Slāpekļa mēslojums un kultūraugu ražas Saldus pētījumu poligonā
2017
Karklins, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Agriculture | Lipenite, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Agriculture | Ruza, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Agriculture
In intensive farming only part of nitrogen applied as fertilisers is utilised for yield formation. Nitrogen surplus in soil after crop harvesting may cause environmental problems, therefore optimization of N fertiliser use is of high importance. Fertiliser application rate and timing are the main factors influencing the amount of nitrogen surplus in soil. The field experiment with winter and spring wheat was performed in 2015–2015 growing season with five rates of fertiliser applications – from 0 to 240 kg haE-1 N. The grain yield was strongly determined by N application rate. For winter wheat from 3.17 t haE-1 , without N fertilisation up to 7.83 t haE-1 in the plot where 240 kg haE-1 N was applied for winter wheat. For spring wheat 2.77 t haE-1 and 6.07 t haE-1 respectively. The increase of fertiliser rate also increased the amount of soil mineral nitrogen (N–NO3 + N–NH4), especially directly after fertiliser use. The main amount of Nmin. was located in the soil layer 0–30 cm depth, but when high fertiliser rates were applied, also in 30–60 cm depth. The ratio between N–NO3 and N–NH4 in soil was different regarding fertiliser rate. Both forms were almost equal in the treatment without N fertilisation, but with increasing fertiliser nitrogen increase of nitrates in soil was observed. The lowest amount of N–NO3 in soil was during growing season, but its content was growing after harvesting of crops – in all treatments, also without N fertilisation. Soil Nmin. resources in spring in the plot without N application in 0–30 cm and 0–60 cm depth were not able to form positive N balance, because N take-up was higher compared with N resources, whereas application of 120 and 240 kg haE-1 N made surplus nitrogen accumulation after crop harvest.
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