Thursday, 31 October 2019 11:26

News from the field: Portuguese Study Site Spring legume Open Day

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The Portugal Study Site held an Open Day this April to show local farmers the progress of their SICS trials on green manures.

Green Manures

One SICS includes growing green manure to look at the effect on soil quality and was particularly well received by the farmers and technicians. The Open Day was perfectly timed for the full flowering of the legumes, which caused a very enthusiastic reaction from the participants. It was suggested that besides monitoring the change in soil quality, calculating the nutrient release of the legumes would be a good idea. This in turn would help calculate only the necessary amount of mineral fertilization needed for application. The hopes would be to cut both cost and reliance on chemicals.

 OPenDay Discussions

Following the Open Day, the nutrient release was determined for 5 species of legumes: Pea, Yellow Lupin, Red Clover, Balansa Clover and Arrowleaf Clover. In addition to improving SOC and weed control, the green manures supply an average of 35%, 25% and 100% of the NPK extraction of the grain maize. A paper publishing these results was recently released (September 2019) in a national agricultural technical-scientific Journal.


Urban waste applications

Stakeholders assessing green manuresThe second SICS, a soil amendment consisting of urban sludge, is used by some farmers in the region. Despite its use, this practice is very controversial, and stakeholders felt it needed to be thoroughly tested before there is a wider uptake. Concerns include the waste containing too many heavy metals leading to disease for crops and potentially consumers. The study sites involved 2 trial fields, one field fertilized every spring for 3 years with urban sludge and a control field fertilized exclusively with a conventional mineral amendment. Soil sampling results point to a significant increase of many indicators of soil quality for the trial field with the urban sewage sludge amendment, confirming the effectiveness of the technique. In terms of heavy metals, the concentration in soil is slightly higher for sludge experiment than for the control, however, it is still below the maximum concentration authorized by law. The release of these results is very important due to the polemic surrounding urban sludge fertilization. So far, the results are encouraging and point towards this being a viable waste resource to be reused as fertiliser for food growth. A poster about the trial and results has been presented to academics at the European Geosciences Union (EGU) conference and is further planned for publication in a national paper in order to reach a larger public audience.OPenDay Discussions2

For more information about this  Study Site, please contact Anne Karine This email address is being protected from spambots. You need JavaScript enabled to view it.




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