Tomato plant growth in soil amended with Folgers™ caffeinated and decaffeinated coffee ground composts

Andrea Peabody

Final Draft

May 7, 2008

Bio 402


Table of Contents:

  • Abstract ......
  • Introduction and Background information ......
  • Ciuberkis (2006). Long term manuring ......
  • Baker and Bryson (2006). Effects of nutrient rich and nutrient poor compost on tomato plant growth.
  • Shu and Chung (2006). High rate applications of different compost on rice growth.
  • Meunchang (2006). Filter cake and bagasse compost.
  • Ebid et al. (2007). Compared tea leaf compost, coffee waste compost, and kitchen garbage compost.
  • Hypothesis. Effects of caffeinated and decaffeinated coffee ground compost on tomato plant growth.
  • Methods ......
  • Statistical analysis ......
  • Results ......
  • Discussion ......
  • Acknowledgements ......
  • Literature Cited ......

Abstract

Organic composting is used as a soil amendment to increase plant growth. I studied the effects of Folgers™ caffeinated and decaffeinated coffee grounds compost on tomato plant growth during a 19-day growing period. I started by mixing three coffee ground with compost 1:1 with soil: decaffeinated coffee grounds, caffeinated coffee grounds, and decaffeinated coffee grounds with added caffeine. My control contained only the soil and compost, no coffee grounds. The control plants were the first to emerge on the seventh day after being planted. The control group had statistically the largest mean plant length, mean stem width and mean number of leaves at the end of the growing period (p ≤ 0.001). The caffeinated coffee group, decaffeinated coffee group, and the decaffeinated coffee group with added caffeine had no difference between the mean length, mean stem width, and the mean number of leaves. At the end of the 19-day growing period all grown plants in each group were harvested and there average color and gross masses were recorded. Again the control had the greenest mean color value and had the largest grossed leaf mass and dried mass. At the end of the experiment the control plants highest growth in all categories compared to the coffee groups. For the caffeinated coffee group, the decaffeinated coffee group, and decaffeinated coffee with added caffeine group, there was no difference among groups.

Introduction

Composting is an organic method of recycling nutrients that has been used as a soil amendment to increase plant growth for many years. Compost can help condition and replenish nutrients to the soil. Composts provide an increase in soil pH, organic carbon, potassium and phosphorus (Shu and Chung, 2006). They can also enrich soil by promoting microbial growth. Not only is composting good for your plants, but it is also good for the environment. According to the Environmental Protection Agency, (epa.gov, 2007) compost can help clean up soils contaminated by volatile organic compounds such as heating fuels, polyaromatic hydrocarbons and explosives. It can also be used to prevent pollutants such as heavy metals in storm water, from migrating to surface water resources or from being absorbed by plants. Compost can reduce plant diseases and pests, reducing the need for pesticides and chemical fertilizers that can be harmful to the environment. Compost provides a low cost marketable product that reduces the need to produce artificial soil amendments, and can clean contaminated soil.

Mature composts are a mixture of organic materials, which contains humus (U.S.EPA, 2007). Humus is a dark brown soil-like material that increases soil nutrients and helps moisture retention. Compost can be made from many different types or combinations of organic materials. Compost can include materials such as animal manures, clean paper, coffee grounds, eggshells, leaves, tea bags, fruits, vegetables, and grass clippings. If the material being used is manure it is called manuring; this is still considered to be a type of composting. These materials can then be converted to mulch by shredding or chopping. Composting can take anywhere from 14 days to 1 year to complete (Dept. of Environmental Protection Pennsylvania, 2007). The compost can then be mixed into the soil, increasing soil nutrients and plant growth. In one study, sugar mill by-product compost was observed to increase tomato plant growth by 50% (Menunchanget al., 2006). Coffee grounds are common ingredients in organic composting (U.S.EPA, 2007). Ebid et al. (2007) observed that coffee waste compost is a good source of nutrients for the soil and that it promotes an increase in plant growth.

In my study, I compared the effects of Folgers™ caffeinated and decaffeinated coffee grounds composts on the growth of tomato plants. The Folgers™ decaffeinated coffee grounds go through a direct method for stripping the caffeine from the green coffee beans (McGraw-Hill, 2007). Green coffee beans are harvested, cultivated, and ready for commercial processing (McGraw-Hill, 2007). The decaffeination process involves the direct contact of water-moistened beans with the solvent ethyl acetate. The moisturized beans make possible the transport of caffeine through the cell walls (McGraw-Hill, 2007). This process removes 97% of the caffeine from the green bean, but also leaves behind trace amounts of the solvent ethyl acetate (McGraw-Hill, 2007). Ethyl acetate is an organic compound derived from fruits and vegetables. However, because ethyl acetate is a common solvent it is synthetically derived and is relatively non-toxic to humans,It’s effects on plants are unknown. The beans are then further processed in the same way as caffeinated beans (McGraw-Hill, 2007). I hypothesized that because of the solvent, ethyl acetateleft behind after thecaffeine stripping; caffeinated coffee grounds would increase tomato plant growth.

Ciuberkis et al. (2006) studied the long term effects of manure addition on topsoil weed seed and weed flora in acid and limed soils. They used manure to partially neutralize aluminum, which is toxic to plants, and decreases the soil’s acidity. The long-term studies have been going on since 1949 on an acid sandy loam soil. The Ciuberkis et al. (2006) study was carried out from 1996-2002, and weed flora were analyzed from the end of May through June 10 of each year. The researchersused two experimental sites close together; one site had acid soil and the other had limed soil amended with pulverized limestone. Each site had increasing additions of manureof 20, 40, 80, and 120th-1, with one treatment without manure, the control. They predicted that long-term manuring would change the agrochemical properties of the soil, thus influencing soil and crop weeds in acid soils more than in limed soils. Ciuberkis et al. (2006) observed and recorded the weed flora and took soil samples to determine weed seed in topsoil. They concluded that over the long term (1996-2002), increasing manuring rates influenced plant growth by decreasing pH, decreasing aluminum, and increasing humus in both acid and limed soils. They also reported that manuring decreased the number of weed seeds in acid and limed soil. In the acid soils, manuring decreased German knotgrass (Scleranthus annuus) and corn spurry (Spergula arvensis) seeds. Inlimed soil, manuring decreased Spergula arvensis seeds. Ciuberkis et al. (2006) observed that increasing the rate of manuring in acidic soils decreased weed flora in all crops compared to crops without manure, thus promoting better crop yields. This is relevant to my topic because the Ciuberkis et al. (2006) study showed that manuring can improve soil nutrients by decreasing the pH, decreasing aluminum, and increasing humus, which influences plant growth. My study used coffee ground compost, so I predicted an improved soil quality and an increase in humus thus, increased tomato plant growth.

Baker and Bryson (2006) compared the effects of nutrient rich compost to nutrient poor compost on the growth of young tomato plants in containers. For the nutrient rich compost, called the Massachusetts compost, they used a mixture of hen manure, sawdust, and hay. For the nutrient poor compost, called the Maine compost, they used a mixture of cow and hen manure and aspen bark. The compost was further mixed with soil or peat at 0, 25, 50, 75, and 100% by volume. A fertilizer solution was added to half the pots 3 times a week; the other half was left unfertilized. The fertilizer solution was composted yard wastes. The tomatoes were grown in containers for 30 days in a greenhouse. After 30 days, Baker and Bryson (2006) weighed the plants and took leaf samples. They then compared the plants’ weights and concluded that the Massachusetts compost was higher in macronutrients. They concluded that the plants grown in the Massachusetts compost were larger, with an average shoot mass of 82g/plant. The plants given the Maine compost, only had a shoot mass of 45g/plant. They also concluded that the addition of fertilizer increased plant growth only when used with 100% compost. Overall, Baker and Bryson (2006) concluded that the manure composts could be used to promote tomato plant growth in containers. This study demonstrates that organic composts can have a considerable effect on tomato growth. This study was conducted in a relatively short amount of time using plastic pots to grow the plants. I too will be comparing effects of organic compost on the growth of tomato plants in plastic pots over a short amount of time. I tested caffeinated, decaffeinated and decaffeinated with added caffeine, coffee ground compost on tomato plant growth over 19-days.

Shu and Chung (2006) studied the effects of the high rate application of different composts on rice growth and nutrient increases at different growth stages of the plant. In this study, they used four different compost mixtures: 1) pea-rice hull (PRC); 2) cattle dung-tea compost (CTC); 3) hog dung-rice hull compost (HDR); and 4) hot dung and sawdust compost (HDS). They used air-dried soil in pots, using 6 different soil treatments including each compost-treated plot, one treated with a chemical fertilizer, and the other with no fertilizer (the control). They mixed with soil 4 different compost mixtures; three g of soil each was mixed with 404g PRC, 395g CTC, 378g HDR, and 450g HDS. They conducted their first crop-growing season in 1997 from March to July and their second crop-growing season in 1997 from August to December. After each season, they dried the whole plants and weighed them to determine the amount of dry matter. The first crops’ dry matter yields were significantly different (p ≤ 0.05). The first crop dry matter yield of the CTC and HDS treatments were greater than the crop given only the chemical fertilizer treatment. The control showed almost no dry matter. Shu and Chung (2006) reported no difference in the dry matter using the PRC, HDR, and CNT composts. For the second crop, the control had the least amount of dry matter compared to the other treatments. The PRC, CTC, and HDR showed a greater dry matter yield than the chemical fertilizer treatment. The nitrogen accumulation was reported to be lowest in the control and greatest in the CTC and HDS treatments. Shu and Chung (2006) concluded that the effects of compost on the dry matter yield and the nutrient accumulation depend on the chemical composition of the compost mixture. They also concluded that crops given the PRC, CTC, and HDR compost treatments showed higher dry matter production than the other treatments in both the first and second crops. They reported that the plant growth and nutrient accumulation was higher in plants given the PRC compost. The nutrient accumulation of the plants given the CTC, HDS, and PCR treatments showed an increase in the dry matter yields. This study related to my topic, because it provided results that organic composts can enhance plant growth and dry matter production by nutrient accumulation. I analyzed the dry matter production of tomato plants given a coffee ground compost mixture.

A recent study by Meunchang et al. (2006) revealed that waste products such as filter cake and bagasse can be composted and used to provide nitrogen, phosphorus, and calcium to the soil. Filter cake and bagasse are waste products from sugar mills. Sugar mill waste products make good compost because of their neutral pH, low phyto-toxicity, and nutrient content. Meunchang et al. (2006) experimentally compared the effects of inoculated and uninoculated sugar mill by-products compost on the growth of tomato plants with and without nitrogen fertilizer. The inoculated soil contained N2-fixing bacteria, and the uninoculated soil did not contain N2-fixing bacteria. The sampling units were 45 clay pots, each filled with 10 kg of soil. The compost was a mixture of filter cake and bagasse 2:1 by weight. They separated the compost into two parts, one inoculated with the N2-fixing bacteria Azosporillum, Azotobacter vinelandii, and Bijerinckia derxii, and the other was uninoculated. After inoculation, the composting process continued for 50 days. The compost was used at rates of 15g and 45g dry weight per pot. The control received no compost, only nitrogen fertilizer. Next, they grew the tomato seedlings in unfertilized 1:1 volume mixtures of compost and sterilized washed fine sand for 20 days. Then, after 55 days, the tomato plant shoots, green fruit, and roots were washed, dried and weighed. Meunchang et al. (2006) study showed that with respects to shoot weights there was a significant difference between plants given compost compared to plants not given any compost (p ≤0.05). Meunchang et al. (2006) observed an increase in shoot weight with the addition of the nitrogen fertilizer and the compost. They also observed that the plants given a high rate of uninoculated compost without N-fertilizer, produced 33% more shoot weight, compared to the plants given high rates of N-fertilizer without compost. Also, the plants given high rates of inoculated compost without N-fertilizer produced 50% more shoot weight, compared to the plants given high rates of N-fertilizer without compost. The root dry weight depended on the type of compost, but was not significantly influenced by the nitrogen fertilizer. The study did show that with respect to root weights, there was a significant difference between plants not given compost compared to plants given compost (p ≤ 0.05). The plants given compost did statistically better with respects to shoot and root weights, compared to plants not given compost. Overall, Meunchang et al. (2006) observed that the highest rate of uninoculated compost, without the N-fertilizer, doubled the shoot growth of the tomato plant. Also, the inoculated compost increased the tomato plants’ growth and nitrogen content more efficiently than the uninoculated compost. Meunchang’s et al. (2006) study related to mine, because I compared the effects of organic composts on the growth of the tomato plant in pots. Their study showed that plants given compost compared to plants not given compost did statistically better with respects to shoot and root weights. Instead of using sugar mill by-product compost, I used coffee ground mixture composts. From Meunchang’s et al. (2006) study, I predicted an increase in plant weightsusing organic coffee composts.

Ebid et al. (2007), compared tea leaf compost, coffee waste compost, and kitchen garbage compost. They compared the differences in these by-product composts and their effects on nitrogen release, nitrogen mineralization and inorganic nutrients released into the soil under controlled conditions. Nitrogen mineralization is when the nitrogen in organic matter decomposes into plant accessible forms. The tea leaf and coffee waste composts were by-products of beverage industries, but the authors did not describe what exactly they were; and the kitchen garbage compost was made form Nagai Rainbow Plan Compost Center (Ebid et al. 2007). The composts were incubated under aerobic conditions for nitrogen mineralization for 7, 14, 21, 42, and 63 days. They concluded that the nitrate (NO3) concentrations were high in all the compost mixtures; but were greatly increased in the kitchen garbage compost after 7 days of incubation. Ebid et al. (2007) observed that the pH of the composted by-products was important in providing proper nutrients to the plant. They reported that the pH of the tea leaf compost was higher than the pH of coffee waste and the kitchen garbage composts. Ebid et al. (2007) observed the release of ammonium from the tea leaf and coffee waste composts after 21 days of incubation. The kitchen garbage compost showed the highest peak in mineralized nitrogen followed by the tea leaf compost, then the coffee waste compost, and then the soil control. The coffee compost had the highest carbon/nitrogen ratio and the lowest mineralization degree. Ebid et al. (2007) concluded that the release of nutrients varied among the compost. The tea leaf, coffee waste, and garbage composts were all observed to be successful sources of nitrogen, phosphorus, potassium, calcium, and magnesium. Ebid et al. (2007) concluded that coffee waste compost could be a good source of nutrients for the soil and that it promotes an increase in plant growth. This helped develop my hypothesisthat coffee waste composts improved soil quality and increased the growth of tomato plants. Ebid et al. (2007) did not define or describe their coffee waste compost, but sincecoffee grounds are a type of coffee waste, I expected similar results.

Composting is used to improve soil nutrient quality, and increase plant growth. In my experiment, I analyzed the effects of adding Folgers™ caffeinated and decaffeinated coffee ground compost to soil of tomato plants. I hypothesized that the coffee ground compost will increase tomato plant germination rates, growth rates, and total dry weight, compared to plants with no added coffee grounds compost. I compared caffeinated and decaffeinated coffee ground compost and the effects they had on tomato plant growth. Decaffeinated coffee grounds go through a direct method caffeine stripping process, which changed the chemical properties of the coffee grounds. I predicted there is a difference in these composts due to the caffeine stripping process of decaffeinated coffee grounds. I hypothesized that the caffeinated coffee ground compost will result in a greater increase in plant growth than the decaffeinated coffee ground compost due to the direct method caffeine stripping. I also believed that the caffeine plays an important role in the effectiveness of the decomposition process. I predicted that the caffeine would increase the decomposition process and increase the rate of mineral release to the soil. Also the caffeine stripping process leaves behind trace amounts of the solvent ethyl acetate, which can be harmful to plants. I also tested a group of tomato plants using decaffeinated coffee ground compost, with added caffeine to the coffee. This way I could examine whether caffeine plays an important role in the effectiveness of the compost.