ISHS Acta Horticulturae 563: International Conference on Environmental Problems Associated with Nitrogen Fertilisation of Field Grown Vegetable Crops
NITROGEN DYNAMICS IN INTENSIVE VEGETABLE CROP ROTATION INFLUENCED BY ORGANIC FERTILISATION |
| Authors: | R. Mihelic, M. Jakse |
| Keywords: | Farm yard manure (FYM), compost, soil mineral nitrogen (SMN), N mineralisation, N immobilisation, N losses, Brassica oleracea L. var. capitata, Spinacea oleracea, Lactuca sativa L., Foeniculum vulgare L. var. dulce Mill., Allium cepa L. |
| Abstract:
The effect of organic fertilisation on soil N dynamics was observed in two consecutive years of intensive vegetable crop rotations (early cabbage, spinach, lettuce, fennel, onion). Field trials with five treatments (0 = non-fertilised control; COMP = composted chicken manure, shredded wood and bark; FYM = well matured farmyard manure; NPK1 = mineral fertilisation with split application of N; NPK2 = mineral fertilisation with all N applied at planting) were established in Ljubljana, Slovenia. The total quantity of applied N was the same for all treatments. The experimental field soil was an ameliorated alluvial brown clay loam with a pseudogley horizon 60 cm below surface. Soil samples were taken frequently and analysed for soil mineral N (SMN). There was a similar breakdown pattern of organic matter in soil and FYM (R2=89%). Where FYM had been applied, SMN was consistantly higher than that of the control. The apparent N recovery from FYM was 19%. In contrast, COMP showed slight N immobilisation for 12 months after the first application. Later, following net (re) mineralisation with COMP, there was an apparent N recovery of 5%. Crop yields closely followed N uptake (R2=95%). After two years, NPK1, NPK2 and FYM treatments resulted in higher yields compared to COMP. The most erratic curve of N-dynamics was obtained with NPK2, with excesses of N after applications. Although NPK1 generally met the N demand more closely, N side-dressings and poor plant growth during autumn caused great losses of N during winter. N mineralisation was the most intense during summer, supplying enough N (150 - 400 kg SMN/ha; 0-60 cm) in the root zone for autumn crops, without additional N. These results indicate that N fertilisation for autumn crops should be planned very carefully in order to avoid N leaching during winter. | |
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