Fertilisation of irrigated maize with pig slurry combined with mineral nitrogen

摘要

Maize (Zea mays L.) is a very important crop in many of the irrigated areas of the Ebro Valley (NE Spain). Intensive pig (Sus scrofa domesticus) production is also an important economic activity in these areas, and the use of pig slurry (PS) as a fertiliser for maize is a common practise. From 2002 to 2005, we conducted a field trial with maize in which we compared the application of 0, 30 and 60mpd hap# of PS combined with 0, 100 and 200kghap# of mineral N at sidedress. Yield, biomass and other related yield parameters differed from year to year and all of them were greatly influenced by soil NO -N content before planting and by N (organic and/or mineral) fertilisation. All years average grain yield and biomass at maturity ranged from 9.3 and 18.9Mghap# (0 PS, 0 mineral N) to 14.4 and 29.6Mghap# (60mpd hap# of PS, 200kghap#of mineral N), respectively. Grain and total N biomass uptake average of the studied period ranged from 101 and 155kghap# (0 PS, 0 mineral N) to 180 and 308kghap# (60mpd hap# of PS, 200kghap#of mineral N), respectively. All years average soil NO -N content before planting and after harvest were very high, and ranged from 138 and 75kghap# (0 PS, 0 mineral N) to 367 and 457kghap# (60mpd hap# of PS, 200kghap#of mineral N), respectively. The optimal N (organic and/or mineral) rate varied depending on the year and was influenced by the soil NO -N content before planting. For this reason, soil NO -N content before planting should be taken into account in order to improve N fertilisation recommendations. Moreover, the annual optimal N rates also gave the lowest soil NO -N contents after harvest and the lowest N losses, as a consequence they also could be considered as the most environmentally friendly N rates.