put a mesh fence around the entire garden. (Unfortunately, this did not prevent the peacocks or rabbits from entering the area.)

Part Four: Germination Rate for Directly seeded beds

Beets

Totals: 131 treated and 136-untreated

Bush Beans

Totals: 37 treated and 41 untreated

Generally, beds without compost germinated only slightly better than those treated.

Part Five: Measurement Guidelines for Harvesting and Recording

The weight of the edible parts of each plant was the guideline for measuring the experiment. Beet weights included root and leafy portions of the plant as both are edible and are regularly used for consumption. Broccoli was cut when the heads and side shoots were mature but before starting to flower. Beans were picked when about the diameter of a pencil. To ensure consistency, the same individual harvested an entire crop while another weighed and recorded on any given day. In order not to overwhelm the Food Bank, beets were harvested in 2 batches, 2 treated and 2 untreated replicates at each harvesting.

Beet Harvest

Totals:

Difference in yield:

Broccoli

Difference in yield:

Bush Beans

All weights are in pounds

Difference in yield:

General Observations and dates:

5/25 Broccoli plants set out
6/2 Beets planted
6/9 Beans planted

Comment: It was easier to plant in the soil of the treated replicates. It was also easier to water because the treated soil seemed to more readily absorb water.

6/30 Broccoli: For some reason the plants in both replicates I (control) and 5 (treated) did poorly. 4 broccoli plants were replaced, 2 each in RI and R5. It is noted that both of these replicates as a result were 2 weeks slower to produce mature stalks

7/14: All of the bean plants of control replicates have interveinal chlorosis with necrosis on the leaves. Upon close inspection it was noted that not a single plant in the treated areas was observed to have this. A possible explanation is magnesium deficiency in the plants in non-treated areas.

Samples of soil from the treated, untreated and of pure compost revealed big differences in extractalble magnesium, as well as calcium, potassium and sodium.

At the end of the growing season, bean plants were tested to determine the magnesium content, to further substantiate the diagnosis of magnesium deficiency. The results supported the hypothesis:

7/31 Visually, broccoli plants in the treated area have larger heads developing. Bean plants in the treated replicates look bigger, lusher. No sign of the rusty areas on any bean leaves. Apparently those leaves affected withered away, leaving the plants with no telltale indication that this condition ever existed.

Several people noted that weeds in the treated replicates were easier to pull. Treated replicates continue to be easier to water.

8/11 Beets: On the second beet harvest, it was noted that in R2 (treated) gray "mold" was observed on several of the beet roots. According to resources that Joyce Jimerson consulted, this is a positive finding.

Part Six: Conclusion

Adding composted dairy manure increased yields measurably in the, overall harvest totals. It was interesting to note that the control replicates of bush beans initially yielded more but later the treated areas quickly caught up and then surpassed the controls. Possible explanations include a) untreated bushes were less leafy and lush which allowed sun and warmth to mature the beans earlier b) untreated bushes were a little more stressed-and needed to complete their fife cycle more quickly.

Part Seven Recommendations

We recommend that this study be continued for several more seasons for several reasons. It would be interesting to see if the results of this year's experiment can be duplicated and what accumulative effects, if any, annual applications of dairy manure compost to the treated sites produces over a period of several years.

Report completed by Dianna Sarich on 10/4/99 and submitted to: Craig MacConnell, WSU Cooperative Extension Agent, Joyce Jimerson, Master Composter Coordinator and David Simonson. Also copies given to each member participating in this project.

Whatcom County Agriculture Page | Whatcom County Home Page | Whatcom County Home Composting Page