Exploring the use of bokashi as a soil fertility amendment in Northeast vegetable production systems

Exploring the use of bokashi as a soil fertility amendment in Northeast vegetable production systems

Summary

Cycling nutrients from farm and food wastes will become an ever more important part of a sustainable future agriculture. Composts and vermicomposts are among the commonly used soil fertility amendments that aim towards closing the nutrient loop; but might farmers have another option? Bokashi is a fermented organic material with Japanese origins traditionally used as a soil fertility amendment by subsistence farming communities.  Bokashi holds the promise of faster turnover of wastes on a smaller foot print with less labor than conventional composting, and has been shown to have positive effects on plant growth and soil quality.  The purpose of this study is to explore the viability of bokashi as a tool that may supplement or replace commonly used organic amendments in soil fertility regimes of vegetable production systems. This study is currently being conducted at the University of Vermont through greenhouse and hoop house trials while growing spinach.  Bokashi is being compared against thermophilic compost and vermicompost, assessing its effects on soil nutrient profiles, available nitrogen, soil enzyme activity and microbial community, spinach root health, and crop yields.  The study is still in progress, however preliminary results from the hoop house trial indicate no differences in total carbon and total nitrogen concentrations in soils amended with bokashi compared to the control.  This initial sampling occurred just three weeks after treatments were applied in the late fall when soil temperatures were falling, so this was likely not sufficient time for drastic changes in soil properties to occur.  More complete results are expected in spring.  

Objectives/Performance Targets

Objective 1: Compare the nutrient profiles, functional characteristics of the microbial community and the enzyme activity of bokashi with those of high quality, commercially produced thermophilic and vermicompost.

• • Analyzed bokashi for total carbon and total nitrogen, pH, urease activity

Objective 2: Evaluate the effect of bokashi on soil quality factors, soil enzymatic activity and nutrient composition post application.

• • Analyzed soil from greenhouse study for total carbon and nitrogen (First sampling)

Objective 3: Determine the effect of bokashi amendments on the growth of tomatoes and spinach.

• • CHANGE in objective details: switched to spinach crop for both greenhouse and hoophouse trials.  This switch is reasoned by the fact that this project is aimed towards conducting research in a way that mirrors what a farmer would do on his or her own farm. Very few farmers grow tomatoes throughout the winter in a greenhouse, however spinach is a common winter crop.  Also, winter tomato production may not be sustainable; lighting and temperature conducive to tomato growth in the winter require a lot of energy.  Using spinach for both experiments is also more consistent, for experimental design and data analysis purposes.   

Objective 4: Supply extension agents and farmers with results from baseline bokashi study to catalyze further research and experimentation.

• • I presented this project to the UVM Beginning Farmers course this fall. 

Accomplishments/Milestones

There have been deviations to my original timeline. I provide a summarized update here:

Perhaps the most important thing that I have accomplished since the start of the grant was making the bokashi from scratch.  This took longer than I expected, though it was necessary for me to take my time to get the fermentation process right.  I made two batches of bokashi, one for the hoophouse trial and another for the greenhouse trial.  I applied the first batch to the greenhouse.  This was another important step, as it made me realize some of the possible inefficiencies that exist with using bokashi (I dug trenches by hand and buried it with a shovel).  This helped me think about some other possible equipment to use in a farm situation.  After burying the bokashi in the hoophouse, the trenches had to sit for two weeks to “cure” and for the pH to stabilize.  Then I planted the spinach.  The planting date got pushed back later than I would have liked; as I said, the bokashi preparation took time, and my studies and teaching assistant responsibilities caught up with me quickly.  But my little spinach plants are coming along nicely and I’ve collected my first soil sampling.  I have been getting trained on various laboratory equipment, and analyzed my first sampling for total carbon and nitrogen.  So far we are not observing any differences between the bokashi and the other treatments.

The timeline for the greenhouse experiment has deviated from the original timeline.  This is set to commence in January.  Since the crop of choice was switched from tomatoes to spinach, a much shorter season crop, I have no doubts that results may still be obtained and delivered in a timely fashion. During the month of September I coordinated with the greenhouse staff at UVM and set up a small trial to determine the best light and temperature conditions for my experiment in January.  

Impacts and Contributions/Outcomes

This project is very much still in the fetal stages. Perhaps the most fruitful information gained thus far, was the observation and insight gained while making the bokashi from scratch. As I mentioned, this was  a lengthier process than I originally thought. However, producing the amendment on my own, from collecting the food waste to making the bran, creating the different layers, observing all the sights and smells, and then applying it in a realistic setting will help me when communicating my research to others.  This especially applies to the application process.  Since I buried the bokashi by hand and dug my own trenches, I am already trying to think of different types of equipment a farmer may use if they were to consider trying bokashi themselves.  This process has also compelled me to add on a simple technical feasability analysis, factoring in variables such as time and yield data (when we have it).  I will be working with the UVM Agricultural Economics extension professor, Bob Parsons, to help me with this.  In summary, though extensive data has yet to be collected, the work I’ve done thus far has enriched my understanding of the bokashi production process, and thus has allowed me to anticipate farmer concern, critiques, and questions.

Collaborators: