Tag Archives: nitrate

xxx N. Montemurro, G. Cucci, M. A. Mastro, G. Lacolla and A. Lonigro
The nitrogen role in vegetables irrigated with treated municipal wastewater
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The nitrogen role in vegetables irrigated with treated municipal wastewater

N. Montemurro, G. Cucci*, M. A. Mastro, G. Lacolla and A. Lonigro

Department of Agricultural and Environmental Sciences – University of Bari – Via Amendola 165/A, IT70126 Bari, Italy
*Correspondence: giovanna.cucci@uniba.it

Abstract:

The reuse of treated municipal wastewater for irrigation is an established alternative to conventional water, in many countries of the world, particularly where or when water resources are extremely limited. Wastewater reuse could represent a double benefit when used in agriculture, helping overcome any lack of water resources and additionally, enriching the soil with nutrients – especially nitrogen and phosphorus.
In the experimental site of Castellana Grotte (Apulia region, Southern Italy) during the 2012/13 and 2013/14 growing seasons, vegetable crops (fennel and lettuce) in succession were drip-irrigated with three different water sources. Two reclaimed water streams, obtained by applying different treatment schemes to the same municipal wastewater (an effluent from the full-scale treatment plant and an effluent from the Integrated Fixed-film Activated Sludge – Membrane BioReactor pilot plant) and a conventional source, to verify the crops response and nutrient contribution through wastewater supply.
Both lettuce and fennel yields were enhanced by the high content of nutrients in the effluent of one of the treatment plants, which had been operated for partial nitrogen removal. For Fennel 2013/14, wastewater-reuse led to a 54% reduction of nitrogen supply in relation to the other plots normally fertilized. In this way, an estimated saving of about 98.00 € ha-1 was achieved.
Crops irrigated with treated wastewater operated for partial nitrogen removal (IMBR) showed early ripening (8 days for lettuce and 35 days for fennel 2013/14) and better quality than others not similarly-treated. However, the wastewater presented a nitrate content in excess of legal limits (35 mg L-1, D.M. 185/2003). Therefore, the contribution of nutrients increased production (47 vs 32 t ha-1 in IMBR and WELL 2012/13 fennel theses, 53 vs 31 t ha-1 in IMBR and WELL 2013 lettuce theses and 40 vs 31 t ha-1 in IMBR and WELL 2013/14 fennel theses respectively) and improved product quality, while simultaneously saving money for chemical fertilizers not supplied, producing less environmental impact.

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39–48 M. Järvan and P. Põldma
Content of plant nutrients in vegetables depending on various lime materials used for neutralising bog peat
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Content of plant nutrients in vegetables depending on various lime materials used for neutralising bog peat

M. Järvan¹ and P. Põldma²

¹Department of Field Crops, Estonian Research Institute of Agriculture, Teaduse 13, 75501 Saku, Estonia; e-mail: malle.jarvan@mail.ee
²Department of Horticulture, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: ppoldma@eau.ee

Abstract:

The trials were performed in the years 1998–2000 in Saku (59°18’N, 24º39’E) in greenhouse conditions. The aim was to establish how lime materials used for the neutralisation of bog peat acidity (oil shale ash, clinker dust, limestone meal, dolomite meal and their mixtures), which changed significantly the contents of available Ca, K and Mg in the peat substrata, affect the mineral composition of vegetable leaves (lettuce, cucumber, tomato, paprika) and the mutual relationships between elements (K, Ca, Mg, P). In the case of all vegetables, a strong Ca and Mg antagonism occurred. The Mg content of plants was very sensitive to the Ca:Mg ratio in the lime material used for peat neutralisation. In the case of limestone meal, the tomato plants contained Mg 0.18–0.24% and cucumber plants 0.36–0.40%; in the case of dolomite meal, 0.66–0.71% and 0.78–0.90, respectively. The Ca and K contents of vegetables were somewhat less affected by the difference of lime materials than the Mg content. Abundant Mg in lime material increased P content in plants, a synergism between Mg and P occurred.
Lettuce grown on substrata neutralised with mixtures of limestone and dolomite meal contained less nitrates than that grown on substrata with clinker dust and oil shale ash. Too high K content in the substrate neutralised with clinker dust had a negative effect on the carotene content of lettuce.

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