Some gardeners swear by it. Others are not so sure. Research has yet to provide conclusive results. Heba A K Ibrahim from the Desert Research Center in Egypt argues that compost tea is a crop’s best friend.
Compost tea is deﬁned as ﬁltered product of compost (Litterick et al. 2004) steeped in any solvent, usually water, for more than an hour (NOSB 2004).
The two basic methods for production of this compost are anaerobic, or aerobic. There’s research to support both approaches. The aerobic method ‘brews’ beneficial bacteria with added oxygen, introduced by something like an aquarium pump. This creates an environment that favours bacteria that require oxygen (aerated compost tea, ACT). Anaerobic takes the opposite view- you put the lid on, and keep the air out.
View to a brew
It can be made with or without additives, some of which may stimulate microbial biomass during the brewing time (Lanthier 2007 and Naidu et al. 2010).
Due to the aqueous nature of compost tea, microbial biomass, soluble nutrient components and fine particulate organic matter can be applied to soils and plant surfaces in ways not possible with solid compost (Hargreaves et al. 2009).
Compost tea is an agricultural tool, when produced with microbiological quality, and integrated into managed biological farming systems. It can be used as a carrier to deliver plant nutrients and manage plant diseases (Scheuerell 2004)
Rich in soluble mineral nutrients, compost tea delivers beneficial organic compounds and contains a high population of microorganisms. It can be used to fertilize crops, helps a plant’s leaves to absorb nutrients and assists a plant’s root system to extract nutrients from the soil.
Another benefit of compost tea is that it can also inoculate crop residue, which facilitates decomposition, resulting in improved nutrient cycling in soil by increasing microorganism activity.
It can help manage certain plant pathogens through microbial competition and build soil structure when applied as a drench (Shrestha et al., 2011a, b and Pane et al. 2012).
Way to grow?
- Composted mulch has been documented to suppress disease through a variety of methods
- Non-aerated compost teas may be useful in suppressing some pathogens on some plants
- Aerated compost teas have no scientifically documented effect as pathogen suppressors
- Overuse and runoff of compost teas could conceivably contribute to water pollution
- There is no “silver bullet” for plant health problems caused by poor soil health and improper plant selection and management
Ha K V, Marschner P and Bünemann E K (2008). Dynamics of C, N, P and microbial community composition in particulate soil organic matter during residue decomposition. Plant and Soil. 303: 253–264
Hargreaves J C, Adl M S and Warman P R (2009). Are compost teas an effective nutrient amendment in the cultivation of strawberries? Soil and plant tissue effects. J. Sci. Food Agric., 89: 390-397
Lanthier M (2007). Compost tea and its impact on plant diseases. BC Org. Grower. 10: 7-11
Litterick AM, Harrier L, Wallace P, Watson CA, Wood M (2004) The role of uncomposted materials, composts, manures, and compost extracts in reducing pest and disease incidence and severity in sustainable temperate agricultural and horticultural crop production—a review. Crit Rev Plant Sci 23(6):453–479.
Naidu Y, Meon S, Kadir J and Siddiqui Y (2010). Microbial starter for the enhancement of biological activity of compost tea. Int. J. Agric. Biol., 12: 51–5 NOSB (2004) Compost tea task force report. National Organic Standards Board, Washington, D.
Pane C, Celano G, Villecco D and Zaccardelli M (2012). Control of Botrytis cinerea, Alternaria alternata and Pyrenochaeta lycopersici on tomato with whey compost- tea applications. Crop Protection. 38: 80- 86.
Scheuerell, S.J. (2003). Understanding how compost tea can control disease. Biocycle, 44 (2): 20-25
Scheuerell S J (2004). Compost tea production practices, microbial properties, and plant disease suppression. 1st International Conf. on Soil and Compost Eco-Biology, Spain, pp. 41-51.
Scheuerell S J and Mahaffee W F (2004). Compost tea as a container medium drench for suppressing seedling damping-off caused by Pythium ultimum. Phytopathology, 94:1156-1163
Shrestha K, Adetutu E M, Shrestha P, Walsh K B, Harrower K M, Ball A S and Midmore D J (2011a). Comparison of microbially enhanced compost extracts produced from composted cattle rumen content material and from commercially available inocula. Bioresource Technol., 102: 7994–8002.
Shrestha K; Shrestha P; Walsh K B, Harrower KM and Midmore D J (2011 b). Microbial enhancement of compost extracts based on cattle rumen content compost–characterisation of a system. Bioresource Technol., 102: 8027–8034.
Siddiqui Y, Meon S, Ismail R, Rahmani M, Ali A (2008). Bio-efﬁciency of compost extracts on the wet rot incidence, morphological and physiological growth of okra Abelmoschus esculentus [(L.) Moench]). Sci Hortic 117(1):9–14.
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