Continuing Compost Research
Continuing Compost Research
California State University, Chico, Research Foundation Project # 69225
1. Soil Incorporation
2. Compost Degradation
3. Strawberry Fungus
4. Plant Phytotoxicity
5. Plant Pathogen Suppression
6. Marketing Class Activities
7. Rice Productivity
8. Winter Forage
1. Soil Incorporation Study:
A pilot study was completed to determine the effect of compost on plant toxicity, soil fertility and rice productivity. The study begun in June (2000) and focused on a 22 acre plot in Williams, California, an area that is primarily rice producing land in the Sacramento Valley.
The test site was divided into plots to evaluate the following treatments: 1) Compost @ 4 tons/acre, 2) Chicken manure @ 2 tons/acre, and 3) Urea at 300#/acre. Each of these plots were replicated and harvested in 18' X 350' strips for analysis of total rice yield/square yard. Both chicken and compost was applied via flail wagon application, urea was flown on with an applicator plane.
For comparison purposes, 3 other plots were also planted to determine the added effects of urea in both the compost and chicken manure treatments. Because these plots were not replicated, they serve primarily as a demonstration site. Following application, the ground was prepared and planted to a short-season rice variety, variety 202.
The rice was harvested in November of 2000 using conventional methods. Each plot was harvested in 18' X 350' strips, each strip was weighed using a mechanized weigh wagon, the use of which was generously donated by the University of California.
Compost, provided by CSU Research Foundation, has been shown to be free from plant toxicities in field tests with rice variety 202 and in green house experiments with strawberry plant varieties.
Yield data shows no significant difference between the fertilization regimes used in this preliminary study. This data would suggest that compost, at 4T/acre, is comparable to urea at 300#/acre and chicken manure at 2T/acre in this particular soil type. Because organic growers are looking for alternatives to chicken manure, further study is needed to determine if this data can be replicated on a larger scale. Next spring, 5 replicates of these same 3 treatments will be conducted on 15 checks in Williams, providing the necessary replications to more fully evaluate this comparison.
2. Compost Degradation Study:
This project will address the issue of compost inoculants on the rate of material breakdown within the in-vessel pod system. Currently, compost breaks down over a 60 day period, followed by a 30 day cure in a static pile. Inoculants may enhance the rate of breakdown within the pods through production of added cellulase and lignase enzymes. This particular experiment will be conducted by CSU Chico students on the University Farm where the pods and the samples can be controlled precisely.
Following site approval and committee recommendations, we are cleared to move on site development at the University Farm. This will provide for small scale composting research under a more controlled setting to fully evaluate the effects of mixture and inoculants on compost degradation and quality.
3. Strawberry Fungus Study:
This particular project addresses the effects of compost on plant pathogens. There is some evidence that compost derived from livestock waste has pathogen suppressing capabilities. Dr. Hoitink, Professor of Plant Pathology at Ohio State University believes that compost can actually induce systemic resistance to plant disease.
Vegetable Crop Applications
Compost was also tested under greenhouse conditions as a fertilizing agent for strawberry production. For this particular study, strawberry seedlings were obtained and planted in 1/2 gallon containers containing a peat moss based soil mix. Fertilizer was added to each pot according to a standard quantity of N. Again, the fertilizers compared were raw cow manure, chicken litter, compost and both a positive (miracle grow) and a negative control (no fertilization). All plants were monitored for leaf eruptions over time as well as fruit productivity.
Both chicken manure and compost had a considerable portion of total N in the organic form. To accommodate the slow rate of demineralization, chicken manure, and compost were added at 2.5 times N. At present, it is not known what the exact rate of demineralization is for the various organic compounds, so we also included a 5 times N treatment group to accommodate the possibility of a 20% demineralization rate.
Miracle Grow produced the leafiest growth and the most visually appealing strawberry plants. However, it did not produce the most fruit. The 5 times N compost group produced the most fruit while stimulating a more moderate amount of green leaf growth.
Chicken manure tended to burn the plants at higher concentrations, i.e. 5 times N. Those plants tended to be stunted early on and then seemed to compensate following recovery.
Post-harvest Soil Conditions
Soil samples were collected post-harvest to determine if in fact, compost leaves behind nitrogen stores for the next crop. Indeed, the compost treated soils contained the highest total N, with the lowest NO3 ppm (leachable N) of any treatment, although not statistically different from it's leading competitor, chicken manure. In addition, soil pH was also affected by fertilizer regime and organic fertilizers maintained a more favorable pH than the inorganic treatment, i.e., Miracle Grow. Ideal soil pH would be considered greater than 7; miracle grow reduced post-harvest soil pH by roughly 15%.
4. Plant Phytotoxicity Index:
As with any new product, it is important that the material does no harm. Two separate assays were conducted to determine if plant toxicities existed. Seeds were germinated in compost extract to determine the rate of seed germination and rate of growth as compared to chicken litter, compressed pig manure and an untreated control.
Relative root growth was also stunted by raw chicken manure, as demonstrated in the above photo and the graph below. Compost, on the other hand, stimulated significant root growth.
These data suggest that compost is superior to chicken manure in the critical areas of seed germination and seedling growth.
5. Plant Pathogen Suppression:
Manure based composts have been shown to inhibit soil borne plant pathogens, particularly fungal organisms. We felt it was important to determine if rice straw compost possessed pathogen-suppressing capabilities. Certainly this would be of significant benefit to growers and add value to the marketability of this material.
This particular study was completed in cooperation with Dr. Patricia Delwiche, Plant Pathologist, California State University, Chico and Summer White, student intern. Dr. Delwiche has worked with a variety of fungal organisms and felt that watermelons would provide an appropriate test for the soil suppressing nature of the compost. The fungus used in this experiment is called Fusarium, an organism that lives in infected soils, causing leaf wilt in a variety of vegetable crops across the country.
To test this hypothesis, watermelon seedlings were germinated and tap roots clipped to mimic root tip damage, thus compromising the seedling prior to exposure to the Fusarium inoculation. Approximately 20 seedlings were allotted to one of eight treatments.
1. Control, non - inoculated (NI)
2. Control, inoculated (I)
3. 10% compost, NI
4. 10% compost, I
5. 20% compost, NI
6. 20% compost, I
7. 30% compost, NI
8. 30% compost, I
Seedlings from treatments 2, 4, 6 and 8 were bathed in Fusarium inoculum prior to planting, providing a complete exposure to the fungus.
Each treatment contained 24 seedlings, which were monitored daily for signs of disease. After 3 weeks, the data was compiled and is summarized in the following graph. Non-inoculated control plants were slightly cross contaminated, developing a 20 % incidence of Fusarium-like symptoms. As expected, 100% of the control inoculated seedlings developed symptoms.
Seedlings treated with 10% compost demonstrated 40% sickness, a 60% reduction as compared to the inoculated controls. There was a slight increase in the % suppression as the concentration of compost increased in the soil mix. Thus, our data suggests that rice straw compost has soil pathogen suppressing capabilities that enhance plant health and productivity.
6. Marketing Class Activities
Additional marketing options are being explored in cooperation with Broken Box Ranch. Solvita testing of the CSU Chico compost indicates that the compost is mature and may be saleable to California Transportation Department for road improvement purposes. Passing the Solvita test is the first criteria towards satisfying the CalTrans expectations for compost quality.
Our initial tests indicated that the compost was still active and required further curing. Following a 30 day cure, further testing indicated that both carbon-dioxide and ammonia levels resulted in a high maturity index.
7. Rice Productivity Study
A pilot study was recently completed in the summer of 2000 to determine the effect of compost on plant toxicity, soil fertility and rice productivity. The study focused on a 22-acre plot in Williams, California, an area that has been used primarily for rice production in the Sacramento Valley.
The test site was divided into plots and treated with the following: 1) Compost @ 4 tons/acre; 2) Chicken manure @ 2 tons/acre; and 3) Urea at 300#/acre. The amount of fertilizer was calculated for a standard N. Each treatment was replicated 3 times and harvested in 18' X 350' strips for analysis of total rice yield /square yard. Both chicken and compost was applied via flail wagon application, urea was flown on with an applicator plane.
The rice was harvested in November of 2000 using conventional methods. Each 18' X 350' strip was weighed using a mechanized weigh wagon.
Urea produced the most consistent yield as shown by the narrow standard deviation, although there were no statistical differences between plots in total yield.
8. Winter Forage Trial
A winter forage trial was conducted in the fall of 2001, designed to compare compost with its major competitor for the organic growers market, turkey manure. As a positive control, a third treatment implemented anhydrous nitrogen at 140 units/acre. All other treatments were standardized to similar N concentrations. Applications of turkey manure reached 4 T/acre, while compost was applied at 6T/acre to achieve comparable N values. Each treatment was replicated 5 times and covered roughly 3 acres/plot.
Each test plot was swathed/chopped and weighed separately generating tonnage values for each replicate. Special thanks to Dan Luis for his cooperation and generous donation of time, equipment and energy.
At constant N, the inorganic fertilizer produced 5 ton to the acre while turkey and compost produced roughly 3.5 and 3 tons/acre, respectively. As expected, the plant material also tested higher for crude protein content as compared to either turkey or compost treated crops. Turkey had a slight advantage over compost in both overall tonnage and crude protein content within the plant material.
However, the organic fertilizers contained higher TDN (total digestible nutrients) values than aqua treated forage, suggesting that the overall nutrient content may be enhanced by organic fertilizers.
Compost tends to demineralize slower, releasing N over time, thus reducing the amount of leachable N in the soil. Indeed, post harvest soil analysis indicates that the aqua treated soil contained significantly higher NO3 levels than the composted treatment, leaving the possibility for nitrate leaching into ground water. The real benefit of compost becomes reality in year 2 or 3 of consistent use, at that point in time, there is enough organic N demineralizing to supply the crop with adequate N for optimal growth and yield.