Mineraliskt kväve i marken
Soil mineral N (min-N) analyses from Swedish agricultural soils were compiled from 1990 to 2006. All the data originate from field experiments with different N-levels throughout the country. All values refer to the 0-60 cm layer and in-clude both NH4-N and NO3-N. Altogether 316 spring sampled analyses on mineral soils, were compiled. The average was 40 kg ha-1 of which 12 kg was NH4-N. On spring sampled sites on bare soils the average was 47 kg whereas on sites with a winter crop growing min-N was 34 kg ha-1. Looking on spring sampled sites with bare soils and spring cereals cropped the preceding year min-N was 46 kg compared with 54 when winter cereals were cropped. After root crops like sugar beets min-N was 29 kg ha-1 on average. On sites with growing winter cereals min-N was similar regardless of preceding crops. Correlations between N-rates with best net return and min-N showed that adjust-ments of N-rates for for spring cereals with ± 0,7 kg ha-1 for each kg deviation in min-N from average values could be recommended. For winter cereals ±0,5 is recommended.
Kvävegödsling; Optimal N-giva
Rapport / Sveriges lantbruksuniversitet, Institutionen för markvetenskap, Avd. för växtnäringslära
Publisher: Inst. för markvetenskap, Sveriges lantbruksuniversitet
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