Fertilizer Type Found to Affect Growth & Antioxidants in Tomatoes,
but not Yield

Tomatoes are known to be an important source of antioxidants such as lycopene, phenolics, and vitamin C (ascorbic acid).
Previous studies had shown that different fertilizers release nutrients differently, leading to varying carbon/nitrogen ratios in plants, which in turn effects the production of secondary metabolites. Additionally, taste, colour, vulnerability to pests, and nutrient qualities of tomatoes can be affected by their antioxidant content. 

Tomatoes are known to be an important source of antioxidantsThe researchers studied greenhouse grown tomatoes treated with five different fertilizers: three inorganic (varying mineral nutrient solutions) and two organic (chicken manure and grass clover mulch). 

Looking at the carpometric characteristics of their crop, they found that the plant shoot biomass was significantly higher in the inorganic treatments. However, "there was no significant difference in the yield...of ripe tomatoes from different treatments." 

In terms of antioxidant components, they found that "the use of chicken manure and grass-clover mulch has ... been found to improve the levels of total phenolics and ascorbic acid in tomatoes."

This study concludes that organic fertilizer sources can increase antioxidant levels in tomatoes, while producing yields comparable to conventional production systems and fertilizers. 

Source: "Influence of different types of fertilisers on the major antioxidant components of tomatoes"
Authors: R. K. Toor, Geoffrey P. Savage, Anuschka Heeb
Journal: Journal of Food Composition and Analysis, Volume 19, pp 20-27, 2006. 

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Benefits of Composted Manure Vs Raw Manure

Applications of manure can be of great benefit to the soil.  However, there are problems that can occur when applying raw manure to soil or a growing crop.

A common problem with raw manures is weed seeds and unhealthy pathogens like e-colli and salmonella.  The benefit of using composted manure is that when compost is regularly turned and monitored, it reaches temperatures high enough to destroy weed seeds and any nasty pathogens.

Due to their volatility and often high levels of ammonia, raw manures can even burn plants and kill soil organisms.  With composted manure soil life is actually enhanced, as compost is biologically active, containing a diverse population of micro organisms.  These beneficial organisms are generally known to help suppress disease, assist in strong root production and reduce the need for fungicides. 

One of the great benefits of composting manures is that the final humus-rich compost product is a lot more stable than the original manure. This means that the soluble nutrients, in particular nitrogen and phosphorus are less likely to be leached out by rain and irrigation.  Composting manures will also reduce potential odour and fly problems that can be associated with applying raw manures.

If composted manures are pelletised, they can be excellent sources of nutrients, especially nitrogen.  They are significantly more concentrated so only small quantities are required.  Composted manures are a faster acting soil conditioner, while pelletised manures tend to break down and release nutrients over a number of weeks or months. 

All Katek products are manufactured from fully composted poultry manure.

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Organic Strawberries come up tops!

Some very interesting research came out last month highlighting the many benefits of organic strawberries.   A study from the US compared organically grown with conventionally grown strawberries, with organic strawberries being found to be tastier, more nutritious, have better colour and a longer shelf life.

As well as the fruit being superior, the soil the organic strawberries were grown in showed greater diversity and had more total carbon and nitrogen, greater microbial biomass and activity and higher concentrations of micronutrients.  Interestingly, the organic soils had more than 30% higher levels of nitrogen without the use of synthetic nitrogen fertilisers which are used in conventional farming.  Levels of iron, boron, sodium and zinc were also higher in the organic soils.  

In the study, twenty six farms were tested, with the fruit undergoing chemical analysis, tests for anti-oxidant levels, nutritional value, weight, firmness and shelf life.  Organic strawberries had significantly higher antioxidant activity and scored higher on colour, taste and general appearance than their conventionally grown counterparts.

Read more about this study at www.ploson.org/article/info:doi/10.1371/journal.pone.0012346 
Source: Reganold et al (2010), Fruit and Soil Quality of Organic and Conventional Strawberry Agroecosystems