|Authors: ||N. Vázquez, A. Pardo, M.L. Suso|
|Keywords: ||nitrate leaching, apparent N mineralization, crop residues|
To study the effects of both plastic mulch and N fertilization in yield of cauliflower crop, as well as efficiency in the use of nitrogen, a field experiment was carried out during the 2007-2008 crop season in a loamy soil.
Two different managements of soil - black polyethylene mulch and bare soil - and different doses of nitrogen were studied.
The amounts of fertigated N were 0, 120, 186 and 252 kg N•ha-1. Marketable yields ranged between 20 and 36 t•ha-1. The average weight of the curds varied between 1.1 and 1.7 kg•unit-1. Nitrogen percentage in the leaves and curds were 3.5 and 3.7%. The amount of nitrogen that was removed along with the harvested portion of the crop extended between 25.4 and 27.4% of the N present in the aboveground biomass, thus leaving more than 70% in crop residues.
Drainage at 90 cm depth ranging between 86 and 109 L•m-2, was associated with rainfall events.
Leached nitrate was low, varying between 5 and 27 kg-N•ha-1. Calculated values of the apparent N mineralization were high, between 119 and 248 kg N•ha-1. The use of plastic mulch compared to bare soil did not improve the yield of cauliflowers.
Excess of N fertilizer in mulched plots increased the aboveground crop residues.
The amount of nitrogen in crop residues increased in line with application rates of nitrogen in plots with plastic mulch; that nitrogen may be used either by the following crops or lost by leaching.
N mineralization was an important factor as a source of nitrogen that must be taken into account in the fertilization programs.
More research is necessary to predict the N mineralization rate.
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