Improving Organic Crop Production with Enhanced Biofumigation and Composting Systems

Improving Organic Crop Production with Enhanced Biofumigation and Composting Systems

Summary

During the second year of the project we were able to establish plots on three organic growers farms. These plots will be repeated this year. Since the effects of the treatments are cummulative over several years we will attempt to put the same treatments in the same locations on each farm. The influence of biofumigation and compost on the soil microbial activity takes 2 to 3 years to cause the shift from pathogens to beneficial organisms. During the second year of the project we were able to demonstrate at the North Carolina State University Agricultural Experiment Station at Fletcher,NC(second year for these plots)that there was an increase in bacterial counts in the soil and a favorable effect on yield. This confirms previous findings at the Knoxville location (at the University of Tennessee Agricultural Experiment Station). Demonstrations and discussions of biofumigation and composting were presented at several grower and scientific meetings this year and a web page for the project was constructed.

Objectives/Performance Targets

Objectives for the second year of the project (2004) were:
1) Testing the effect of biofumigation (cover crop, mustard meal and compost application) on tomato yield and early and late blight development in the field experiments.
2) Testing the effect of biofumigation on Early, Late, and Southern Blight development in the field experiments.
3) Testing the effect of biofumigation (cover crop, mustard meal and compost application) on bacterial and fungal characteristics of the soil in the field experiments and commercial sites at different locations.
4) Validation of the optimal combinations of mustard meal and compost in experiments with commercial growers.
5) Developing a webpage for the project “Enhanced Biofumigation & Composting”

1) The use of Brassica cover crop (fall and spring incorporation), mustard seed meal (three doses) and compost in combination with mustard meal for biofumigation was studied in field experiments with tomato plants at two locations. The first experiment was established in the fall of 2003, at the Knoxville Experimental Station (Tennessee) on the lower terrace of the Tennessee River. The soil is classified as a fine-loamy, siliceous, thermic Typic Hapludult. There were no significant differences among the treatments for yield or disease control for the experiment. This was the first year the biological amendments were applied. The results are consistent with previous studies in field experiment at the Fletcher location in 2003. This experiment was established in the fall of 2002, and also didn’t demonstrate any effects of biofumigation during the first year. It supports the view that the establishment of a healthy soil microenvironment requires repeated treatments. A significant difference was observed among some treatments in the field experiment at the Fletcher location (Mountain Horticultural Crops Reseach Station, Fletcher, NC) during 2004 (the second year of the experiment). Total tomato yield in the experiment was significantly higher for the treatment with mustard meal (8 lb/plot) and compost (240 lb/plot) application if compared with the other treatments (Fig. 1).
Moreover, the increase of the yield for this treatment was provided by an increase of fruit in the jumbo, extra large and large tomato sizes. Treatments revealed the same pattern for these groups as for total yield. Medium size and small tomatoes did not correlate with the total yield and did not show significant difference among the treatments in the experiment.

Contact project investigator for hard copy of figures or tables referenced below.

Fig. 1. Mean total tomato yield in the field experiment at Fletcher (Treatments are indicated as: 1 – Control; 2 -Telone-C 35 gal/acre; 3 – Compost 240 lb/plot; 4 – Mustard Meal 8 lb/plot; 5 – Mustard Meal 16 lb/plot; 6 – Mustard Meal 8 lb/plot + Compost 240 lb/plot)

2) The effect of biofumigation on Early, Late and Southern Blight development was studied in two field experiments with tomato plants at Knoxville and Fletcher locations. The infection of each plot was counted weekly after the first manifestations of the diseases. The infection of tomato plants with Early Blight was recorded as both the percentage of affected leaf area and by using a modified Horsfall-Barratt scale of 0 to 12. The infection of tomato plants with Southern Blight was estimated as the number of diseased plants at each plot. Only about 3.6% (10 plants) of plants in the experiments developed symptoms of Southern Blight at Knoxville location. No effect of treatments was found. However, the development of Early Blight in the experiment was quick and severe this year because of favorable weather conditions. 1-2% of the leaf area was affected at 15 June, with damage quickly increasing to 70-95% (at the last tomato picking on 29 July). No effect of treatments on the Early Blight development was found in the experiment. At the Fletcher location, counts of the Early Blight were significantly lower for the treatment with mustard meal (8 lb/plot) and compost (240 lb/plot) application when compared with other treatments except Telone-C (Fig. 2). Counts of the Late Blight were not statistically different among treatments.

Fig 2. Early blight disease rating (0= No lesions present; 12 = 100% of leaves have at least one lesion) in the experiment at Fletcher on 09/30/04. Treatments are the same as in Fig.1.

3) The effect of biofumigation using Brassica cover crop, mustard seed meal (different doses) and compost (alone and in combination with mustard meal) on bacterial and fungal characteristics of the soil was studied in two field experiments with tomato plants, in two field experiments with strawberry plants and at commercial sites at two locations. The bacterial activity of the soil was estimated as population densities of heterotrophic bacteria measured by CFU (Colony FormingUnits) per 1 g of dry soil (*10E-6). The fungal activity of the soil was estimated as population densities of fungi measured by CFU (Colony FormingUnits) per 1 g of dry soil (*10E-4). There were no statistically significant differences in the bacterial and fungal soil characteristics among treatments for the first year of application of the mustard meal and compost in the field experiment at Knoxville location. Statistically significant differences were found only in the field experiment at Fletcher during the second year of the experiment. Statistically significant effects on the bacterial counts in post treatment soil samples were found for the application of mustard meal (8 lb/plot) in combination with compost (240 lb/plot). This treatment resulted in an increase in the bacterial counts when compared with the control and the Telon-C application. A comparison of the effect of treatments in the experiments at Fletcher on tomato yield, soil bacterial counts and Early Blight development shows correlation among these parameters as shown in Fig. 3. Soil treatment with a combination of mustard meal (8 lb/plot) and compost (240 lb/plot) before planting tomato significantly increased the bacterial population (BA value) in the soil when compared with the control and the Telone – C application (Fig. 3,a). This treatment also provided the lowest Early Blight counts (Fig. 3,b) and, therefore, the highest total tomato yield in the experiment (Fig. 3,c).

(a) (c) (b)

Fig 3. The comparison of the effect of Telone-C application and the combination of mustard meal and compost application on Bacterial Assay value (BA), Early Blight rating (EB) and total tomato yield, lb/plot (W) in the experiment at Fletcher.

4) In order to validate the effect of the combination of mustard meal and compost on plant yield and disease control, the experiments were also established at two commercial sites (Hank and Cindy Delvin’s organic farm and David Tannin’s organic farm). Hank Delvin’s farm experiment includes two one quarter acre treatments (1 – Mustard (fall planting) +mustard meal + compost; 2 – Clover (fall planting) + compost ) and two replicates. David Tannin’s organic farm experiment includes five plots in an organic greenhouse (1- Mustard Meal, 4000 lb/acre; 2- Mustard Meal, 4000 lb/acre; 3- Control; 4- Mustard Meal, 4000 lb/acre; 5-Control). It was found that, although differences in tomato yield were not statistically significant in the experiment at Hank Delvin’s farm, tomato yield for the plots treated with mustard meal (treatment 1) was 36% higher for replicate 1 and higher 20% for replicate 2. Mean increase in yield was 28%. In the first year of application there was no difference in yield or disease at the Tannin farm.

5) The information presented on the webpage includes a description of the project, schemes and descriptions of the field experiments carried out in the project, a description of the commercial sites for testing the obtained results, pictures of the experimental plots at different stages of the experiments and reports on the main results obtained in the experiments. The page is in progress and will be frequently modified during 2005.

Accomplishments/Milestones

1) The main experimental results obtained in the project were presented to scientific community and producers at the following meetings:

Carl Sams. Natural Soil Pest Control; Biofumigation. Presented at the Tennessee Fruit and Vegetable Association Convention, Dec. 12-14, 2004. Nashville, TN.

Carl Sams. Biofumigation and Composting to Control Soilbourne Pest. Organic Production of fruits and Vegetables Shortcourse. Feb. 24, 2005. The University of Tennessee, Knoxville, Tn.

Carl Sams. Disease Control with Biofumigation and Compost. Tennessee Organic Growers Association State Conference. April 16, 2005. Tennessee State University, Nashville, TN.

2) A demonstration of the experiment “Control of soil-borne pests of tomato with enhanced biofumigation and composting systems” (Fletcher, NC) was made at the Tomato Field Day (08/05/04) at the Mountain Horticultural Crops Research & Extension Center. The results of the experiment were presented by Doug Sanders.

3) A webpage “Enhanced Biofumigation & Composting” was established to inform farmers, growers, agents and scientific community on the objectives of the project, established experiments and main findings. The webpage will promote enhanced biofumigation to producers and will be upgraded throughout the 2005 and 2006. The web address is http://web.utk.edu/~tkarpine/EnhBiofum.htm.

4) Demonstration experiments were established and first year results were obtained at Delvin’s Organic farm and Tannin’s organic farm (growers involved are David Tannin and Hank and Cindy Delvin).

5) A biofumigation experiment was also conducted on an organic producers farm near Wilmington, NC. The results from this demonstrations showed enhanced root development on crops in the biofumigation and compost treatment but no-statistical effect was seen in the first year of the experiment.

Impacts and Contributions/Outcomes

1)The previous finding on the requirement of repeated applications of mustard meal and compost for the establishment of a healthy soil microenvironment was confirmed during the second year of the field experiments at the Fletcher location (Mountain Horticultural Crops Research Station, Fletcher, NC). Mustard meal and compost application in this experiment increased tomato yield and improved its quality.

2)A significant suppressive effect of mustard meal (8 lb/plot) and compost (240 lb/plot) application on Early Blight development was found in the field experiments with the tomato plants during the second year of application. Since this is not a soilbourne pathogen the effect may be due to treatment effects on general plant health (reduction of stress from soilbourne pest). It was demonstrated that the biofumigation and compost treatment resulted in an increase in soil bacterial activity.

Collaborators: